Bio


Dr. Anson Lee specializes in the surgical treatment of all heart diseases, including ischemic heart disease, structural heart disease, aortic disease, and arrhythmias. He has practiced cardiothoracic surgery at Stanford since 2015. Dr. Lee has a special interest in the surgical treatment of abnormal heart rhythms and minimally invasive techniques to treat heart disease.

Clinical Focus


  • Arrhythmia Surgery
  • Atrial Fibrillation
  • Arrhythmias, Cardiac
  • Maze procedure
  • Hybrid ablation
  • Aortic Aneurysm
  • Aortic Valve
  • Mitral Valve
  • Coronary Artery Bypass
  • minimally invasive surgery
  • Mitral Valve Repair
  • Valve Replacement Surgery
  • Heart Failure
  • Heart Transplantation
  • Lung Transplantation
  • Reoperative Cardiac Surgery
  • Transcatheter Aortic Valve Replacement
  • Thoracic and Cardiac Surgery

Academic Appointments


Professional Education


  • Board Certification: American Board of Thoracic Surgery, Thoracic and Cardiac Surgery (2016)
  • Residency: Washington University General Surgery Residency (2013) MO
  • Medical Education: Washington University School Of Medicine Registrar (2005) MO
  • Fellowship: Washington University School of Medicine Cardiothoracic Training (2015) MO

2023-24 Courses


All Publications


  • A Modified 4Ts Score for Heparin-Induced Thrombocytopenia in the Mechanical Circulatory Support Population. Journal of cardiothoracic and vascular anesthesia Pong, T., Cyr, K., Aparicio-Valenzuela, J., Carlton, C., Lee, A. M. 2023

    Abstract

    OBJECTIVE: To identify risk factors and develop a pretest scoring system to differentiate patients with heparin-induced thrombocytopenia (HIT) in the mechanical circulatory support (MCS) population. The authors present a modified "4TMCS" scoring system, which considers the "type of mechanical circulatory support" that may help identify patients at risk for developing postoperative HIT.DESIGN: A retrospective cohort study. Patients who underwent cardiac surgery were categorized into 3 groups: (1) normal platelet count, (2) thrombocytopenia with a negative HIT test, and (3) thrombocytopenia with a positive HIT test. A comparison of diagnostic accuracy between the 4Ts and 4TMCS probability scores was performed.SETTING: At a single adult tertiary-care center.PARTICIPANTS: A total of 5,314 patients who underwent cardiac surgery between May 1, 2008 and December 31, 2016.INTERVENTIONS: None.MEASUREMENTS AND MAIN RESULTS: In total, 125 out of 5,314 patients (2.4%) were diagnosed with HIT, of whom 75 out of 5,314 (1.4%) had clinical evidence of thrombosis. Overall, in-hospital mortality was 25.6%, 11.7%, and 1.5% in the HIT(+), HIT(-), and control groups, respectively (p < 0.001). Mechanical circulatory support was associated with a significantly increased risk for HIT, with an incidence of 5.9% in patients receiving MCS versus 1.9% in those without (p < 0.001). Area under the receiver operator curve (AUC) analysis demonstrated improved diagnostic accuracy of the 4TMCS score compared with the 4Ts (AUC=0.83 v 0.77, p < 0.044). The 4TMCS score had higher sensitivity than the 4Ts, using the guideline-recommended score cutoff of ≥4 (95.2% v 85.7%).CONCLUSION: Heparin-induced thrombocytopenia is associated with worse outcomes and increased morbidity and mortality in the MCS population. Awareness of patient risk factors and the application of a modified 4TMCS probability score may allow for more accurate screening and treatment of HIT in the MCS population.

    View details for DOI 10.1053/j.jvca.2023.06.033

    View details for PubMedID 37407329

  • Atrial Fibrillation Occurring During Acute Hospitalization: A Scientific Statement From the American Heart Association CIRCULATION Chyou, J. Y., Barkoudah, E. W., Dukes, J. B., Goldstein, L. A., Joglar, J. M., Lee, A. A., Lubitz, S. A., Marill, K. B., Sneed, K. M., Streur, M. C., Wong, G. C., Gopinathannair, R. 2023; 147 (15): E676-E698

    Abstract

    Acute atrial fibrillation is defined as atrial fibrillation detected in the setting of acute care or acute illness; atrial fibrillation may be detected or managed for the first time during acute hospitalization for another condition. Atrial fibrillation after cardiothoracic surgery is a distinct type of acute atrial fibrillation. Acute atrial fibrillation is associated with high risk of long-term atrial fibrillation recurrence, warranting clinical attention during acute hospitalization and over long-term follow-up. A framework of substrates and triggers can be useful for evaluating and managing acute atrial fibrillation. Acute management requires a multipronged approach with interdisciplinary care collaboration, tailoring treatments to the patient's underlying substrate and acute condition. Key components of acute management include identification and treatment of triggers, selection and implementation of rate/rhythm control, and management of anticoagulation. Acute rate or rhythm control strategy should be individualized with consideration of the patient's capacity to tolerate rapid rates or atrioventricular dyssynchrony, and the patient's ability to tolerate the risk of the therapeutic strategy. Given the high risks of atrial fibrillation recurrence in patients with acute atrial fibrillation, clinical follow-up and heart rhythm monitoring are warranted. Long-term management is guided by patient substrate, with implications for intensity of heart rhythm monitoring, anticoagulation, and considerations for rhythm management strategies. Overall management of acute atrial fibrillation addresses substrates and triggers. The 3As of acute management are acute triggers, atrial fibrillation rate/rhythm management, and anticoagulation. The 2As and 2Ms of long-term management include monitoring of heart rhythm and modification of lifestyle and risk factors, in addition to considerations for atrial fibrillation rate/rhythm management and anticoagulation. Several gaps in knowledge related to acute atrial fibrillation exist and warrant future research.

    View details for DOI 10.1161/CIR.0000000000001133

    View details for Web of Science ID 000964824400001

    View details for PubMedID 36912134

  • Atrial Fibrillation Ablation Outcome Prediction with a Machine Learning Fusion Framework Incorporating Cardiac Computed Tomography. Journal of cardiovascular electrophysiology Razeghi, O., Kapoor, R., Alhusseini, M. I., Fazal, M., Tang, S., Roney, C. H., Rogers, A. J., Lee, A., Wang, P. J., Clopton, P., Rubin, D. L., Narayan, S. M., Niederer, S., Baykaner, T. 2023

    Abstract

    BACKGROUND: Structural changes in the left atrium (LA) modestly predict outcomes in patients undergoing catheter ablation for atrial fibrillation (AF). Machine learning (ML) is a promising approach to personalize AF management strategies and improve predictive risk models after catheter ablation by integrating atrial geometry from cardiac computed tomography (CT) scans and patient-specific clinical data. We hypothesized that ML approaches based on a patient's specific data can identify responders to AF ablation.METHODS: Consecutive patients undergoing AF ablation, who had preprocedural CT scans, demographics, and 1-year follow-up data, were included in the study for a retrospective analysis. The inputs of models were CT-derived morphological features from left atrial segmentation (including the shape, volume of the LA, LA appendage, and pulmonary vein ostia) along with deep features learned directly from raw CT images, and clinical data. These were merged intelligently in a framework to learn their individual importance and produce the optimal classification.RESULTS: 321 patients (64.2 + 10.6 years, 69% male, 40% paroxysmal AF) were analyzed. Post 10-fold nested cross-validation, the model trained to intelligently merge and learn appropriate weights for clinical, morphological, and imaging data (AUC 0.821) outperformed those trained solely on clinical data (AUC 0.626), morphological (AUC 0.659) or imaging data (AUC 0.764).CONCLUSION: Our machine learning approach provides an end-to-end automated technique to predict AF ablation outcomes using deep learning from CT images, derived structural properties of LA, augmented by incorporation of clinical data in a merged ML framework. This can help develop personalized strategies for patient selection in invasive management of AF. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/jce.15890

    View details for PubMedID 36934383

  • Phrenic Relocation by Endoscopy, Intentional Pneumothorax Using Carbon Dioxide, and Single Lung Ventilation (PHRENICS) Technique. JACC. Clinical electrophysiology Shah, R. L., Perino, A., Wang, P., Lee, A., Badhwar, N. 2023; 9 (5): 692-696

    Abstract

    Strategies to prevent right phrenic nerve (PN) injury during catheter ablation can be difficult to employ, ineffective, and risky. A novel PN-sparing technique involving single lung ventilation followed by "intentional pneumothorax" was prospectively evaluated in patients with multidrug refractory periphrenic atrial tachycardia (AT). This hybrid technique, termed PHRENICS (Phrenic Relocation by Endoscopy & Intentional Pneumothorax using Carbon Dioxide & Single Lung Ventilation), resulted in effective PN relocation away from the target site in all cases, allowing successful catheter ablation of AT without procedural complication or arrhythmia recurrence. The PHRENICS hybrid ablation technique can effectively mobilize the PN, avoiding unnecessary invasion of the pericardium, and can expand the safety of catheter ablation for periphrenic AT.

    View details for DOI 10.1016/j.jacep.2023.01.015

    View details for PubMedID 37225311

  • High-resolution spatiotemporal changes in dominant frequency and structural organization during persistent atrial fibrillation. PloS one Pong, T., Aparicio-Valenzuela, J., Obafemi, O., Cyr, K., Carlton, C., Taylor, C., Lee, A. 2023; 18 (2): e0271846

    Abstract

    OBJECTIVE: Analyze changes in frequency activity and structural organization that occur over time with persistent atrial fibrillation (AF).BACKGROUND: Little is known about the frequency characteristics of the epicardium during transition from paroxysmal to persistent AF. Accurate identification of areas of high dominant frequency (DF) is often hampered by limited spatial resolution. Improvements in electrode arrays provide high spatiotemporal resolution, allowing for characterization of the changes that occur during this transition.METHODS: AF was induced in adult Yorkshire swine by atrial tachypacing. DF mapping was performed using personalized mapping arrays. Histological analysis and late gadolinium enhanced magnetic resonance imaging were performed to determine structural differences in fibrosis.RESULTS: The left atrial epicardium was associated with a significant increase in DF in persistent AF (6.5 ± 0.2 vs. 7.4 ± 0.5 Hz, P = 0.03). The organization index (OI) significantly decreased during persistent AF in both the left atria (0.3 ± 0.03 vs. 0.2 ± 0.03, P = 0.01) and right atria (0.33 ± 0.04 vs. 0.23 ± 0.02, P = 0.02). MRI analysis demonstrated increased ECV values in persistent AF (0.19 vs 0.34, paroxysmal vs persistent, P = 0.05). Tissue sections from the atria showed increase in fibrosis in pigs with persistent AF compared to paroxysmal AF. Staining demonstrated decreased myocardial fiber alignment and loss of anisotropy in persistent AF tissue.CONCLUSIONS: Changes in tissue organization and fibrosis are observed in the porcine model of persistent AF. Alterations in frequency activity and organization index can be captured with high resolution using flexible electrode arrays.

    View details for DOI 10.1371/journal.pone.0271846

    View details for PubMedID 36787287

  • Mapping Atrial Fibrillation After Surgical Therapy to Guide Endocardial Ablation. Circulation. Arrhythmia and electrophysiology Bhatia, N. K., Shah, R. L., Deb, B., Pong, T., Kapoor, R., Rogers, A., Badhwar, N., Brodt, C., Wang, P. J., Narayan, S. M., Lee, A. M. 2022: 101161CIRCEP121010502

    Abstract

    Surgical ablation for atrial fibrillation (AF) can be effective, yet has mixed results. It is important to improve the success of AF surgery, yet unclear which endocardial lesions will best augment surgical lesion sets in individual patients. We addressed this question by systematically mapping AF endocardially after surgical ablation and relating findings to early recurrence.We studied 81 consecutive patients undergoing epicardial surgical ablation (stage 1 hybrid), of whom 64 proceeded to endocardial catheter mapping and ablation (stage 2). Stage 2 comprised high-density mapping of pulmonary vein (PV) or posterior wall (PW) reconnections, low-voltage zones (LVZs), and potential localized AF drivers. We related findings to postsurgical recurrence of AF.Mapping at stage 2 revealed PW isolation reconnection in 59.4%, PV isolation reconnection in 28.1%, and LVZ in 42.2% of patients. Postsurgical recurrence of AF occurred in 36 patients (56.3%), particularly those with long-standing persistent AF (P=0.017), but had no relationship to reconnection of PVs (P=0.53) or PW isolation (P=0.75) when compared with those without postsurgical recurrence of AF. LVZs were more common in patients with postsurgical recurrence of AF (P=0.002), long-standing persistent AF (P=0.002), advanced age (P=0.03), and elevated CHA2DS2-VASc (P=0.046). AF mapping revealed 4.4±2.7 localized focal/rotational sites near and also remote from PV or PW reconnection. After ablation at patient-specific targets, arrhythmia freedom at 1 year was 81.0% including and 73.0% excluding previously ineffective antiarrhythmic medications.After surgical ablation, AF may recur by several modes including recovery of PW or PV isolation, mechanisms related to localized LVZ, or other sustaining mechanisms. LVZs are more common in patients at high clinical risk for recurrence. Patient-specific targeting of these mechanisms yields excellent long-term outcomes from hybrid ablation.

    View details for DOI 10.1161/CIRCEP.121.010502

    View details for PubMedID 35622437

  • Hybrid Ablation for Atrial Fibrillation: Safety & Efficacy of Unilateral Epicardial Access. Seminars in thoracic and cardiovascular surgery Pong, T., Shah, R. L., Carlton, C., Truong, A., Fann, B., Cyr, K., Aparicio-Valenzuela, J., Brodt, C., Wang, P. J., Lee, A. M. 2022

    Abstract

    Hybrid ablation combines thoracoscopic epicardial ablation with percutaneous catheter based endocardial ablation for the treatment of AF. The purpose of this study was to evaluate the safety and efficacy of hybrid ablation surgery for the treatment of atrial fibrillation (AF), and to compare outcomes of unilateral versus bilateral thoracoscopic epicardial ablation. Patients with documented AF who underwent hybrid ablation were followed post-operatively for major events. Major events were classified into two categories consisting of 1) safety, comprising all-cause mortality and major morbidities, and 2) efficacy, which included recurrence of atrial arrhythmia, cessation of antiarrhythmic drugs (AAD), and completeness of lesion set. A total of 84 consecutive patients were consented for hybrid ablation. Patients presented with an average AF duration of 85.9 months before hybrid ablation. 80 patients underwent successful thoracoscopic epicardial ablation. At one-year, 87% (60/69) of patients were free from AF and 73% (50/69) were free from AF and off AAD. 63 patients completed both epicardial and endocardial hybrid ablation with posterior wall isolation achieved in 89% (56/63) of patients. Unilateral epicardial ablation was associated with significantly shorter hospital length of stay compared to bilateral surgical approached (3.9 vs. 6.7 days, p = 0.002) with no difference in freedom from AF between groups at 1 year. Hybrid ablation for atrial fibrillation is effective for patients at high risk for recurrence after catheter ablation. The unilateral surgical approach may be associated with shorter hospital stay with no appreciable effect on procedure success rates. This study evaluates the safety and efficacy of unilateral epicardial access for hybrid ablation in patients with symptomatic atrial fibrillation refractory to antiarrhythmic treatment. Hybrid ablation for atrial fibrillation is effective for patients at high risk for recurrence after catheter ablation. The unilateral surgical approach may be associated with shorter hospital stay with no appreciable effect on procedure success rates.

    View details for DOI 10.1053/j.semtcvs.2022.03.003

    View details for PubMedID 35278664

  • Characteristics of Integrated Thoracic Surgery Residency Matriculants: A Survey of Program Directors. The Annals of thoracic surgery Obafemi, O. O., Mullis, D. M., Rogers, A. B., Lee, A. M. 2022

    Abstract

    BACKGROUND: The six-year Integrated Thoracic Surgery (I-6) residency programs have evolved over the past decade. Despite the rising number of programs, there is minimal data published about the criteria utilized by program directors to select candidates. We analyze the characteristics and qualities of successful matriculants using the American Association of Medical College's (AAMC) data reports and survey responses from program directors.METHODS: Using a survey administered via the RedCap service, program directors were asked to rate the importance of a variety of factors in their evaluations of candidates. AAMC data reports from 2018-2020 provided information on the mean matriculant research productivity, United States Medical Licensing Examination (USMLE) Step 1 scores, and Step 2 Clinical Knowledge (CK) scores.RESULTS: Responses were received from 19 of 33 (58%) I-6 programs. Program directors consistently rated interview performance as a very important factor in their evaluation of applicants. Matching into the specialty is becoming more competitive, with mean USMLE Step 1, Step 2 CK, and research productivity increasing over the past few years; matriculants had mean Step 1 and Step 2 CK scores of 247.3 and 254.2, respectively, in the 2020 match.CONCLUSIONS: Thoracic surgery program directors place high value on applicant Interview Performance, Letters of Recommendation, and Professionalism. Program directors agree that a forthcoming pass/fail USMLE Step 1 score report will lead to closer scrutiny of other factors during the decision-making process and may cause future evaluation of applicants to be heavily reliant on letters of recommendation and medical school pedigree.

    View details for DOI 10.1016/j.athoracsur.2022.01.030

    View details for PubMedID 35157846

  • Post-Transplant Extracorporeal Membrane Oxygenation for Severe Primary Graft Dysfunction to Support the Use of Marginal Donor Hearts. Transplant international : official journal of the European Society for Organ Transplantation Shudo, Y., Alassar, A., Wang, H., Lingala, B., He, H., Zhu, Y., Hiesinger, W., MacArthur, J. W., Boyd, J. H., Lee, A. M., Currie, M., Woo, Y. J. 2022; 35: 10176

    Abstract

    Severe primary graft dysfunction (PGD) is the leading cause of early postoperative mortality following orthotopic heart transplantation (OHT). Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has been used as salvage therapy. This study aimed to evaluate the outcomes in adult OHT recipients who underwent VA-ECMO for severe PGD. We retrospectively reviewed 899 adult (≥18years) patients who underwent primary OHT at our institution between 1997 and 2017. Recipients treated with VA-ECMO (19, 2.1%) exhibited a higher incidence of previous cardiac surgery (p = .0220), chronic obstructive pulmonary disease (p = .0352), and treatment with a calcium channel blocker (p = .0018) and amiodarone (p = .0148). Cardiopulmonary bypass (p = .0410) and aortic cross-clamp times (p = .0477) were longer in the VA-ECMO cohort and they were more likely to have received postoperative transfusion (p = .0013); intra-aortic balloon pump (IABP, p < .0001), and reoperation for bleeding or tamponade (p < .0001). The 30-day, 1-year, and overall survival after transplantation of non-ECMO patients were 95.9, 88.8, and 67.4%, respectively, compared to 73.7, 57.9, and 47.4%, respectively in the ECMO cohort. Fourteen (73.7%) of the ECMO patients were weaned after a median of 7days following OHT (range: 1-12days). Following OHT, VA-ECMO may be a useful salvage therapy for severe PGD and can potentially support the usage of marginal donor hearts.

    View details for DOI 10.3389/ti.2022.10176

    View details for PubMedID 35340846

  • Electrophysiologic Conservation of Epicardial Conduction Dynamics After Myocardial Infarction and Natural Heart Regeneration in Newborn Piglets. Frontiers in cardiovascular medicine Wang, H., Pong, T., Obafemi, O. O., Lucian, H. J., Aparicio-Valenzuela, J., Tran, N. A., Mullis, D. M., Elde, S., Tada, Y., Baker, S. W., Wang, C. Y., Cyr, K. J., Paulsen, M. J., Zhu, Y., Lee, A. M., Woo, Y. J. 2022; 9: 829546

    Abstract

    Newborn mammals, including piglets, exhibit natural heart regeneration after myocardial infarction (MI) on postnatal day 1 (P1), but this ability is lost by postnatal day 7 (P7). The electrophysiologic properties of this naturally regenerated myocardium have not been examined. We hypothesized that epicardial conduction is preserved after P1 MI in piglets. Yorkshire-Landrace piglets underwent left anterior descending coronary artery ligation at age P1 (n = 6) or P7 (n = 7), After 7 weeks, cardiac magnetic resonance imaging was performed with late gadolinium enhancement for analysis of fibrosis. Epicardial conduction mapping was performed using custom 3D-printed high-resolution mapping arrays. Age- and weight-matched healthy pigs served as controls (n = 6). At the study endpoint, left ventricular (LV) ejection fraction was similar for controls and P1 pigs (46.4 ± 3.0% vs. 40.3 ± 4.9%, p = 0.132), but significantly depressed for P7 pigs (30.2 ± 6.6%, p < 0.001 vs. control). The percentage of LV myocardial volume consisting of fibrotic scar was 1.0 ± 0.4% in controls, 9.9 ± 4.4% in P1 pigs (p = 0.002 vs. control), and 17.3 ± 4.6% in P7 pigs (p < 0.001 vs. control, p = 0.007 vs. P1). Isochrone activation maps and apex activation time were similar between controls and P1 pigs (9.4 ± 1.6 vs. 7.8 ± 0.9 ms, p = 0.649), but significantly prolonged in P7 pigs (21.3 ± 5.1 ms, p < 0.001 vs. control, p < 0.001 vs. P1). Conduction velocity was similar between controls and P1 pigs (1.0 ± 0.2 vs. 1.1 ± 0.4 mm/ms, p = 0.852), but slower in P7 pigs (0.7 ± 0.2 mm/ms, p = 0.129 vs. control, p = 0.052 vs. P1). Overall, our data suggest that epicardial conduction dynamics are conserved in the setting of natural heart regeneration in piglets after P1 MI.

    View details for DOI 10.3389/fcvm.2022.829546

    View details for PubMedID 35355973

  • Graft Type and Routing for Repair of Aortoesophageal Fistula ANNALS OF THORACIC SURGERY Zhu, Y., Lee, A. M. 2021; 112 (3): 1033-1034
  • Sinus node sparing novel hybrid approach for treatment of inappropriate sinus tachycardia/postural sinus tachycardia: multicenter experience. Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing de Asmundis, C., Chierchia, G., Lakkireddy, D., Romeya, A., Okum, E., Gandhi, G., Sieira, J., Vloka, M., Jones, S. D., Shah, H., Winner, M., Patel, D., Whalen, S. P., Beaty, E. H., Kincaid, E. H., Lee, A., Brodt, C., Taylor, B. J., Colombowala, I., Romano, M., Morady, F., Stroker, E., Overeinder, I., Bala, G., Van Meeteren, J., Krauthammer, Y., Koerber, S., Shults, C., Thomaides, A., Badhwar, N., Gopinathannair, R., Shah, A., Tummala, R., Bello, D., Hoff, S., Almorad, A., Frazier, K., Brugada, P., La Meir, M. 2021

    Abstract

    BACKGROUND: The ideal treatment of inappropriate sinus tachycardia (IST) and postural orthostatic tachycardia syndrome (POTS) still needs to be defined. Medical treatments yield suboptimal results. Endocardial catheter ablation of the sinus node (SN) may risk phrenic nerve damage and open-heart surgery may be accompanied by unjustified invasive risks.METHODS: We describe our first multicenter experience of 255 consecutive patients (235 females, 25.94±3.84years) having undergone a novel SN sparing hybrid thoracoscopic ablation for drug-resistant IST (n=204, 80%) or POTS (n=51, 20%). As previously described, the SN was identified with 3D mapping. Surgery was performed through three 5-mm ports from the right side. A minimally invasive approach with a bipolar radiofrequency clamp was used to ablate targeted areas while sparing the SN region. The targeted areas included isolation of the superior and the inferior caval veins, and a crista terminalis line was made. All lines were interconnected.RESULTS: Normal sinus rhythm (SR) was restored in all patients at the end of the procedure. All patients discontinued medication during the follow-up. After a blanking period of 6months, all patients presented stable SR. At a mean of 4.07±1.8years, normal SN reduction and chronotropic response to exercise were present. In the 51 patients initially diagnosed with POTS, no syncope occurred. During follow-up, pericarditis was the most common complication (121 patients: 47%), with complete resolution in all cases. Pneumothorax was observed in 5 patients (1.9%), only 3 (1.1%) required surgical drainage. Five patients (1.9%) required a dual-chamber pacemaker due to sinus arrest>5s.CONCLUSIONS: Preliminary results of this multicenter experience with a novel SN sparing hybrid ablation of IST/POTS, using surgical thoracoscopic video-assisted epicardial ablation combined with simultaneous endocardial 3D mapping may prove to be an efficient and safe therapeutic option in patients with symptomatic drug-resistant IST and POTS. Importantly, in our study, all patients had a complete resolution of the symptoms and restored normal SN activity.

    View details for DOI 10.1007/s10840-021-01044-5

    View details for PubMedID 34424446

  • Computational fluid dynamics simulations to predict false lumen enlargement after surgical repair of Type-A aortic dissection. Seminars in thoracic and cardiovascular surgery Shad, R., Kong, S., Fong, R., Quach, N., Kasinpila, P., Bowles, C., Lee, A., Hiesinger, W. 2021

    Abstract

    We aim to use computational fluid dynamics to investigate the hemodynamic conditions that may predispose to false lumen enlargement in this patient population. Nine patients who received surgical repairs of their type-A aortic dissections between 2017-2018 were retrospectively identified. Multiple contrast-enhanced post-operative CT scans were used to construct 3D models of aortic geometries. Computational fluid dynamics simulations of the models were run on a high-performance computing cluster using SimVascular - an open source simulation package. Physiological pulsatile flow conditions (4.9 L/min) were used at the aortic true lumen inlet, and physiological vascular resistances were applied at the distal vascular ends. Exploratory analyses showed no correlation between rate of false lumen growth and blood pressure, immediate post-op aortic diameter, or the number of fenestrations (p = 0.2). 1-year post-operative CT scans showed a median (IQR) false lumen growth rate of 4.31 (3.66, 14.67) mm/year Median (Interquartile range) peak systolic, mid-diastolic, and late diastolic velocity magnitudes were 0.90 (1.40); 0.10 (0.16); and 0.06 (0.06) cm/s respectively. Spearman's ranked correlations between fenestration velocity and 1-year false lumen growth rates were found to be statistically significant: Velocity magnitude at peak systolic (p = 0.025; rho = 0.75), mid diastolic (p = 0.025; rho = 0.75) and late diastolic phases of the cardiac cycle (p = 0.006; rho = 0.85). We have shown that false lumen growth is strongly correlated to fenestration flow velocity, which has potential implications for post-operative surveillance and risk stratification.

    View details for DOI 10.1053/j.semtcvs.2021.05.012

    View details for PubMedID 34091015

  • INTRAOPERATIVE INDUCIBILITY OF ATRIAL FIBRILLATION IMPROVES RISK STRATIFICATION AND REDUCES POST-OPERATIVE ATRIAL FIBRILLATION Pong, T., Cyr, K., Carlton, C., Niesen, J., Aparicio-Valenzuela, J., Fischbein, M., Woo, Y., Boyd, J., Lee, A. ELSEVIER SCIENCE INC. 2021: 1592
  • CTA pulmonary artery enlargement in patients with severe aortic stenosis: Prognostic impact after TAVR. Journal of cardiovascular computed tomography Turner, V. L., Jubran, A., Kim, J. B., Maret, E., Moneghetti, K. J., Haddad, F., Amsallem, M., Codari, M., Hinostroza, V., Mastrodicasa, D., Sailer, A. M., Kobayashi, Y., Nishi, T., Yeung, A. C., Watkins, A. C., Lee, A. M., Miller, D. C., Fischbein, M. P., Fearon, W. F., Willemink, M. J., Fleischmann, D. 2021

    Abstract

    BACKGROUND: Identifying high-risk patients who will not derive substantial survival benefit from TAVR remains challenging. Pulmonary hypertension is a known predictor of poor outcome in patients undergoing TAVR and correlates strongly with pulmonary artery (PA) enlargement on CTA. We sought to evaluate whether PA enlargement, measured on pre-procedural computed tomography angiography (CTA), is associated with 1-year mortality in patients undergoing TAVR.METHODS: We retrospectively included 402 patients undergoing TAVR between July 2012 and March 2016. Clinical parameters, including Society of Thoracic Surgeons (STS) score and right ventricular systolic pressure (RVSP) estimated by transthoracic echocardiography were reviewed. PA dimensions were measured on pre-procedural CTAs. Association between PA enlargement and 1-year mortality was analyzed. Kaplan-Meier and Cox proportional hazards regression analyses were performed.RESULTS: The median follow-up time was 433 (interquartiles 339-797) days. A total of 56/402 (14%) patients died within 1 year after TAVR. Main PA area (area-MPA) was independently associated with 1-year mortality (hazard ratio per standard deviation equal to 2.04 [95%-confidence interval (CI) 1.48-2.76], p​<​0.001). Area under the curve (95%-CI) of the clinical multivariable model including STS-score and RVSP increased slightly from 0.67 (0.59-0.75) to 0.72 (0.72-0.89), p​=​0.346 by adding area-MPA. Although the AUC increased, differences were not significant (p​=​0.346). Kaplan-Meier analysis showed that mortality was significantly higher in patients with a pre-procedural non-indexed area-MPA of ≥7.40​cm2 compared to patients with a smaller area-MPA (mortality 23% vs. 9%; p​<​0.001).CONCLUSIONS: Enlargement of MPA on pre-procedural CTA is independently associated with 1-year mortality after TAVR.

    View details for DOI 10.1016/j.jcct.2021.03.004

    View details for PubMedID 33795188

  • Graft Type and Routing for Repair of Aortoesophageal Fistula. The Annals of thoracic surgery Zhu, Y., Lee, A. M. 2021

    View details for DOI 10.1016/j.athoracsur.2021.01.062

    View details for PubMedID 33631152

  • Complete transmural epicardial ablation reduces organized areas in atrial fibrillation Rogers, A., Ravi, N., Bhatia, N. K., Shah, R. L., Pong, T., Tung, J. S., Purewal, S., Baykaner, T., Rappel, W. J., Brodt, C. R., Wang, P. J., Lee, A., Narayan, S. M. OXFORD UNIV PRESS. 2020: 623
  • Impact of cognitive behavioral therapy on depression symptoms after transcatheter aortic valve replacement: A randomized controlled trial. International journal of cardiology Edwards, K. S., Chow, E. K., Dao, C., Hossepian, D., Johnson, A. G., Desai, M., Shah, S., Lee, A., Yeung, A. C., Fischbein, M., Fearon, W. F. 2020

    Abstract

    BACKGROUND: Depression is a significant concern after cardiac surgery and has not been studied in patients undergoing transcatheter aortic valve replacement (TAVR). We sought to examine the prevalence of pre-procedure depression and anxiety symptoms and explore whether brief bedside cognitive behavioral therapy (CBT) could prevent post-TAVR psychological distress.METHODS: We prospectively recruited consecutive TAVR patients and randomized them to receive brief CBT or treatment as usual (TAU) during their hospitalization. Multi-level regression techniques were used to evaluate changes by treatment arm in depression, anxiety, and quality of life from baseline to 1 month post-TAVR adjusted for sex, race, DM, CHF, MMSE, and STS score.RESULTS: One hundred and forty six participants were randomized. The mean age was 82 years, and 43% were female. Self-reported depression and anxiety scores meeting cutoffs for clinical level distress were 24.6% and 23.2% respectively. Both TAU and CBT groups had comparable improvements in depressive symptoms at 1-month (31% reduction for TAU and 35% reduction for CBT, p = .83). Similarly, both TAU and CBT groups had comparable improvements in anxiety symptoms at 1-month (8% reduction for TAU and 11% reduction for CBT, p = .1). Quality of life scores also improved and were not significantly different between the two groups.CONCLUSIONS: Pre-procedure depression and anxiety may be common among patients undergoing TAVR. However, TAVR patients show spontaneous improvement in depression and anxiety scores at 1-month follow up, regardless of brief CBT. Further research is needed to determine whether more tailored CBT interventions may improve psychological and medical outcomes.

    View details for DOI 10.1016/j.ijcard.2020.08.007

    View details for PubMedID 32800909

  • Relation of Length of Survival After Orthotopic Heart Transplantation to Age of the Donor. The American journal of cardiology Shudo, Y., Guenther, S. P., Lingala, B., He, H., Hiesinger, W., MacArthur, J. W., Currie, M. E., Lee, A. M., Boyd, J. H., Woo, Y. J. 2020

    Abstract

    We aim to evaluate the impact of donor age on the outcomes in orthotropic heart transplantation recipients. The United Network for Organ Sharing database was queried for adult patients (age; ≥60) underwent first-time orthotropic heart transplantation between 1987 and 2019 (n = 18,447). We stratified the cohort by donor age; 1,702 patients (9.2%) received a heart from a donor age of <17 years; 11,307 patients (61.3%) from a donor age of 17 ≥, < 40; 3,525 patients (19.1%) from a donor age of 40 ≥, < 50); and 1,913 patients (10.4%) from a donor age of ≥50. There was a significant difference in the survival likelihood (p < 0.0001) based on donor's age-based categorized cohort, however, the median survival was 10.5 years in the cohort in whom the donor was <17, 10.3 years in whom the donor was 17 ≥, < 40, 9.4 years in whom the donor was 40 ≥, < 50, and 9.0 years in whom the donor was ≥ 50. Additionally, there was no significant difference in the episode of acute rejection (p = 0.19) nor primary graft failure (p = 0.24). In conclusion, this study demonstrated that patients receiving hearts from the donor age of ≥50 years old showed slight inferior survival likelihood, but appeared to be equivalent median survival.

    View details for DOI 10.1016/j.amjcard.2020.06.036

    View details for PubMedID 32736794

  • Screening and Prophylactic Amiodarone Reduces Post-Operative Atrial Fibrillation in At-Risk Patients JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Pong, T., Cyr, K., Niesen, J., Aparicio-Valenzuela, J., Carlton, C., Fischbein, M. P., Woo, Y., Boyd, J. H., Lee, A. M. 2020; 75 (11): 1361–63

    View details for DOI 10.1016/j.jacc.2020.01.016

    View details for Web of Science ID 000520057100016

    View details for PubMedID 32192666

  • Impact of Surgical Approach in Double Lung Transplantation: Median Sternotomy vs Clamshell Thoracotomy. Transplantation proceedings Shudo, Y. n., Rinewalt, D. n., Lingala, B. n., Kim, F. Y., He, H. n., Boyd, J. H., Lee, A. M., Hiesinger, W. n., Currie, M. E., MacArthur, J. W., Woo, Y. J. 2020

    Abstract

    Double lung transplantation (DLT) remains the gold standard for end-stage lung disease. Although DLT was historically performed via clamshell thoracotomy, recently the median sternotomy has emerged as a viable alternative. As the ideal surgical approach remains unclear, the aim of our study was to compare the short- and long-term outcomes of these 2 surgical approaches in DLT.We retrospectively reviewed 192 consecutive adult patients who underwent primary DLT at our institution between 2012 and 2017 (sternotomy, n = 147; clamshell, n = 45). The impact of each surgical approach on post-transplant morbidity was investigated, and the overall survival probability analyses were performed.There were no significant differences in recipients' baseline and donors' characteristics and bilateral allograft ischemic time. Freedom from primary graft dysfunction, acute rejection episodes, postoperative prolonged ventilator support, tracheostomy, postoperative stroke, and airway dehiscence were comparable between these 2 groups. The duration of cardiopulmonary bypass and operative time were significantly longer in the clamshell thoracotomy group. Postoperative extracorporeal membrane oxygenation usage tended to be more frequent in the clamshell thoracotomy group than the median sternotomy group, despite no statistical significance. Length of hospital and intensive care unit stay were not influenced by the type of incision. There was no significant difference in overall survival between these 2 procedure groups (P = .61, log-rank test).The median sternotomy approach in DLT decreases operative time and more importantly leads to a shorter duration of cardiopulmonary bypass. The type of surgical approach did not show any statistically significant impact on adult DLT recipients' morbidity and survival.

    View details for DOI 10.1016/j.transproceed.2019.10.018

    View details for PubMedID 31911057

  • Commentary: Arrhythmia surgery at the time of left ventricular assist device implant-use of caution. JTCVS techniques Maeda, K., Lee, A. M. 2020; 1: 60-61

    View details for DOI 10.1016/j.xjtc.2020.01.019

    View details for PubMedID 34317715

    View details for PubMedCentralID PMC8288721

  • Type A Aortic Dissection-Experience Over 5 Decades: JACC Historical Breakthroughs in Perspective. Journal of the American College of Cardiology Zhu, Y. n., Lingala, B. n., Baiocchi, M. n., Tao, J. J., Toro Arana, V. n., Khoo, J. W., Williams, K. M., Traboulsi, A. A., Hammond, H. C., Lee, A. M., Hiesinger, W. n., Boyd, J. n., Oyer, P. E., Stinson, E. B., Reitz, B. A., Mitchell, R. S., Miller, D. C., Fischbein, M. P., Woo, Y. J. 2020; 76 (14): 1703–13

    Abstract

    The Stanford classification of aortic dissection was described in 1970. The classification proposed that type A aortic dissection should be surgically repaired immediately, whereas type B aortic dissection can be treated medically. Since then, diagnostic tools and management of acute type A aortic dissection (ATAAD) have undergone substantial evolution. This paper evaluated historical changes of ATAAD repair at Stanford University since the establishment of the aortic dissection classification 50 years ago. The surgical approaches to the proximal and distal extent of the aorta, cerebral perfusion methods, and cannulation strategies were reviewed. Additional analyses using patients who underwent ATAAD repair at Stanford University from 1967 through December 2019 were performed to further illustrate the Stanford experience in the management of ATAAD. While technical complexity increased over time, post-operative survival continued to improve. Further investigation is warranted to delineate factors associated with the improved outcomes observed in this study.

    View details for DOI 10.1016/j.jacc.2020.07.061

    View details for PubMedID 33004136

  • Intrinsically stretchable electrode array enabled in vivo electrophysiological mapping of atrial fibrillation at cellular resolution. Proceedings of the National Academy of Sciences of the United States of America Liu, J. n., Zhang, X. n., Liu, Y. n., Rodrigo, M. n., Loftus, P. D., Aparicio-Valenzuela, J. n., Zheng, J. n., Pong, T. n., Cyr, K. J., Babakhanian, M. n., Hasi, J. n., Li, J. n., Jiang, Y. n., Kenney, C. J., Wang, P. J., Lee, A. M., Bao, Z. n. 2020

    Abstract

    Electrophysiological mapping of chronic atrial fibrillation (AF) at high throughput and high resolution is critical for understanding its underlying mechanism and guiding definitive treatment such as cardiac ablation, but current electrophysiological tools are limited by either low spatial resolution or electromechanical uncoupling of the beating heart. To overcome this limitation, we herein introduce a scalable method for fabricating a tissue-like, high-density, fully elastic electrode (elastrode) array capable of achieving real-time, stable, cellular level-resolution electrophysiological mapping in vivo. Testing with acute rabbit and porcine models, the device is proven to have robust and intimate tissue coupling while maintaining its chemical, mechanical, and electrical properties during the cardiac cycle. The elastrode array records epicardial atrial signals with comparable efficacy to currently available endocardial-mapping techniques but with 2 times higher atrial-to-ventricular signal ratio and >100 times higher spatial resolution and can reliably identify electrical local heterogeneity within an area of simultaneously identified rotor-like electrical patterns in a porcine model of chronic AF.

    View details for DOI 10.1073/pnas.2000207117

    View details for PubMedID 32541030

  • Acute type A dissection causing impending rupture of abdominal aortic aneurysm previously treated with EVAR. Annals of vascular surgery Ogawa, Y., Watkins, A. C., Lee, A., Iwakoshi, S., Dua, A., Pedroza, A. J., Dake, M. D., Lee, J. T. 2019

    Abstract

    This report describes the rapid expansion of a previously excluded abdominal aortic aneurysm (AAA) following type A aortic dissection repair in a 74-year-old male. Following successful hemi-arch replacement, CT angiography (CTA) showed residual dissection throughout the thoracoabdominal aorta which had created a proximal endoleak at the prior endovascular stentgraft resulting in rapid growth of the residual AAA sac. Urgent thoracic endovascular aortic repair (TEVAR) did not fully obliterate false lumen flow allowing further unstable expansion of the AAA and abdominal pain. This was ultimately managed with an open replacement of the infrarenal neck with a Dacron interposition graft sewn to the prior EVAR. Post-op CTA showed resolution of the false lumen communication to the infrarenal AAA and no further endoleak. Open interposition AAA neck replacement is a possible treatment for new onset endoleak in patients with aortic dissection following prior infrarenal EVAR.

    View details for DOI 10.1016/j.avsg.2019.11.047

    View details for PubMedID 31863952

  • "Cheese Wire" Fenestration of Dissection Intimal Flap to Facilitate Thoracic Endovascular Aortic Repair in Chronic Dissection. Journal of vascular and interventional radiology : JVIR Iwakoshi, S., Watkins, C. A., Ogawa, Y., Fischbein, M., Lee, A., Lee, J. T., Hiesinger, W., Dake, M. D. 2019

    Abstract

    Thoracic endovascular aortic repair (TEVAR) for aneurysmal chronic dissection is often complicated by retrograde filling of the false lumen and dissected distal landing zone. A "cheese wire"-style fenestration of the dissection intimal flap can create a landing zone facilitating TEVAR. This technique successfully aided TEVAR in 3 patients with an average age of 57.3 years. Complications included type III endoleak requiring relining and renal artery occlusion requiring stent placement. Average duration of clinical follow-up was 19 ± 4 months. Imaging follow-up was 8 ± 10 months. All patients have survived for more than 1 year without aneurysm enlargement.

    View details for DOI 10.1016/j.jvir.2019.06.004

    View details for PubMedID 31542270

  • Comprehensive Analysis of Differential Expressed Genes Related with Myocardial Reverse Remodeling Following HeartWare Ventricular Assist Device Implantation Shudo, Y., Jaatinen, K. J., NIshiga, M., Chen, I. Y., Greene, C. L., Koyano, T. K., Fong, R. W., Boyd, J. H., Lee, A. M., Hiesinger, W., Woo, J. ELSEVIER SCIENCE INC. 2019: S244
  • Successful heart-lung-kidney and domino heart transplantation following veno-venous extracorporeal membrane oxygenation support INTERACTIVE CARDIOVASCULAR AND THORACIC SURGERY Zhu, Y., Shudo, Y., Lee, A. M., Woo, Y. 2019; 28 (2): 316–17
  • Evaluation of Risk Factors for Heart-Lung Transplant Recipient Outcome: An Analysis of the United Network for Organ Sharing Database. Circulation Shudo, Y. n., Wang, H. n., Lingala, B. n., He, H. n., Kim, F. Y., Hiesinger, W. n., Lee, A. M., Boyd, J. H., Currie, M. n., Woo, Y. J. 2019; 140 (15): 1261–72

    Abstract

    Heart-lung transplantation (HLTx) is an effective treatment for patients with advanced cardiopulmonary failure. However, no large multicenter study has focused on the relationship between donor and recipient risk factors and post-HLTx outcomes. Thus, we investigated this issue using data from the United Network for Organ Sharing database.All adult patients (age ≥18 years) registered in the United Network for Organ Sharing database who underwent HLTx between 1987 and 2017 were included (n=997). We stratified the cohort by patients who were alive without retransplant at 1 year (n=664) and patients who died or underwent retransplant within 1 year of HLTx (n=333). The primary outcome was the influence of donor and recipient characteristics on 1-year post-HLTx recipient death or retransplant. Kaplan-Meier curves were created to assess overall freedom from death or retransplant. To obtain a better effect estimation on hazard and survival time, the parametric Accelerated Failure Time model was chosen to perform time-to-event modeling analyses.Overall graft survival at 1-year post-HLTx was 66.6%. Of donors, 53% were male, and the mean age was 28.2 years. Univariable analysis showed advanced donor age, recipient male sex, recipient creatinine, recipient history of prior cardiac or lung surgery, recipient extracorporeal membrane oxygenation support, transplant year, and transplant center volume were associated with 1-year post-HLTx death or retransplant. On multivariable analysis, advanced donor age (hazard ratio [HR], 1.017; P=0.0007), recipient male sex (HR, 1.701; P=0.0002), recipient extracorporeal membrane oxygenation support (HR, 4.854; P<0.0001), transplant year (HR, 0.962; P<0.0001), and transplantation at low-volume (HR, 1.694) and medium-volume centers (HR, 1.455) in comparison with high-volume centers (P=0.0007) remained as significant predictors of death or retransplant. These predictors were incorporated into an equation capable of estimating the preliminary probability of graft survival at 1-year post-HLTx on the basis of preoperative factors alone.HLTx outcomes may be improved by considering the strong influence of donor age, recipient sex, recipient hemodynamic status, and transplant center volume. Marginal donors and recipients without significant factors contributing to poor post-HLTx outcomes may still be considered for transplantation, potentially with less impact on the risk of early postoperative death or retransplant.

    View details for DOI 10.1161/CIRCULATIONAHA.119.040682

    View details for PubMedID 31589491

  • Incremental Value of Aortomitral Continuity Calcification for Risk Assessment after Transcatheter Aortic Valve Replacement. Radiology. Cardiothoracic imaging Willemink, M. J., Maret, E. n., Moneghetti, K. J., Kim, J. B., Haddad, F. n., Kobayashi, Y. n., Nishi, T. n., Nieman, K. n., Cauwenberghs, N. n., Kuznetsova, T. n., Higashigaito, K. n., Sailer, A. M., Yeung, A. C., Lee, A. M., Miller, D. C., Fischbein, M. n., Fearon, W. F., Fleischmann, D. n. 2019; 1 (5): e190067

    Abstract

    To investigate the association of aortomitral continuity calcification (AMCC) with all-cause mortality, postprocedural paravalvular leak (PVL), and prolonged hospital stay in patients undergoing transcatheter aortic valve replacement (TAVR).The authors retrospectively evaluated 329 patients who underwent TAVR between March 2013 and March 2016. AMCC, aortic valve calcification (AVC), and coronary artery calcification (CAC) were quantified by using preprocedural CT. Pre-procedural Society of Thoracic Surgeons (STS) score was recorded. Associations between baseline AMCC, AVC, and CAC and 1-year mortality, PVL, and hospital stay longer than 7 days were analyzed.The median follow-up was 415 days (interquartiles, 344-727 days). After 1 year, 46 of the 329 patients (14%) died and 52 (16%) were hospitalized for more than 7 days. Of the 326 patients who underwent postprocedural echocardiography, 147 (45%) had postprocedural PVL. The CAC score (hazard ratio: 1.11 per 500 points) and AMCC mass (hazard ratio: 1.13 per 500 mg) were associated with 1-year mortality. AVC mass (odds ratio: 1.93 per 100 mg) was associated with postprocedural PVL. Only the STS score was associated with prolonged hospital stay (odds ratio: 1.19 per point).AMCC is associated with mortality within 1 year after TAVR and substantially improves individual risk classification when added to a model consisting of STS score and AVC mass only.Supplemental material is available for this article.© RSNA, 2019See also the commentary by Brown and Leipsic in this issue.

    View details for DOI 10.1148/ryct.2019190067

    View details for PubMedID 33778530

    View details for PubMedCentralID PMC7977784

  • Intentional pneumothorax avoids collateral damage: Dynamic phrenic nerve mobilization through intrathoracic insufflation of carbon dioxide. HeartRhythm case reports Shah, R. L., Perino, A. n., Obafemi, O. n., Lee, A. n., Badhwar, N. n. 2019; 5 (9): 480–84

    View details for DOI 10.1016/j.hrcr.2019.07.007

    View details for PubMedID 31934546

    View details for PubMedCentralID PMC6951311

  • Surgical Management for Aortoesophageal Fistula After Endovascular Aortic Repair. The Annals of thoracic surgery Zhu, Y. n., MacArthur, J. W., Lui, N. n., Lee, A. M. 2019

    Abstract

    This case demonstrates successful surgical management of a 6 cm-long aortoesophageal fistula from an infected stent graft. A 69-year-old woman with a penetrating descending thoracic aortic ulcer underwent endovascular aortic repair. Two weeks later, she presented with nausea and melena, and was found to have an infected stent graft on imaging. She underwent a two-stage procedure encompassing aortic arch debranching and extra-anatomic aortic bypass in stage one, and stent graft resection, primary esophageal repair, intercostal and omental flap and jejunostomy tube placement in stage two. She was discharged one month later and is doing well 1.5 years after the operation.

    View details for DOI 10.1016/j.athoracsur.2019.08.076

    View details for PubMedID 31586613

  • Diagnosing Epithelioid Hemangioendothelioma With Pericardial Involvement ANNALS OF THORACIC SURGERY Balansay, B. E., Zhang, X., Loftus, P. D., Valenzuela, J., Zambrano, E., Lee, A. M. 2018; 106 (4): E173–E175
  • Outcomes of Transcatheter Aortic Valve Replacement compared to Surgical Aortic Valve Replacement in patients with prior Chest Radiation Chacko, Y., Zhang, X., Jaluba, K., Lee, A., Miller, D., Yeung, A. C., Kim, B., Fearon, W. ELSEVIER SCIENCE INC. 2018: B244–B245
  • Ambulating femoral venoarterial extracorporeal membrane oxygenation bridge to heart-lung transplant JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Shudo, Y., Kasinpila, P., Lee, A. M., Rao, V. K., Woo, Y. 2018; 156 (3): E135–E137
  • Successful heart-lung-kidney and domino heart transplantation following veno-venous extracorporeal membrane oxygenation support. Interactive cardiovascular and thoracic surgery Zhu, Y., Shudo, Y., Lee, A. M., Woo, Y. J. 2018

    Abstract

    A 60-year-old man with cystic fibrosis, mediastinal shift and end-stage kidney disease underwent a heart-lung-kidney transplantation. His explanted heart was used for a domino heart transplantation. This case showed an excellent outcome, even with high preoperative acuity requiring veno-venous extracorporeal membrane oxygenation and continuous veno-venous haemodialysis.

    View details for PubMedID 30113636

  • Emergency valve-sparing aortic root replacement and coronary artery bypass grafting for giant left sinus of Valsalva aneurysm presenting as acute coronary syndrome JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Pedroza, A. J., Brewer, Z. E., Lee, A. M. 2018; 156 (2): E81–E84
  • Diagnosing Epithelioid Hemangioendothelioma with Pericardial Involvement. The Annals of thoracic surgery Balansay, B. E., Zhang, X., Loftus, P. D., Valenzuela, J. A., Zambrano, E., Lee, A. M. 2018

    Abstract

    Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor that commonly affects lung, liver, and bone. Among all known EHE cases, only 20% have a pulmonary origin, with metastases to the pericardium occurring in less than 1% of these. Due to its low prevalence, variable presentation, and unknown latency period, a thoracic EHE diagnosis can be easily missed. This case outlines the unique pathologic features of EHE in a patient with cardiovascular disease, provides further insight into diagnosing a rare tumor, and provides a better understanding of the pathophysiology and progression of thoracic EHE.

    View details for PubMedID 29689240

  • Emergency valve-sparing aortic root replacement and coronary artery bypass grafting for giant left sinus of Valsalva aneurysm presenting as acute coronary syndrome. The Journal of thoracic and cardiovascular surgery Pedroza, A. J., Brewer, Z. E., Lee, A. M. 2018

    View details for PubMedID 29615334

  • Ambulating femoral venoarterial extracorporeal membrane oxygenation bridge to heart-lung transplant. The Journal of thoracic and cardiovascular surgery Shudo, Y., Kasinpila, P., Lee, A. M., Rao, V. K., Woo, Y. J. 2018

    View details for PubMedID 29628344

  • Video-assisted thoracoscopic surgery to displace the phrenic nerve during endocardial ablation of right atrial tachycardia. HeartRhythm case reports Mesquita, J. n., Bisla, J. n., Lee, A. n., Perez, M. n. 2018; 4 (7): 304–6

    View details for PubMedID 30023277

  • Acute Right Ventricular Failure After Successful Opening of Chronic Total Occlusion in Right Coronary Artery Caused by a Large Intramural Hematoma. Circulation. Cardiovascular interventions Kawana, M., Lee, A. M., Liang, D. H., Yeung, A. C. 2017; 10 (2)
  • Successful Minimally Invasive Surgical Ablation of Atrial Fibrillation: A Call to Do Better. Circulation. Arrhythmia and electrophysiology Lee, A. M. 2017; 10 (11)

    View details for PubMedID 29138144

  • Maze permutations during minimally invasive mitral valve surgery. Annals of cardiothoracic surgery Lee, A. M. 2015; 4 (5): 463-468

    Abstract

    Surgical ablation for atrial fibrillation is most frequently done in the concomitant setting, and most commonly with mitral valve surgery. Minimally invasive surgical techniques for the treatment of atrial fibrillation have developed contemporaneously with techniques for minimally invasive mitral valve surgery. As in traditional surgery for atrial fibrillation, there are many different permutations of ablations for the less invasive approaches. Lesion sets can vary from simple pulmonary vein isolation (PVI) to full bi-atrial lesions that completely reproduce the traditional cut-and-sew Cox Maze III procedure with variable efficacy in restoring sinus rhythm. Additionally, treatment of the atrial appendage can be done through minimally invasive approaches without any ablation at all in an attempt to mitigate the risk of stroke. Finally, hybrid procedures combining minimally invasive surgery and catheter-based ablation are being developed that might augment surgical treatment of atrial fibrillation at the time of minimally invasive mitral valve repair. These various permutations and their results are reviewed.

    View details for DOI 10.3978/j.issn.2225-319X.2015.09.07

    View details for PubMedID 26539352

    View details for PubMedCentralID PMC4598463

  • Proteomic Profiling of Early Chronic Pulmonary Hypertension: Evidence for Both Adaptive and Maladaptive Pathology. Journal of pulmonary & respiratory medicine Aziz, A., Lee, A. M., Ufere, N. N., Damiano, R. J., Townsend, R. R., Moon, M. R. 2015; 5 (1)

    Abstract

    The molecular mechanisms governing right atrial (RA) and ventricular (RV) hypertrophy and failure in chronic pulmonary hypertension (CPH) remain unclear. The purpose of this investigation was to characterize RA and RV protein changes in CPH and determine their adaptive versus maladaptive role on hypertrophic development.Nine dogs underwent sternotomy and RA injection with 3 mg/kg dehydromonocrotaline (DMCT) to induce CPH (n=5) or sternotomy without DMCT (n=4). At 8-10 weeks, RA and RV proteomic analyses were completed after trypsinization of cut 2-D gel electrophoresis spots and peptide sequencing using mass spectrometry.In the RV, 13 protein spots were significantly altered with DMCT compared to Sham. Downregulated RV proteins included contractile elements: troponin T and C (-1.6 fold change), myosin regulatory light chain 2 (-1.9), cellular energetics modifier: fatty-acid binding protein (-1.5), and (3) ROS scavenger: superoxide dismutase 1 (-1.7). Conversely, beta-myosin heavy chain was upregulated (+1.7). In the RA, 22 proteins spots were altered including the following downregulated proteins contractile elements: tropomyosin 1 alpha chain (-1.9), cellular energetic proteins: ATP synthase (-1.5), fatty-acid binding protein (-2.5), and (3) polyubiquitin (-3.5). Crystallin alpha B (hypertrophy inhibitor) was upregulated in both the RV (+2.2) and RA (+2.6).In early stage hypertrophy there is adaptive upregulation of major RA and RV contractile substituents and attenuation of the hypertrophic response. However, there are multiple indices of maladaptive pathology including considerable cellular stress associated with aberrancy of actin machinery activity, decreased efficiency of energy utilization, and potentially decreased protein quality control.

    View details for DOI 10.4172/2161-105X.1000241

    View details for PubMedID 26246959

    View details for PubMedCentralID PMC4523278

  • Quantification of the functional consequences of atrial fibrillation and surgical ablation on the left atrium using cardiac magnetic resonance imaging EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY Robertson, J. O., Lee, A. M., Voeller, R. K., Damiano, M. S., Schuessler, R. B., Damiano, R. J. 2014; 46 (4): 720-728

    Abstract

    The effect of atrial fibrillation (AF) on left atrial (LA) function has not been well defined and has been largely based on limited echocardiographic evaluation. This study examined the effect of AF and a subsequent Cox-Maze IV (CMIV) procedure on atrial function.Cardiac magnetic resonance imaging (cMRI) was performed in 20 healthy volunteers, 8 patients with paroxysmal atrial fibrillation (PAF) and 7 patients with persistent or long-standing persistent atrial fibrillation (LSP AF). Six of the PAF patients underwent surgical ablation with the CMIV procedure and 5 underwent both pre- and postoperative cMRIs. The persistent or LSP AF patients underwent only postoperative cMRIs because all scans were performed with patients in normal sinus rhythm. Volume-time curves throughout the cardiac cycle and regional wall shortening were evaluated using the cine images and compared across groups.Compared with normal volunteers, patients with PAF had significantly decreased reservoir contribution to left ventricular (LV) filling (P = 0.0010), an increased conduit function contribution (P = 0.04) and preserved booster pump function (P = 0.14). Following the CMIV procedure, significant reductions were noted with respect to reservoir and booster pump function, with corresponding increases in conduit function. These differences were more drastic in patients with persistent/LSP AF. Regional wall motion was significantly reduced by PAF in all wall segments (P < 0.05), but was not further reduced by the CMIV. Despite changes in LA function, LV function was preserved following surgery.PAF significantly altered LA function and has a detrimental effect on regional wall motion. Surgical intervention further altered LA function, but the reasons for this are likely multifactorial and not entirely related to the lesion set itself.

    View details for DOI 10.1093/ejcts/ezt656

    View details for Web of Science ID 000344968500024

    View details for PubMedID 24523494

    View details for PubMedCentralID PMC4271083

  • Importance of atrial surface area and refractory period in sustaining atrial fibrillation: Testing the critical mass hypothesis JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Lee, A. M., Aziz, A., Didesch, J., Clark, K. L., Schuessler, R. B., Damiano, R. J. 2013; 146 (3): 593-598

    Abstract

    The critical mass hypothesis for atrial fibrillation (AF) was proposed in 1914; however, there have been few studies defining the relationship between atrial surface area and AF. This study evaluated the effect of tissue area and effective refractory period (ERP) on the probability of sustaining AF in an in vivo model.Domestic pigs (n = 9) underwent median sternotomy. Epicardial activation maps were constructed from bipolar electrograms recorded from form-fitting electrode templates placed on the atria. Baseline ERPs were determined. ERP was lowered with a continuous infusion of acetylcholine (0.005-0.04 mg/Kg/min) until AF could be sustained after burst pacing. The atria were sequentially partitioned using bipolar radiofrequency ablation. ERPs were lowered using acetylcholine until AF could be sustained in each subdivision of atrial tissue. Each subdivision was further divided until AF was no longer inducible. At study completion, the heart was excised and the surface area of each section was measured.Over a range of ERPs from 75 to 250 ms, the probability of AF was correlated with increasing tissue area (range, 19.5-105 cm(2)) and decreasing ERP. Logistic regression analysis identified shorter ERP (P < .001) and larger area (P = .006) as factors predictive of an increased probability of sustained AF (area under the curve of the receiver-operator characteristic = 0.878).The probability of sustained AF was significantly associated with increasing tissue area and decreasing ERP. These data may lead to a greater understanding of the mechanism of AF and help to design better interventional procedures.

    View details for DOI 10.1016/j.jtcvs.2012.04.021

    View details for Web of Science ID 000323605800023

    View details for PubMedID 22995722

    View details for PubMedCentralID PMC3966059

  • Differential calcium handling in two canine models of right ventricular pressure overload JOURNAL OF SURGICAL RESEARCH Moon, M. R., Aziz, A., Lee, A. M., Moon, C. J., Okada, S., Kanter, E. M., Yamada, K. A. 2012; 178 (2): 554-562

    Abstract

    The purpose of this investigation was to characterize differential right atrial (RA) and ventricular (RV) molecular changes in Ca(2+)-handling proteins consequent to RV pressure overload and hypertrophy in two common, yet distinct models of pulmonary hypertension: dehydromonocrotaline (DMCT) toxicity and pulmonary artery (PA) banding.A total of 18 dogs underwent sternotomy in four groups: (1) DMCT toxicity (n = 5), (2) mild PA banding over 10 wk to match the RV pressure rise with DMCT (n = 5); (3) progressive PA banding to generate severe RV overload (n = 4); and (4) sternotomy only (n = 4).In the right ventricle, with DMCT, there was no change in sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) or phospholamban (PLB), but we saw a trend toward down-regulation of phosphorylated PLB at serine-16 (p[Ser-16]PLB) (P = 0.07). Similarly, with mild PA banding, there was no change in SERCA or PLB, but p(Ser-16)PLB was down-regulated by 74% (P < 0.001). With severe PA banding, there was no change in PLB, but SERCA fell by 57% and p(Ser-16)PLB fell by 67% (P < 0.001). In the right atrium, with DMCT, there were no significant changes. With both mild and severe PA banding, p(Ser-16)PLB fell (P < 0.001), but SERCA and PLB did not change.Perturbations in Ca(2+)-handling proteins depend on the degree of RV pressure overload and the model used to mimic the RV effects of pulmonary hypertension. They are similar, but blunted, in the atrium compared with the ventricle.

    View details for DOI 10.1016/j.jss.2012.04.066

    View details for Web of Science ID 000311090700009

    View details for PubMedID 22632938

    View details for PubMedCentralID PMC3430801

  • Congenital fistula from the left main coronary artery to the left atrium presenting with an acute myocardial infarction JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Anastacio, M. M., Lee, A. M., Lawton, J. S. 2012; 144 (6): E147-E148

    View details for DOI 10.1016/j.jtcvs.2012.09.015

    View details for Web of Science ID 000311086600002

    View details for PubMedID 23040318

  • Evaluation of a novel cryoablation system: in vivo testing in a chronic porcine model. Innovations (Philadelphia, Pa.) Weimar, T., Lee, A. M., Ray, S., Schuessler, R. B., Damiano, R. J. 2012; 7 (6): 410-416

    Abstract

    Cryoablation is commonly used at present in the surgical treatment of atrial fibrillation (AF). However, there have been few studies examining the efficacy of the commonly used ablation devices. This report compares the efficacy of two cryoprobes in creating transmural endocardial lesions on the beating heart in a porcine model for chronic AF.In six Hanford miniature swine, the right atrial appendage and the inferior vena cava were isolated using a bipolar radiofrequency clamp to create areas of known conduction block. A connecting ablation line was performed endocardially via a purse string with the novel malleable 10-cm Cryo1 probe for 2 minutes at -40°C. Additional ablation lines were created with the Cryo1 and the 3.5-cm 3011 Maze Linear probe on the right and the left atrial wall. Epicardial activation mapping was performed before and immediately after ablation as well as 14 days postoperatively. Histologic examination was performed 14 days postoperatively.Transmural lesions were confirmed in 83/84 cross-sections (99%) for the Cryo1 probe and in 40/41 cross-sections (98%) for the 3011 Maze Linear probe. There was no difference between the devices in lesion width (mean ± SD, Cryo1, 10.7 ± 3.5 mm; 3011, 10.0 ± 3.9 mm; P = 0.31), lesion depth (Cryo1, 4.5 ± 1.7 mm; 3011, 4.6 ± 1.5 mm; P = 0.74), or atrial wall thickness (Cryo1, 4.5 ± 1.8 mm; 3011, 4.7 ± 1.7 mm; P = 0.74). There was a conduction delay across the right atrial ablation line (20 ± 2 milliseconds vs 51 ± 8 milliseconds, P < 0.001) that remained unchanged at 14 days (51 ± 8 milliseconds vs 52 ± 10 milliseconds, P = 0.88).The Cryo1 probe created transmural lesions on the beating heart, resulting in sustained conduction delay. Both probes had a similar performance in lesion geometry in this chronic animal model.

    View details for DOI 10.1097/IMI.0b013e31828534e5

    View details for PubMedID 23422803

    View details for PubMedCentralID PMC3578219

  • Evaluation of a novel cryoablation system: in vitro testing of heat capacity and freezing temperatures. Innovations (Philadelphia, Pa.) Weimar, T., Lee, A. M., Ray, S., Schuessler, R. B., Damiano, R. J. 2012; 7 (6): 403-409

    Abstract

    Cryoablation has been used to ablate cardiac tissue for decades and has been shown to be able to replace incisions in the surgical treatment of atrial fibrillation. This in vitro study evaluates the performance of a novel cryoprobe and compares it with existing commercially available devices.A new malleable 10-cm aluminum cryoprobe was compared with a rigid 3.5-cm copper linear probe using in vitro testing to evaluate performances under different thermal loads and with different tissue thicknesses. Radial dimensions of ice formation were measured in each water bath by a high-precision laser 2 minutes after the onset of cooling. Probe-surface temperatures were recorded by thermocouples. Tissue temperature was measured at depths of 4 mm and 5 mm from the probe-tissue interface. Time to reach a tissue temperature of -20°C was recorded.Ice formation increased significantly with lower water-bath temperatures (P < 0.001). Width and depth of ice formation were significantly less for the rigid linear probe (P < 0.012 and P < 0.001, respectively). There was no difference between the probes in the maximal negative temperature reached under different thermal loads or at different tissue depths. The malleable probe achieved significantly lower temperatures at the proximal compared with the distal end (-61.7°C vs -55.0°C, respectively; P < 0.001). A tissue temperature of -20°C was reached earlier at 4 mm than at 5 mm (P < 0.001) and was achieved significantly faster with the 3011 Maze Linear probe (P < 0.021).The new malleable probe achieved rapid freezing to clinically relevant levels in up to 5-mm-thick tissue. Both probes maintained their performance under a wide range of thermal loads.

    View details for DOI 10.1097/IMI.0b013e3182853e74

    View details for PubMedID 23422802

    View details for PubMedCentralID PMC3578216

  • Chronic performance of a novel radiofrequency ablation device on the beating heart: Limitations of conduction delay to assess transmurality JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Lee, A. M., Aziz, A., Clark, K. L., Schuessler, R. B., Damiano, R. J. 2012; 144 (4): 859-865

    Abstract

    The creation of consistently transmural lesions with epicardial ablation on the beating heart has represented a significant challenge for current technology. This study examined the chronic performance of the AtriCure Coolrail device (AtriCure Inc, West Chester, Ohio), an internally cooled, bipolar radiofrequency ablation device designed for off-pump epicardial ablation. The study also examined the reliability of using acute intraoperative conduction delay to evaluate lesion integrity.Seven swine underwent median sternotomy. The right atrial appendage and inferior vena cava were isolated with a bipolar radiofrequency clamp. Linear ablation lines were created between these structures with the AtriCure Coolrail. Paced activation maps were recorded with epicardial patch electrodes acutely before and after ablation and after keeping the animals alive for 4 weeks. The conduction time across the linear ablation was calculated from these maps. The lesions were histologically evaluated with trichrome staining.Only 76% of cross-sections of Coolrail lesions were transmural, and only 1 of 12 ablation lines was transmural in every cross-section examined. Mapping data were available in 5 of the animals. Significant conduction delay was present after the creation of each line of ablation acutely; however, after 4 weeks, conduction time returned to preablation values, demonstrating lack of transmurality.The AtriCure Coolrail failed to reliably create transmural lesions. Although the Coolrail was able to create acute conduction delay, its failure to transmurally ablate the atrial myocardium left gaps along the length of the lesion, which resulted in neither chronic conduction block nor delay across any line of ablation.

    View details for DOI 10.1016/j.jtcvs.2012.01.001

    View details for Web of Science ID 000309111600020

    View details for PubMedID 22305553

    View details for PubMedCentralID PMC3966079

  • Cardiac Surgery The Washington ManualTM of Surgery Lee, A., Damiano, Jr, R. edited by Aziz, A., Bharat, A., Fox, A., Porembka, M. Lippincott, Williams & Wilkins, Philadelphia. 2012; 6th: 695–722
  • Surgical ablation of atrial fibrillation Electrophysiological Disorders of the Heart Lee, A., Voeller , R., Damiano, Jr, R. edited by Saksena , S., Camm, A. Elsevier, Philadelphia. 2011; 2nd: 1415–1424
  • A minimally invasive cox-maze procedure: operative technique and results. Innovations (Philadelphia, Pa.) Lee, A. M., Clark, K., Bailey, M. S., Aziz, A., Schuessler, R. B., Damiano, R. J. 2010; 5 (4): 281-286

    Abstract

    The Cox-Maze procedure (CMP) for the surgical treatment of atrial fibrillation (AF) traditionally has required a median sternotomy and cardiopulmonary bypass. This study describes a method using ablation technologies to create the full Cox-Maze lesion set through a 5- to 6-cm right minithoracotomy.Twenty-two consecutive patients underwent a CMP through a right mini-thoracotomy and cardiopulmonary bypass. All patients were followed prospectively with electrocardiogram and 24-hour Holter monitoring at 3, 6, and 12 months. The CMP lesion set was created using bipolar radiofrequency energy and cryotherapy.There was no operative mortality or major complications.Two patients required a permanent pacemaker. Five patients (23%) had early atrial tachyarrhythmias. At last follow-up(mean, 18 ± 12 months), all the patients (n=22) were free from atrial dysrhythmias. At 3 months (n=19), 84% of patients were off antiarrhythmic drugs. At 6 months (n=18), 94% of patients were free from AF and off antiarrhythmic medications. At 12 months (n=16), 81% of patients were free from AF and off antiarrhythmic drugs and three patients remained on warfarin for a mechanical mitral valve.A full CMP can be performed through a right mini-thoracotomy with outstanding short-term results. This less invasive procedure can be offered to patients without compromising efficacy.

    View details for DOI 10.1097/IMI.0b013e3181ee3815

    View details for PubMedID 21057605

    View details for PubMedCentralID PMC2967773

  • Vagal denervation and reinnervation after ablation of ganglionated plexi JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Sakamoto, S., Schuessler, R. B., Lee, A. M., Aziz, A., Lall, S. C., Damiano, R. J. 2010; 139 (2): 444-452

    Abstract

    Surgical ablation of ganglionated plexi has been proposed to increase efficacy of surgery for atrial fibrillation. This experimental canine study examined electrophysiologic attenuation and recovery of atrial vagal effects after ganglionated plexi ablation alone or with standard surgical lesion sets for atrial fibrillation.Dogs were divided into 3 groups: group 1 (n = 6) had focal ablation of the 4 major epicardial ganglionated plexi fat pads, group 2 (n = 6) had pulmonary vein isolation with ablation, and group 3 (n = 6) had posterior left atrial isolation with ablation. All fat pads were ablated. Sinus and atrioventricular interval changes during bilateral vagosympathetic trunk stimulation were examined before and both immediately and 4 weeks after ablation. Vagally induced effective refractory period changes and mean QRST area changes (index of local innervation) were examined in 5 atrial regions.Sinus and atrioventricular interval changes and heart rate variability decreased immediately after ablation, but only sinus interval changes were restored significantly after 4 weeks in all groups. Ablation-modified vagal effects on effective refractory period or QRST area changed heterogeneously in groups 1 and 2. In group 3, regional vagal effects were attenuated extensively postablation in both atria. Posterior left atrial isolation with ablation incrementally denervated the atria. In the long term, vagal stimulation increased QRST area changes relative to control values in all groups. Heart rate variability was also assessed.Ganglionated plexi ablation significantly reduced atrial vagal innervation. Restoration of vagal effects at 4 weeks suggests early atrial reinnervation.

    View details for DOI 10.1016/j.jtcvs.2009.04.056

    View details for Web of Science ID 000274014300026

    View details for PubMedID 19740492

    View details for PubMedCentralID PMC2813372

  • Complications after Atrial Fibrillation Surgery Complications in Cardiothoracic Surgery: Avoidance and Treatment Lee, A., Damiano, Jr, R. edited by Little, A., Merrill , W. Wiley-Blackwell, London. 2010; 2nd: 404–418
  • Animal studies of epicardial atrial ablation HEART RHYTHM Schuessler, R. B., Lee, A. M., Melby, S. J., Voeller, R. K., Gaynor, S. L., Sakamoto, S., Damiano, R. J. 2009; 6 (12): S41-S45

    Abstract

    The Cox maze procedure is an effective treatment of atrial fibrillation, with a long-term freedom from recurrence greater than 90%. The original procedure was highly invasive and required cardiopulmonary bypass. Modifications of the procedure that eliminate the need for cardiopulmonary bypass have been proposed, including use of alternative energy sources to replace cut-and-sew lesions with lines of ablation made from the epicardium on the beating heart. This has been challenging because atrial wall muscle thickness is extremely variable, and the muscle can be covered with an epicardial layer of fat. Moreover, the circulating intracavitary blood acts as a potential heat sink, making transmural lesions difficult to obtain. In this report, we summarize the use of nine different unidirectional devices (four radiofrequency, two microwave, two lasers, one cryothermic) for creating continuous transmural lines of ablation from the atrial epicardium in a porcine model. We define a unidirectional device as one in which all the energy is applied by a single transducer on a single heart surface. The maximum penetration of any device was 8.3 mm. All devices except one, the AtriCure Isolator pen, failed to penetrate 2 mm in some nontransmural sections. Future development of unidirectional energy sources should be directed at increasing the maximum depth and the consistency of penetration.

    View details for DOI 10.1016/j.hrthm.2009.07.028

    View details for Web of Science ID 000276186900007

    View details for PubMedID 19959142

    View details for PubMedCentralID PMC2907672

  • Evaluation of Revascularization Subtypes in Octogenarians Undergoing Coronary Artery Bypass Grafting CIRCULATION Aziz, A., Lee, A. M., Pasque, M. K., Lawton, J. S., Moazami, N., Damiano, R. J., Moon, M. R. 2009; 120 (11): S65-S69

    Abstract

    Recent data suggest that octogenarians' long-term survival after complete coronary artery bypass graft revascularization is superior to incomplete revascularization. Discriminating between variable definitions of "complete" complicates interpretation of survival data. We aimed to clarify octogenarian long-term survival rates by stratifying revascularization subtypes.From 1986 to 2007, 580 patients 80 to 94 years of age underwent coronary artery bypass graft. Functional complete revascularization was defined as at least 1 graft to all diseased coronary vessels with >50% stenosis. Traditional complete revascularization was defined as 1 graft to each major arterial system with at least 50% stenosis. Incomplete revascularization was defined as leaving diseased, ungrafted regions. Revascularization was functional in 279 (48%), traditional in 181 (31%), and incomplete in 120 (21%). Long-term survival was evaluated by Kaplan-Meier analysis. Of 537 operative survivors, there were 402 late deaths. Cumulative long-term survival totaled 2890 patient-years. Late survival (Kaplan-Meier) was similar between functional (mean, 6.8 years) and traditional (6.7 years) groups (P=0.51), but diminished with incomplete (4.2 years) revascularization (P=0.007). Survival by group at 5 years was: 59+/-3% functional, 57+/-4% traditional, and 45+/-5% incomplete. Survival at 8 years was: 40+/-3% functional, 37+/-4% traditional, and 26+/-5% incomplete. To minimize selection bias in patients with limited life expectancy, Kaplan-Meier analysis was repeated including only patients with survival >12 months. Survival was again impaired with incomplete revascularization (P=0.04), and there was no difference between functional and traditional complete revascularization (P=0.73).Bypassing all diseased arterial vessels after revascularization does not afford significant long-term survival advantage compared to a traditional approach. Incomplete revascularization, related to more extensive disease, is associated with an 18% decline in survival. These data suggest that it is important to avoid incomplete revascularization in octogenarians, but the supplementary endeavor required to perform functional complete revascularization does not improve survival.

    View details for DOI 10.1161/CIRCULATIONAHA.108.844316

    View details for Web of Science ID 000269773000010

    View details for PubMedID 19752388

    View details for PubMedCentralID PMC2752867

  • The surgical treatment of atrial fibrillation. The Surgical clinics of North America Lee, A. M., Melby, S. J., Damiano, R. J. 2009; 89 (4): 1001-20, x-xi

    Abstract

    Atrial fibrillation is a complex disease affecting a significant portion of the general population. Although medical therapy is the mainstay of treatment, intervention plays an important role in selected patients. The Cox-Maze procedure is the gold standard for the surgical treatment of atrial fibrillation and has more than 90% success in eliminating atrial fibrillation. Ablation technologies have played a key role in simplifying this technically demanding procedure and making it available to more patients. A myriad of new lesion sets and approaches were introduced over the last decade which has made the operative treatment of atrial fibrillation less invasive and more confusing.

    View details for DOI 10.1016/j.suc.2009.06.001

    View details for PubMedID 19782848

    View details for PubMedCentralID PMC4332830

  • Epicardial Ablation on the Beating Heart: Limited Efficacy of a Novel, Cooled Radiofrequency Ablation Device. Innovations (Philadelphia, Pa.) Lee, A. M., Aziz, A., Sakamoto, S. I., Schuessler, R. B., Damiano, R. J. 2009; 4 (2): 86-92

    Abstract

    OBJECTIVE: To perform a minimally invasive procedure for atrial fibrillation without cardiopulmonary bypass, it is necessary to create transmural lesions on the beating heart. Although bipolar radiofrequency clamps can isolate the pulmonary veins, they have difficulty in performing any other left atrial lesions, particularly those of the traditional Cox-Maze procedure. This study examined the performance of an internally cooled, bipolar radiofrequency device designed for such an application. METHODS: Eleven domestic pigs underwent median sternotomy. Five animals had eight atrial lesions created with the radiofrequency device at times of 20, 30, 40, and 50 seconds. In six other pigs, the device was compared with another technology that has been used clinically for epicardial, beating heart ablation, the Guidant Flex 4 microwave device. The tissue was stained with 2,3,5-triphenyl-tetrazoluim chloride, and the lesions were sectioned at 5-mm intervals. Lesion width, depth, and transmurality were evaluated. RESULTS: The radiofrequency device had a linear dose-response relationship. Lesions were wider and deeper with increasing ablation times. A total of 40%, 45%, 60%, and 67% of lesions were transmural at times of 20, 30, 40, and 50 seconds, respectively. Ninety-one percent of lesions in tissue up to 4-mm thick were transmural after 50 seconds. However, performance in thicker tissue was poor. Lesions created by the device were deeper and more likely to be transmural than the Flex 4. CONCLUSIONS: This internally cooled, bipolar radiofrequency device can reliably create transmural lesions on tissue up to 4-mm thick and performs better than a microwave device.

    View details for DOI 10.1097/IMI.0b013e3181a348a2

    View details for PubMedID 22323899

    View details for PubMedCentralID PMC3273869

  • The surgical treatment of atrial fibrillation Surg Clin North Am Lee, A., Melby , S., Damiano, Jr, R. 2009: 1001–1020, x-xi
  • Atrial fibrillation propagates through gaps in ablation lines: Implications for ablative treatment of atrial fibrillation HEART RHYTHM Melby, S. J., Lee, A. M., Zierer, A., Kaiser, S. P., Livhits, M. J., Boineau, J. P., Schuessler, R. B., Damiano, R. J. 2008; 5 (9): 1296-1301

    Abstract

    It has been hypothesized that atrial lesions must be transmural to successfully cure atrial fibrillation (AF). However, ablation lines often do not extend completely across the atrial wall.The purpose of this study was to determine the effect of residual gaps on conduction properties of atrial tissue.Canine right atria (n = 13) were isolated, perfused, and mounted on a 250-lead electrode plaque. The atria were divided with a bipolar radiofrequency ablation clamp, leaving a gap that was progressively narrowed. Conduction velocities at varying pacing rates and AF frequencies were measured before and after ablations. AF was induced with an extra stimulus and acetylcholine.Gap widths from 11.2 to 1.1 mm were examined. Conduction velocities through gaps were dependent cycle length (P = .002) and gap size (P <.001). Overall, 253 (97%) of a total of 260 gaps allowed paced propagation; 51 (91%) of 56 gaps 1-3 mm in width permitted paced propagation, as did 202 (99%) of 204 gaps >or=3.0 mm. Similarly, 253 (97%) of a total of 260 gaps allowed propagation of AF. For AF, 51 (93%) of 55 gaps 1-3 mm allowed AF to pass through, as did 202 (99%) of 205 gaps >or=3.0 mm. Gaps as small as 1.1 mm conducted paced and AF impulses.Conduction velocities were slowed through residual gaps. However, propagation of wave fronts during pacing and AF occurred through the majority of residual gaps, down to sizes as small as 1.1 mm. Leaving viable tissue in ablation lines for the treatment of AF could account for failures.

    View details for DOI 10.1016/j.hrthm.2008.06.009

    View details for Web of Science ID 000259281600013

    View details for PubMedID 18774106

    View details for PubMedCentralID PMC2923579

  • Efficacy and safety of right and left atrial ablations on the beating heart with irrigated bipolar radiofrequency energy: A long-term animal study JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Melby, S. J., Gaynor, S. L., Lubahn, J. G., Lee, A. M., Rahgozar, P., Caruthers, S. D., Williams, T. A., Schuessler, R. B., Damiano, R. J. 2006; 132 (4): 853-860

    Abstract

    The Cox maze procedure is the most effective surgical treatment for atrial fibrillation; however, its complexity has limited its clinical utility. The purpose of this study was to simplify the procedure by using an irrigated bipolar radiofrequency ablation device on the beating heart without cardiopulmonary bypass.Six domestic pigs underwent median sternotomy. The pulmonary veins were circumferentially ablated. Electrical isolation was confirmed by pacing. Eight lesions were performed epicardially, and three lesions were performed through purse-string sutures with one of the jaws of the device introduced into the right atrium. After 30 days, magnetic resonance imaging was performed to assess atrial function, pulmonary vein anatomy, and coronary artery patency. Cholinergic stimulation and burst pacing were administered to induce atrial fibrillation. Histologic assessment of the heart was performed after the animal was killed.A modified Cox maze procedure was successfully performed with the irrigated bipolar radiofrequency device with no deaths. In every instance, the pulmonary veins were electrically isolated. Cholinergic stimulation with burst pacing failed to produce atrial fibrillation. Imaging studies revealed tricuspid regurgitation without evidence of pulmonary vein stenosis, coronary artery stenosis, or intra-atrial thrombus. Total atrial ejection fraction was 16.9% +/- 7.5%, a significant reduction. Histologically, 99% of the lesions were transmural, and there was no evidence of coronary sinus injury.Lesions on both the right and left atria can be created successfully on the beating heart with irrigated bipolar radiofrequency. The great majority of lesions with this device were transmural. This device should not be used on valvular tissue.

    View details for DOI 10.1016/j.jtcvs.2006.05.048

    View details for Web of Science ID 000240954600016

    View details for PubMedID 17000297

  • Microwave ablation for atrial fibrillation: Dose-response curves in the cardioplegia-arrested and beating heart ANNALS OF THORACIC SURGERY Gaynor, S. L., Byrd, G. D., Diodato, M. D., Ishii, Y., Lee, A. M., Prasad, S. M., Gopal, J., Schuessler, R. B., Damiano, R. J. 2006; 81 (1): 72-77

    Abstract

    Microwave ablation has been used to replace the traditional incisions used in the surgical treatment of atrial fibrillation. However, dose-response curves have not been established in surgically relevant models. The purpose of this study was to develop dose-response curves for the Flex 10 (Guidant, Inc) microwave device in both the acute cardioplegia-arrested heart and on the beating heart.Twelve domestic pigs (40 to 45 kg) were subjected to microwave ablation in either the arrested (n = 6) or beating heart (n = 6). The cardioplegia-arrested heart was maintained at 10 degrees to 15 degrees C while six atrial endocardial and seven right ventricular epicardial lesions were created in each animal. On the beating heart, six right atrial and seven ventricular epicardial lesions were created. Ablations were performed for 15, 30, 45, 60, 90, 120, and 150 seconds (65 W, 2.45 GHz). The tissue was stained with 2,3,5-triphenyl-tetrazolium chloride, and sectioned at 5-mm intervals. Lesion depth and width were determined from digital micrographs.Mean atrial wall thickness was 2.8 mm (range, 1 to 8 mm). In the arrested heart, 94% of atrial lesions were transmural at 45 seconds and 100% were transmural at 90 seconds. In the beating heart, only 20% of atrial lesions were transmural despite prolonged ablation times (90 seconds). Ventricular lesion width and depth increased with duration of application, and were similar on the arrested and beating hearts.Microwave ablation produces linear dose-response curves. Transmural lesions can be reliably produced on the arrested heart, but not consistently on the beating heart.

    View details for DOI 10.1016/j.athotacsur.2005.06.062

    View details for Web of Science ID 000234585400009

    View details for PubMedID 16368338

  • Dose response curves for microwave ablation in the cardioplegia-arrested porcine heart. heart surgery forum Gaynor, S. L., Byrd, G. D., Diodato, M. D., Ishii, Y., Lee, A. M., Prasad, S. M., Gopal, J., Berube, D., Schuessler, R. B., Damiano, R. J. 2005; 8 (5): E331-6

    Abstract

    Microwave ablation has been used clinically for the surgical treatment of atrial fibrillation, particularly during valve procedures. However, dose- response curves have not been established for this surgical environment. The purpose of this study was to examine dosimetry curves for the Flex 4 and Flex 10 microwave devices in an acute cardioplegia-arrested porcine model.Twelve domestic pigs (40-45 kg) were acutely subjected to Flex 4 (n = 6) and Flex 10 (n = 6) ablations. On a cardioplegically arrested heart maintained at 10-15(o)C, six endocardial atrial and seven epicardial ventricular lesions were created in each animal. Ablations were performed for 15 s, 30 s, 45 s, 60 s, 90 s, 120 s, and 150 s (65 W, 2.45 GHz). The tissue was stained with 2,3,5-triphenyl-tetrazolium chloride and lesions were sectioned at 5 mm intervals. Lesion depth and width were determined from digital photomicrographs of each lesion (resolution +/- .03 mm).Average atrial thickness was 2.88 +/- .4 mm (range 1.0 to 8.0 mm). 94% of ablated atrial sections created by the FLEX 4 (n = 16) and the FLEX 10 (n = 16) were transmural at 45 seconds. 100% of atrial sections were transmural at 90 seconds with the FLEX 10 (n = 14) and at 60 seconds with the Flex 4 device (n = 15). Lesion width and depth increased with duration of application.Both devices were capable of producing transmural lesions on the cardioplegically arrested heart at 65 W. These curves will allow surgeons to ensure transmural ablation by tailoring energy delivery to the specific atrial geometry.

    View details for PubMedID 16099735

  • Advances in surgical ablation devices for atrial fibrillation. New Arrhythmia Technologies Melby, S., Lee, A., Damiano, Jr, R. edited by Wang, P., Naccarelli , G., Rosen , M., Estes III , N., Hayes, D., Haines , D. Blackwell Publishing, Malden, Massachusetts. 2005: 233–241