All Publications

  • Electrophysiological mapping of the epicardium via 3D-printed flexible arrays BIOENGINEERING & TRANSLATIONAL MEDICINE Pong, T., Cyr, K. J., Carlton, C., Aparicio-Valenzuela, J., Wang, H., Babakhanian, M., Maiuolo, A., Lucian, H., Wang, P. J., Woo, Y., Lee, A. M. 2023

    View details for DOI 10.1002/btm2.10575

    View details for Web of Science ID 001033419000001

  • 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


    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

  • 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


    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


    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


    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

  • 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


    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

  • Electrophysiologic Conservation of Epicardial Conduction Dynamics After Myocardial Infarction in Newborn Piglets Wang, H., Pong, T., Lucian, H., Aparicio-Valenzuela, J., Tada, Y., Sakhamuri, S., Baker, S. W., Tran, N. A., Paulsen, M. J., Zhu, Y., Lee, A. M., Woo, Y. LIPPINCOTT WILLIAMS & WILKINS. 2020
  • 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

  • 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


    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