Mohan Viswanathan

All Publications

• Electrical Substrate Ablation for Refractory Ventricular Fibrillation: Results of the AVATAR Study. Circulation. Arrhythmia and electrophysiology Krummen, D. E., Ho, G. n., Hoffmayer, K. S., Schweis, F. n., Baykaner, T. n., Rogers, A. J., Han, F. T., Hsu, J. C., Viswanathan, M. N., Wang, P. J., Rappel, W. J., Narayan, S. M. 2021

  Abstract

  Background - Refractory ventricular fibrillation (VF) is a challenging clinical entity, for which ablation of triggering premature ventricular complexes (PVCs) is described. When PVCs are infrequent and multifocal, the optimal treatment strategy is uncertain. Methods - We prospectively enrolled consecutive patients presenting with multiple ICD shocks for VF refractory to antiarrhythmic drug therapy, exhibiting infrequent (≤3%), multifocal PVCs (≥3 morphologies). Procedurally, VF was induced with rapid pacing and mapped, identifying sites of conduction slowing and rotation or rapid focal activation. VF electrical substrate ablation (VESA) was then performed. Outcomes were compared against reference patients with VF who were unable or unwilling to undergo catheter ablation. The primary outcome was a composite of ICD shock, electrical storm, or all-cause mortality. Results - VF was induced and mapped in 6 patients (60±10 y, LVEF 46±19%) with ischemic (n=3) and nonischemic cardiomyopathy. An average of 3.3±0.5 sites of localized reentry during VF were targeted for radiofrequency ablation (38.3±10.9 minutes) during sinus rhythm, rendering VF non-inducible with pacing. Freedom from the primary outcome was 83% in the VF ablation group versus 17% in 6 non-ablation reference patients at a median of 1.0 years (IQR 0.5-1.5 years, p=0.046) follow-up. Conclusions - VESA is associated with a reduction in the combined endpoint compared with the non-ablation reference group. Additional work is required to understand the precise pathophysiologic changes which promote VF in order to improve preventative and therapeutic strategies.

  View details for DOI 10.1161/CIRCEP.120.008868

  View details for PubMedID 33550811

• Pulmonary Vein Stenosis and Pulmonary Hypertension Following a Catheter-Based Radiofrequency Ablation for Atrial Fibrillation: A Case Report. The American journal of case reports Thomas, C. A., Cruz Morel, K. J., Viswanathan, M. N., de Jesus Perez, V. A. 2020; 21: e924709

  Abstract

  BACKGROUND Pulmonary vein (PV) stenosis is a rare condition characterized by progressive luminal size reduction of one or more pulmonary veins (PVs), which can increase postcapillary pressure resulting in shortness of breath, cough, hemoptysis, and pulmonary hypertension (PH). The diagnosis of PV stenosis requires a high degree of suspicion. PV stenosis is a rare but recognized complication of catheter-based radiofrequency ablation (RFA) for atrial fibrillation (AF). CASE REPORT We present a case of a 78-year-old man who underwent a surgical MAZE procedure followed by catheter-based RFA to treat AF. He subsequently developed shortness of breath, exercise limitation, and PH. The patient was ultimately diagnosed with PV stenosis, which was a sequela of the RFA and the cause of his PH. The patient was treated by stenting of his PV, with improvement in his exercise capacity and PH. Follow-up imaging showed improved pulmonary blood flow and reduced pulmonary pressures. CONCLUSIONS We conclude that PV stenosis should be high in the differential as the cause of dyspnea in patients with PH and a previous history of RFA for AF management. Early recognition and treatment can prevent complete occlusion of the affected PV and lead to an improvement in the patient's symptoms and quality of life.

  View details for DOI 10.12659/AJCR.924709

  View details for PubMedID 32844783

• Extended cardiac ambulatory rhythm monitoring in adults with congenital heart disease: Arrhythmia detection and impact of extended monitoring CONGENITAL HEART DISEASE Schultz, K. E., Lui, G. K., McElhinney, D. B., Long, J., Balasubramanian, V., Sakarovitch, C., Fernandes, S. M., Dubin, A. M., Rogers, I. S., Romfh, A. W., Motonaga, K. S., Viswanathan, M. N., Ceresnak, S. R. 2019; 14 (3): 410–18

  View details for DOI 10.1111/chd.12736

  View details for Web of Science ID 000471070900013

• Effect of Catheter Ablation vs Medical Therapy on Quality of Life Among Patients With Atrial Fibrillation The CABANA Randomized Clinical Trial JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Mark, D. B., Anstrom, K. J., Sheng, S., Piccini, J. P., Baloch, K. N., Monahan, K. H., Daniels, M. R., Bahnson, T. D., Poole, J. E., Rosenberg, Y., Lee, K. L., Packer, D. L., Robb, R. A., Rettmann, M. E., Martinez, B., Mascette, A., Jeffries, N., Mitchell, L., Flaker, G. G., Al-Khalidi, H. R., Silverstein, A., Ellis, A., Ussery, S. A., Moretz, K. L., Hagen, S., Anstrom, K., Baloch, K., Liu, D. M., Blount, J., Cowper, P., Knight, D., O'Neal, E. F., Holmes, D. R., Breen, J., Wilber, D., Reiffel, J., Kowey, P., Naccarelli, G., DiMarco, J. P., Davies, D., Cappato, R., Kalman, J. M., Kuck, K., Hindricks, G., Calkins, H., Stevenson, W. G., Buxton, A., Curtis, A. B., Davis, B. R., Ulrich, C. M., Lazzara, R., Peters, T., Bunch, J. T., Daubert, J., Halperin, B., Holshouser, J., Kutalek, S., Michaud, G., Mounsey, P., Wyse, G., Flaker, G., Bell, R., Greenspon, A., Logan, W., Sahota, P., Singh, N., Calkins, H., Schilling, R., Verma, A., Bahnson, T., DeVille, B., Monahan, K., DiMarco, J., Naccarelli, G., Gonzalez, M., Monahan, K., Poole, J., Patton, K., Prutkin, J., Johnson, G., Akoum, N., Auokar, P., Blatt, J., Birgersdotter-Green, U., Cha, Y., Mulpuru, S., Noseworthy, P., Chung, M., Gleva, M., Glotzer, T., Henrikson, C., Stecker, E., Kanjwal, Y., Kron, J., Kuriachan, V., Obel, O., Ranjan, R., Rho, R., Russo, A., Sullivan, R., Tzou, W., van der Zee, S., Serdoz, L., Wilson, M., Bowen, W., Pokushalov, E., Romanov, A., Meshalkin, E., Bunch, T., Bahnson, T., Noelker, G., Packer, D., Hindricks, G., Ardashev, A., Revishvili, A., Matsonashvili, G., Vijayaraman, P., Ince, H., Piorkowski, C., Neumann, T., Veenhuyzen, G., Gehi, A., Wilber, D., Sogade, F., Pappone, C., Berman, A., Shalaby, A., Kuck, K., Halperin, B., Tholakanahalli, V., Palma, E., Holshouser, J., Badhwar, N., Rashid, H., Cameron, C., Hummel, J., Saavedra, P., Deville, B., Chun, J., Roman-Gonzalez, J., Willems, S., Garan, H., Crespo, E., Cheung, P., Groenefeld, G., Schuger, C., Salam, T., Yang, Y., Pappone, C., Wichterle, D., Brachmann, J., Kautzner, J., Jayachandran, J., Kim, Y., Cole, C., Herweg, B., Lowe, M., Dougherty, A., Popov, S., Lowe, M., Spitzer, S., Bernstein, R., Simonson, J., Buch, E., Wu, S., Khan, M., Shinn, T., Neuzil, P., Mangrum, J., Calkins, H., Gonzalez, M., Mansour, M., Zabel, M., Kalman, J., Sanchez, J., Rothman, S., Bhandari, A., Tracy, C., Mitrani, R., Vorperian, V., Connelly, D., Wells, D., Ma, C., Verma, A., Robinson, M., Rubenstein, D., Vanoli, E., Zhang, S., Cummings, J., Viswanathan, M., Monir, G., Marchlinski, F., Franklin, J., Koplan, B., Sanders, P., Rashba, E., Gallagher, M., Gonska, B., Chen, M., Leong-Sit, P., Zimmerman, J., Pezeshkian, N., Cohen, A., Kalvaitis, S., Davies, D., Borggrefe, M., Pak, H., Russo, A., Henrikson, C., Greer, G., Coromilas, J., Khairallah, F., Sosa-Suarez, G., Lindsay, B., Fisher, W., Bailin, S., Tran, A., Starek, Z., Preminger, M., Sheppard, R., Costea, A., Ellenbogen, K., Arentz, T., De Ponti, R., Aleong, R., Colley, B., Baig, K., Krishnan, K., Menon, S., Simmons, T., Bruce, G., Chinitz, L., Natale, A., Cappato, R., CABANA Investigators, CABANA Rhythm Monitoring, Clinical Site Principal Investigat 2019; 321 (13): 1275–85

  Abstract

  Catheter ablation is more effective than drug therapy in restoring sinus rhythm in patients with atrial fibrillation (AF), but its incremental effect on long-term quality of life (QOL) is uncertain.To determine whether catheter ablation is more beneficial than conventional drug therapy for improving QOL in patients with AF.An open-label randomized clinical trial of catheter ablation vs drug therapy in 2204 symptomatic patients with AF older than 65 years or 65 years or younger with at least 1 risk factor for stroke. Patients were enrolled from November 2009 to April 2016 from 126 centers in 10 countries. Follow-up ended in December 2017.Pulmonary vein isolation, with additional ablation procedures at the discretion of the investigators, for the catheter ablation group (n = 1108) and standard rhythm and/or rate-control drugs selected and managed by investigators for the drug therapy group (n = 1096).Prespecified co-primary QOL end points at 12 months, including the Atrial Fibrillation Effect on Quality of Life (AFEQT) summary score (range, 0-100; 0 indicates complete disability and 100 indicates no disability; patient-level clinically important difference, ≥5 points) and the Mayo AF-Specific Symptom Inventory (MAFSI) frequency score (range, 0-40; 0 indicates no symptoms and 40 indicates the most severe symptoms; patient-level clinically important difference, ≤-1.6 points) and severity score (range, 0-30; 0 indicates no symptoms and 30 indicates the most severe symptoms; patient-level clinically important difference, ≤-1.3 points).Among 2204 randomized patients (median age, 68 years; 1385 patients [63%] were men, 946 [43%] had paroxysmal AF, and 1256 [57%] had persistent AF), the median follow-up was 48.5 months, and 1968 (89%) completed the trial. The mean AFEQT summary score was more favorable in the catheter ablation group than the drug therapy group at 12 months (86.4 points vs 80.9 points) (adjusted difference, 5.3 points [95% CI, 3.7-6.9]; P < .001). The mean MAFSI frequency score was more favorable for the catheter ablation group than the drug therapy group at 12 months (6.4 points vs 8.1 points) (adjusted difference, -1.7 points [95% CI, -2.3 to -1.2]; P < .001) and the mean MAFSI severity score was more favorable for the catheter ablation group than the drug therapy group at 12 months (5.0 points vs 6.5 points) (adjusted difference, -1.5 points [95% CI, -2.0 to -1.1]; P < .001).Among patients with symptomatic atrial fibrillation, catheter ablation, compared with medical therapy, led to clinically important and significant improvements in quality of life at 12 months. These findings can help guide decisions regarding management of atrial fibrillation.ClinicalTrials.gov Identifier: NCT00911508.

  View details for DOI 10.1001/jama.2019.0692

  View details for Web of Science ID 000463076800014

  View details for PubMedID 30874716

• Year in Review in Cardiac Electrophysiology. Circulation. Arrhythmia and electrophysiology Tzou, W. S., Hussein, A. A., Madhavan, M., Viswanathan, M. N., Steinberg, B. A., Ceresnak, S. R., Davis, D. R., Park, D. S., Wang, P. J., Kapa, S. 2019; 12 (2): e007142

  View details for PubMedID 30744401

• Year in Review in Cardiac Electrophysiology CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY Tzou, W. S., Hussein, A. A., Madhavan, M., Viswanathan, M. N., Steinberg, B. A., Ceresnak, S. R., Davis, D. R., Park, D. S., Wang, P. J., Kapa, S. 2019; 12 (2)

  View details for DOI 10.1161/CIRCEP.118.007142

  View details for Web of Science ID 000459028300007

• Extended cardiac ambulatory rhythm monitoring in adults with congenital heart disease: Arrhythmia detection and impact of extended monitoring. Congenital heart disease Schultz, K. E., Lui, G. K., McElhinney, D. B., Long, J., Balasubramanian, V., Sakarovitch, C., Fernandes, S. M., Dubin, A. M., Rogers, I. S., Romfh, A. W., Motonaga, K. S., Viswanathan, M. N., Ceresnak, S. R. 2019

  Abstract

  BACKGROUND: Arrhythmias are a leading cause of death in adults with congenital heart disease (ACHD). While 24-48-hour monitors are often used to assess arrhythmia burden, extended continuous ambulatory rhythm monitors (ECAM) can record 2 weeks of data. The utility of this device and the arrhythmia burden identified beyond 48-hour monitoring have not been evaluated in the ACHD population. Additionally, the impact of ECAM has not been studied to determine management recommendations.OBJECTIVE: To address the preliminary question, we hypothesized that clinically significant arrhythmias would be detected on ECAM beyond 48hours and this would lead to clinical management changes.METHODS: A single center retrospective cohort study of ACHD patients undergoing ECAM from June 2013 to May 2016 was performed. The number and type of arrhythmias detected within and beyond the first 48hours of monitoring were compared using Kaplan-Meier curves and Cox proportional hazard models.RESULTS: Three hundred fourteen patients had monitors performed [median age 31 (IQR 25-41) years, 61% female). Significant arrhythmias were identified in 156 patients (50%), of which 46% were noted within 48 hours. A management change based on an arrhythmia was made in 49 patients (16%).CONCLUSIONS: ECAM detects more clinically significant arrhythmias than standard 48-hour monitoring in ACHD patients. Management changes, including medication changes, further testing or imaging, and procedures, were made based on results of ECAM. Recommendations and guidelines have been made based on arrhythmias on 48-hour monitoring; the predictive ability and clinical consequence of arrhythmias found on ECAM are not yet known.

  View details for PubMedID 30604934

• AF Drivers Where Ablation Terminates Persistent AF Fluctuate Due to Competing Drivers but Remain Anchored in Specific Locations Meckler, G. L., Kowalewski, C. A., Rogers, A. J., Rodrigo, M., Clopton, P., Shenasa, F., Alhusseini, M., Swerdlow, M., Joshi, V., Hossainy, S., Zaman, J., Baykaner, T., Brachmann, J., Miller, J., Krummen, D. E., Sauer, W., Viswanathan, M., Wang, P., Narayan, S. M. LIPPINCOTT WILLIAMS & WILKINS. 2018

  View details for Web of Science ID 000528619407352

• Comparing Multiple Mapping Methods at Sites of AF Termination: The COMPARE-AF Registry. Zaman, J. A., Baykaner, T., Meckler, G., Clopton, P., Alhusseini, M., Shenasa, F., Kowalewski, C., Rogers, A., Vidmar, D., Krummen, D., Viswanathan, M., Rappel, W., Brachmann, J., Peters, N., Miller, J., Wang, P., Sauer, W., Atienza, F., Narayan, S. LIPPINCOTT WILLIAMS & WILKINS. 2018

  View details for Web of Science ID 000528619405012

• Machine Learning Reveals That Drivers for Persistent Atrial Fibrillation at Termination Sites Show Irregular Rotational Cycles and Domain Size Alhusseini, M., Abuzaid, F., Swerdlow, M., Clopton, P., Meckler, G. L., Maniar, N. M., Rogers, A., Rodrigo, M., Baykaner, T., Zaman, J., Kowalewski, C., Shenasa, F., Tamboli, M., Viswanathan, M., Wang, P., Atienza, F., Rappel, W. J., Bailis, P., Zaharia, M., Narayan, S. M. LIPPINCOTT WILLIAMS & WILKINS. 2018

  View details for Web of Science ID 000528619404020

• Rotor Substrate Ablation for Antiarrhythmic-Refractory Ventricular Fibrillation With Infrequent, Multifocal Triggers Krummen, D. E., Ho, G., Hoffmayer, K. S., Schweis, F., Bradshaw, A., Baykaner, T., Wang, P. J., Viswanathan, M. N., Rappel, W., Narayan, S. M. LIPPINCOTT WILLIAMS & WILKINS. 2018

  View details for Web of Science ID 000528619404256

• Year in Review in Cardiac Electrophysiology. Circulation. Arrhythmia and electrophysiology Kapa, S., Davis, D. R., Park, D. S., Steinberg, B. A., Viswanathan, M. N., Tzou, W., Madhavan, M., Ceresnak, S. R., Wang, P. J. 2018; 11 (7): e006648

  View details for PubMedID 30012874

• Year in Review in Cardiac Electrophysiology CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY Kapa, S., Davis, D. R., Park, D. S., Steinberg, B. A., Viswanathan, M. N., Tzou, W., Madhavan, M., Ceresnak, S. R., Wang, P. J. 2018; 11 (7)

  View details for DOI 10.1161/CIRCEP.118.006648

  View details for Web of Science ID 000438922000016

• Independent mapping methods reveal rotational activation near pulmonary veins where atrial fibrillation terminates before pulmonary vein isolation JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY Navara, R., Leef, G., Shenasa, F., Kowalewski, C., Rogers, A. J., Meckler, G., Zaman, J. B., Baykaner, T., Park, S., Turakhia, M. P., Zei, P., Viswanathan, M., Wang, P. J., Narayan, S. M. 2018; 29 (5): 687–95

  View details for DOI 10.1111/jce.13446

  View details for Web of Science ID 000433580000005

• Clinical Implications of Ablation of Drivers for Atrial Fibrillation A Systematic Review and Meta-Analysis CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY Baykaner, T., Rogers, A. J., Meckler, G. L., Zaman, J., Navara, R., Rodrigo, M., Alhusseini, M., Kowalewski, C. B., Viswanathan, M. N., Narayan, S. M., Clopton, P., Wang, P. J., Heidenreich, P. A. 2018; 11 (5)

  View details for DOI 10.1161/CIRCEP.117.006119

  View details for Web of Science ID 000439150300011

• CAVOTRICUSPID ISTHMUS ABLATION FOR TREATMENT OF RECURRENT ATRIAL TACHYARRHYTHMIA IN PATIENT WITH DRUG-INDUCED TORSADE DE POINTES AND SEVERE SYSTOLIC HEART FAILURE Rogers, A., Viswanathan, M. ELSEVIER SCIENCE INC. 2018: 2565

  View details for DOI 10.1016/S0735-1097(18)33106-1

  View details for Web of Science ID 000429659705015

• Independent mapping methods reveal rotational activation near pulmonary veins where atrial fibrillation terminates before pulmonary vein isolation. Journal of cardiovascular electrophysiology Navara, R., Leef, G., Shenasa, F., Kowalewski, C., Rogers, A. J., Meckler, G., Zaman, J. A., Baykaner, T., Park, S., Turakhia, M. P., Zei, P., Viswanathan, M., Wang, P. J., Narayan, S. M. 2018

  Abstract

  OBJECTIVE: To investigate mechanisms by which atrial fibrillation (AF) may terminate during ablation near the pulmonary veins before the veins are isolated (PVI).INTRODUCTION: It remains unstudied how AF may terminate during ablation before PVs are isolated, or how patients with PV reconnection can be arrhythmia-free. We studied patients in whom PV antral ablation terminated AF before PVI, using two independent mapping methods.METHODS: We studied patients with AF referred for ablation, in whom biatrial contact basket electrograms were studied by both an activation/phase mapping method and by a second validated mapping method reported not to create false rotational activity.RESULTS: In 22 patients (age 60.1 ± 10.4, 36% persistent AF), ablation at sites near the PVs terminated AF (77% to sinus rhythm) prior to PVI. AF propagation revealed rotational (n=20) and focal (n=2) patterns at sites of termination by mapping method 1 and method 2. Both methods showed organized sites that were spatially concordant (P<0.001) with similar stability (P<0.001). Vagal slowing was not observed at sites of AF termination.DISCUSSION: PV antral regions where ablation terminated AF before PVI exhibited rotational and focal activation by two independent mapping methods. These data provide an alternative mechanism for the success of PVI, and may explain AF termination before PVI or lack of arrhythmias despite PV reconnection. Mapping such sites may enable targeted PV lesion sets and improved freedom from AF.

  View details for PubMedID 29377478

• Clinical Implications of Ablation of Drivers for Atrial Fibrillation: A Systematic Review and Meta-Analysis. Circulation. Arrhythmia and electrophysiology Baykaner, T. n., Rogers, A. J., Meckler, G. L., Zaman, J. n., Navara, R. n., Rodrigo, M. n., Alhusseini, M. n., Kowalewski, C. A., Viswanathan, M. N., Narayan, S. M., Clopton, P. n., Wang, P. J., Heidenreich, P. A. 2018; 11 (5): e006119

  Abstract

  The outcomes from pulmonary vein isolation (PVI) for atrial fibrillation (AF) are suboptimal, but the benefits of additional lesion sets remain unproven. Recent studies propose ablation of AF drivers improves outcomes over PVI, yet with conflicting reports in the literature. We undertook a systematic literature review and meta-analysis to determine outcomes from ablation of AF drivers in addition to PVI or as a stand-alone procedure.Database search was done using the terms atrial fibrillation and ablation or catheter ablation and driver or rotor or focal impulse or FIRM (Focal Impulse and Rotor Modulation). We pooled data using random effects model and assessed heterogeneity with I2 statistic.Seventeen studies met inclusion criteria, in a cohort size of 3294 patients. Adding AF driver ablation to PVI reported freedom from AF of 72.5% (confidence interval [CI], 62.1%-81.8%; P<0.01) and from all arrhythmias of 57.8% (CI, 47.5%-67.7%; P<0.01). AF driver ablation when added to PVI or as stand-alone procedure compared with controls produced an odds ratio of 3.1 (CI, 1.3-7.7; P=0.02) for freedom from AF and an odds ratio of 1.8 (CI, 1.2-2.7; P<0.01) for freedom from all arrhythmias in 4 controlled studies. AF termination rate was 40.5% (CI, 30.6%-50.9%) and predicted favorable outcome from ablation(P<0.05).In controlled studies, the addition of AF driver ablation to PVI supports the possible benefit of a combined approach of AF driver ablation and PVI in improving single-procedure freedom from all arrhythmias. However, most studies are uncontrolled and are limited by substantial heterogeneity in outcomes. Large multicenter randomized trials are needed to precisely define the benefits of adding driver ablation to PVI.

  View details for PubMedID 29743170

• Identification and Characterization of Sites Where Persistent Atrial Fibrillation Is Terminated by Localized Ablation CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY Zaman, J. B., Sauer, W. H., Alhusseini, M. I., Baykaner, T., Borne, R. T., Kowalewski, C. B., Busch, S., Zei, P. C., Park, S., Viswanathan, M. N., Wang, P. J., Brachmann, J., Krummen, D. E., Miller, J. M., Rappel, W., Narayan, S. M., Peters, N. S. 2018; 11 (1): e005258

  Abstract

  The mechanisms by which persistent atrial fibrillation (AF) terminates via localized ablation are not well understood. To address the hypothesis that sites where localized ablation terminates persistent AF have characteristics identifiable with activation mapping during AF, we systematically examined activation patterns acquired only in cases of unequivocal termination by ablation.We recruited 57 patients with persistent AF undergoing ablation, in whom localized ablation terminated AF to sinus rhythm or organized tachycardia. For each site, we performed an offline analysis of unprocessed unipolar electrograms collected during AF from multipolar basket catheters using the maximum -dV/dt assignment to construct isochronal activation maps for multiple cycles. Additional computational modeling and phase analysis were used to study mechanisms of map variability. At all sites of AF termination, localized repetitive activation patterns were observed. Partial rotational circuits were observed in 26 of 57 (46%) cases, focal patterns in 19 of 57 (33%), and complete rotational activity in 12 of 57 (21%) cases. In computer simulations, incomplete segments of partial rotations coincided with areas of slow conduction characterized by complex, multicomponent electrograms, and variations in assigning activation times at such sites substantially altered mapped mechanisms.Local activation mapping at sites of termination of persistent AF showed repetitive patterns of rotational or focal activity. In computer simulations, complete rotational activation sequence was observed but was sensitive to assignment of activation timing particularly in segments of slow conduction. The observed phenomena of repetitive localized activation and the mechanism by which local ablation terminates putative AF drivers require further investigation.

  View details for PubMedID 29330332

  View details for PubMedCentralID PMC5769709

• Radiation Safety in Children with Congenital and Acquired Heart Disease: A Scientific Position Statement on Multimodality Dose Optimization from the Image Gently Alliance. JACC. Cardiovascular imaging Hill, K. D., Frush, D. P., Han, B. K., Abbott, B. G., Armstrong, A. K., deKemp, R. A., Glatz, A. C., Greenberg, S. B., Herbert, A. S., Justino, H., Mah, D., Mahesh, M., Rigsby, C. K., Slesnick, T. C., Strauss, K. J., Trattner, S., Viswanathan, M. N., Einstein, A. J. 2017

  Abstract

  There is a need for consensus recommendations for ionizing radiation dose optimization during multi-modality medical imaging in children with congenital and acquired heart disease (CAHD). These children often have complex diseases and may be exposed to a relatively high cumulative burden of ionizing radiation from medical imaging procedures including cardiac computed tomography, nuclear cardiology studies and fluoroscopically guided diagnostic and interventional catheterization and electrophysiology procedures. Although these imaging procedures are all essential to the care of children with CAHD and have contributed to meaningfully improved outcomes in these patients, exposure to ionizing radiation is associated with potential risks, including an increased lifetime attributable risk of cancer. The goal of these recommendations is to encourage informed imaging to achieve appropriate study quality at the lowest achievable dose. Other strategies to improve care include a patient-centered approach to imaging, emphasizing education and informed decision making and programmatic approaches to ensure appropriate dose monitoring. Looking ahead, there is a need for standardization of dose metrics across imaging modalities, so as to encourage comparative effectiveness studies across the spectrum of CAHD in children.

  View details for DOI 10.1016/j.jcmg.2017.04.003

  View details for PubMedID 28514670

• Multicentre safety of adding Focal Impulse and Rotor Modulation (FIRM) to conventional ablation for atrial fibrillation. Europace Krummen, D. E., Baykaner, T., Schricker, A. A., Kowalewski, C. A., Swarup, V., Miller, J. M., Tomassoni, G. F., Park, S., Viswanathan, M. N., Wang, P. J., Narayan, S. M. 2017; 19 (5): 769-774

  Abstract

  Focal Impulse and Rotor Modulation (FIRM) uses 64-electrode basket catheters to identify atrial fibrillation (AF)-sustaining sites for ablation, with promising results in many studies. Accordingly, new basket designs are being tested by several groups. We set out to determine the procedural safety of adding basket mapping and map-guided ablation to conventional pulmonary vein isolation (PVI).We collected 30 day procedural safety data in five US centres for consecutive patients undergoing FIRM plus PVI (FIRM-PVI) compared with contemporaneous controls undergoing PVI without FIRM. A total of 625 cases were included in this analysis: 325 FIRM-PVI and 300 PVI-controls. FIRM-PVI patients were more likely than PVI-controls to be male (83% vs. 66%, P < 0.001) and have long-standing persistent AF (26% vs. 13%, P < 0.001) reflecting patients referred for FIRM. Total ablation time was greater for FIRM-PVI (62 ± 22 min) vs. PVI-controls (52 ± 18 min, P = 0.03). The complication rate for FIRM-PVI procedures (4.3%) was similar to controls (4.0%, P = 1) for both major and minor complications; no deaths were reported. The rate of complications potentially attributable to the basket catheter was small and did not differ between basket types (Constellation 2.8% vs. FIRMap 1.8%, P = 0.7) or between cases in which basket catheters were and were not used (P = 0.5). Complication rates did not differ between centres (P = 0.6).Procedural complications from the use of the basket catheters for AF mapping are low, and thus procedural safety appears similar between FIRM-PVI and PVI-controls in a large multicentre cohort. Future studies are required to determine the optimal approach to maximize the efficacy of FIRM-guided ablation.

  View details for DOI 10.1093/europace/euw377

  View details for PubMedID 28339546

• What Explains Atrial Fibrillation Mechanisms at Sites Where Ablation Terminates Persistent Atrial Fibrillation Prior to Pulmonary Vein Isolation? Navara, R., Meckler, G. L., Kowalewski, C. B., Shenasa, F., Baykaner, T., Zaman, U. B., Al-Husseini, M., Hossainy, S., Krummen, D., Brachmann, J., Viswanathan, M., Park, S., Turakhia, M., Wang, P. J., Narayan, S. M. WILEY. 2017: 607

  View details for Web of Science ID 000403296100063

• The precise timing of tachycardia entrainment is determined by the postpacing interval, the tachycardia cycle length, and the pacing rate: Theoretical insights and practical applications HEART RHYTHM Kaiser, D. W., Hsia, H. H., Dubin, A. M., Liem, L. B., Viswanathan, M. N., Zei, P. C., Wang, P. J., Narayan, S. M., Turakhia, M. P. 2016; 13 (3): 695-703

  Abstract

  Previous observations have reported that the number of pacing stimuli required to entrain a tachycardia varies on the basis of arrhythmia type and location, but a quantitative formulation of the number needed to entrain (NNE) that unifies these observations has not been characterized.We sought to investigate the relationship between the number of pacing stimulations, the tachycardia cycle length (TCL), the overdrive pacing cycle length (PCL), and the postpacing interval (PPI) to accurately estimate the timing of tachycardia entrainment.First, we detailed a mathematical derivation unifying electrophysiological parameters with empirical confirmation in 2 patients undergoing catheter ablation of typical atrial flutter. Second, we validated our formula in 44 patients who underwent various catheter ablation procedures. For accuracy, we corrected for rate-related changes in conduction velocity.We derived the equations NNE = |(PPI - TCL)/(TCL - PCL)| + 1 and Tachycardia advancement = (NNE - 1) × (TCL - PCL) - (PPI - TCL), which state that the NNE and the amount of tachycardia advancement on the first resetting stimulation are determined using regularly measured intracardiac parameters. In the retrospective cohort, the observed PPI - TCL highly correlated with the predicted PPI - TCL (mean difference 5.8 ms; r = 0.97; P < .001), calculated as PPI - TCL = (NNE - 1) × (TCL - PCL) - tachycardia advancement.The number of pacing stimulations required to entrain a reentrant tachycardia is predictable at any PCL after correcting for cycle length-dependent changes in conduction velocity. This relationship unifies established empirically derived diagnostic and mapping criteria for supraventricular tachycardia and ventricular tachycardia. This relationship may help elucidate when antitachycardia pacing episodes are ineffective or proarrhythmic and could potentially serve as a theoretical basis to customize antitachycardia pacing settings for improved safety and effectiveness.

  View details for DOI 10.1016/j.hrthm.2015.11.032

  View details for Web of Science ID 000372367800012

  View details for PubMedCentralID PMC4770895

• The precise timing of tachycardia entrainment is determined by the postpacing interval, the tachycardia cycle length, and the pacing rate: Theoretical insights and practical applications. Heart rhythm Kaiser, D. W., Hsia, H. H., Dubin, A. M., Liem, L. B., Viswanathan, M. N., Zei, P. C., Wang, P. J., Narayan, S. M., Turakhia, M. P. 2016; 13 (3): 695-703

  Abstract

  Previous observations have reported that the number of pacing stimuli required to entrain a tachycardia varies on the basis of arrhythmia type and location, but a quantitative formulation of the number needed to entrain (NNE) that unifies these observations has not been characterized.We sought to investigate the relationship between the number of pacing stimulations, the tachycardia cycle length (TCL), the overdrive pacing cycle length (PCL), and the postpacing interval (PPI) to accurately estimate the timing of tachycardia entrainment.First, we detailed a mathematical derivation unifying electrophysiological parameters with empirical confirmation in 2 patients undergoing catheter ablation of typical atrial flutter. Second, we validated our formula in 44 patients who underwent various catheter ablation procedures. For accuracy, we corrected for rate-related changes in conduction velocity.We derived the equations NNE = |(PPI - TCL)/(TCL - PCL)| + 1 and Tachycardia advancement = (NNE - 1) × (TCL - PCL) - (PPI - TCL), which state that the NNE and the amount of tachycardia advancement on the first resetting stimulation are determined using regularly measured intracardiac parameters. In the retrospective cohort, the observed PPI - TCL highly correlated with the predicted PPI - TCL (mean difference 5.8 ms; r = 0.97; P < .001), calculated as PPI - TCL = (NNE - 1) × (TCL - PCL) - tachycardia advancement.The number of pacing stimulations required to entrain a reentrant tachycardia is predictable at any PCL after correcting for cycle length-dependent changes in conduction velocity. This relationship unifies established empirically derived diagnostic and mapping criteria for supraventricular tachycardia and ventricular tachycardia. This relationship may help elucidate when antitachycardia pacing episodes are ineffective or proarrhythmic and could potentially serve as a theoretical basis to customize antitachycardia pacing settings for improved safety and effectiveness.

  View details for DOI 10.1016/j.hrthm.2015.11.032

  View details for PubMedID 26611239

• Right-sided subcutaneous implantable cardioverter-defibrillator placement in a patient with dextrocardia, tetralogy of Fallot, and conduction disease. HeartRhythm case reports Ceresnak, S. R., Motonaga, K. S., Rogers, I. S., Viswanathan, M. N. 2015; 1 (4): 186-189

  View details for DOI 10.1016/j.hrcr.2015.02.001

  View details for PubMedID 28491545

• Electrical Integration of Human Embryonic Stem Cell-Derived Cardiomyocytes in a Guinea Pig Chronic Infarct Model JOURNAL OF CARDIOVASCULAR PHARMACOLOGY AND THERAPEUTICS Shiba, Y., Filice, D., Fernandes, S., Minami, E., Dupras, S. K., Van Biber, B., Trinh, P., Hirota, Y., Gold, J. D., Viswanathan, M., Laflamme, M. A. 2014; 19 (4): 368-381

  Abstract

  Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) were recently shown to be capable of electromechanical integration following direct injection into intact or recently injured guinea pig hearts, and hESC-CM transplantation in recently injured hearts correlated with improvements in contractile function and a reduction in the incidence of arrhythmias. The present study was aimed at determining the ability of hESC-CMs to integrate and modulate electrical stability following transplantation in a chronic model of cardiac injury.At 28 days following cardiac cryoinjury, guinea pigs underwent intracardiac injection of hESC-CMs, noncardiac hESC derivatives (non-CMs), or vehicle. Histology confirmed partial remuscularization of the infarct zone in hESC-CM recipients while non-CM recipients showed heterogeneous xenografts. The 3 experimental groups showed no significant difference in the left ventricular dimensions or fractional shortening by echocardiography or in the incidence of spontaneous arrhythmias by telemetric monitoring. Although recipients of hESC-CMs and vehicle showed a similar incidence of arrhythmias induced by programmed electrical stimulation at 4 weeks posttransplantation, non-CM recipients proved to be highly inducible, with a ∼3-fold greater incidence of induced arrhythmias. In parallel studies, we investigated the ability of hESC-CMs to couple with host myocardium in chronically injured hearts by the intravital imaging of hESC-CM grafts that stably expressed a fluorescent reporter of graft activation, the genetically encoded calcium sensor GCaMP3. In this work, we found that only ∼38% (5 of 13) of recipients of GCaMP3+ hESC-CMs showed fluorescent transients that were coupled to the host electrocardiogram.Human embryonic stem cell-derived cardiomyocytes engraft in chronically injured hearts without increasing the incidence of arrhythmias, but their electromechanical integration is more limited than previously reported following their transplantation in a subacute injury model. Moreover, non-CM grafts may promote arrhythmias under certain conditions, a finding that underscores the need for input preparations of high cardiac purity.

  View details for DOI 10.1177/1074248413520344

  View details for Web of Science ID 000338394200006

  View details for PubMedCentralID PMC4127378

• Electrical Integration of Human Embryonic Stem Cell-Derived Cardiomyocytes in a Guinea Pig Chronic Infarct Model. Journal of cardiovascular pharmacology and therapeutics Shiba, Y., Filice, D., Fernandes, S., Minami, E., Dupras, S. K., Biber, B. V., Trinh, P., Hirota, Y., Gold, J. D., Viswanathan, M., Laflamme, M. A. 2014; 19 (4): 368-381

  Abstract

  Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) were recently shown to be capable of electromechanical integration following direct injection into intact or recently injured guinea pig hearts, and hESC-CM transplantation in recently injured hearts correlated with improvements in contractile function and a reduction in the incidence of arrhythmias. The present study was aimed at determining the ability of hESC-CMs to integrate and modulate electrical stability following transplantation in a chronic model of cardiac injury.At 28 days following cardiac cryoinjury, guinea pigs underwent intracardiac injection of hESC-CMs, noncardiac hESC derivatives (non-CMs), or vehicle. Histology confirmed partial remuscularization of the infarct zone in hESC-CM recipients while non-CM recipients showed heterogeneous xenografts. The 3 experimental groups showed no significant difference in the left ventricular dimensions or fractional shortening by echocardiography or in the incidence of spontaneous arrhythmias by telemetric monitoring. Although recipients of hESC-CMs and vehicle showed a similar incidence of arrhythmias induced by programmed electrical stimulation at 4 weeks posttransplantation, non-CM recipients proved to be highly inducible, with a ∼3-fold greater incidence of induced arrhythmias. In parallel studies, we investigated the ability of hESC-CMs to couple with host myocardium in chronically injured hearts by the intravital imaging of hESC-CM grafts that stably expressed a fluorescent reporter of graft activation, the genetically encoded calcium sensor GCaMP3. In this work, we found that only ∼38% (5 of 13) of recipients of GCaMP3+ hESC-CMs showed fluorescent transients that were coupled to the host electrocardiogram.Human embryonic stem cell-derived cardiomyocytes engraft in chronically injured hearts without increasing the incidence of arrhythmias, but their electromechanical integration is more limited than previously reported following their transplantation in a subacute injury model. Moreover, non-CM grafts may promote arrhythmias under certain conditions, a finding that underscores the need for input preparations of high cardiac purity.

  View details for DOI 10.1177/1074248413520344

  View details for PubMedID 24516260

  View details for PubMedCentralID PMC4127378