Parikshit S. Sharma

Long-term clinical outcomes of focal impulse and rotor modulation for treatment of atrial fibrillation: A multicenter experience

BACKGROUND New approaches to ablation of atrial fibrillation (AF) include focal impulse and rotor modulation (FIRM). Studies of this technology with short-term follow-up have shown favorable outcomes. OBJECTIVE The purpose of this study was to characterize the long-term results of FIRM ablation in a cohort of patients treated at 2 academic medical centers. METHODS All FIRM-guided ablation procedures (n = 43) at UCLA Medical Center and Virginia Commonwealth University Medical Center performed between January 2012 and October 2013 were included for analysis. During AF, FIRM software constructed phase maps from unipolar atrial electrograms to identify putative AF sources. These sites were targeted for ablation, along with pulmonary vein isolation in 77% of patients. RESULTS AF was paroxysmal in 56%, and 67% had prior AF ablation. All patients had rotors identified (mean 2.6 ± 1.2 per patient, 77% in LA). Prespecified acute procedural end-point was achieved in 47% of patients (n = 20): AF termination in 4, organization in 7, >10% slowing of AF cycle length in 9. Acute complications occurred in 4 patients (9.3%). At 18 ± 7 months of follow-up, 37% were free from documented recurrent AF after a 3-month blanking period; 21% were free from documented atrial tachyarrhythmias and off antiarrhythmic drugs. Multivariate analysis did not reveal any significant predictors of AF recurrence, including pattern of AF, acute procedural success, or prior failed ablation. CONCLUSION Long-term clinical results after FIRM ablation in this cohort of patients showed poor efficacy, different from previously published studies. Randomized studies are needed to evaluate the efficacy and clinical utility of this ablation approach for treating AF.

Permanent His bundle pacing: Recommendations from a Multicenter His Bundle Pacing Collaborative Working Group for standardization of definitions, implant measurements, and follow-up

His bundle pacing (HBP) prevents ventricular dyssynchrony and its long-term consequences by preserving normal electrical activation of the ventricles. Since the original description of permanent HBP in 2000, the adoption of HBP has increased over the past several years. However, the reporting of procedural and clinical outcomes to date is not uniform. This article is a collaboration between several implanters with significant experience in HBP to establish a uniform set of definitions encompassing the different forms of HBP as well as define a standardized approach to gathering data end points to ensure consistency in reported outcomes.

Recruitment of bundle branches with permanent His bundle pacing in a patient with advanced conduction system disease: What is the mechanism?

Case report The patient was a 69-year-old man with coronary artery disease who presented with syncope. His electrocardiogram showed sinus rhythm with a first-degree atrioventricular block, right bundle branch block (RBBB), and left anterior fascicular block (LAFB), and he was referred for an electrophysiology (EP) study. Baseline electrograms suggested intra-Hisian conduction disease, with split His potentials, H0 and H, and an intra-Hisian interval of 78 ms (Figure 1A). It was difficult to maintain His catheter stability during the EP study, and only the distal His signal (H) was consistent, with an His-ventricular (HV) interval of 70 ms (Figure 1A). Decremental atrial pacing demonstrated progressive raterelated HV prolongation up to 280 ms, beyond which HV Wenckebach block occurred (Figure 1B). No arrhythmias were induced with programmed atrial or ventricular stimulation. Given the evidence of infranodal AV conduction disease with probable intra-Hisian disease, we decided to implant a pacemaker. Pacing from the proximal His bundle (HB) position with the His catheter resulted in a wide QRS complex (duration 164 ms) with RBBB/LAFB and a long stimulus-QRS interval, whereas pacing at the distal HB resulted in a narrower QRS using a pacing output of 5 mA at 2 ms (threshold). Given narrowing of the QRS with distal

Permanent His-bundle pacing in patients with prosthetic cardiac valves

BACKGROUND Conduction disease is not uncommon after prosthetic valve (PV) surgery. The feasibility of His-bundle pacing (HBP) in this patient population is not well studied. OBJECTIVE The purpose of this study was to report our experience with permanent HBP in patients undergoing pacemaker implantation after PV surgery. METHODS Permanent HBP was attempted in patients with AV conduction disease after PV surgery referred for pacemaker implantation. Conduction disease was characterized as AV nodal vs infranodal. Feasibility, relationship of HBP lead to PVs, and HBP characteristics were recorded. RESULTS Thirty patients (47% men, age 74 ± 12 years, left ventricular ejection fraction 49% ± 11%) with AV conduction disease (100% patients; 14 with infranodal block; right bundle branch block 9, left bundle branch block 5, intraventricular conduction delay 1) underwent HBP. PVs included aortic valve replacement (AVR) in 8 patients (infranodal block 6 patients), tricuspid valve (TV) ring with mitral valve replacement or repair (MVR) in 10 patients (AV nodal block 9 patients), transcatheter aortic valve replacement (TAVR) in 4 patients (infranodal block 4 patients), and MVR alone in 6 patients. HBP was successful in 28 patients (93%) (selective HBP 50%). His bundle (HB) recruitment was unsuccessful in 2 patients with TAVR. AVR/TAVR and TV ring served as anatomic landmarks for localizing the HB. Successful sites of HBP were posterior and inferior to AVR/TAVR and distal and septal to the TV ring. Baseline QRSd improved from 124 ± 32 ms to 118 ± 20 ms (P = .39). HBP threshold at implant was 1.45 ± 1 V at 1 ms. CONCLUSION Permanent HBP was feasible in 93% of patients with PVs. Patients with AVR/TAVR predominantly developed infranodal block compared to AV nodal block in patients with TV ring/MVR. Location of PV might serve as a landmark for identifying the site of the HB.

Permanent His Bundle Pacing: The Past, Present and Future

Long‐term right ventricular (RV) apical pacing has been associated with an increased risk of death, heart failure, and atrial fibrillation (AF). Alternative sites for RV pacing have not proven to be superior to RV apical pacing. Cardiac resynchronization therapy (CRT) using a biventricular (BiV) lead system is indicated for patients with a low left ventricular ejection fraction and QRS prolongation, but there remains about a 25–30% nonresponse rate. CRT has been less effective for nonleft bundle branch block conduction delay and with normal/low normal left ventricular function. Over the past decade, there have been more data on the feasibility and advantages of pacing at the His Bundle (HB) region. We review the anatomy and physiology of the HB, the available data on permanent HB pacing, its current and potential future applications.

Permanent His Bundle Pacing: Long-Term Lead Performance and Clinical Outcomes

BACKGROUND Right ventricular pacing (RVP) is associated with heart failure and increased mortality. His-bundle pacing (HBP) is a physiological alternative to RVP. OBJECTIVE The purpose of this study was to report long-term performance and compare the clinical outcomes of permanent HBP vs RVP. METHODS All patients requiring pacemaker implantation underwent an attempt at permanent HBP in 2011 at one hospital and RVP at the sister hospital. Patients were followed from implantation, 2 weeks, 2 months, and yearly for 5 years. Left ventricular ejection fraction (LVEF), pacing thresholds, lead revision, and generator change were tracked. Primary outcome was the combined endpoint of death or heart failure hospitalization (HFH) at 5 years. RESULTS HBP was attempted in 94 consecutive patients and was successful in 75 (80%); 98 patients underwent RVP. LVEF remained unchanged in the HBP group (55% ± 8% vs 57% ± 6%; P = .13), whereas significant decline was noted in the RVP group (57% ± 7% vs 52% ± 11%; P = .002). Incidence of pacing-induced cardiomyopathy was significantly lower in HBP compared to RVP patients (2% vs 22%; P = .04). At 5 years, death or HFH was significantly lower in HBP compared to RVP patients with >40% ventricular pacing (32% vs 53%; hazard ratio 1.9; P = .04). At 5 years, the need for lead revisions (6.7% vs 3%) and for generator change (9% vs 1%) were higher in the HBP group. CONCLUSION In patients undergoing pacemaker implantation, permanent HBP was associated with reduction in death or HFH during long-term follow-up compared to RVP. HBP was associated with higher rates of lead revisions and generator change.

Vascular Complications During Catheter Ablation of Cardiac Arrhythmias: A Comparison Between Vascular Ultrasound Guided Access and Conventional Vascular Access.

Vascular access related complications are the most common complications from catheter based EP procedures and have been reported to occur in 1–13% of cases. We prospectively assessed vascular complications in a large series of consecutive patients undergoing catheter based electrophysiologic (EP) procedures with ultrasound (US) guided vascular access versus conventional access.

Overcoming left bundle branch block by permanent His bundle pacing: Evidence of longitudinal dissociation in the His via recordings from a permanent pacing lead

Introduction Narrowing of the QRS and overcoming left bundle branch block (LBBB) with His bundle pacing (HBP) has been previously described. We present the first 2 reported cases of left bundle branch (LBB) delay with evidence of a split His electrogram during unipolar mapping from the tip of the His bundle (HB) lead during pacemaker implantation. These findings suggest that the site of LBB delay is intraHisian, thus further validating the theory of “longitudinal dissociation in the HB.”

Interconnections between Left Atrial Ganglionic Plexi: Insights from Minimally Invasive Maze Procedures and Their Outcomes

Ganglionic plexi (GPs) have been implicated as triggers of atrial fibrillation (AF) and are known to have functional interconnections. Understanding these connections could result in a more effective ablation. The objective of this study is to assess relationships between right‐ and left‐sided GPs in patients undergoing mini‐maze (MM) surgery. We also analyzed the impact of these findings on AF recurrence.

Factors Influencing Diaphragmatic Compound Motor Action Potentials During Cryoballoon Ablation for Atrial Fibrillation.

The diaphragmatic compound motor action potentials (CMAPs) have been used to predict and prevent phrenic nerve injury (PNI) during cryoballoon ablation of right pulmonary veins. We sought to assess factors that influence the amplitude of the surface CMAP recordings.