Gopi Dandamudi

Permanent His-bundle pacing is feasible, safe, and superior to right ventricular pacing in routine clinical practice

BACKGROUNDnRight ventricular pacing (RVP) has been associated with heart failure and increased mortality. His-bundle pacing (HBP) is more physiological but requires a mapping catheter or a backup right ventricular lead and is technically challenging.nnnOBJECTIVEnWe sought to assess the feasibility, safety, and clinical outcomes of permanent HBP in an unselected population as compared to RVP.nnnMETHODSnAll patients requiring pacemaker implantation routinely underwent attempt at permanent HBP using the Select Secure (model 3830) pacing lead in the year 2011 delivered through a fixed-shaped catheter (C315 HIS) at one hospital and RVP at the second hospital. Patients were followed from implantation, 2 weeks, 2 months, 1 year, and 2 years. Fluoroscopy time (FT), pacing threshold (PTh), complications, heart failure hospitalization, and mortality were compared.nnnRESULTSnHBP was attempted in 94 consecutive patients, while 98 patients underwent RVP. HBP was successful in 75 patients (80%). FT was similar (12.7 ± 8 minutes vs 10 ± 14 minutes; median 9.1 vs 6.4 minutes; P = .14) and PTh was higher in the HBP group than in the RVP group (1.35 ± 0.9 V vs 0.6 ± 0.5 V at 0.5 ms; P < .001) and remained stable over a 2-year follow-up period. In patients with >40% ventricular pacing (>60% of patients), heart failure hospitalization was significantly reduced in the HBP group than in the RVP group (2% vs 15%; P = .02). There was no difference in mortality between the 2 groups (13% in the HBP group vs 18% in the RVP group; P = .45).nnnCONCLUSIONnPermanent HBP without a mapping catheter or a backup right ventricular lead was successfully achieved in 80% of patients. PTh was higher and FT was comparable to those of the RVP group. Clinical outcomes were better in the HBP group than in the RVP group.

Electrophysiologic Insights Into Site of Atrioventricular Block: Lessons From Permanent His Bundle Pacing

OBJECTIVESnThis study sought to report the feasibility of permanent His bundle pacing (HBP) in patients with advanced atrioventricular block (AVB) and electrophysiological observations into site of block in patients with infranodal AVB.nnnBACKGROUNDnHBP is a physiological alternative to right ventricular pacing. Historic studies have reported a low incidence of intra-His AVB. Recent studies of permanent HBP reported limited success in patients with infranodal AVB.nnnMETHODSnConsecutive patients with advanced AVB underwent permanent HBP using Medtronic 3830 lead (Minneapolis, Minnesota) and a fixed-shaped catheter (C315 His). The HB was mapped using unipolar recording from thexa0lead tip or by pace mapping. Success of HBP, type of AVB, and pacing outcomes were documented. Patients were followed at 2 weeks, 2 months, and then yearly.nnnRESULTSnA total of 100 patients with advanced AVB (age 75 ± 12 years; male 62%; AV nodal 46%; infranodal 54%) underwent permanent HBP. HBP was successful in 84 patients (84%; AV nodal 93%, infranodal 76%). Mean procedure time was 71 ± 21 min, mean fluoroscopy time was 11 ± 6 min. Baseline QRS duration was 122 ± 27 ms; paced QRSdxa0was 124 ± 22 ms. The HB pacing threshold at implant, 2 weeks, 2 months, and last follow-up (19 ± 12 months; range: 6 toxa046 months) was 1.3 ± 0.9 V, 1.6 ± 1.0 V, 1.6 ± 1.1 V, and 1.7 ± 1.0 V at 0.5 ms, respectively. Five patients required lead revision.nnnCONCLUSIONSnPermanent HBP was successful in 84% of unselected patients with AVB. His-Purkinje conduction could be normalized in 76% of patients with infranodal block, suggesting intra-His block. Incidence of infra-His AVB was low (24%) in this series. Routine HBP in patients with AVB is feasible and safe for at least up to 18 months.

Assessment of exit block following pulmonary vein isolation: Far-field capture masquerading as entrance without exit block

BACKGROUNDnComplete electrical isolation of pulmonary veins (PVs) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of the patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block, and this may appear as persistent conduction from PV to left atrium (LA).nnnOBJECTIVEnTo facilitate accurate assessment of exit block.nnnMETHODSnTwenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block by using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed, pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs.nnnRESULTSnAll 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins: mean age 58 ± 9 years; paroxysmal atrial fibrillation 40%; hypertension 70%, diabetes mellitus 30%, coronary artery disease 15%; left ventricular ejection fraction 55% ± 10%; LA size 42 ± 11 mm. Despite entrance block, exit block was absent in only 16% of the PVs, suggesting persistent PV to LA conduction. FFC of LA appendage was noted in 38% of the left superior PVs. FFC of the superior vena cava was noted in 30% of the right superior PVs. The mean pacing threshold for FFC was 7 ± 4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block.nnnCONCLUSIONSnFFC of LA appendage or superior vena cava can masquerade as persistent PV to LA conduction. A careful assessment for PV capture at decreasing pacing output is essential to exclude FFC.

Imaging evaluation of implantation site of permanent direct His bundle pacing lead

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Three-Dimensional Printing for In Vivo Visualization of His Bundle Pacing Leads

-see front matter B 2014 Heart Rhythm Society. All rights reserved. the location of the DHBP lead with respect to the plane of the tricuspid valve (TV). We present a patient with DHBP and imaging visualization of the location of the pacing lead. A 42-year-old man with persistent atrial fibrillation, mildly reduced left ventricular function, and sinus and atrioventricular nodal dysfunction underwent a dual chamber pacemaker implantation using the Select Secure Medtronic 3830 ventricular lead with a Medtronic Select Site deflectable catheter (C304) by mapping the HB with unipolar recordings from the lead tip. DHBP was verified by showing that pacing produced an identical morphology of paced QRS to native QRS with an isoelectric interval between the pacing spike

Adenosine facilitates dormant conduction across cavotricuspid isthmus following catheter ablation.

Transvenous pacing leads have been implicated in tricuspid valve dysfunction, and our group has adopted routine use of His bundle pacing to mitigate this effect. Three-dimensional (3D) printing technology holds great promise for advancing medicine, but the high start-up costs can be a deterrent. Seeking confirmation of optimal lead placement relative to the tricuspid annulus, we used low-cost commercial and public domain technologies to generate 3D-printed hearts from selected patients with His bundle pacing leads. Our models successfully demonstrated that such lead placements avoided interference with the tricuspid valve apparatus in these cases. Future applications of 3D printing include facilitating research to minimize lead-valve interactions, understand complex cardiac anatomy, and plan complex surgical procedures.

Abstract 17180: Longitudinal Dissociation in the His Bundle: Persistent Bundle Branch Block Can be Corrected by Permanent His Bundle Pacing

BACKGROUNDnRecurrence of trans-isthmus conduction following catheter ablation of common right atrial flutter (AFL) has been reported to be as high as 15%-31% at 3 months with invasive follow-up. Intravenous adenosine has previously been shown to facilitate acute, transient reconnection of pulmonary veins following catheter ablation of atrial fibrillation.nnnOBJECTIVEnTo determine whether intravenous adenosine can facilitate dormant trans-isthmus conduction after achieving bidirectional conduction block (BDB) with catheter ablation.nnnMETHODSnThirty-two patients underwent radiofrequency catheter ablation of cavotricuspid isthmus (CTI) for common right AFL at 2 institutions. Once persistent BDB was achieved for 30 minutes and during isoproterenol infusion, 18 mg of intravenous adenosine was injected during coronary sinus pacing. Evidence for transient reconduction across the isthmus was observed. Additional ablation lesions were performed, and adenosine infusion was repeated to reassess for dormant conduction.nnnRESULTSnThirty-two (men 81%, hypertension 72%, coronary artery disease 15%, congestive heart failure 25%, diabetes mellitus 30%, left atrial size 42 ± 11 mm, left ventricular ejection fraction 51% ± 10%) patients underwent ablation of CTI. BDB was achieved in 30 of the 32 patients. Following adenosine infusion, transient reconduction was observed in 7 of the 30 patients (23%) for 10-45 seconds. Following additional ablation lesions, persistent BDB could be achieved in all 7 patients without evidence for reconduction with repeat adenosine infusion. During a mean follow-up of 19 ± 12 months, only 1 of 30 patients (3%) had clinical recurrence of AFL. None of the patients with transient reconduction after adenosine developed symptomatic recurrence of AFL.nnnCONCLUSIONSnAdenosine infusion can facilitate dormant conduction across CTI following catheter ablation. Persistent BDB can be achieved with additional ablation. Adenosine challenge with additional ablation may improve long-term clinical outcome.