Pacing For Atrioventricular Block Research Articles

Short Term Outcomes with Dual Chamber Pacing versus Single Chamber Ventricular Pacing for Atrioventricular Block - A Randomized Controlled Crossover Trial

Short Term Outcomes with Dual Chamber Pacing versus Single Chamber Ventricular Pacing for Atrioventricular Block - A Randomized Controlled Crossover Trial

Spontaneous Restoration of Sinus Rhythm during Heart Transplantation is Associated with a Reduced Incidence of Primary Graft Dysfunction and Early Mortality

Insults to the donor heart during heart transplantation (HT) include ischemia and reperfusion injury after release of the aortic cross-clamp in the recipient. Restoration of heart beat after aortic unclamping can be by spontaneous resumption of sinus rhythm, pacing for atrioventricular (AV) block, or direct-current (DC) cardioversion for ventricular fibrillation. We investigated the association between mode of heart beat restoration and primary graft dysfunction (PGD). HT recipients between 1997-2017 were grouped by mode of heart beat restoration after aortic unclamping into: spontaneous (S; 126 pts), pacing (P; 17 pts) or DC (58 pts) groups. Endpoints were 30-day mortality and PGD (defined by the ISHLT consensus statement). Baseline characteristics differing among the groups included proportion of women, pre-HT amiodarone and gender mismatch (Table). PGD was significantly higher for the P-group (71%) >DC-group (59%) >S-group (21%, p<0.001). Multivariable analysis consistently showed that restoration of sinus by DC, and pacing for AV block, were independently associated with significant ∼5-fold and ∼10-fold increased risk for PGD, respectively (Figure) compared to spontaneous sinus restoration. Consistently, 30-day mortality was significantly lower for S- (6%) than for DC- (17%) patients and highest for the P group (22%, p<0.001). Spontaneous restoration of sinus after aortic unclamping at HT is associated with a reduced risk for PGD and early mortality, whereas pacing for AV block and DC are associated with an increased risk.

P6017Permanent left bundle branch area pacing for atrioventricular block: feasibility, safety and acute effect

Abstract Background Left bundle branch area pacing (LBBAP), lacks adequate evaluation for AVB. Purpose We aimed to assess the feasibility, safety, and acute clinical outcomes of permanent LBBAP in patients with AVB. Methods We retrospectively recruited AVB patients with indication for ventricular pacing who had underwent LBBAP from May to Sep. 2018. ECG characteristics, pacing parameters, echocardiographic parameters and adverse events were evaluated during follow-up. Successful LBBAP was defined as the paced QRS morphology of RBBB pattern and QRSd less than 130ms. Results A total of 33 patients were involved in this study (mean age: 55.1±18.5 years; 66.7% male, 48.4% with bundle branch block,BBB). LBBAP was successfully performed in 90.9% (30/33) of all patients. The mean capture threshold of LBBAP was 0.76±0.26 V/0.4 ms during the procedure and 0.64±0.20 V/0.4ms at 3-month follow-up. The paced QRSd was 112.8±10.9 ms during the procedure and 116.8±10.4ms at 3-month follow-up. Baseline left or right BBB was corrected by LBBAP (153.3±27.8 ms vs. 122.2±9.9 ms) with a success rate of 68.7% (11/16). One ventricular septal lead perforation occurred soon after the procedure and LBBAP was successfully repeated by lead revision. Cardiac function and left ventricular synchronization at three-month follow-up presented slightly improvement as compared with baseline. Table 1. Complications and changes in pacing parameters within 3 months after LBBAP Pacing parameters LBBAP (N=30) During the procedure Before discharge 3-month follow up Sensing amplitude, mV 14.4±5.1 15.8±11.7 14.6±4.6 Pacing threshold@0.4ms, V 0.76±0.26 0.59±0.16 0.64±0.20 Pacing impedance, Ω 691.7±133.8 588.0±79.3 554.7±93.7 Paced QRSd at 3.0V@0.4 ms output, ms 112.8±10.9 114.4±14.2 116.8±10.4 VP, % NA NA 79.4±24.6 Complications, n (%) 1 (3.3) 0 (0.0) 0 (0.0) Infection, n (%) 0 (0.0) 0 (0.0) 0 (0.0) Septal perforation, n (%) 1 (3.3) 0 (0.0) 0 (0.0) Dislodgement, n (%) 0 (0.0) 0 (0.0) 0 (0.0) QRSd, QRS duration; VP, ventricular pacing percentage. Figure 1. Characteristics of LBBAP Conclusion Permanent LBBAP yielded stable threshold, narrow QRSd and preserved left ventricle synchrony with few complications. Our preliminary results indicate that LBBAP holds promise as an attractive physiological pacing strategy for AVB.

Right Ventricular Versus Biventricular Pacing for Heart Failure and Atrioventricular Block.

The use of cardiac resynchronization therapy (CRT) is well accepted as an important option for the treatment of patients with systolic heart failure and prolonged QRS duration. CRT for patients with narrow QRS complexes is reserved for patients who are undergoing implantation of new or replacement pacemakers or implantable cardioverter defibrillators with an anticipated significant requirement for ventricular pacing. The Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) Trial examined the role of CRT in heart failure patients with atrioventricular block and demonstrated significantly better outcomes with CRT compared to right ventricular pacing. On the other hand, conflicting preliminary data were reported by the Biventricular Pacing for Atrioventricular Block to Prevent Cardiac Desynchronization (BioPace) Trial investigators. In this review, we will discuss the adverse consequences of chronic right ventricular pacing, the options of alternate pacing sites in the right ventricle versus biventricular pacing, and the findings from the BLOCK HF Trial as well as the preliminary data from the BioPace Trial. Our goal is to explore the role of biventricular pacing in patients with atrioventricular block.

BLOCK HF: how far does it extend indications for cardiac resynchronization therapy?

The Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) trial, published in April 2013 [Curtis AB, Worley SJ, Adamson PB, et al; Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) Trial Investigators. Biventricular pacing for atrioventricular block and systolic dysfunction. N Engl J Med 2013; 368:1585-1593], explored whether cardiac resynchronization therapy (CRT) was superior to conventional pacing in patients with conventional indications for pacing, left ventricular dysfunction and NYHA (New York Heart Association) class I-III. The trial took 8 years and a source of concern is selection bias, because participating centers had an average of two patients enrolled per center, per year. Both the internal and external validity of the trial merit some comments. BLOCK HF showed a relatively low treatment effect of CRT as compared with other CRT trials. As a matter of fact, the absolute risk reduction for death or hospitalization because of heart failure was 4.8%, in a relatively long follow-up, with a number needed to treat (NNT) of 21, much higher than the NNT of other CRT trials. We estimate that at least one third of patients in BLOCK HF could meet current indications for CRT. Moreover, the study did not consider the additional risks and costs of CRT versus conventional pacing, both having important implications for cost-effectiveness estimates. For these and other reasons, uncertainties arise as to how far BLOCK HF extends current recommendations for CRT and how much it should be implemented in daily clinical practice.

Syncope in Patients with Pacemakers.

Syncope in a pacemaker patient is a serious symptom but it is rarely due a pacemaker system malfunction. Syncope occurs in about 5 % of patients paced for atrioventricular (AV) block in 5 years, 18% in those paced for sinus node disease in 10 years, 20 % of those paced for carotid sinus syndrome in 5 years and 5-55 % of those older patients paced for vasovagal syncope in 2 years. The vastly different results in vasovagal syncope depend on the results of tilt testing, where those with negative tests approach results in pacing for AV block and those with a positive tilt test show no better results than with no pacemaker. The implication of tilt results is that a hypotensive tendency is clearly demonstrated by tilt positivity pointing to syncope recurrence with hypotension. This problem may be addressed by treatment with vasoconstrictor drugs in those who are suited or, more commonly, a reduction or cessation of hypotensive therapy in hypertensive patients. Other causes of syncope such as tachyarrhythmias are rare. The clinical approach to patients who report syncope is detailed.

Will biventricular pacing replace right ventricular pacing for antibradycardia therapy?

Evaluation of: Curtis AB, Worley SJ, Adamson PB, et al; Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) Trial Investigators. Biventricular pacing for atrioventricular block and systolic dysfunction. N. Engl. J. Med. 368(17), 1585–1593 (2013).Recent trials have shown the benefit of cardiac resynchronization (CRT) in mild or moderate heart failure with a left bundle branch block or intraventricular conduction delay. Randomized trials (including the BLOCK-HF study) have now shown that irrespective of baseline QRS duration, long-term left ventricular (LV) remodeling, dysfunction and heart failure are more common in patients with long-term conventional right ventricular (RV) than those with biventricular (BiV) pacing. The detrimental effects of long-term RV pacing may occur in patients with normal and abnormal LV ejection fractions (LVEF). LV dysfunction induced by RV pacing can be improved by upgrading to a BiV system. Possible new indications for CRT (currently under investigation), include heart failure due to diastolic dysfunction (normal LVEF) with left bundle branch block or intraventricular conduction delay in the absence of bradycardia, and conditions not necessarily associated with a wide QRS complex or bradycardia, such as hypertrophic cardiomyopathy and LV non-compaction. The widespread use of CRT will be limited by the greater complications of LV pacing, unfamiliarity with implantation techniques and cost. At first, CRT will be favored in young patients and those with a low LVEF where ventricular pacing is required >40% of the time.

How can the rate-adaptive atrioventricular delay be programmed in atrioventricular block pacing?

To optimize recommendations for programming of the rate-adaptive atrioventricular (AV) delay. Optimal AV delay (AVD(opt)) is the net effect of the pacemaker-related interatrial conduction time (IACT), duration of the left-atrial electromechanical action (LA-EAC(long)) and duration of left-ventricular latency (S(V)-EAC(short)). It can be calculated by AVD(opt) = IACT + LA-EAC(long)-S(V)-EAC(short). We measured these three components in 20 DDD pacemaker patients (EF >45%) with the third degree AV block (AVB) at rest and submaximal ergometric exercise load of 71 +/- 9 W which resulted in a 31.5 +/- 9.9 bpm rate increase. Between exercise and rest, the components of and the final AVD(opt) showed no significant differences. Interatrial conduction time in VDD and DDD pacing varied by 2.3 +/- 8.4 ms and 1.4 +/- 8.8 ms, respectively, S(V)-EAC(short) changed by -2.6 +/- 21.8 ms and AVD(opt) by -3.5 +/- 33.3 ms and -4.3 +/- 37.8 ms in VDD and DDD operation, respectively. The greatest variation was of LA-EAC(long) by -8.4 +/- 32.7 ms. Linear regressions of the rate-dependent variations (Deltaf) in VDD operation yielded DeltaIACT(f) = 0.04Deltaf + 0.95 ms, DeltaLA-EAC(long) = -0.59Deltaf + 10.1 ms, and DeltaS(V) - EAC(short) = 0.14Deltaf -7.2 ms which resulted in DeltaAVD(opt) = -0.69Deltaf + 18.2 ms. A recommendation for programming of rate-adaptive AV delay in AV block patients cannot be given.

Structural basis for cardiac function.

Structural basis for cardiac function.

Interrelationship of architecture and function of the right ventricle.

Interrelationship of architecture and function of the right ventricle.