Pacemaker-Based Cardiac Neuromodulation Therapy in Patients With Hypertension: A Pilot Study

Background In prior unblinded studies, cardiac neuromodulation therapy (CNT) employing a sequence of variably timed short and longer atrioventricular intervals yielded sustained reductions of systolic blood pressure (SBP) in patients with hypertension. The effects of CNT on SBP were investigated in this double-blind randomized pilot study. Methods and Results Eligible patients had daytime ambulatory SBP (aSBP) ≥130 mm Hg and office SBP ≥140 mm Hg despite taking ≥1 antihypertensive medication, and an indication for a dual-chamber pacemaker. Patients underwent Moderato device implantation, which was programmed as a standard pacemaker during a 1-month run-in phase. Patients whose daytime aSBP was ≥125 mm Hg at the end of this period were randomized (1:1, double blind) to treatment (CNT) or control (CNT inactive). The primary efficacy end point was the between-group difference of the change in 24-hour aSBP at 6 months. Of 68 patients initially enrolled and who underwent implantation with the Moderato system, 47 met criteria for study continuation and were randomized (26 treatment, 21 control). The mean age was 74.0±8.7 years, 64% were men, left ventricular ejection fraction was 59.2%±5.7%, and aSBP averaged 141.0±10.8 mm Hg despite the use of 3.3±1.5 antihypertensive medications; 81% had isolated systolic hypertension. Six months after randomization, aSBP was 11.1±10.5 mm Hg (95% CI, -15.2 to -8.1 mm Hg) lower than prerandomization in the treatment group compared with 3.1±9.5 mm Hg (-7.4 to 1.2 mm Hg) lower in controls, yielding a net treatment effect of 8.1±10.1 mm Hg (-14.2 to -1.9 mm Hg) (P=0.012). There were no Moderato device- or CNT-related adverse events. Conclusions CNT significantly reduced 24-hour aSBP in patients with hypertension with a clinical indication for a pacemaker. The majority of patients had isolated systolic hypertension, a particularly difficult group of patients to treat. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02837445.

Treatment and follow-up of fetuses that developed congenital heart block due to autoantibody in two cases

Objective

Autoantibody-related congenital heart block (ACHB) is a passively acquired autoimmune disease. This study aimed to examine the pathogenesis, clinical manifestations, and treatment of ACHB.

Method

The clinical data of two fetuses with first-degree ACHB were retrospectively analyzed.

Results

Two pregnant women were strongly positive for anti-Sjögren’s syndrome-related antigen A (SSA) antibody. Among these two cases, one had a prolonged atrioventricular (AV) interval at 28⁺³ weeks in utero, while the other had a prolonged AV interval at 24⁺⁶ weeks in utero. After prenatal intervention, one patient recovered to normal, while one fetus continued to have ACHB after treatment with dexamethasone and intravenous immunoglobulin. Furthermore, the two neonates were positive for anti-SSA antibody and were diagnosed with ACHB.

Conclusion

The pathogenesis of ACHB is closely correlated with anti-SSA/Ro antibody and anti-SSB/La antibody from the mother, and is affected by fetal susceptibility. Early screening and early intervention for ACHB are important.

Occurrence of persistent atrial fibrillation during pacing for sinus node disease: The influence of His bundle pacing versus managed ventricular pacing

INTRODUCTION

In patients with sinus node disease (SND), the dual-chamber pacemaker (PM) is programmed in DDDR mode with an algorithm to avoid unnecessary right ventricular (RV) pacing. This pacing mode may prolong PR interval with consequently atrioventricular (AV) asynchrony which is associated with a higher risk of atrial fibrillation (AF). We evaluate whether preserving AV synchrony by setting a fixed AV delay during physiological RV pacing, that is, His bundle pacing (HBP), could reduce the risk of AF occurrence in comparison with a standard pacing mode with an algorithm to avoid unnecessary RV pacing (DDD-VPA).

METHODS AND RESULTS

We collected retrospective data from 313 consecutive patients who had undergone PM for SND. The first occurrence of persistent AF (>7 consecutive days) as a function of the pacing mode was evaluated. HBP and DDD-VPA were implemented in 82 and 231 patients, respectively. Persistent AF occurred in 128 (40.9%) patients over a median follow-up of 70 months (67-105). The DDD-VPA pacing mode was significantly correlated with the occurrence of persistent AF only when the basal PR was long (>180 ms). The risk of persistent AF was significantly lower in patients on HBP than in those on DDD-VPA, adjusted HR = .57 (95% CI, .36- .89, p=.014). Other independent predictors of persistent AF occurrence were: A history of AF (HR = 3.91; 95% CI, 2.48-6.19, p = .001), age, and long PR interval (HR = 2.98; 95% CI, 2.00-4.43, p=.001).

CONCLUSION

In SND patients and long basal PR interval, the HBP may reduce the risk of persistent AF in comparison with the DDD-VPA.

Cardiac electrophysiology and the susceptibility to sustained ventricular tachycardia in intact, conscious mice

Cardiac electrophysiological dysfunction is a major cause of death in humans. Accordingly, electrophysiological testing is routinely performed in intact, conscious, humans to evaluate arrhythmias and disorders of cardiac conduction. However, to date, in vivo electrophysiological studies in mice are limited to anesthetized open-chest or closed-chest preparations. However, cardiac electrophysiology in anesthetized mice or mice with surgical trauma may not adequately represent what occurs in conscious mice. Accordingly, an intact, conscious murine model of cardiac electrophysiology has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of cardiac electrophysiology. The conscious mouse model permits measurements of atrioventricular interval, sinus cycle length, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, Wenckebach cycle length, the ventricular effective refractory period (VERP) and the electrical stimulation threshold to induce sustained ventricular tachyarrhythmias in an intact, complex model free of the confounding influences of anesthetics and surgical trauma. This is an important consideration because anesthesia and surgical trauma markedly reduced cardiac output and heart rate as well as altered cardiac electrophysiology parameters. Most importantly, anesthesia and surgical trauma significantly increased the VERP and virtually eliminated the ability to induce sustained ventricular tachyarrhythmias. Accordingly, the methodology allows for the accurate documentation of cardiac electrophysiology in complex, conscious mice and may be adopted for advancing the concepts and ideas that drive cardiovascular research.