Response of mean arterial pressure to temporary biventricular pacing after chest closure during cardiac surgery

Abstract

Objectives We have previously demonstrated that biventricular pacing increased cardiac output within 1 hour of weaning from cardiopulmonary bypass in selected patients. To assess the possible sustained benefit, we reviewed in the present study the effects of biventricular pacing on the mean arterial pressure after chest closure. Methods A total of 30 patients (mean ejection fraction 35%± 15%, mean QRS 119 ± 24 ms) underwent coronary bypass and/or valve surgery. The mean arterial pressure was maximized during biventricular pacing using atrioventricular delays of 90 to 270 ms and interventricular delays of+80 to−80 ms during 20-second intervals in random sequence. Optimized biventricular pacing was finally compared with atrial pacing at a matched heart rate and to a sinus rhythm during 30-second intervals. Vasoactive medication and fluid infusion rates were held constant. The arterial pressure was digitized, recorded, and integrated. Statistical significance was assessed using linear mixed effects models and Bonferroni’s correction. Results Optimized atrioventricular delay, ranging from 90 to 270 ms, increased the mean arterial pressure 4% versus nominal and 7% versus the worst (P<.001). Optimized interventricular delay increased pressure 3% versus nominal and 7% versus the worst. Optimized biventricular pacing increased the mean arterial pressure 4% versus sinus rhythm (78.5 ± 2.4 vs 75.1 ± 2.4 mm Hg; P = .002) and 3% versus atrial pacing (76.4 ± 2.7 mm Hg; P = .017). Conclusions Temporary biventricular pacing improves the hemodynamics after chest closure, with effects similar to those within 1 hour of bypass. Individualized optimization of atrioventricular delay is warranted, because the optimal delay was longer in 80% of our patients than the current recommendations for temporary postoperative pacing.

Primary Endpoints of the Biventricular Pacing After Cardiac Surgery Trial

“…Our study protocol was approved by the Columbia Institutional Review Board and was conducted under an Investigational Device Exemption from the Food and Drug Administration. We have described details of recruitment [3,13,32] and Phase I [3], II [4] and III [3,13,32] testing, summarized below.…”

“…Alternatively, patients undergoing combined mitral and aortic valve surgery qualified, irrespective of LVEF or QRSd. Exclusion criteria included atrial fibrillation, 2° or 3° atrioventricular block, congenital heart dise ase, intracardiac shunts, or heart rate > 120 beats/min after bypass [3,4,13,32–34]. …”

“…Optimization was similar to phase I, with testing intervals increased to 20 seconds [4]. The newly optimized protocol was then applied to BiVP patients [4,33] until phase III on the first postoperative day. The clinical endpoint, cardiac index, was measured by thermal dilution immediately prior to phase III testing.…”

“…Temporary postoperative pacing can affect recovery from cardiac surgery by heart rate acceleration [1,2] and/or cardiac resynchronization [1–4]. Cardiac resynchronization (CRT) is well-established treatment for congestive heart failure in patients with dilated cardiomyopathy affecting the left ventricle (LV) [5–9].…”

“…Development of BiVP involved surgically implanted epicardial leads [15], and surgical investigators have examined benefits of temporary BiVP for LV dysfunction after cardiopulmonary bypass with mixed results [3,4,16–28]. However, aside from limited examination of lead location [18,24,28] and VVD [25], formal optimization of BiVP had not been attempted in temporary pacing.…”