Short-term reduction in intrinsic heart rate during biventricular pacing after cardiac surgery: A substudy of a randomized clinical trial

Abstract

Background The Biventricular Pacing After Cardiac Surgery trial investigates hemodynamics of temporary pacing in selected patients at risk of left ventricular dysfunction. This trial demonstrates improved hemodynamics during optimized biventricular pacing compared with atrial pacing at the same heart rate 1 and 2 hours after bypass and reduced vasoactive-inotropic score over the first 4 hours after bypass. However, this advantage of biventricular versus atrial pacing disappears 12 to 24 hours later. We hypothesized that changes in intrinsic heart rate can explain variable effects of atrial pacing in this setting. Methods Heart rate, mean arterial pressure, cardiac output, and medications depressing heart rate were analyzed in patients randomized to continuous biventricular pacing (n = 16) or standard of care (n = 18). Results During 30-second testing periods without pacing, intrinsic heart rate was lower in the paced group 12 to 24 hours after bypass (76.5 ± 17.5 vs 91.7 ± 13.0 beats per minute; P = .040) but not 1 or 2 hours after bypass. Cardiac output (4.4 ± 1.2 vs 3.6 ± 1.9 L/min; P = .054) and stroke volume (53 ± 2 vs 42 ± 2 mL; P = .051) increased overnight in the paced group. Vasoactive medication doses were not different between groups, whereas dexmedetomidine administration was prolonged over postoperative hours 12 to 24 in the paced group (793 ± 528 vs 478 ± 295 minutes; P = .013). Conclusions These observations suggest that hemodynamic benefits of biventricular pacing 12 to 24 hours after cardiopulmonary bypass lead to withdrawal of sympathetic drive and decreased intrinsic heart rate. Depression of intrinsic rate increases the apparent benefit of atrial pacing in the chronically paced group but not in the control group. Additional study is needed to define clinical benefits of these effects.

Effects of dexmedetomidine on postoperative cognitive function in patients undergoing coronary artery bypass grafting

“…Incidence of postoperative cognitive impairment in patients with coronary artery surgery was significantly higher than that in patients without the surgery ( 8 ). Studies have shown that >40% patients will develop cognitive dysfunction within 7 days after coronary artery-related surgery ( 9 ), and the incidence in elderly patients is even higher. Dexmedetomidine is currently the most widely used α2 adrenergic receptor agonist in the clinical treatment ( 10 ).…”

Clinical application of intra-aortic balloon pump in patients with cardiogenic shock during the perioperative period of cardiac surgery

“…Although all selected patients met the criteria for cardiogenic shock, there were differences in the severity of conditions. We adopted VIS score to assess the critical conditions of patients ( 18 , 21 , 22 ), and EuroSCORE to evaluate baseline status of patients ( 23 , 24 ). The results showed that the overall EuroSCORE in patients was 6.48±3.16 points (out of 17 points).…”

Anesthetic Management for Cardiopulmonary Bypass

“…The results of this study revealed that BiV pacing increased cardiac output by 13% versus patients without pacing while patients who only had atrial pacing at the same heart rate did not have an increased cardiac output immediately after discontinuation from CPB. 60 De-Airing. Air emboli can have significant negative effects while weaning from CPB, after separation from bypass, and in the postoperative period including neurological deficits, ventricular dysfunction, and arrhythmias.…”

“…The results of this study revealed that BiV pacing increased cardiac output by 13% versus patients without pacing while patients who only had atrial pacing at the same heart rate did not have an increased cardiac output immediately after discontinuation from CPB. 60…”