CARC20: Intra-operative Use of Intra-aortic Balloon Pump to Generate Pulsatile Flow During Heart Transplantation

Abstract

Introduction: The physiologic impact of pulsatile flow (PF) on end-organ perfusion during cardiopulmonary bypass (CPB) is controversial. One method of generating PF during CPB is to use an intra-aortic balloon pump (IABP). Maintaining the IABP during CPB to produce a state of PF for patients undergoing heart transplantation (HT) may impact end-organ perfusion, with implications for short-term graft function and immediate post-operative outcomes. Methods: A single-center retrospective cohort study of adult patients bridged to HT with IABP was conducted between January 2018 and December 2022. Patients were excluded if they were <18 years old, not bridged to HT with IABP, or underwent simultaneous multi-organ transplant. For patients bridged to HT with IABP, beginning in May 2022 the IABP was allowed to continue inflating and deflating during CPB. Upon initiation of CPB, the IABP was set on an internal rate of 80 beats per minute. Patients who underwent HT with IABP turned off while on CPB (IABP-Off) and patients maintained on IABP during HT (IABP-On) were propensity matched according to age, organ ischemia time, and intraoperative dobutamine dose (mcg/kg/min). Results: A total of 70 patients bridged to HT with IABP were propensity matched into IABP-Off (n=12) versus IABP-On (n=12) groups. IABP-Off and IABP-On groups were similar with respect to age (p=0.93), sex (p=0.54), race (p=0.68), BMI (p=0.37), previous sternotomy (p=0.27), and waitlist time (p=0.31). IABP-Off and IABP-On groups had similar organ ischemia times (166.9±40.3 vs. 165.8±55.0 minutes, p=0.96), similar CPB times (109.3±20.6 vs. 111.3±29.7 minutes, p=0.43), and similar case lengths (449.5±108.7 vs. 449.4±115.3 minutes, p=0.50). The groups received similar amounts of intraoperative products and fluids. IABP-Off and IABP-On groups were matched on intraoperative dobutamine dose (2.85±1.73 vs. 3.09±1.76, p=0.74) and received similar doses of other intraoperative inotropes, with the IABP-Off group trending towards a higher norepinephrine dose that did not reach statistical significance. There was no difference in the first measured post-operative lactate between groups, although patients in the IABP-On group had significantly lower peak lactates in the first 24 hours post-transplant (2.39±1.17 vs. 4.31±2.95, p=0.02). There was no difference between groups with respect to post-operative creatinine or length of stay or mortality. Conclusion: Patients maintained on IABP had lower peak lactates in the first 24 hours post-transplant compared to patients in whom IABP was turned off and trended to require less norepinephrine. This limited preliminary data suggests that maintaining pulsatility during CPB may result in improved end-organ perfusion. Table 1. Characteristics of the IABP-Off and IABP-On Cohorts