Recipients with shorter cardiopulmonary bypass time achieve improvement of parasympathetic reinnervation within 6 months after heart transplantation

Although cross-sectional late-phase reinnervation in heart transplantation (HTx) recipients has been demonstrated by several earlier studies, early-phase successive analyses especially for parasympathetic reinnervation remain unknown. Successive heart rate variability (HRV) data calculated by the MemCalc power spectral density method were obtained from 16 non-rejection recipients 1-24 weeks after HTx. High frequency (HF) level representing parasympathetic magnitude increased significantly at 6 months after HTx (from 0.9 ± 0.7 to 4.1 ± 2.8 ms^2*). Only intraoperative shorter cardiopulmonary bypass time (181 ± 59 minutes) correlated with a higher level of HF at post-HTx 6 months among all baseline variables (r = -0.530^*). Higher level of HF was associated with recovery of tachycardia at post-HTx 6 months (r = -0.514^*). In conclusion, parasympathetic reinnervation emerges along with recovery of tachycardia < 6 months after HTx, which is accelerated by shorter intraoperative cardiopulmonary bypass time (^*P < 0.05 for all).