Analysis of Heart Rate Variability With Electromyography in Heart Transplant Recipients

Objective: To investigate vagal parasympathetic functions by electromyographic R-R interval variation analyses in heart transplant recipients. Design: Cross-sectional and longitudinal study. Setting: Department of physical medicine and rehabilitation, university hospital. Participants: Early (n=8; <3mo) and late (n=17; >1y) heart transplant recipients and healthy volunteers (n=20) were included. Interventions: Not applicable. Main Outcome Measures: The R-R interval variations at rest and in response to deep breathing, Valsalva, and tilt/standup maneuvers were analyzed in all patient and control groups. Further, 8 early heart transplant recipients were followed up at the sixth and twelfth months after transplantation. Results: Compared with controls, both early and late transplant recipients had significantly lower R-R interval variation ratios (P<.05). There were no statistically significant differences between the early and late groups (P>.05). R-R interval variation ratios showed no significant changes from baseline (P>.025) in the early heart transplant recipients. Conclusions: The findings of the study suggest that parasympathetic activities are suppressed in the early stage after heart transplantation and do not significantly recover with time. The electromyographic analysis of R-R interval variation is a simple test that may offer an attractive alternative for routine evaluation of autonomic dysfunction in heart transplant recipients.