Evidence of Time-Dependent Autonomic Reinnervation After Heart Transplantation

BACKGROUND: Confirming the clinical significance of reinnervation is important in understanding and anticipating how heart rate (HR) responses of transplant recipients to physiologic stress differs early and late after transplant from that of normal individuals. OBJECTIVES: To evaluate the functional significance of cardiac reinnervation early and late after heart transplantation. METHODS: Handgrip and deep breathing tests, passive 80 degrees head-up tilt, and heart rate (HR) responsiveness of 33 transplant recipients (n = 16 at < 5 months and n = 17 at > 1 year after transplant) were compared with those of 16 age- and sex-matched control participants. RESULTS: HR responses to handgrip and passive tilt were absent early after transplant. HR acceleration normalized but was blunted late after transplant. These findings are consistent with late (>1 year) sympathetic reinnervation in transplant recipients. CONCLUSIONS: When caring for transplant recipients, nurses should consider the time elapsed since transplant in evaluating HR responsiveness to common procedures and interventions.