Functional and neurochemical evidence for partial cardiac sympathetic reinnervation after cardiac transplantation in humans.

BACKGROUNDThe presence of cardiac reinnervation in humans after cardiac transplantation has been widely debated, based on the application of differing methods for the assessment of neuronal function. Some of these techniques have been rather indirect; consequently, the time course and extent of cardiac reinnervation remains uncertain.METHODS AND RESULTSTo test for the presence of cardiac reinnervation after transplantation, we examined neurochemical (radiolabeled norepinephrine [NE] kinetics) and functional markers (power spectral analysis, heart rate response to exercise) of cardiac sympathetic nerve integrity in 15 cardiac transplantation recipients and 25 healthy control subjects of similar age. Cardiac transplantation subjects were studied 9 weeks to 8 years after cardiac transplantation (10 "early" patients 2 years after cardiac transplantation). At rest, cardiac NE spillover was markedly attenuated early after transplantation (11.2 +/- 18.3 pmol/min) compared with...