HEART-RATE REACTIVITY AND HEART PERIOD VARIABILITY THROUGHOUT THE FIRST YEAR AFTER HEART-TRANSPLANTATION

Heart rate reactivity to mental stress is substantially blunted early after heart transplantation, suggesting that the loss of neural modula tion limits the cardiovascular response to mental stress. We tested wh ether reactivity to mental stress recovers during the first year after heart transplantation. Hemodynamic and respiratory responses to menta l arithmetic challenge were studied in 20 heart transplant recipients 3, 6, and 12 months after surgery. A normal comparison group was studi ed at equivalent intervals. Heart rate reactivity to mental arithmetic was significantly reduced in the cardiac transplant group compared to the normal subjects. This effect persisted up to 1 year after transpl antation. Heart period variability in the heart transplant recipients was minimal in all three test sessions. The findings suggest that no f unctional reinnervation or other compensatory adaptation occurs up to 1 year after heart transplantation.