The 24-hour rhythm of blood pressure differs from that of leg hemodynamics in orthotopic heart transplant recipients.

Background: This study was aimed at investigating whether a circadian rhythm of peripheral resistance exists in patients with orthotopic cardiac transplantation (OCT) and whether it parallels that of blood pressure (BP).
Methods: BP and leg flow and resistance (plethysmography) were monitored for 24 hours in 13 denervated OCT recipients and 13 control patients with native heart, matched for casual blood pressure.
Results: On the basis of BP trend, control patients showed a BP reduction during sleep, whereas OCT recipients did not. Leg resistance was significantly lower and leg flow significantly higher during sleep than during waking in all patients, and the extent of the nocturnal decrease was similar in the two categories.
Conclusions: The decrease in leg resistance in patients confined to bed for 24 hours is caused by peripheral mechanisms and does not depend on the autonomic control of the heart. The nocturnal decline in BP depends, on the contrary, on cardiac control and is lost in patients with denervated heart.