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

Background This studs was aimed at investigating whether a circadian rhythm of peripheral resistance exists in patients with orthotopic cardiac transp lantation (OCT) and whether it parallels that of blood pressure (BP). Methods sp and leg flow and resistance (plethysmography) were monitored for 24 hours in 13 denervated OCT recipients and 13 control patients with nati ve heart, matched for casual blood pressure. Results On the basis of BP trend, control patients showed a BP reduction du ring sleep, whereas OCT recipients did not. leg resistance was significantl y lower and leg flow significantly higher during sleep than during waking i n 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 auto nomic control of the heart. The nocturnal decline in BP depends, on the con trary, on cardiac control and is lost in patients with denervated heart.