Idema R N, van den Meiracker A H, Balk A H, Bos E, Schalekamp M A, Man in 't Veld A J
Department of Internal Medicine, University Hospital Rotterdam Dijkzigt, Erasmus University, The Netherlands.
Circulation. 1994 Dec;90(6):2797-803. doi: 10.1161/01.cir.90.6.2797.
An attenuated or absent nocturnal decline in blood pressure has repeatedly been documented in cardiac transplant recipients. The present study was aimed at investigating the hemodynamic mechanism underlying this abnormality.
In 23 cardiac transplant recipients (11 to 36 months after transplantation) and in 23 control subjects matched for age and 24-hour mean arterial pressure, invasive 24-hour ambulatory blood pressure was measured by means of the Oxford technique. Beat-to-beat relative values of stroke volume were determined by means of a pulse-contour method, and relative changes of cardiac output (stroke volume x heart rate) and total peripheral vascular resistance (blood pressure/cardiac output) over the 24-hour period were calculated. The nocturnal decline in blood pressure was 20 +/- 8% (mean +/- SD) in control subjects but only 5 +/- 9% (P < .001) in cardiac transplant recipients. In control subjects, the nocturnal decline in blood pressure was associated with a nocturnal fall in cardiac output of 24 +/- 13%, whereas vascular resistance compared with daytime value did not change. The small nocturnal decline in blood pressure in cardiac transplant recipients was associated with an attenuated nocturnal fall in cardiac output of 14 +/- 12% (P < .05 versus control subjects). In addition, vascular resistance compared with daytime value was increased by 9 +/- 9% (P < .05) during the night. Both in cardiac transplant recipients and in control subjects, the nocturnal changes in blood pressure were correlated with the nocturnal changes in cardiac output but not with the nocturnal changes in total peripheral vascular resistance.
This study confirms the attenuated nocturnal fall in blood pressure in cardiac transplant recipients. Hemodynamically, this attenuated blood pressure decline is characterized by a reduced nocturnal fall in cardiac output, and it is associated with a nocturnal increase in vascular resistance.
心脏移植受者夜间血压下降减弱或消失的情况已被多次记录。本研究旨在探究这种异常现象背后的血流动力学机制。
选取23名心脏移植受者（移植后11至36个月）以及23名年龄和24小时平均动脉压相匹配的对照者，采用牛津技术测量其24小时动态有创血压。通过脉搏轮廓法测定每搏输出量的逐搏相对值，并计算24小时内心输出量（每搏输出量×心率）和总外周血管阻力（血压/心输出量）的相对变化。对照者夜间血压下降20±8%（均值±标准差），而心脏移植受者仅为5±9%（P<.001）。在对照者中，夜间血压下降与心输出量夜间下降24±13%相关，而与白天相比血管阻力未发生变化。心脏移植受者夜间血压下降幅度较小，与心输出量夜间下降减弱14±12%相关（与对照者相比，P<.05）。此外，与白天相比，夜间血管阻力增加了9±9%（P<.05）。在心脏移植受者和对照者中，夜间血压变化均与心输出量夜间变化相关，但与总外周血管阻力夜间变化无关。
本研究证实了心脏移植受者夜间血压下降减弱。从血流动力学角度来看，这种血压下降减弱的特征是心输出量夜间下降减少，且与夜间血管阻力增加有关。
