Blood pressure response to head-up tilt (HUT) in 7 healthy subjects and 9 patients before and after coronary artery bypass grafting (CABG) was measured during supine and 15-min 60° HUT. Stroke volume (SV) and ejection fraction (EF) were assessed by echocardiography. Baseline mean arterial pressure (MAP) and heart rate (HR) in patients before CABG were similar to healthy subjects. MAP in patients decreased by 6 (4–9) mmHg [median (1st–3rd quartiles)] during 7–12 mmHg of HUT with decreased cardiac output (CO = SV × HR) while HR remained unchanged. MAP in healthy subjects remained unchanged during HUT with increased HR. Body weight decreased by 3.5 (2.5–3.7) kg and MAP decreased by 6 (2–13) mmHg during the last 3-min HUT while HR increased after CABG. Decreases in SV and CO during HUT disappeared after CABG. Blood pressure decreased during HUT in patients before and after CABG regardless of HR response.

中文翻译：

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冠状动脉搭桥术对平视倾斜血压反应的影响

在仰卧位和 15 分钟 60° HUT 期间，测量了 7 名健康受试者和 9 名患者在冠状动脉旁路移植术 (CABG) 前后对抬头倾斜 (HUT) 的血压反应。通过超声心动图评估每搏输出量（SV）和射血分数（EF）。CABG 前患者的基线平均动脉压 (MAP) 和心率 (HR) 与健康受试者相似。在 HUT 7-12 mmHg 期间，患者的 MAP 降低 6 (4-9) mmHg [中位数（第 1-3 个四分位数）]，心输出量减少 (CO = SV × HR)，而 HR 保持不变。HUT 期间健康受试者的 MAP 保持不变，但 HR 增加。在最后 3 分钟 HUT 期间，体重下降了 3.5 (2.5–3.7) kg，MAP 下降了 6 (2–13) mmHg，而 CABG 后 HR 增加。HUT 期间 SV 和 CO 的降低在 CABG 后消失。无论 HR 反应如何，CABG 前后患者的 HUT 期间血压均下降。