心脏前负荷减低对主动脉压及主动脉扩增指数的影响

心脏前负荷减低对主动脉压及主动脉扩

增指数的影响

(作者：__________ 单位：___________ 邮编：___________ )

【摘要】目的了解心脏前负荷减低对中心动脉压及主动

脉扩增指数的影响。方法10例健康志愿者，行下肢负压(LBNP)抽吸造成不同程度前负荷减低。采用超声心动图检测心输出量的变化；采用中心动脉压力分析系统(SphymoCor)检测桡动脉压力波形，经平均转换功能形成中心动脉压力波形。结果①随着下肢负压的加大，上

腔静脉血流进行性减低，在-30mmHg阶段，S波减低22.4% , VTIs+d 减低了15.8%，同时SV减少24.7%，CO减少18.7% ;②中心动脉收缩压(CSBP)除在-30mmHg阶段轻度下降外，在-10及-20mmHg 阶段没有明显改变，中心动脉舒张压(CDBP)在各个负压阶段没有明显改变；③主动脉压力波P1在各个负压阶段均明显下降，在-30mmHg 阶段，P1 减少了19.6%[(28.2 i5.02)mmHg vs. (22.65 ±3.08)mmHg, P0.01]，而总外周阻力(TPR)在各负压阶段均较基础阶段明显升高，在-30mmHg 阶段升高21.3%[(16.0 ±2.9)(mmHg min)/L vs. (20.3 ± 3.4)(mmHg min)/L,

P0.001]。主动脉扩增指数(AI)无明显改变。结论

前负荷减低使中心主动脉压及主动脉压力波P1降低，同时使TPR

升高，由于TPR的升高抵消了P1的降低，因而AI保持不变。

【关键词】前负荷；中心动脉压；扩增压；扩增指数；下肢负压；

主动脉压；总外周阻力

ABSTRACT: Objective To investigate the effect of decreased cardiac preload on central blood pressure and central aortic augme ntati on in dex (cAI). Methods Ten healthy no rmote nsive men aged 27 to 51 were studied. They were placed in a sta ndard lower body negative pressure (LBNP) chamber to induce different degrees of LBNP. Hemod yn amic and echocardiographic measureme nts were made at each stage of LBNP and baseli ne. A SphygmoCor tono metry system was used to obtai n the radial pulse waveform. Aortic pressure was derived, via a validated transfer function, from radial pressure, and used to estimate cAI and central systolic blood pressure (cSBP). Results ① There was a progressive decrease in the SVC S wave and VTIs+d with in creased LBNP with a maximum cha nge of 0.21 ±).03m/s (22.4% change) and 2.8 ±2.34cm (15.8% change) at 30mmHg LBNP (P0.001), respectively. This reduction in preload was associated with a progressive decrease in SV (by 24.4% at 30mmHg, P0.001) and decrease in CO (by 18.7 at 30mmHg LBNP, P0.001).②

LBNP decreased CSBP (by 3.7mmHg at 30mmHg LBNP, P0.01), but had no significant change in MAP and CDBP.③ Reduced cardiac output

by LBNP decreased the P1 of aortic pressure waveform [(28.2

±5.O2)mmHg vs. (22.65 ±3.08)mmHg, P0.01] and in creased the peripheral resista nee [(16.0 ±2.9)(mmHg mi n)/L vs. (20.3

±3.4)(mmHg min)/L, P0.001]. cAI had no significant change at the whole LBNP stages. Con clusi on Decreased preload decreased cen tral blood pressure and P1, but in creased peripheral resista nee. AI rema ined un cha nged because TPR in crease offset decrease of P1.

KEY WORDS: preload; central blood pressure; augmentation pressure; augmentation index; lower body negative pressure; cen tral blood pressure; peripheral resista nee

中心动脉压及其压力波形的改变，现已被公认与心血管病危险度密切相关[1 7]。具有降压作用的一些药物如血管转换酶抑制剂、血管紧张素2受体阻滞剂以及硝酸甘油等均可扩张外周小动脉，通过减低心脏后负荷等作用而使中心动脉压力及波形发生改变[810]。然而，

较少见到单纯前负荷改变对中心动脉压力及波形影响的报道。本实验采用下肢负压(lower body negative pressure, LBNP)的方法，造成急性心脏前负荷单纯性降低，从而了解其对中心动脉压(central blood pressure, CBP)、中心动脉压力波扩增指数(augmentation index, AI) 的影响。

1材料与方法

1.1研究对象健康自愿者10例，男性，平均年龄35岁(27〜51 岁)，平均身高174.8cm，平均体重74.6kg ;均为窦性心律，心率在正常范围，无心律失常。经病史、体格检查及相关实验室检查除外高血压病、血脂代谢异常、糖尿病及其他心血管疾病等因素，所有研究对象被告知