在清醒犬中不改变前负荷或后负荷的情况下估计左心室弹性。

Estimation of left ventricular elastance without altering preload or afterload in the conscious dog.

作者信息

Nakamoto T, Cheng C P, Santamore W P, Iizuka M

机构信息

Section of Cardiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina.

出版信息

Cardiovasc Res. 1993 May;27(5):868-73. doi: 10.1093/cvr/27.5.868.

DOI:10.1093/cvr/27.5.868

PMID:8348586

Abstract

OBJECTIVE

The aim was to determine the slope (EES) of the left ventricular end systolic pressure-volume line (ESPVL) without altering preload or afterload in conscious dogs.

METHODS

Dogs (n = 10) were instrumented to determine left ventricular volume from ultrasonic left ventricular internal dimensions, and to measure left ventricular pressure using a micromanometer. Studies were performed one to two weeks after instrumentation while the animals were conscious. ESPVL was determined from variably loaded left ventricular pressure-volume (P-V) loops generated by the vena caval occlusion. Contractile state was increased by intravenous dobutamine (8 micrograms.kg-1 x min-1) and decreased by intravenous verapamil (10 mg) given after autonomic blockade. From a single normally ejecting beat, we calculated EES-single beat (mm Hg.ml-1) as peak isovolumetric pressure (Pmax) minus end systolic pressure divided by stroke volume. Sunagawa's technique was used to estimate Pmax by fitting the pressure during the isovolumetric contraction and relaxation as: P(t) = 1/2 X Piso[1-cos(omega t+c)]+LVEDP, where Piso = peak isovolumetric developed pressure, LVEDP = left ventricular end diastolic pressure, c = constant accounting for variations in phase angle, and omega = 2 pi/T in which T is duration of contraction.

RESULTS

After dobutamine, EES increased, from 8.9(SEM 0.8) to 12.5(1.0) mm Hg.ml-1 (p < 0.05), and EES-single beat increased from 9.1(0.9) to 12.0(1.4) mm Hg.ml-1 (p < 0.05). Conversely, after verapamil, EES decreased, from 11.1(1.2) to 6.3(1.1) mm Hg.ml-1, (p < 0.05), and EES-single beat also decreased, from 9.6(1.0) to 7.3(1.2) mm Hg.ml-1, (p < 0.05).

CONCLUSIONS

EES calculated from one beat is similar to EES determined from variably loaded left ventricular loops and responds appropriately to inotropic stimulation. This technique provides a reasonable method to calculate EES from left ventricular pressure and stroke volume without altering preload or afterload.

摘要

目的

在清醒犬不改变前负荷或后负荷的情况下，测定左心室收缩末期压力-容积线（ESPVL）的斜率（EES）。

方法

对10只犬进行仪器植入，通过超声测量左心室内径来确定左心室容积，并用微测压计测量左心室压力。在仪器植入后1至2周动物清醒状态下进行研究。通过腔静脉闭塞产生的不同负荷的左心室压力-容积（P-V）环来确定ESPVL。在自主神经阻断后，静脉注射多巴酚丁胺（8微克·千克⁻¹·分钟⁻¹）使收缩状态增强，静脉注射维拉帕米（10毫克）使收缩状态减弱。从单个正常射血搏动中，我们计算EES-单次搏动（毫米汞柱·毫升⁻¹），即等容收缩期峰值压力（Pmax）减去收缩末期压力再除以每搏输出量。采用Sunagawa技术，通过将等容收缩期和舒张期的压力拟合为：P(t) = 1/2 × Piso[1 - cos(ωt + c)] + LVEDP来估计Pmax，其中Piso为等容收缩期峰值压力，LVEDP为左心室舒张末期压力，c为考虑相角变化的常数，ω = 2π/T，T为收缩持续时间。

结果

多巴酚丁胺注射后，EES从8.9（标准误0.8）升高至12.5（1.0）毫米汞柱·毫升⁻¹（p < 0.05），EES-单次搏动从9.1（0.9）升高至12.0（1.4）毫米汞柱·毫升⁻¹（p < 0.05）。相反，维拉帕米注射后，EES从11.1（1.2）降至6.3（1.1）毫米汞柱·毫升⁻¹（p < 0.05），EES-单次搏动也从9.6（1.0）降至7.3（1.2）毫米汞柱·毫升⁻¹（p < 0.05）。