运动期间主动脉瓣狭窄严重程度测量的血流依赖性

Flow dependence of measures of aortic stenosis severity during exercise.

作者信息

Burwash I G, Pearlman A S, Kraft C D, Miyake-Hull C, Healy N L, Otto C M

机构信息

Department of Medicine, University of Washington, Seattle.

出版信息

J Am Coll Cardiol. 1994 Nov 1;24(5):1342-50. doi: 10.1016/0735-1097(94)90118-x.

DOI:10.1016/0735-1097(94)90118-x

PMID:7930259

Abstract

OBJECTIVES

This study was designed to investigate the effect of altering transvalvular volume flow rate on indexes of aortic stenosis severity (valve area, valve resistance, percent left ventricular stroke work loss) derived by using Doppler echocardiography.

BACKGROUND

Assessment of hemodynamic severity in aortic stenosis has been limited by the absence of an index that is independent of transvalvular flow rate. The traditional measurement of valve area by the Gorlin equation has been shown to vary with alterations in transvalvular flow. Recently, valve resistance and percent stroke work loss have been proposed as indexes that are relatively independent of flow. Although typically derived with invasive measurements, valve resistance and percent stroke work loss (in addition to continuity equation valve area) can be determined noninvasively with Doppler echocardiography.

METHODS

We performed 110 symptom-limited exercise studies in 66 asymptomatic patients with valvular aortic stenosis. Continuity equation valve area, valve resistance (the ratio between mean transvalvular pressure gradient and mean flow rate) and the steady component of percent stroke work loss (the ratio between mean transvalvular pressure gradient and left ventricular systolic pressure) were assessed by Doppler echocardiography at rest and immediately after exercise.

RESULTS

Mean transvalvular volume flow rate increased 24% (from [mean +/- SD] 319 +/- 80 to 400 +/- 140 ml/s, p < 0.0001); mean pressure gradient increased 36% (from 30 +/- 14 to 41 +/- 18 mm Hg, p < 0.0001); continuity equation aortic valve area increased 14% (from 1.38 +/- 0.50 to 1.58 +/- 0.69 cm2, p < 0.0001); valve resistance increased 13% (from 137 +/- 81 to 155 +/- 97 dynes.s.cm-5, p < 0.0001); and percent stroke work loss increased 17% (from 17.4 +/- 6.9% to 20.3 +/- 8.5%, p < 0.0001). The effects of flow on valve area, valve resistance and percent stroke work loss were independent of the presence of an aortic valve area < or = or > 1.0 cm2 or reduced transvalvular flow rate (rest cardiac output < 4.5 liters/min).

CONCLUSIONS

In patients with asymptomatic aortic stenosis, Doppler echocardiographic measures of valve area, valve resistance and percent stroke work loss are flow dependent. Flow dependence is observed with valve area < or = or > 1.0 cm2 and in the presence of both normal and low transvalvular flow states. The potential effects of transvalvular flow should be considered when interpreting Doppler measures of aortic stenosis severity.

摘要

目的

本研究旨在探讨改变跨瓣容积流速对通过多普勒超声心动图得出的主动脉瓣狭窄严重程度指标（瓣口面积、瓣口阻力、左心室每搏功损失百分比）的影响。

背景

由于缺乏独立于跨瓣流速的指标，主动脉瓣狭窄血流动力学严重程度的评估受到限制。通过 Gorlin 公式对瓣口面积的传统测量已显示会随跨瓣血流的改变而变化。最近，瓣口阻力和每搏功损失百分比被提议作为相对独立于血流的指标。尽管通常通过有创测量得出，但瓣口阻力和每搏功损失百分比（以及连续性方程瓣口面积）可通过多普勒超声心动图进行无创测定。

方法

我们对 66 例无症状的瓣膜性主动脉瓣狭窄患者进行了 110 项症状限制运动研究。通过多普勒超声心动图在静息状态和运动后即刻评估连续性方程瓣口面积、瓣口阻力（平均跨瓣压力阶差与平均流速之比）和每搏功损失百分比的稳定成分（平均跨瓣压力阶差与左心室收缩压之比）。

结果

平均跨瓣容积流速增加了 24%（从[均值±标准差]319±80 增至 400±140 ml/s，p<0.0001）；平均压力阶差增加了 36%（从 30±14 增至 41±18 mmHg，p<0.0001）；连续性方程主动脉瓣口面积增加了 14%（从 1.38±0.50 增至 1.58±0.69 cm²，p<0.0001）；瓣口阻力增加了 13%（从 137±81 增至 155±97 达因·秒·厘米⁻⁵，p<0.0001）；每搏功损失百分比增加了 17%（从 17.4±6.9%增至 20.3±8.5%，p<0.0001）。血流对瓣口面积、瓣口阻力和每搏功损失百分比的影响与主动脉瓣口面积≤或>1.0 cm²或跨瓣流速降低（静息心输出量<4.5 升/分钟）的情况无关。