功能性二尖瓣反流中动态反流口面积变化的机制：近端血流会聚技术的生理学见解

Mechanism of dynamic regurgitant orifice area variation in functional mitral regurgitation: physiologic insights from the proximal flow convergence technique.

作者信息

Hung J, Otsuji Y, Handschumacher M D, Schwammenthal E, Levine R A

机构信息

Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Boston 02114, USA.

出版信息

J Am Coll Cardiol. 1999 Feb;33(2):538-45. doi: 10.1016/s0735-1097(98)00570-1.

DOI:10.1016/s0735-1097(98)00570-1

PMID:9973036

Abstract

OBJECTIVES

We used the Doppler proximal flow convergence technique as a physiologic tool to explore the effects of the time courses of mitral annular area and transmitral pressure on dynamic changes in regurgitant orifice area.

BACKGROUND

In functional mitral regurgitation (MR), regurgitant flow rate and orifice area display a unique pattern, with peaks in early and late systole and a midsystolic decrease. Phasic changes in both mitral annular area and the transmitral pressure acting to close the leaflets, which equals left ventricular-left atrial pressure, have been proposed to explain this dynamic pattern.

METHODS

In 30 patients with functional MR, regurgitant orifice area was obtained as flow (from M-mode proximal flow convergence traces) divided by orifice velocity (v) from the continuous wave Doppler trace of MR, transmitral pressure as 4v(2), and mitral annular area from two apical diameters.

RESULTS

All patients had midsystolic decreases in regurgitant orifice area that mirrored increases in transmitral pressure, while mitral annular area changed more gradually. By stepwise multiple regression analysis, both mitral annular area and transmitral pressure significantly affected regurgitant orifice area; however, transmitral pressure made a stronger contribution (r2 = 0.441) than mitral annular area (added r2 = 0.008). Similarly, the rate of change of regurgitant orifice area more strongly related to that of transmitral pressure (r2 = 0.638) than to that of mitral annular area (added r2 = 0.003). A similar regurgitant orifice area time course was observed in four patients with fixed mitral annuli due to Carpentier ring insertion.

CONCLUSIONS

In summary, the time course and rate of change of regurgitant orifice area in patients with functional MR are predominantly determined by dynamic changes in the transmitral pressure acting to close the valve. Thus, although mitral annular area helps determine the potential for MR, transmitral pressure appears important in driving the leaflets toward closure, and would be of value to consider in interventions aimed at reducing the severity of MR.

摘要

目的

我们使用多普勒近端血流会聚技术作为一种生理学工具，来探究二尖瓣环面积和跨二尖瓣压力的时间进程对反流口面积动态变化的影响。

背景

在功能性二尖瓣反流（MR）中，反流流速和口面积呈现出一种独特的模式，在收缩早期和晚期出现峰值，而在收缩中期减小。有人提出二尖瓣环面积和作用于关闭瓣叶的跨二尖瓣压力（等于左心室 - 左心房压力）的阶段性变化可以解释这种动态模式。

方法

对30例功能性MR患者，反流口面积通过流量（来自M型近端血流会聚轨迹）除以MR连续波多普勒轨迹的口速度（v）得出，跨二尖瓣压力为4v²，二尖瓣环面积通过两个心尖直径得出。

结果

所有患者的反流口面积在收缩中期减小，这与跨二尖瓣压力的增加相对应，而二尖瓣环面积变化更为平缓。通过逐步多元回归分析，二尖瓣环面积和跨二尖瓣压力均对反流口面积有显著影响；然而，跨二尖瓣压力的贡献（r² = 0.441）比二尖瓣环面积（增加的r² = 0.008）更强。同样，反流口面积的变化率与跨二尖瓣压力的变化率的相关性（r² = 0.638）比与二尖瓣环面积的变化率的相关性（增加的r² = 0.003）更强。在4例因插入Carpentier环导致二尖瓣环固定的患者中观察到了类似的反流口面积时间进程。