Lee T M, Su S F, Chen M F, Liau C S, Lee Y T
College of Medicine, National Taiwan University, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
Int J Cardiol. 1996 Oct 25;56(3):211-5. doi: 10.1016/0167-5273(96)02734-9.
The pathophysiological role of mechanical and myocardial factors for impairment of left ventricular performance in mitral stenosis is still not clear. To investigate this controversy, 27 patients of mitral stenosis with left ventricular ejection fraction < 50% were studied. Patients were divided into two groups: Group 1: 20 patients, left ventricular ejection fraction improved to > 50% after valvuloplasty, and Group 2: 7 patients, left ventricular ejection fraction still < 50% after valvuloplasty. The clinical and hemodynamic characteristics were comparable for the two groups before valvuloplasty. Follow-up catheterization done one week later showed similar changes in mitral valve area, cardiac index, pulmonary pressure, left ventricular end-diastolic volume index and systemic vascular resistance between the two groups. However, left ventricular end-systolic volume was significantly decreased after valvuloplasty in Group 1 but not in Group 2, resulting in significantly higher ejection fraction in Group 1 than in Group 2. Postoperatively, regional wall motion scores were lower in Group 1 than in Group 2 (2.0 +/- 0.6 vs. 2.7 +/- 0.5 at the anterolateral wall, P = 0.002; 1.9 +/- 0.6 vs. 2.9 +/- 0.4 at the posterobasal wall, P = 0.0003). Most of our mitral stenosis patients with impaired left ventricular ejection fraction showed improvement after mitral valvuloplasty had released the mechanical obstruction. However, in some patients, impaired ejection fraction persisted after valvuloplasty, suggesting the mechanism of myocardial failure. Thus, both myocardial and mechanical factors play important roles in the pathogenesis of left ventricular ejection performance impairment.
二尖瓣狭窄时，机械因素和心肌因素对左心室功能损害的病理生理作用仍不明确。为研究这一争议问题，我们对27例左心室射血分数<50%的二尖瓣狭窄患者进行了研究。患者被分为两组：第1组：20例患者，瓣膜成形术后左心室射血分数提高至>50%；第2组：7例患者，瓣膜成形术后左心室射血分数仍<50%。两组患者在瓣膜成形术前的临床和血流动力学特征具有可比性。术后1周进行的随访心导管检查显示，两组患者的二尖瓣瓣口面积、心脏指数、肺压力、左心室舒张末期容积指数和体循环血管阻力变化相似。然而，第1组患者瓣膜成形术后左心室收缩末期容积显著降低，而第2组未降低，导致第1组射血分数显著高于第2组。术后，第1组的局部室壁运动评分低于第2组（前侧壁：2.0±0.6对2.7±0.5，P = 0.002；后基底壁：1.9±0.6对2.9±0.4，P = 0.0003）。我们大多数左心室射血分数受损 的二尖瓣狭窄患者在二尖瓣瓣膜成形术解除机械性梗阻后病情有所改善。然而，在一些患者中，瓣膜成形术后射血分数仍受损，提示存在心肌衰竭机制。因此，心肌因素和机械因素在左心室射血功能损害的发病机制中均起重要作用。
