Mechanism of mitral regurgitation in patients with myocardial infarction: a study using real-time two-dimensional Doppler flow imaging and echocardiography.

Abstract

The aim of the present study was to elucidate the mechanisms of mitral regurgitation accompanying myocardial infarction. Severity and site of mitral regurgitation was evaluated by the real-time two-dimensional Doppler flow imaging technique in 81 patients with old myocardial infarction. The incidence of mitral regurgitation did not depend on the region of infarction. There was, however, a close relationship between the site of regurgitation and the region of infarction. In patients with mitral regurgitation spurting from the posteromedial area of the valve, the inferior wall was involved in infarction without exception and in some of these patients, the posteromedial papillary muscle was also found to be affected by myocardial infarction; in those with regurgitation spurting from the anterolateral area, the anterior wall showed asynergy. On the other hand in patients with mitral regurgitation spurting from the central area, the region of infarction varied. In these patients, however, the larger the diameter of the mitral anulus, the more severe the grade of regurgitation. The extent of asynergy was another factor related to the severity of mitral regurgitation. Both longitudinally and transversely, broad infarction leads to the enlargement of the mitral anulus. However, even if the mitral anulus is not so dilated, severe involvement of either commissural area results in severe mitral regurgitation from the same commissural side. Thus, there are two major causative factors of mitral regurgitation: (1) asynergy of the papillary muscle or the ventricle that results in mitral regurgitation located in the commissural area of the same side as asynergy, and (2) enlargement of mitral anulus, which results in regurgitation from the central area of the orifice. The mechanisms of mitral regurgitation unveiled in the present study will contribute much to the clarification of the concept of so-called papillary muscle dysfunction." Circulation 76, No. 4, 777-785, 1987. MITRAL REGURGITATION is frequently observed in patients with myocardial infarction. Since it develops in the absence of any lesions in the mitral valve leaflet, its pathogenesis has been explained by the concept of "papillary muscle dysfunction" proposed by Burch et al. 1 At present, papillary muscle dysfunction is thought to be a sequence of unsuccessful coordination of the whole mitral apparatus (which is composed of the anulus, leaflets, chordae tendineae, papillary muscles, and the left ventricular wall), rather than a mere disorder of the papillary muscle. However, the concept of papillary muscle dysfunction is a rather theoretical one and its existence has not been proven from the point of view of functional anatomy. The purpose of this present study was to elucidate the pathogenesis of mitral regurgitation observed in patients with old myocardial infarction by assessment of the topographic features of regurgitation with a realtime two-dimensional Doppler flow imaging technique as well as two-dimensional echocardiography. Materials and methods...

Surgical Correction of Mitral Regurgitation in the Elderly

“…Valve disease was considered degenerative 18,19 if it was due to primary floppy valves, flail leaflets, and/or calcified mitral annulus. Clinical characteristics, comorbidity (Charlson index 20 ), and symptoms were based on independent physician assessment of the patients.…”

Assessment of mitral apparatus in patients with acute inferoposterior myocardial infarction and ischaemic mitral regurgitation with two-dimensional echocardiography from anatomically correct imaging planes

“…The results of many studies demonstrate higher incidence of IMR in inferior compared with anterior MI. Inferior basal LV remodelling causes more severe geometric alterations in the mitral valve apparatus with greater displacement of PMPM [15][16][17][18][19]. Based on these findings, in this study mitral valve geometry was assessed in patients with inferoposterior MI.…”

Dobutamine-Induced Improvement in Inferior Myocardial Contractile Function Predicts Reduction in Functional Mitral Regurgitation

“…1,2 Left ventricular (LV) dilatation, 3,4 sphericalization, 4 local rather than global LV remodeling, [5][6][7] and global LV dysfunction 8 leading to geometric changes in the mitral apparatus have been proposed as causes of FMR. The main cause of FMR is augmented leaflet tethering by apical displacement of the papillary muscle (PM) because of LV remodeling.…”

“…The main cause of FMR is augmented leaflet tethering by apical displacement of the papillary muscle (PM) because of LV remodeling. [3][4][5][6][7][8] In the presence of adjacent LV wall remodeling, regional LV dysfunction where PMs insert in can potentially increase leaflet tethering and FMR. However, clarification of the quantitative evaluation of the relationship between FMR and regional myocardial function has not been satisfactory.…”