Friendly Infarcts in ACS : Ischemic mitral regurgitation  and the Papillary muscle paradox !

Ischemic MR is a critical entity in determining the long-term survival in post MI patients as well as dilated cardiomyopathy. (Originally described  by J. H. Philips Ann Intern Med. 1963;59(4):508-520) The mechanism of MR  can really be complex .We know mitral apparatus consists of  six components.The sub valvular apparatus plays a key role. LV  free wall especially the inferior and lateral segments which subtends the two papillary muscle has a critical role in maintaining the mitral valve competency . There seems to me a complex mechano -anatomical behavior of subvalvular structures in progressive LV dysfunction especially so in ischemic cardiomyopathy. The LV size, shape eccentricity in attachment of leaflets to papillary muscle is (Simply called altered geometry ) .The intraventricular desynchrony ,disproportionate  LV dysfunction also make MR more likely . Beware of a striking  physiological irony in ischemic MR. While infero basal free wall dysfunction occurs commonly with  LCX/RCA Infarct and  is commonly associated with Ischemic of MR .There is something unique happens . . . when the infarct is larger and involves the head of the papillary muscle .Yes, it attenuates the severity of MR.(Friendly Infarct extension!) The mechanism is , papillary muscle dysfunction  tends to prevent apical tensor effect leading to   improved tethering of leaflets .This may appear a blessing in terms of  prevention of acute pulmonary edema. This also explains why some pat...
Source: Dr.S.Venkatesan MD - Category: Cardiology Authors: Tags: Dilated cardiomyopathy Mitral regurgitation mechanism of ischemic mitral regurgitation papillary muscle dysfunction Source Type: blogs