A clinicopathological study on the papillary muscle dysfunction.

A total of 11 cases of papillary muscle dysfunction (PMD) was found among 600 consecutive autopsy (1.8%). There were 5 men and 6 women, with their ages ranging from 64 to 92 years. Auscultation and phonocardiograms revealed holosystolic murmurs in 9 cases and early systolic murmurs in 2. There were accentuated 1st sound in 8 cases, 3rd sound in 7, and 4th sound in 5. PMD was classified into 3 types according to the clinical course and pathologic examinations. In type A (6 cases), myocardial infarction (MI) preceded the occurence of mitral regurgitation (MR) by 3 or 4 years, with pathological verification of old MI. In type B (1 case), MR developed during acute MI. In type C (4 cases), pathological examinations disclosed various degrees of myocardial fibrosis, in which clinical diagnosis was MR of unknown etiology. In a total of 113 cases of MI, 36 cases (32%) showed papillary muscle infarction (PMI), which occurred with significantly high incidence in (1) male, (2) large MI, and (3) subendocardial or lateral MI. Among 36 cases of PMI, 9 cases developed PMD, which showed high incidence in inferior MI and in female. Various other factors concerning PMD and PMI were examined, and it was pointed out that not only PMI but also severe lesions in corresponding ventricular wall were necessary for the development of PMD.