[A case of mitral regurgitation caused by necrosis and total rupture of the papillary muscle].

Mitral regurgitation (MR) caused by total rupture of the papillary muscle has so ominous prognosis that it is treated by surgery exceedingly rarely. We recently experienced a case of MR caused by total rupture of the posterior papillary muscle that had presumably occurred after myocardial infarction. The patient was a 52-year-old male who was admitted to a hospital with liver dysfunction where he was noticed for the first time of his having cardiac murmurs and was diagnosed as having MR on the basis of echocardiography. With this diagnosis he was transferred to our department. Examination on admission revealed the patient to have an NYHA class III mitral incompetence with ECG evidence of old posteroinferior myocardial infarction. Cardiac catheterization demonstrated total occlusion of the segment 1 of the right coronary artery and MR, Sellers III. Abnormal echoes were noted in the left ventricle that moved almost synchronously with the posterior leaflet of the mitral valve, a finding leading to a suspected diagnosis of rupture of the posterior papillary muscle or chordae tendineae. Intraoperative findings were confirmative of total rupture of the posterior papillary muscle and mitral valve replacement was performed using a SJM prosthetic valve. Histological examination of the ruptured muscle revealed presence of necrosis, but no other specific inflammatory changes. Documented cases of surgically treated total papillary muscle rupture are quite limited in number, the present case being the 4th to be reported in Japan.