POSTINFARCT CARDIAC FREE-WALL RUPTURE - THE RELATIONSHIP OF RUPTURE SITE TO PAPILLARY-MUSCLE INSERTION

The objective of this study was to examine for any relationship betwee n the sites of papillary muscle insertion in left ventricular free wal l. (LVFW) and the site of LVFW rupture postinfarct. Twenty-five consec utive patients with LVFW rupture (12 men and 13 women, mean age 72.3 y r, range 48 to 93) at the University of Ottawa Heart Institute during the period July 1, 1988 to 1992 were studied. Clinical charts were rev iewed, and the Formalin-fixed hearts were re-examined grossly and micr oscopically. Each patient died of tamponade or after surgery for tampo nade. Eight (32%) of the 25 infarcts were anteroseptal or anterior, 11 of 25 (44%) were lateral, and 6 of 25 (24%) were inferior or inferose ptal. Four (16%) of the 25 infarcts were less than 2 days old, 9 of 25 (36%) were 2 to 5 days old, and 12 of 25 (48%) were 5 to 10 days old. A separate pre-existent and healed infarct was noted in 36% of patien ts; however, rupture adjacent to these areas of old infarct occurred i n only 8% of cases. In 15 of 25 (60%) cases, free wall rupture occurre d in the lateral wall between and at the level of the two papillary mu scles. In a further 5 of 25 (20%) cases, the rupture was beside one of the papillary muscles but in anterior or posterior walls. In 20 of 25 (80%) eases, the endocardial tear associated with the LVFW rupture wa s within 1 cm of the base of one of the papillary muscles as they inse rted in LVFW. Asymmetric papillary muscle contraction forces in the ar ea of the infarct may play a role in the genesis of LVFW rupture as mo st ruptures appear in close association to the papillary muscle insert ions in the LVFW.