PAPILLARY-MUSCLE PERFUSION PATTERN - A HYPOTHESIS FOR ISCHEMIC PAPILLARY-MUSCLE DYSFUNCTION

Background The pathogenesis of posterior papillary muscle dysfunction is poorly understood. We hypothesized that papillary muscle perfusion pattern may explain the higher prevalence of posterior papillary muscl e dysfunction after myocardial infarction. Methods and Results Twenty patients were monitored by transesophageal echocardiography during cor onary surgery. Superselective coronary graft injections of 0.2 to 0.5 mL of sonicated albumin microbubbles were performed to assess graft pa tency and papillary muscle perfusion. Thirty-five graft injections wer e analyzed: 13 in the right coronary artery, 15 in an obtuse marginal branch, 1 in the left anterior descending coronary artery, and 6 in th e first diagonal branch. The posterior papillary muscle was opacified in 16 patients, 11 from the right coronary artery and 5 from one obtus e marginal branch. In 10 of 16 patients (63%), the papillary muscle wa s perfused by one vessel, while in 6 of 16 (37%), it was perfused by t wo vessels. The anterior papillary muscle was opacified in 14 patients . Ten patients (71%) had double-vessel and 4 (29%) had single-vessel s upply. In the subgroup of 10 patients with old inferior myocardial inf arction, mitral regurgitation was present only among those 6 with sing le rather than double blood supply (P<.05). Conclusions Myocardial inf arction may cause papillary muscle dysfunction when the blood supply i s provided by one rather than two vessels, as is more frequently the c ase with the posterior rather than the anterior papillary muscle.