Anterolateral Papillary Muscle Rupture Complicated by the Obstruction of a Single Diagonal Branch
A 66-year-old woman presented with a sudden onset of anterior chest pain lasting 2 days and a 1-year history of atrial fibrillation. She had never taken medication for the atrial fibrillation, and this was her first episode of chest pain. The physical examination, including cardiac enzymes, ECG, and echocardiogram, showed that she had acute myocardial infarction with severe mitral regurgitation (Figure 1). There was no evidence of systemic embolism other than the infarction. The coronary angiography revealed a total occlusion of the first diagonal branch coming from the left anterior descending artery (Figure 2). As a result of clinical deterioration, transesophageal echocardiography was not performed. The patient underwent emergent mitral valve replacement with coronary artery bypass grafting with saphenous vein. There was a complete rupture of anterior papillary muscle, but the valve leaflets and chordae were relatively clean (Figure 3A, B). The arteriotomy of the first diagonal branch revealed an impacted thrombus (Figure 4A, B) without definite atherosclerotic lesion. After the surgical intervention, her symptoms markedly improved.
In most cases, the anterior papillary muscle has a dual blood supply from the obtuse marginal branch of the left circumflex artery and the first diagonal branch of the left anterior descending artery. In this case, however, the patient had only a single blood supply of anterior papillary muscle, which was totally occluded by thromboembolism as a result of chronic atrial fibrillation.
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