Isolated Right Ventricular Myocardial Infarction
Shelley I Odronic, E Rene Rodriguez, Carmela D Tan. Cleveland Clinic, Cleveland, OH
Background: Isolated acute right ventricular myocardial infarctions (RVMI) are not well characterized. The right ventricle is less susceptible to ischemia, but several factors can increase oxygen demand or decrease oxygen supply, and predispose the right ventricle to ischemic damage. The incidence of isolated acute RVMI may be underestimated due to lack of detection. Tetrazolium staining is useful in the detection of early myocardial ischemia, but it is often not routinely used in the autopsy setting. The purpose of this study was to investigate the cardiac and associated findings of isolated acute RVMI and the utility of tetrazolium staining to detect myocardial ischemia in this setting.
Design: We retrospectively searched all adult autopsy cases over a 60-month period for isolated acute RVMI. Pathologic evidence of myocardial ischemia was defined by gross examination after incubation with nitroblue tetrazolium solution and by microscopic evidence of neutrophil margination, contraction band necrosis or coagulation necrosis.
Results: Thirteen cases of isolated acute RVMI were identified comprising 0.7% of all autopsies in the study period. There were 5 males and 13 females with age ranging from 43-86 years. Eleven patients had cardiomegaly (85%) with right ventricular dilation in 8 cases. The thickness of the right ventricle was ≥0.5 cm in 6 cases (46%). Ten cases had right dominant coronary circulation, one case had co-dominant circulation, and two cases had undescribed circulation. Right coronary circulation pathology included significant coronary artery disease defined as ≥ 75% luminal stenosis in 4 patients, hypoplastic right coronary artery in 1 patient and small vessel disease in another patient. Three patients had clinical evidence of pulmonary hypertension. The lungs demonstrated hypertensive vasculopathy in 4 patients and pulmonary thromboembolism in 4 cases. Tetrazolium staining was performed in 10 cases and identified areas of myocardial ischemia in all cases that were confirmed on microscopy. Ischemia involved the entire free wall in 10 cases, the posterior wall in 2 cases, and the anterior wall in 1 case. The cause of death was determined directly related to RVMI in 10 cases, while 2 patients died of massive pulmonary embolism and one patient died of respiratory failure.
Conclusions: Right coronary artery disease and pulmonary hypertension are risk factors for developing isolated acute RVMI. This study shows that tetrazolium staining is a useful and sensitive method to look for evidence of early acute ischemic changes.
Monday, March 19, 2012 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 7, Monday Morning