Fístula de enxerto coronariano da artéria torácica interna esquerda para artéria pulmonar esquerda após cirurgia de revascularização miocárdica: causa rara de isquemia miocárdica

Abstract

Left internal thoracic artery fistula draining to left pulmonary artery is an extremely rare complication following myocardial revascularization. It may cause recurrent angina, dyspnea, heart failure, endocarditis, among other conditions. It should always be considered in the absence of a clear cause for the onset of these symptoms after myocardial revascularization. The diagnosis is made by coronary angiography, and most patients are treated by surgical or percutaneous closure of the fistula. CASE REPORTA 73-year-old white male patient with a history of systemic arterial hypertension and coronary artery bypass grafting six years ago using the following grafts: left internal thoracic (mammary) artery to anterior descending artery, sequential saphenous vein to the 1 st and 2 nd left marginal arteries and saphenous vein to the 1 st diagonal artery. The patient presented with asthenia and progressive exertional dyspnea, which has been getting worse over the last few months even on mild exertion. He had been taking captopril 150 mg/d, hydrochlorothiazide 25 mg/d, and acetylsalicylic acid 200 mg/d. The cardiovascular physical examination was normal, except for a fourth heart sound (S4). His lungs were found to be clean. First-degree atrioventricular block and left anterior hemiblock was seen on ECG. The echocardiogram revealed only left ventricular hypertrophy and diastolic disfunction. Myocardial ischemia investigation was performed through stress/rest myocardial perfusion scintigraphy. The scan ( fig.1) showed low uptake of the radiopharmaceutical (Tc-99 sestamibi) in the anteroseptal region on stress, which returned to normal at rest, a finding consistent with anteroseptal ischemia. Coronary angiography and left ventriculography were thus performed, showing patency of all grafts and a 70% obstruction of the right coronary artery. However, a large fistula arising at the initial portion of the left mammary artery draining to the left pulmonary artery was detected ( fig. 2 e 3). This fistula resulted in a significant steal of flow from the anterior descending artery, thought to be the cause of the anteroseptal ischemia. A surgical ligation of the fistula was performed, and the patient was discharged from the hospital. During the oneyear follow-up period, the patient was free of the symptoms which led to his hospitalization.We report a patient who developed dyspnea on mild exertion six years after coronary artery bypass graft surgery (CABG). Myocardial ischemia was documented by radionuclide imaging, and coronary angiography showed patency of all grafts and a large fistula between the left internal thoracic artery (LITA) and the left pulmonary artery (LPA). The patient was submitted to surgical closure of the fistula and made an excellent recovery.