Congenital Fistula between the Left Internal Mammary Artery (LIMA) and the Pulmonary Artery: Cause of LIMA Bypass Occlusion?

Abstract

Congenital fistulas from the left internal mammary artery to the pulmonary artery are rare. We describe a 49-year-old patient with severe aortic valve regurgitation and coronary artery disease. Percutaneous transluminal coronary angioplasty and left anterior descending artery (LAD) stenting had been performed because of a significant proximal LAD lesion. Repeated coronary angiogram 3 months later revealed a patent stent but severe sclerosis up to a 40% stenosis of the LAD after the area of stenting. An aortic valve replacement and a left internal mammary artery (LIMA) bypass to LAD were performed during standard cardiopulmonary bypass (CPB). Because of patient chest pain, a control angiogram was carried out 2 years after surgery and revealed a LIMA-bypass occlusion and a large fistula deriving from the proximal part of the LIMA to the pulmonary artery. The fistula was occluded by coils during an interventional cardiological procedure. Diminished flow in the LIMA bypass due to the fistula in combination with a nonsignificant proximal LAD stenosis are possible reasons for IMA-bypass occlusion. From this case we conclude that angiography of the IMA to detect malformations preoperatively should be mandatory in all cases of arterial coronary revascularization using IMA bypasses.

Congenital left internal thoracic artery–pulmonary artery fistula used as an inflow for a coronary artery bypass graft

“…LITA-PA fistula is known to cause recurrent angina and LITA bypass occlusion. [1][2][3] In contrast, a congenital LITA-PA fistula is rare, but angiography of the LITA before surgical intervention is generally not a standard procedure, and as a result, the presence of a congenital fistula might be overlooked. 2 In this report, we have described, for the first time, that a congenital LITA-PA fistula can be used as an inflow for the SVG and that the SVG can remain patent for more than 3 years after surgical intervention.…”

“…[1][2][3] In contrast, a congenital LITA-PA fistula is rare, but angiography of the LITA before surgical intervention is generally not a standard procedure, and as a result, the presence of a congenital fistula might be overlooked. 2 In this report, we have described, for the first time, that a congenital LITA-PA fistula can be used as an inflow for the SVG and that the SVG can remain patent for more than 3 years after surgical intervention. Although recognizing that the fistula in this case was usable in view of its appropriate location and size, it is significant in that it allowed any surgical manipulation of the aorta to be avoided because the patient was more than 80 years old and had a diffusely calcified aorta that could not be clamped.…”

Internal mammary artery-to-pulmonary vasculature fistula: Systematic review of case reports

“…[4][5][6] Current knowledge about the formation of these fistulas primarily comes from case reports; no consensus guidelines for the evaluation and management of IMA fistulas are available. [7][8][9][10][11][12][13][14][15][16][17][18] Anatomically, most cases of congenital IMA-to-PV fistulas arise from the middle third of the IMA, while other cases of IMA fistulas to the internal mammary vein or the inferior vena cava arise from the proximal third of the IMA. 19,20 The primary mechanism for developing an IMA fistula is not fully understood.…”