The Novel Use of a Covered Stent in the Management of a Left Internal Mammary Artery to Pulmonary Vasculature Fistula

Left internal mammary artery (LIMA) to pulmonary vasculature fistulas are rare complications following coronary artery bypass surgery. In symptomatic cases, management tends to be either conservative or surgical ligation of the fistula. This case describes the use of a covered JOSTENT^™ (Jomed GmbH Rangendingen, Germany) to occlude the origin of the fistulous communication. Case Report. A 79-year-old male with a history of coronary artery disease, type 2 diabetes mellitus and hyperlipidemia presented with a recurrence of unstable angina resulting in multiple hospital admissions. He had previously undergone coronary artery bypass grafting in 1985 for symptomatic coronary artery disease. He had a left internal mammary artery to left anterior descending (LAD) artery and two saphenous vein grafts (SVG); one to a marginal branch of the AV circumflex, and one to the right coronary artery (RCA). His symptoms showed improvement, and he remained pain-free for the following 10 years, at which point he subsequently developed angina on exertion. Coronary angiography revealed a long stenotic lesion of the SVG to the circumflex, a 60% stenosis at the junction of the LIMA and the LAD artery and an occluded SVG to RCA. There was only minimal progression of his native coronary arterial disease. He underwent angioplasty and stenting of the SVG to the circumflex in which the lesion was covered with a 3.5 x 32 mm Rx Multi-Link^™ (Guidant Corporation, Santa Clara, California) stent with a good angiographic result. Eight months later, following a non-ST-elevation myocardial infarction in the lateral wall, a coronary angiogram revealed a new lesion proximal to the previous stent. This was pre-dilated and stented with a 4.0 x 25 mm NIR PRIMO^™(Boston Scientific Ireland Ltd./Medinol Ltd., Galway, Ireland) stent with excellent flow. The patient was stable over the next 2 years, but following this, had a recurrence of ischemic symptoms. Angiography revealed a vascular communication between the left internal mammary artery graft and the left pulmonary vasculature (Figure 1). There was no other significant disease progression and excellent flow through the saphenous vein graft to the circumflex stents. A covered JOSTENT^™ (Jomed) was used to occlude the proximal end of the communication in the left internal mammary artery (Figures 2A, 2B) with complete obliteration of flow. The patient also underwent intervention to the distal lesion at the junction of the left internal mammary artery and the left anterior descending artery. At the end of the procedure there was good flow in the left internal mammary artery graft with no evidence of flow in the fistula (Figure 3). An enhanced computer tomography of the patient’s chest showed no abnormalities. The patient remained well after this procedure with a good improvement in symptoms but was admitted 12 months later with an episode of unstable angina. Angiography showed restenosis with some recurrence of flow in the fistula. After further balloon dilatation and deployment of a Cypher^™ (Cordis, Warren, New Jersey) drug-eluting stent the fistula was completely obliterated. Discussion. Internal mammary to pulmonary vascular fistulas can be classified as either congenital1,2 or acquired; the latter being secondary to surgical intervention. They are thought to be caused by an inflammatory process around the myocardium or visceral pleura, and there is an increased frequency in patients who have had multiple operations.^3,5,6 The symptoms are caused by coronary-pulmonary steal syndrome, which typically presents as a recurrence of angina. This patient had no ischemic symptoms for 10 years post-coronary artery bypass graft (CABG) and his initial symptoms were related to progressive graft disease. This case was unusual in that the presentation was 14 years post-CABG. Although the fistula may have developed before its detection review of his angiograms performed between 10 and 12 years, post-surgery reveals no evidence of fistula formation. Previous case reports have described fistula formation anywhere from 5 months to 6 years.^5,7,8 Clinical examination often reveals a new onset systolic murmur which was not evident in this patient. Suggested investigations include myocardial perfusion scanning, CT, MRI and selective LIMA angiography. Management is dictated by the severity of symptoms and previous cases have been treated either conservatively,^3,6,8 surgically⁵ or with the use of a percutaneous coil spring. This patient clearly was describing significant pain at rest despite optimum medical management. Surgical ligation requires a left thoracotomy with the associated operative and anaesthetic risks, and percutaneous coil springs^3,4 can cause thrombosis and distal embolization.³ The use of a covered stent has never been reported as a method of managing these particular communications but theoretically seems to be a plausible alternative option in patients with high operative risks. A previous case has been reported where a similar stent was used to repair a coronary artery bypass graft-related pseudoaneurysm.⁹ This case represents an additional management option in this rare but extremely significant condition, and is particularly of value in patients for whom further surgical intervention carries a significant risk of morbidity and mortality.

1. Schumacker HB Jr., Girod DA. Fistulous communication between internal mammary and pulmonary arteries. Am Surg 1973;39:12–14. 2. Ruberti U, Odero A, Arpesani A, et al. Internal mammary artery to pulmonary artery fistula. J Cardiovasc Surg (Torino) 1986;27:734–736. 3. Najm H, Gill IS, Fitzgibbon GM, et al. Coronary – pulmonary steal syndrome. Ann Thorac Surg 1996;62:264–265. 4. Oldenburg O, Philipp T, Forsting M, et al. Percuraneous catheter-based coil embolization of coronary fistula: Determination of haemodynamic relevance. Journal of Interventional Cardiology 2003;16:343–346. 5. Johnson JA, Schmaltz R, Landreneau RJ, et al. Internal mammary artery graft to pulmonary vasculature fistula: A cause of recurrent angina. Ann Thorac Surg 1990;50:197–198. 6. Kimmelstiel CD, Udelson J, Salem D, et al. Recurrent angina due to a left internal mammary artery to pulmonary artery fistula. Am Heart J 1993;125:234–236. 7. Blanche C, Eigler N, Bairey CN. Internal mammary to lung parenchyma fistula after aotocoronary bypass grafting. Ann Thorac Surg 1991;52:141–142. 8. Groh WJ, Hovaguimian H, Morton MJ. Bilateral internal mammary to pulmonary artery fistula after a coronary operation. Ann Thorac Surg 1994;57:1642–1643. 9. RogersJH, Chang D, Lasala JM. Percutaneous Repair of coronary artery bypass graft–related pseudoaneurysms using covered JOSTENT. The Journal of Invasive Cardiology 2003;15:533–535.