Multiple Coronary Artery Aneurysms and Coronary–Pulmonary Artery Fistula Associated with Vieussens’ Arterial Ring

INTRODUCTION: Vieussens' arterial ring (VAR) is a vascular anomaly characterized by a communication between the conus branch of the right coronary artery (or the isolated conus artery) and the left anterior descending artery. Pathological changes of VAR, including dilation or aneurysmal formation, are exceedingly rare, and the mechanisms underlying these changes have yet to be elucidated. CASE PRESENTATION: A 65-year-old woman presented with dyspnea. Contrast-enhanced CT revealed that the isolated conus artery, arising directly from the right sinus of Valsalva, communicated with the left anterior descending artery, corresponding to VAR. The vessel exhibited beaded dilation and aneurysmal formation, and formed a fistula to the main pulmonary artery. We performed surgical resection of the coronary artery aneurysms and closure of the fistulous connection. The postoperative course was uneventful. Histopathological examination of the resected coronary aneurysm wall revealed thinning of the vessel wall and disruption of elastic fibers in the media. Of particular note was the prominent infiltration of CD8-positive T cells in the VAR specimen, in addition to the presence of atherosclerotic changes. CONCLUSIONS: We present a rare case in which VAR developed multiple coronary artery aneurysms and a coronary - pulmonary artery fistula, and discuss the potential mechanisms underlying its pathological alterations. Our findings suggest that inflammation associated with CD8-positive T cells may contribute to vascular wall fragility in VAR.