Coronary Arteriovenous Fistula: Direct Connection of the Proximal Circumflex Artery to the Coronary Sinus

Abstract

There exists an extensive literature describing the clinical and morphologic characteristics of coronary artery fistulas [1, 2]. The angiographic and echocardiographic appearances of the two cases in the reports that follow highlight the confusion in the current literature with regard to differentiating coronary arteriovenous fistulas and the entity known as the aorto-right atrial tunnel [3, 4]. The aorto-right atrial tunnel is a very rare anatomic condition in which the communication arises directly from the aorta, with dilation of the corresponding sinus of Valsalva [4]. The ‘‘tunnel’’ consists of a dilated and tortuous vessel originating from either the left, or noncoronary, sinus with variable entry to the right atrium. The coronary arteries arise independently of the aorto-right atrial tunnel, and no branching vessels (coronary artery) arise from the tunnel itself. Two-dimensional echo cardiography can differentiate a coronary arteriovenous fistula by visualizing both coronary origins separately away from the tunnel. They manifest as a dilated main coronary artery with proximal and distal branches that distribute into the myocardium [4, 5]. The sinus of Valsalva has normal morphology.