Aortic Root Sign

Abstract

Appearance: The aortic root sign describes an anomalous circumflex coronary artery (ACCA) that emerges from the contralateral coronary sinus, and travels underneath the aorta to supply blood to its normal vascular territory. Explanation: The moniker, “aortic root sign,” was first coined by Page et al1 on conventional angiography to describe ACCA as arising from the proximal right coronary artery or right coronary sinus. The aberrant vessel courses inferiorly behind the aortic root within the groove between the left atrium and aorta,2 hence the term “aortic root sign” (Fig. 1).FIGURE 1: Fifty-six-year-old patient with atypical chest pain. A, Right anterior oblique ventriculogram from left heart catheterization demonstrates anomalous course of the left circumflex (LCX) en face below the aortic root (classic aortic root “dot” sign; thin arrow) (LV=left ventricle). B, Electrocardiogram-gated cardiac computed tomography (CT) matched in projection of the cardiac catheterization reveals the same signature appearance of the anomalous LCX (thin arrow). C, CT correlate of the conventional aortic root “dot” sign seen on an axial image from an electrocardiogram-gated CT reveals the anomalous LCX coursing inferior to the noncoronary sinus of the aortic root (medium arrow) (RA=right atrium, RV=right ventricle, LA=left atrium). D, Volume-rendered image of the aortic root demonstrates coronary origin from the right sinus of Valsalva (asterisk) with immediate takeoff of the anomalous LCX (arrowhead) from the normal right coronary artery (large arrow).Discussion: Traditionally coronary artery anomalies (CAAs) were thought to have little significance, and were often discovered as incidental findings on angiography. However, patients may present with clinically significant disease.2 In fact, CAAs are the second most common cause of sudden cardiac death in young athletes in the United States.2 ACCA was first described by Antopol and Kugel.3 The prevalence of ACCA reported in the coronary angiography literature ranges from 0.18% to 0.67%, making it the most common CAA. Some authors postulate that the oblique angulation of its origin predisposes ACCA to atherosclerosis. However, most clinicians agree that ACCA is a benign, asymptomatic anomaly. Indeed, the retroaortic course of ACCA, as described by the aortic root sign, rarely leads to ischemia or sudden cardiac death. On the contrary, CAAs that travel along an interarterial course between the aorta and pulmonary artery are more prone to ischemia during strenuous exercise.2 Despite the low risk of ischemia and sudden death with ACCA, recognition of this anomaly is still of great clinical importance because failure to identify this aberrant vessel can lead to adverse patient outcomes, especially during cardiac surgery. Therefore, it is crucial for the angiographer as well as the radiologist to be adept at recognizing ACCA and the other coronary anomalies, especially given the ease of diagnosis with noninvasive coronary imaging techniques, such as multidetector computed tomography4 and cardiac magnetic resonance imaging.5