**4.2 Aberrant coronary arteries**

The aberrant origin of the CA is a rare abnormality with its origin from the contralateral aortic sinus of Valsalva [16]. In aberrant left CA, the left CA originates from the right sinus of Valsalva (rarely from the right CA) with a short intramural (within the aortic wall) course and continues between the pulmonary trunk anteriorly and the aorta posteriorly. The ostium of the left CA is often Slit-like forming a potential site for obstruction to coronary blood flow. In aberrant right CA, the right coronary artery arises from the left sinus of Valsalva (less commonly from the left main CA). This is the counterpart of aberrant left CA. The right CA then traverses rightward with a short intramural course within the aortic wall and then traverses between the pulmonary artery and aorta to get to its usual course. There is adequate coronary flow at rest, but during exercise, ischemia may develop secondary to either

#### **Figure 10.**

*A short-axis view at the level of aortic sinuses demonstrating normal left and right (RC) coronary arteries and their branches. The left main coronary artery (LMC) continues in the same direction to become the left anterior descending (LAD) artery. The circumflex (CiR) and marginal (MR) branches traverse perpendicular to the axis of LMC. The aorta (AO) and pulmonary artery (PA) are also shown. Demonstration of color flow within the coronary arteries is required to ensure that these indeed are coronary arteries. (modified from reference [16]).*

#### **Figure 11.**

*The short-axis views at the level of aortic sinuses demonstrate the origin and course of the left (LCA) (A and B) and right (RCA) (C and D) coronary arteries. The LCA continues in the same direction to become the left anterior descending artery (LAD). The circumflex (CIRC) traverses perpendicular to the axis of LCA. Color flow within the coronary arteries is demonstrated in 'B' and 'D' and is required to ensure that these indeed are coronary arteries and not parallel lines of the transverse sinus of the pericardium. Ao, aorta.*

#### **Figure 12.**

*A. a short-axis view at the level of aortic sinuses, similar to Figures 10 and 11, focusing on the left main coronary artery showing its division into left anterior descending (AD) and circumflex (CIR) coronary arteries. Note the red flow in the AD and the blue flow in the CIR. B. a short-axis view at the level of aortic sinuses, similar to figure a, but focusing on to the right coronary artery (RCA) showing its origin from the right sinus with the color flow within it. AO, aorta.*

partial or total occlusion of the CA [17, 18]. Several hypotheses have been proposed to elucidate the reason(s) for inadequate CA blood flow. One such hypothesis is compression of the CA (left or right) between the great arteries by the expansion of the aorta and pulmonary artery against each other during the exercise. Another hypothesis suggests that an angle is created between ostium of the CA and its main axis creating additional tension, during aortic expansion [19–21]. The intramural course of the coronary artery also contributes to the risk of SCD during exertion. Echocardiographic examples of aberrant left CA arising from the right sinus of Valsalva (**Figure 13**) and of aberrant right CA arising from the left sinus of Valsalva (**Figures 14**–**16**) are shown in **Figures 13**–**16**.
