A 66-year-old male with no prior cardiac history presented to the hospital with persistent hiccups, causing shortness of breath. A nuclear stress test showed a fixed perfusion defect involving the inferior wall, possibly due to diaphragmatic attenuation artifact with no evidence of stress-induced myocardial ischemia, and a mildly decreased left ventricular ejection fraction of 44% (Figure 1). Coronary angiography revealed two-vessel coronary artery disease, 80% stenosis of the middle right coronary artery (RCA), diffuse heavy calcification of the left anterior descending artery (LAD) involving the proximal and mid-portions with 80% maximal stenosis, a small caliber left marginal, and a sinoatrial (SA) nodal branch originating from the right posterolateral artery (RPLA) (Figure 2 A, B).
The SA nodal artery, a branch of the main coronary arteries, supplies blood to the SA node. The SA node is also known as the natural pacemaker of the heart. In 60% to 70% of cases, its blood supply originates from the RCA, and in 20% to 30% from the LAD and left circumflex coronary artery (LCX). The SA nodal artery provides vital oxygen and nutrients to the SA node, which is a key component in heart contraction that originates the initial electrical signal for atrial contraction.1 When originating from the RCA, the SA nodal artery most frequently arises at a mean distance of 1.2 cm (range 0.2–2.2 cm) from its beginning.2 In less than 1% of cases, the artery originates from the distal RCA.3 The posterolateral artery, also known as the posterior left ventricular artery, arises from the RCA in a typical dominant circulation. It is a terminal branch that supplies the inferior portion of the heart along with the posterior descending artery (PDA). It can also arise from the LAD or LCX.4 Based on available data, this the first documented case of an SA nodal artery originating from the RPLA.