Shepherd's crook right coronary artery: a multidetector computed tomography coronary angiography study

Shepherd's crook deformity of the right coronary artery (RCA) is considered a haemodynamically non-significant course anomaly. It may be challenging for cardiologists during percutaneous transluminal coronary angioplasty.

To investigate the radiological anatomy of the high riding course of the proximal segment of the RCA, especially focused on the Shepherd's crook RCA (SCRCA), on multidetector computed tomography (MDCT) coronary angiography.

A total of 1,118 MDCT coronary angiography examinations were reviewed retrospectively (349 [31.2%] male; 769 [68.8%] female, age range from 18 to 88 years [54.4 ± 14.7 years, mean ± standard deviation]). We classified the segments that had a higher course than RCA ostium (high riding RCA) into two types: type 1--courses turning inferior with an angle equal to or more than 90 degrees, type 2 (SCRCA)--courses turning inferior with an angle less than 90 degrees. The origin of the sinoatrial node artery (SANA) and conus artery were also noted.

High riding RCA was detected in 146 (13%) patients. Of them, 105 (71%) had type 1 and 41 (29%) had type 2. Atherosclerotic plaque formations, to varying degrees, were presented in 10 (24.3%) of the patients with SCRCA. Approximately half of SANA originated from the SCRCA segment of the RCA in SCRCA cases.

This is the first study about SCRCA that has been performed with MDCT coronary angiography. This study brings important anatomical knowledge to cardiologists. To have knowledge about the origin of the SANA prior to PTCA procedures is important to prevent possible arrhythmias and infarcts.