CLINICAL SPOTLIGHT Clinical Spotlight Anomalous Origin of Posterior Descending Artery from Left Anterior Descending in the Presence of a Diminutive Right Coronary Artery: Diagnosed by ECG Gated Multi-detector CT Mahmood Tehrai, MD a , Bahare Saidi, MD a,b,* , Mahmoud Goodarzi, MD a , Hamidreza Baharjoo, MD a , Farideh Roshanali, MD b and Mohammad Davoodi, MD a a Radiology Department, Day General Hospital, Tehran, Iran b Cardiology Department, Day General Hospital, Tehran, Iran Coronary anomalies are easily detected on ECG gated multi-detector CT which has shown to be superior to conventional angiography is demonstrating their origin and course. We present an unusual case of posterior descending artery arising as the continuation of the left anterior descending artery (LAD) in the presence of a diminutive right coronary artery (RCA). The LAD crossed over the apex and continued its course to the base of the heart in the posterior interventricular groove as PDA. The RCA, although normal in origin, was diminutive and terminated on the lateral wall of the right ventricle. This anomaly has been rarely reported and the previous cases have all been conventional angiographic findings. (Heart, Lung and Circulation 2011;20:734–735) © 2011 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of Australia and New Zealand. Published by Elsevier Inc. All rights reserved. Keywords. Coronary; Anomaly; Computed tomography scan Introduction C oronary artery anomalies have an incidence of 0.2–1.2% in general population and are usually dis- covered incidentally [1]. Anomalous origin of the PDA as from the left anterior descending artery (LAD) is a very rare anomaly [2–6]. Herein we report a case of poste- rior descending artery as a continuation of LAD in the presence of a diminutive but normal originating right coronary artery (RCA) discovered during a coronary CT angiogram. Case Presentation A 50 year-old woman presented to our centre to undergo coronary CT angiography for evaluation of chest pain. Her past medical history was insignificant except for hyperlip- idaemia. Retrospectively gated cardiac CT was performed on a 64-slice scanner (Somatom Sensation 64; Siemens Medical Solutions, Erlangen, Germany). It was observed that the left main coronary artery was normal sized and gave off the LAD and the left circumflex (LCx) arteries. Received 27 January 2011; received in revised form 24 February 2011; accepted 7 March 2011; available online 3 April 2011 * Corresponding author at: Tavanir st, Vali Asr Ave, Day General Hospital, Tehran, Iran. Tel.: +98 912 3805902; fax: +98 21 88797353. E-mail address: bahare saidi@yahoo.com (B. Saidi). LCx was a normal and non-dominant artery which pro- vided the obtuse marginal branches. LAD was present in the anterior interventricular groove with a small super- ficial myocardial bridging in the mid segment, it did not show distal tapering, instead ran across the apex as a loop to the posterior interventricular groove and continued as PDA (Fig. 1) which also had a small myocardial bridging in the proximal segment. The PDA extended up to the crux region, where it tuned to the left and terminated by giv- ing rise of two small branches to the left ventricle. The RCA originating normally from the right coronary sinus, was a diminutive vessel ended at the lateral wall of the right ventricle (Fig. 1). No connexion was present between the RCA and the PDA. No other abnormality of the coro- nary vasculature was found and other thoracic structures including aorta and pulmonary arteries appeared unre- markable. The patient was treated medically. Discussion Coronary artery anomalies have an incidence of 0.2–1.2% in general population [1] and some of them are haemo- dynamically significant and are associated with adverse outcome. Coronary CT angiography is gaining a major role in the diagnosis of the coronary artery disease and is con- sidered as a first line in the detection and evaluation of the coronary anomalies [7]. © 2011 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of Australia and New Zealand. Published by Elsevier Inc. All rights reserved. 1443-9506/04/$36.00 doi:10.1016/j.hlc.2011.03.007