A 65 year old woman presented with intermittent atypical substernal discomfort and mild exertional dyspnoea for one year. A transthoracic echocardiogram showed the dilated right coronary artery (RCA) coming from the right coronary cusp of the aorta (AO). Left ventricular function was well preserved without regional wall motion abnormalities.

Subsequent conventional coronary angiography showed the absence of the left coronary artery (LCA) arising from the aorta. Selective right coronary angiography demonstrated an enormously dilated, tortuous and dominant RCA from the right aortic sinus, with profuse collateral channels feeding the left coronary system, and the retrograde left main coronary artery blood flow was later seen emptying into the main pulmonary artery (PA). Multidetector computed tomography (MDCT) coronary angiography was performed by using a 16 channel multi-detector row CT scanner (Somatom Sensation 16; Siemens, Forchheim, Germany) with retrospective ECG gating. Scanning parameters were 210 ms temporal resolution and 16 × 0.75 mm detector collimation, and axial images were reconstructed with 1 mm slice thickness and 0.7 mm increment. Reconstruction window which was optimal for anomalous coronary artery was chosen at 30% of the R-R interval. A 110 ml dose of non-ionic iodinated contrast material (Ultravist; Schering, Berlin, Germany) was injected intravenously at 4 ml/s. A 30 ml normal saline bolus was given following contrast material injection to decrease artefact from contrast material in the right heart.

The three dimensional reconstruction of the CT coronary angiograph confirmed the anatomic features of the disease demonstrated in the conventional coronary angiography (panels A–D).

Three dimensional volume rendered view from CT coronary angiography enabled visualisation of dilated right coronary artery (RCA) from the aorta (panel A), anomalous origin of the left coronary artery (LCA) from the pulmonary artery (PA) (panel B), and their anatomical relation with surrounding structures (panel C). Rich collateral channels between the RCA and LCA are shown in panel D (arrows). AO, aorta.