Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery: Diagnosis with CT Angiography
A 10-year-old girl was admitted to our hospital with complaints of syncope and shortness of breath during exercise. No detailed medical record could be reached but her parents declaimed that she has been on follow up for dilated cardiomyopathy in another hospital for 4 years and she has been taking digoxin since that time.\nOn physical examination, a parasternal 2/6 sysytolic murmur was detected on auscultation. She was thin, weak and seemed to be much younger than her age. The chest X-ray revealed cardiomegaly and signs of pulmonary congestion. The transthoracic 2-D echocardiography showed dilated left ventricle, mild mitral and tricuspid insufficiency and decreased ejection fraction. She was then referred to MSCT for evaluation of coronary anatomy.\nCT coronary angiography was performed using a 64 slice CT scanner (Acquilion 64 Toshiba, Japan). Scan parameters were as follows: Slice collimation, 64 × 0.5 mm; rotation time, 0.40 mins; tube voltage, 80 kV; tube current, 300 mA; and pitch, 0.2. The scan parameters were modified to decrease the patient dose. The average heart rate was 85 bpm during the scan. The patient did not receive a b-blocker prior to the CT examination for heart rate regulation.\nCT angiography was triggered automatically by the arrival of the main contrast bolus (automatic bolus tracking). A pre-scan was taken at the level of the aortic root and a region of interest (ROI) was identified on the descending aorta. As soon as the signal density level in the descending aorta reached the predefined threshold of 170 Hounsfield units (HU), the scan started. We injected 50 ml nonionic contrast medium (Iomeron 350/ml; Iomeprol, Bracco, Italy) at a flow rate of 3 ml/s in the left antecubital vein. This was followed by a 30 ml saline chaser bolus at a flow rate of 3 ml/s to wash out contrast from the right ventricle.\nDuring the scan, the ECG was recorded simultaneously. The continuous data acquisition allows slice reconstruction at different time points in the cardiac cycle. The reconstruction intervals for both right and left coronary arteries with the fewest motion artifacts were determined (images at 50% and75% of the R-R interval, respectively) and used for further analysis. For reconstruction of axial images, we used a slice thickness of 0.5 mm and a slice width of 0.3 mm. A medium soft-tissue reconstruction kernel (FC 43) was used for reconstruction.\nFor post-processing, an external workstation (Aquarius Intuition, Tera Recon Inc., USA) was used. In addition to the transverse source images, multiplanar reformations (MPRs), curved MPR images, maximum intensity projections (MIPs), and volume rendered (VR) images were utilized for the evaluation. VR reconstructions depicted the vascular anatomy well and were used for 3D orientation.\nIn the CT angiography, the left atrium and left ventricle were shown to be markedly dilated and the left ventricular wall and interventricular septum were hypertrophic. Also CT angiography revealed an enormously dilated, tortuous and dominant right coronary artery (RCA) [] emerging from the right aortic sinus [] with a large number of collateral vessels feeding the left coronary system, which showed enlarged and tortuous vessels []. Left main coronary artery (LCA) was emerging from pulmonary artery trunk []. The left anterior descending artery (LAD) and left circumflex artery (LCX) were branching from LCA. Both LAD, LCX and their diagonal and obtuse branches were dilated and tortious.\nAfter we reported ALCAPA with CT angiography, the patient was transferred to the cardiac catheterization laboratory by the cardiovascular surgeons not only to confirm the diagnosis but also to plan the surgical procedure. In fact, CT angiography images were enough for the diagnosis of ALCAPA and a further invasive diagnostic procedure with radiation exposure was unnecessary.\nCoronary angiography confirmed the diagnosis and showed an anomalous left coronary artery arising from the pulmonary artery (ALCAPA) with retrograde filling through collaterals from an enlarged right coronary artery. It revealed no other additional information.\nConsequently, the patient underwent an uncomplicated aortic reimplantation of the left main coronary artery. No perioperative or postoperative complication occurred. The patient is now on follow up, with no major clinical symptoms in the fourth postoperative month.