Single Coronary Artery

Introduction

Isolated coronary artery anomalies are found in approximately 1% of patients on coronary arteriograms and 0,3% of patients at autopsy. ^1-3 In as little as 0,024% of people, a single coronary artery is formed.^4,5 This variation is usually benign, but may be associated with congenital heart disease such as tetralogy of Fallot, transposition of the great arteries, truncus arteriosus, and coronary artery fistula._⁶ We present a patient with single left coronary artery detected by coronary angiography and further depicted by cardiac CT.
 
Case Description

A 79-years old female with progressive shortness of breath, occasional palpitations, atypical chest pain and diminishing tolerance of exertion was scheduled for diagnostic coronary angiography. On physical examination, the blood pressure was 130/90 mmHg, and her pulse rate was 68. The electrocardiogram displayed atrial fibrillation, slight ST depression and T-wave inversion in V4-6. The transthoracic echocardiographic examination proved normal systolic function of the heart with minor mitral and tricuspid valves regurgitation.  She has also been treated for hypertension for a long time, and had pacemaker implanted in 2006 and repositioned in 2009. She suffered from chronic atrial fibrillation and dyslipidemia. She was on anticoagulation therapy with Warfarin. Previous chest X-ray revealed atherosclerotic plaques in the aortic walls.

The course of the cardiac catheterization was uneventful with no signs of significant coronary arteries stenosing process. The right coronary artery origin was not detected during the procedure. Both attempts of selective catheterization and aortography using power-injector were negative for right coronary artery ostium detection. Instead, a large single left coronary artery was discovered with large calibre left circumflex artery continuing distally, crossing the crux cordis and following the right atrioventricular groove, supplying the right coronary artery territory branches. (Figure 1, 2) This retrocardiac course of the artery is considered a benign variant. Therefore, subsequent coronary computed tomography angiography was ordered to depict thoroughly the cardiac anatomy, and exclude any coincidental anomaly of the chest arteries. The examination was performed without prior beta blockers administration on the single source 128- slice CT, with standard cardiac CT scanning mode and retrospective gating protocol. The CT device employed was Siemens Definition AS+, Erlangen, Germany and the datasets were post-processed using Siemens Circulation and Aquarius Terarecon software. The quality of the images was good and allowed complete depiction of this variation. No accompanying great vessels anomalies were detected. (Figures 3-5) The V/Q lung scan was negative for pulmonary embolization. No correlation between angiographic findings and the patient´s symptoms was found. The patient was treated conservatively; minor changes in her antihypertensive medication were only done, and the patient´s clinical status has been satisfactory so far.

Discussion

Coronary artery variations or anomalies are relatively often encountered in cardiac patients. The incidence is about 1 in 100 patients undergoing cardiac catheterization.  Coronary arteries variations are classified as anomalies with or without shunt or congenital aneurysms.^7,8 

In our patient, a single left coronary artery was detected, which is considered a very rare finding. According to the scientific literature, a single coronary artery occurs in 0,024%-0,066% of people.^4,5  In the large group of 8235 patients examined by coronary angiography published by Donaldson et Al. (1982), there was the right coronary artery entirely replaced by a large circumflex artery only in 4 patients.⁹ Single coronary artery is defined as only one coronary artery originating from sinus of Valsalva, supplying the entire heart, regardless of its distribution pattern. Depending on the course of the RCA, this finding may be benign or may place the patient at increased cardiac risk. If the anomalous artery traverses within the aortic wall or between the aorta and pulmonary artery, it can be associated with myocardial ischemia and increased risk for sudden cardiac death.