Right Anomalous Coronary Artery Origin : The Role of Multislice CT Angiography

Introduction: The anomalous origin of the right coronary artery (RCA) from the left coronary sinus coursing between the aorta and the pulmonary trunk is rare, but may cause myocardial ischemia and sudden death. Multislice CT coronaryangiography offers the possibility to visualize anomalous coronary artery origin non-invasively in details. Case Illustration: A 54-year-old man with a history of arterial hypertension, and hypercholesterolemia began to present with typical chest pain. After some non-invasive examination, he had coronary angiographythat revealed 70% stenosis at mid intermediate artery, normalLMCA, LAD and LCX. Ostium of RCA was found near the left valsava sinus afterrepeated cannulation attempts, no stenosis was found at RCA. After successful revascularization at intermediate artery, patient still had typical chest pain with positive ischemic response in treadmill test. Multislice CT coronary angiography was performedto evaluate the etiology of chest pain. The scan showed patent stent at intermediate artery and anomalous RCA origin from the left coronary sinus withacute angle take-off, luminal narrowing of the osteal-proximal part, as well as luminal compression between the ascending aorta and the pulmonary trunk (an interarterial course) while RCA appeared as dominant vessel. These features were considered as malignant coronary anomaly that could lead to the recommendation of surgical correction. Discussion: Accurate recognition and documentation of coronary artery anomalies are essential to determine the significance of such findings and to avoid furtherclinical complications. Multislice CT coronary angiography is a non-invasive imaging modality that can easily and precisely depict the origin and course of coronary artery anomalies as well as its relationship with adjacent structures.


Introduction
The anomalous origin of the right coronary artery (RCA) from the left coronary sinus (LCS) coursing between the aorta and the pulmonary trunk is rare, but may cause myocardial ischemia and sudden death. 1 Multislice CT coronary angiography offers the possibility to visualize anomalous coronary artery origin non-invasively in details. 2

Case Report
A 54-year-old man with a history of arterial hypertension, and hypercholesterolemia began to present with typical chest pain.After some noninvasive examination, he had coronary angiography that revealed 70% stenosis at mid intermediate artery, normal LMCA, LAD and LCX.Ostium of RCA was found near the left valsava sinus after repeated cannulation attempts, no stenosis was found at RCA.
After successful revascularization at intermediate artery, patient still had typical chest pain with positive ischemic response in treadmill test.
Multislice CT coronary angiography was performed to evaluate the etiology of chest pain.The scan showed patent stent at intermediate artery and anomalous RCA origin from the left coronary sinus with acute angle takeoff, luminal narrowing of the osteal-proximal part, as well as luminal compression between the ascending aorta and the pulmonary trunk (an interarterial course) while RCA appeared as dominant vessel.Measurement of diameters for proximal and mid segments of the RCA were 2,1 mm and 3,9 mm, respectively.(Figure 1)

Discussion
The incidence of the anomalous origin of the RCA from the LCS is 0.019% to 0.49% on coronary angiography. 3As Eckart et al report also suggests, evidence from autopsy series indicates that anomalous origin of the RCA from the LCS is associated with sudden cardiac death in 25% of cases. 4A coronary artery arising at improper sinus follows one of the four possible pathways to reach theirnormal positions.The aberrant vessel may course posterior to the aorta (retroaorta), or between the ascending aorta and pulmonary artery (interarterial), prepulmonary artery (prepulmonic), or septal (subpulmonic). 5(Figure 2) An interarterial course is associated with risk of myocardial ischemia ("malignant anomaly") because it generally occurs with: a small, slit-like orifice, acute angle takeoff, potential of compression between the great vessels during exercise, due to expansion of the aortic root and pulmonary artery trunk root, and the artery with the anomalous course can be the dominant artery. 6Study of the proximal structures, including the takeoff portion, is important in formulating a treatment plan.MSCT coronary angiography is the favored imaging method. 3In our patient, coronary anomaly were considered as malignant that could lead to the recommendation of surgical correction.

Summary
We have bee n reported a case of a patient in whom evaluation of angina pectoris revealed an anomalous RCA arising from the LCS with interarterial course (malignant coronary anomaly) by multislice CT coronary angiography.
Accurate recognition and documentation of coronary artery anomalies are essential to determine the significance of such findings and to avoid complications.Conventional coronary angiography is the standard to assess coronary artery disease, but it has some limitations because of limited number of 2D projection images.Multislice CT coronary angiography is non-invasive imaging modality that can precisely depict the origin and course coronary artery anomalies and is recommended if coronary artery anomaly is suspected, particularly when canulation in coronary angiography was difficult.

Figure 1 .
Figure 1.Oblique axial MPR imaging (A) shows luminal narrowing (arrow) of the proximal portion of the anomalous RCA, as well as a small orifice with acute angle takeoff, the oblique sagittal MPR (B) image shows an anomalous RCA (arrow) arising from left coronary sinus.Oblique coronal MPR imaging (C) shows an interarterial course with luminal compression (arrow).Axial MPR imaging (D) shows luminal narrowing of the proximal portion of the anomalous RCA.Volume rendered cranial view (E) shows RCA arising from the left coronary sinus (an interarterial course).MPR: multiplanar recostruction, RCA: right coronary artery, PA: pulmonary artery, Ao: aorta, LCC: left coronary sinus, RCC: right coronary sinus

Figure 2 .
Figure 2. Scheme of anomalous coronary pathway to reach their normal positions.