Case Report and Brief Review / Cardiovascular Imaging

Utility of Coronary Computed Tomography Guidance for Intervention of an Anomalous Right Coronary Artery

James R. Wilentz, MD and Harvey S. Hecht, MD
James R. Wilentz, MD and Harvey S. Hecht, MD
ABSTRACT: A case of a patient with an anomalous right coronary artery arising anteriorly and superiorly to the left main coronary artery from the left coronary cusp presented a dilemma in terms of treatment strategy for the ostial slit-like lesion and the atherosclerotic lesion in the mid vessel. Both lesions appeared severe on angiography, but the vessel could not be easily cannulated with diagnostic catheters for ideal visualization. Computed tomographic angiography (CTA) allowed high-resolution imaging of the artery, its location and course, and allowed characterization of the ostial lesion as a non-atherosclerotic, but significant, stenosis and showed the mid lesion to be a severe typical atherosclerotic plaque. In addition, CTA served as a map for the selection of optimal views of the coronary artery for cannulation and suggested the use of the guide catheter that was ultimately successful in addressing the unusual location of this ostium and in supporting the implantation of drug-eluting stents safely in the ostial and mid-vessel stenoses. Although previous reports are published on interventional treatment of slit-like ostia of anomalous coronary arteries, this is the first report to our knowledge of the concomitant use of CTA to support interventional treatment of a slit-like ostium. J INVASIVE CARDIOL 2009;21:374–376 Stent implantation for atherosclerotic stenoses of the coronary arteries is a well-established procedure resulting in the reestablishment of rapid flow into the distal bed and resolution of acute ischemic events in the case of unstable angina or myocardial infarction, and resolution of effort-induced ischemia in the case of patients with stable angina. It has been less clear that stent implantation is indicated for the treatment of non-atherosclerotic lesions of the coronary tree, although there have been reports of stenting in cases of ostial lesions of native coronary arteries,1 Takayasu’s arteritis2,3 and myocardial bridging.4 Finally, although stent implants have been successfully reported for atherosclerotic stenoses in the conduit portions of aberrant or anomalous coronary arteries,5 there are few reports of stent insertion for successful treatment of ischemia due to the slitlike ostia of aberrantly placed coronary arteries, where the arterial wall is not thickened by the atherosclerotic process, and thus the stent is implanted at relatively high pressures against the normal trilayer structure of the arterial wall. The stenosis in this location is not in general due to plaque, rather, it is due to distortion of the vessel by the unusual position and angulated origin of the coronary artery at the aortic junction. We report here a case of drug-eluting stent (DES) treatment of an anomalous right coronary artery (RCA) ostium arising from just anterior to the left coronary ostium at the edge of the left coronary cusp. In this case, computed tomographic angiography (CTA) allowed definition of the lesion as non-atherosclerotic, aided in the optimization of angiographic views for cannulation and wire manipulation, and delineated the course of the aberrant artery between the aorta and pulmonary artery. Case Report Clinical findings and catheter angiography. A 60-year-old male presented with dyspnea and angina on walking. A stress nuclear study showed inferolateral ischemia, and catheterization and angiography were performed. Aortic root angiography in the left anterior oblique (LAO) view showed an anomalous origin of the RCA from high on the anterior wall of the aorta, just above the level of the left main coronary artery (Figure 1). We were unable to selectively cannulate this artery, but were able to see in non-selective views that there was at the very least an 80% ostial stenosis with a slit-like configuration (not evident in the Figure presented here, but seen in the moving images). A second area of 75% stenosis was seen approximately 3 cm into the course of the artery (Figure 1, arrow) with a typical atherosclerotic appearance. The patient’s left ventricular function was normal, with an ejection fraction estimated at 55%, and there was no mitral regurgitation. After the diagnostic catheterization, a 64-slice CTA of the coronary arteries was performed to better define the orientation of the ostium of this artery and its course, as well as the nature of the disease at the aortic ostium, and to serve as a guide for potential intervention. The CTA views that best profiled the coronary artery and its stenoses were then chosen for the catheter interventional views, and were helpful in the choice of guiding catheter for intervention. Coronary CTA. Sixty-four-slice coronary CTA with three-dimensional reconstruction was performed on the Brilliance-64 scanner (Philips Medical Systems, Cleveland, Ohio) using the 64 x 0.625 mm detector configuration, 120–140 kVp, 600–1000 mAs, 0.2 pitch and standard or sharp filters (Philips CC and CD filters). Nonionic contrast (Ioversol 350 mg/ml at 5–6 ml/sec) was used, followed by 50 ml of saline at the same rate using a double-head injector (Optivantage DH, Mallinkrodt, Cincinnati, Ohio). Estimated effective radiation dose was 13 mSv. The cardiac phase best demonstrating each artery (75% of the R-R interval) was analyzed using a dedicated CT workstation the Philips CT Extended Brilliance Workspace, Philips Medical Systems, Cleveland, Ohio) and a cardiac adaptive multisegment reconstruction algorithm. Curved and straightened multiplanar reformatted images and cross-sectional images were constructed and evaluated for degree of stenosis and tissue densities. Standard bolus chase technique was used without beta blockade since the intrinsic heart rate was less than 70 beats per minute. CT angiograms are presented with their catheter counterparts taken at the time of intervention (Figure 2). These showed that the ostium of the right coronary was free of atherosclerotic disease in its wall, but had the typical slit-like configuration of a high lying aberrant RCA from the left cusp. The artery then coursed anteriorly and caudally between the aorta and the pulmonary artery to reach the AV groove, continuing in the typical course of a right coronary artery to the crux of the heart where it gave the posterior descending and then the posterolateral segment. Within the segment coursing between the great vessels, there was a second lesion that did have an atherosclerotic appearance of soft plaque with a 75% eccentric stenosis. Cross-sectional analysis (Figure 3A) demonstrated the non atherosclerotic ostial narrowing with reduced minimum luminal area, and the atherosclerotic mid lesion with markedly reduced minimum luminal area secondary to complex mixed plaque. The remainder of the vessel was free of disease. Coronary intervention. Using a 6 Fr system with femoral access, a left Amplatz 1 guiding catheter (Medtronic Corporation) was utilized to reach the unusual location of the right coronary ostium high in the left cusp above and anterior to the left coronary ostium (Figure 2). A 0.014 inch nitinol Runthrough™ wire (Terumo Medical Corp., Somerset, New Jersey) was chosen to access the artery because of its preservation of torque around acute angulations, since the angle of entry into this ostium was severe, with the tip of the guide catheter of necessity pointing cranially and posterior (to reach the ostium) but the artery immediately coursing caudal and anterior (Figure 2C). Two 3.0 x 18mm Cypher® stents, (Cordis Corp., Miami Lakes, Florida) were implanted at high pressure from distal to proximal, first in the atherosclerotic lesion in the conduit portion of the artery and then at the ostium, obliterating the luminal stenosis at both sites (Figure 3). Bivalirudin (Angiomax®, The Medicines Company, Parsippany, New Jersey) was used throughout the procedure as anticoagulant and aspirin 325 mg daily and clopidogrel 75 mg daily had been given for the preceding 5 days. There were no complications of the procedure. The patient was seen in the clinical office 14 days later and reported complete resolution of his previous symptoms of chest pressure and dyspnea while climbing stairs. Discussion. This case, while not unique, is illustrative of the utility of computed tomographic angiography in solving the problem of the high lying anomalous origin of the right coronary artery from the left sinus of Valsalva. This results in a characteristically slit-like orifice, which has been felt to be at least partly the culprit in causing ischemia in these patients along with the variable compression that may occur from a course between the aorta and pulmonary artery as was present in this case.6,7 The aberrant origin of the right coronary from the left coronary sinus is rare, occurring in only 0.107% of 126,595 patients undergoing coronary angiography and representing 8.1% of all coronary anomalies found in a study from the Cleveland Clinic in 1990.8 Due to concern regarding systolic compression and repair of the slit orifice, a surgical approach has been taken by many authors including transposition and reimplantation of the coronary arteries as well as unroofing and repositioning of the artery in question.9,10 Percutaneous techniques were not initially favored, for fear of potential coronary rupture with hematoma formation in a lesion without a developed atherosclerotic plaque with its concomitant thickened wall and greater resistance to radial force.11 Similarly, plain coronary bypass operation has been criticized, since competitive flow from the native artery may lead to decreased graft flow and ultimately to the atresia of the graft, especially in an arterial conduit.12 More recently, multidetector computed tomographic angiography has been utilized (as in this case) to diagnose the patterns of coronary anomaly,13 and has the advantage of supplying a three-dimensional understanding of the course of the artery. This can help in determining the severity of risk to the patient and may also, as in this case, aid in the decision on treatment and the planning of the treatment including the guide catheter selection and the method of cannulating the coronary ostium. Although CTA is limited in that the spatial resolution of 64-slice CTA is not as fine (0.33 mm vs. 0.2 mm) as it is with direct contrast coronary angiography,14 the images attained are diagnostic with respect to the larger portions of the coronary tree, and are of particular help (as in this case) in quantitating the luminal cross-sectional area, understanding the relation of the coronary to the great vessels and in imaging the plaque constituents. Treatment with interventional techniques for the anomalous coronary has been tried with increasing frequency of reports in the literature,15,16 including one other case of stenting the slit-like ostium itself.17 This case is illustrative of one of the ways in which coronary computed tomographic angiography may be key to the diagnosis and treatment of anomalous coronary arteries. From the Lenox Hill Heart & Vascular Institute, New York, New York. Disclosure: H. Hecht is on the speaker’s bureau for Philips Medical Systems. Manuscript submitted December 12, 2008, provisional acceptance given January 14, 2009, final version accepted February 9, 2009. Address for correspondence: James R. Wilentz, MD, FACC, FSCAI, Lenox Hill Heart and Vascular Institute, 130 E. 77th St., New York, NY 10021. E-mail: jwilentz@lenoxhill.net
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