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We report the case of a 32-year-old man who presented at the emergency department with severe chest pressure, left arm pain, and dizziness. These symptoms were described as intermittent, occurring after exercise and at rest. He had undergone several stress tests during the past 8 years, but no objective evidence of ischemia was produced. His history of hyperlipidemia and increasing frequency of symptoms prompted us to perform coronary angiography, which showed a single coronary artery with an ostium at the right sinus of Valsalva. The vessel had an initial, mixed common trunk that gave rise to both the right coronary artery proper and to the left coronary artery. The left main trunk followed a prepulmonic course. The anatomic features were eventually confirmed by computed tomographic angiography. The left main stem had a fixed 50% to 60% area narrowing, at baseline study. A treadmill stress myocardial perfusion study showed no evidence of ischemia.
The patient was referred to a 2nd facility, where intravascular ultrasonography, at baseline, revealed 63% left main narrowing without evidence of atherosclerosis. Acetylcholine provocation demonstrated worsening of the stenosis to about 80%, with reproduction of angina and ST-segment depression, which indicated that medical management of spasm might provide symptomatic relief.
Coronary artery anomalies are found in approximately 1% of individuals who undergo coronary angiography.1 More than 80% of the anomalies found in angiographic series are considered benign and unlikely to cause myocardial ischemia,1 but some coronary anomalies are known to cause cardiac morbidity and death. Typical presentations of coronary anomalies include angina, syncope, congestive heart failure, myocardial infarction, and sudden death.2 Coronary anomalies are 2nd only to hypertrophic cardiomyopathy as the leading cause of sudden death in young athletes.2
Anomalous origin of the left main coronary artery is classified by the course that the vessel traverses to the left of the great vessels. The 5 described courses are as follows: 1) between the aorta and pulmonary trunk, 2) anterior to the pulmonary trunk, 3) intraseptal, 4) posterior to the aorta, and 5) posterior to the atrioventricular valves.2–4 The arterial course between the aorta and pulmonary trunk has a known association with sudden cardiac death, which occurs particularly during exercise; in fact, 82% of sudden death cases in patients with anomalous origin of the left main coronary artery are secondary to this course.2,3
The case described herein presents a unique perspective on the way in which an anomalous origin of the left main coronary artery coursing the 2nd path listed above—anterior to the pulmonary trunk—can induce ischemia.
We report the case of a 32-year-old man who had an 8-year history of intermittent chest pressure associated with left arm pain, nausea, dizziness, and diaphoresis. The symptoms occurred most frequently when he was at rest but occasionally upon exertion. During those years, the patient had undergone several stress tests, including exercise echocardiography and a treadmill stress myocardial perfusion study, but no ischemia was documented. He had been treated with atenolol for mitral valve prolapse and with paroxetine for panic disorder.
He presented at the University of Arkansas for Medical Sciences emergency department in June 2004 because he was experiencing the above symptoms with increasing frequency at rest and on exertion. He reported no history of smoking or diabetes, or family history of premature coronary heart disease. He had a history of hyperlipidemia that was being treated with pravastatin, 40 mg daily.
His chest pain had resolved upon arrival at the emergency department, and his electrocardiogram (ECG) showed no evidence of ischemia. Because of the history of resting angina and hyperlipidemia, cardiac catheterization was performed.
Coronary angiography revealed a single coronary artery, which arose from the right sinus of Valsalva. The vessel had an initial, mixed common trunk that gave rise to both the right coronary artery proper and to the left coronary artery. The left main trunk crossed to the left via a prepulmonic course, reaching the left anterior descending coronary artery (LAD) at the mid-anterior interventricular groove. A 50% to 60% narrowing was noted in the mid-segment of the left main stem, which appeared smooth. Intravenous nitroglycerin was administered but did not cause a notable change in luminal diameter. An end-to-end anastomosis was noted from the right coronary artery–posterior descending artery to the LAD, around the apex.
The patient was given amlodipine for treatment of possible vasospasm of the narrowed segment, and the atenolol was discontinued. A computed tomographic angiogram confirmed the prepulmonic course.
Because of the patient's history of unresolved resting angina, repeat cardiac catheterization was performed at the Texas Heart Institute with intravascular ultrasonography (IVUS) and acetylcholine provocation testing. Intravascular ultrasonography (Fig. 1) showed a 63% area narrowing of the left main prepulmonic segment without evidence of atherosclerosis. Also noted was a 1-mm-diameter bridging collateral vessel around the stenotic segment (Fig. 2). Upon intracoronary administration of 30 μg of acetylcholine over a period of 30 seconds, the baseline stenosis worsened to approximately 80% (Fig. 3), with reproduction of his typical angina; diffuse ST-segment depression was evident on ECG. The bridging collateral vessel did not change, but the LAD filled at this time, preferentially retrograde from the posterior descending artery. Intravenous nitroglycerin quickly relieved the pain and resolved the ECG changes, but a residual diameter stenosis of approximately 25% remained.
The patient was discharged from the hospital on diltiazem (180 mg daily) for vasospasm or Prinzmetal's angina. Low-dose isosorbide mononitrate (15 mg daily) was subsequently added, and diltiazem was changed to verapamil (360 mg daily). When last seen in early 2007, the patient was doing well on medical treatment, although he had been admitted to the hospital several times for chest pain. His follow-up nuclear stress test was negative, and there were no ECG or cardiac enzyme changes. The patient's prognosis was considered good, because of adequate collateral circulation and good clinical response to vasodilator therapy.
This case provides a unique example of ectopic origin of the left coronary artery from the right sinus of Valsalva.4 The single coronary artery arising from the right sinus of Valsalva in our patient had an initial mixed, common trunk that gave rise to both the right coronary artery proper and to the left coronary artery that followed a prepulmonic course.
The peculiarity of our case is related to 2 exceptional phenomena. First, there was a fixed moderate narrowing of the left main trunk at baseline (25%–60% after intracoronary nitroglycerin administration), at the site of likely “stretching” of the ectopic vessel as it coursed over the right ventricular outflow tract. Second, in a patient with resting angina, acetylcholine testing reproduced the presenting symptoms and correlated with the appearance of 80% left main stenosis at the site of the baseline narrowing. To our knowledge, this is the 1st time that such a mechanism of ischemia has been documented in a left coronary artery with a prepulmonic course. The only other pathophysiologic mechanism of ischemia in anomalous origin of a coronary artery from the opposite side is the one associated with an inter-arterial or intramural course (at the aortic wall), as recently documented by our group.5–7
The prognosis for patients who have ectopic coronary arteries should not be judged solely on the generic angiographic determination of anomalous origin or solely on the course that the ectopic vessel traverses to the correct side. Recent IVUS studies5–9 have suggested that it is not the inter-arterial passage per se, nor the slit-like ostium, nor the ostial ridge, nor the tangential origin of an ectopic artery that likely causes clinical manifestations but, rather, the specific circumstances of the crossing, which only IVUS can precisely show. In our patient, IVUS ruled out intimal thickening and fixed stenosis, while the acetylcholine provocation confirmed the clinical diagnosis of Prinzmetal's angina. In fact, spasm could be elicited at a specific segment of the left main trunk, reproducing the main clinical symptom. This coronary site is peculiar because it is likely subject to mechanical stimulation from the right ventricular outflow tract and is not protected by an atrioventricular or interventricular sulcus (which normally assures some slack, by the presence of loose connective and adipose tissue).
Address for reprints: Garrett B. Sanford, MD, 100 Grady 103, Chapel Hill, NC 27517. E-mail: ude.cnu.hcnu@drofnasg