Myocardial Infarction in Children With Hypoplastic Coronary Arteries
An 11-year-old boy with a past history of asthma was admitted to the pediatric intensive care unit (ICU) for a non–Q-wave myocardial infarction that occurred during sustained exercise (a handball match). He presented with chest pain, anterior ST-segment depression on the ECG (Figure 1⇓), and elevation of creatinine kinase (peak, 2580 mU; MB, 240). Initial physical examination was normal, and his ICU course was uncomplicated. He was discharged to the ward after 2 days, and cardiac catheterization was performed 8 days after admission. Left ventriculography (Figure 2⇓) revealed mild apical hypokinesia with an ejection fraction of 55%. Selective coronary arteriography showed no atherosclerotic lesion but hypoplasia of the distal left anterior descending (LAD) and right coronary (RCA) arteries (Figures 3⇓ and 4⇓). There was no supply of the inferior aspect of the interventricular septum by a posterior branch from the RCA or left circumflex coronary artery (LCx). The proximal LAD was normal, with well-developed septal branches but no diagonal branches filled by contrast on the anterolateral free wall of the left ventricle (Figure 4⇓). Intracoronary infusion of nitroglycerin showed no significant changes in coronary artery diameter (Figure 5⇓). Total cholesterol, HDL, sedimentation rate, serological studies for connective-tissue diseases, antithrombin III, protein C, protein S, endogenous tissue plasminogen activator, and plasminogen activator inhibitor were normal. The patient was discharged home on diltiazem after a normal maximal exercise test 16 days after admission.
In 85% of patients, the coronary circulation is right-dominant, and the RCA supplies the inferior aspect of the interventricular septum by giving rise to the posterior descending artery. The LCx, which is often small, does not reach the crux of the heart. Conversely, when the LCx is the dominant coronary artery, it courses to the crux of the heart and the RCA is often small.1 In ≈7% of patients, there is a codominant or balanced system in which both RCA and LCx give rise to a posterior descending branch. Hypoplastic coronary artery disease (HCAD) occurs rarely and refers to the underdevelopment of ≥1 coronary arteries or their major branches.2 Most of the patients reported were young adults and experienced sudden cardiac death without antecedent symptoms. Diagnosis is often made at autopsy.1 2 Although reversible myocardial ischemia has previously been angiographically documented in an infant, it is unusual to see a patient with myocardial infarction and isolated HCAD diagnosed at coronary angiography, as in our patient.3 Hypoplasia of the RCA and LCx with no posterior descending artery supplying the inferior aspect of the interventricular septum is more commonly found.1 Hypoplasia of the LAD has also been reported.2 3 In addition, HCAD was found in several cases of myocardial infarction distal to atherosclerotic or thrombotic occlusions.2
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke’s Episcopal Hospital and Texas Heart Institute, 6720 Bertner Ave, MC1-267, Houston, TX 77030.
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