Dr. Sidney Blumenthal, 80, a former director of the National Institutes of Health. An educator and specialist in pediatric cardiology, Blumenthal was a professor and dean of continuing education at the University of Miami School of Medicine before he took the federal post as director of the heart and vascular disease division of the National Heart, Lung and Blood Institutes. He had also taught at Columbia University and the University of Taiwan. Blumenthal was vice chairman of the Ethics Committee of the American Heart Assn. On Tuesday in New York of leukemia.