A letter to Helen (presidential address).
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001021:Aortic Valve / Q000601:surgery*; D006348:Cardiac Surgical Procedures / Q000639:trends*; D002315:Cardiopulmonary Bypass / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D005260:Female; D006324:Heart Arrest, Induced / Q000401:mortality; D006330:Heart Defects, Congenital / Q000401:mortality / Q000601:surgery*; D006350:Heart Valve Prosthesis / Q000401:mortality; D006801:Humans; D007036:Hypothermia, Induced / Q000401:mortality; D007223:Infant; D007231:Infant, Newborn; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012306:Risk; D012955:Societies, Medical; D013903:Thoracic Surgery / Q000639:trends*; D013997:Time Factors; D014481:United States