ALTHOUGH current evidence is somewhat contradictory, there is reason to believe that restoration of a normal sinus rhythm and the atrial transport function in patients with atrial fibrillation will shift the ventricular function curve to an area of improved performance.1 Atrial fibrillation, a common arrhythmia in adults, is encountered infrequently in infants and children. This probably reflects the relative rarity of mitral valvular disease during this period of life. Atrial fibrillation has been related to prolonged pressure or volume distention of the atria.2The purpose of this report is to describe the clinical course of an infant with endocardial fibroelastosis with mitral insufficiency and mild aortic regurgitation demonstrated during life by left ventricular angiography and retrograde aortography, respectively. He developed atrial fibrillation approximately five weeks before death. Normal sinus rhythm was restored by synchronized direct current countershock, and the patient was given diphenylhydantoin (Dilantin) as an antiarrhythmic agent. A normal sinus mechanism persisted until a few hours prior to his death one month later.
Case ReportA 9-month-old white male infant was evaluated for the first time at this center on April 23, 1965.He had just been discharged from his local com¬ munity hospital where he had been treated for con¬ gestive heart failure which was of a one-week duration and iron deficiency anemia. The referring physician's diagnosis was endocardial fibroelastosis ; there was a positive mumps skin-antigen test as described by Noren et al.3 He was receiving a main¬ tenance dose of digoxin (Elixir of Lanoxin), 0.0375 mg twice a day, and an oral iron preparation for his anemia.He was a 21-year-old mother's third child. Her pregnancy had been uneventful, and delivery oc¬ curred at term. The infant's birth weight was 7 lb 8 oz (3,402 gm). The neonatal coarse was not re¬ markable, and the child was apparently growing and developing normally until the onset of the pres¬ ent illness.A female sibling, evaluated at this clinic two years previously, had died at the age of 14 months ; the clinical diagnosis of endocardial fibroelastosis had been confirmed by postmortem examination. An electrocardiogram obtained just prior to death showed atrial fibrillation.Physical Examination.-Although the infant was pale, he appeared well nourished. He was mildly dyspneic at rest. His weight was 17 lb and 2 oz (7,767.76 gm) ; length, 27.5 inches (70 cm). Blood pressures were 89/60 and 100/60 mm Hg in the arms and legs, respectively. Pulse rate was 120 beats per minute and respiratory rate, during light sleep, was 34/minute. Abnormal physical findings were confined to the chest and abdomen. The lungs were clear to auscul¬ tation and normal to percussion. The cardiac apical impulse was in the fifth left interspace in the an¬ terior axillary line and was characterized by a sus¬ tained systolic heave. No thrills were felt over the precordium. Heart sounds were faint and distant, particularly the first heart sound at the ...