Seymour I. Hepner

Incidence of Acute Rheumatic Fever A Suburban Community Hospital Experience During the 1970s

The incidence of acute rheumatic fever has declined remarkably in the past three decades, but the disease has not been eradicated, as some physicians believe. This study documents the diagnosis of the disease in 23 middle-class children from Fairfax County, Virginia, during the 11-year- period from 1970 through 1980. This county has one of the highest median family incomes in the United States. The annual age-adjusted incidence rate of initial attacks of acute rheumatic fever per 100,000 Fairfax County children declined from 3.0 in 1970 to 0.5 in 1980. In six of the 23 children, carditis accompanied by monarticular arthritis or arthralgia was present. Another seven children had carditis plus polyarthritis. Two patients had Sydenhams chorea. None of the children had erythema marginatum or rheumatoid nodules. In two children, symptoms of acute rheumatic fever developed two weeks after they finished a 10-day course of penicillin for Group A streptococcal pharyngitis. The remaining 21 children had not been considered ill enough to be brought to medical care prior to development of symptoms of acute rheumatic fever.

Successful Treatment of Supraventricular Tachycardia with Metoprolol, a Cardioselective Beta Blocker

Paroxysmal supraventricular tachycardia is a common problem in infancy and childhood. Past treatment has included digitalis and nonselective beta block ers (propranolol). We describe a new mode of therapy with a cardioselective beta blocker (metoprolol) that may be of use in patients resistant to standard therapy.

1201 CARDIAC MALFORMATIONS IN A/J MICE INDUCED BY PHENYTOIN

The fetal hydantoin syndrome is characterized by unusual facies, increased incidence of cleft lip (CL) and/or palate, hypoplasia of the distal phalanges and an increased incidence of cardiac defects. The purpose of this study was to identify phenytoin as a cardiac teratogen in A/J mice and to identify the primordial cardiac structures affected. At 11 a.m. of gestational day 10, mothers of A/J mice were injected intraperitoneally with 75 mg/kg of phenytoin. Embryos, 24, 48, and 72 hours after such treatment, and newborn mice were sacrificed as were controls. The specimens were fixed in glutaraldehyde and dissected the following day. They were dehydrated in alcohol and dried by the critical point technique. The hearts were sputter coated with gold and examined with a scanning electron microscope at 20kv. 89/107 offspring of treated mothers had CL as compared with 8/135 controls. 49/89 were cyanotic at birth. 47 newborns had a patent ductus arteriosus. 44 had an ostium primum atrial septal defect, 11 with an associated cleft in the anterior mitral leaflet and 7 with clefts in the mitral and triscupid valves. Coarctation of the aorta was noted in 11/49 newborn mice. In conclusion, phenytoin can be embryopathic when the embryo is exposed during critical stages of development of the heart and facial processes.

202 ONTOGENY OF CANINE CARDIAC BETA-ADRENERGIC RECEPTORS

Age differences in cardiac chronotropic and inotropic responsiveness to adrenergic agonists and antagonists have been reported. These developmental differences were evaluated at the molecular level by characterizing myocardial beta adrenergic receptors in puppies(1-3 wks old) and adult mongrel dogs.Partially purified cardiac plasma membranes (10,000-30,000xg) were obtained by differential centrifugation techniques. Beta adrenergic receptors were identified using the beta adrenergic antagonist 3H-dihydroalprenolol according to the method of Alexander et al(Proc Nat Acad Sci. 72:1546, 1975). Saturable binding sites were quantified using increasing concentrations of the labelled ligand in the presence of 10−5 M l-propranolol. Specific binding was 55% in puppies (n=20) and 80% in adult dogs (n=6). Scatchard plot analyses showed a greater number of receptors(p<0. 05) in the adult than in puppies:0. 3275±0. 0143 vs 0. 2151±0. 0105 pM/mg protein. Dissociation constant for the puppies was greater(p=0. 05) than adults: 10. 7112±1. 25 vs 4. 0224±0. 6746.These data suggest that the maturation of adrenergic responsiveness of the myocardium may be due to developmental changes in beta adrenergic receptor affinity and number.