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Seven of 48 patients (14.6%) with acute myocardial infarction who were given 2.4 g of magnesium sulfate as a single intravenous dose had potentially lethal arrhythmias during the first 24 hours after admission, whereas 16 (34.8%) of 46 patients receiving placebo had similar arrhythmias. In addition, 14 of these 16 patients in the placebo group had their first arrhythmia (in the intensive coronary-care unit) within two hours after the start of the study, whereas in the magnesium-treated group, there were no such arrhythmias until some four hours later. The higher the lymphocyte potassium concentration, the greater the reduction in the incidence of arrhythmias. Serum magnesium levels increased by 16.5% and lymphocyte magnesium concentrations by 72% in the magnesium treated group. Intravenous magnesium reduces the incidence of serious arrhythmias after acute myocardial infarction.

In anatomically corrected malposition of the great arteries, the great arteries are abnormally related to one another and to the ventricles but arise from their normal ventricles. We present here a case in which this diagnosis was made by echocardiography and confirmed by cardiac catheterization.

The interventricular septal defect in patients with tetralogy of Fallot is, in most cases, a nonrestrictive malalignment type of defect. Rare examples of a restrictive defect have been described. We report a case of tetralogy of Fallot with pulmonic atresia in which the interventricular septal defect was found to be nonrestrictive at birth. The obstruction of the defect developed gradually, until, at the age of 6 years, a gradient of 55 mm Hg across the defect was found at repeat cardiac catheterization. Echocardiography proved that the acquired obstruction was due to excessive tricuspid valve tissue, while Doppler studies suggested a similar gradient between the right ventricle and the ascending aorta. This rare case should alert the clinician to the possibility of an acquired obstruction of the ventricular septal defect, with suprasystemic right ventricular pressure, in cases of tetralogy of Fallot, even if an early study suggested a nonobstructive defect. The diagnosis of this situation is of importance because of the poor prognosis which it carries.

Mitral valve prolapse (M.V.P.) is a noninflammatory degeneration of the mitral valve leaflets which results in a billowing of the redundant valve tissue toward the left atrium during the systolic phase. Mitral valve prolapse can be diagnosed by echocardiography or by auscultation where a characteristic mid-systolic click and late systolic murmur can be heard. Ophthalmic complications of MVP include chronic external progressive ophthalmoplegia and an association with keratoconus. In this case we present a case of a young woman who presented with sudden recurrent decrease in vision secondary to retinal arterioli emboli associated with the mitral valve prolapse syndrome.

Fifteen patients (median age 73 years) with severe congestive heart failure were treated with Enalapril for a total of 12 weeks with a significant improvement in their right atrial pressures and in their functional state. Renal function, serum potassium, magnesium and calcium levels were unchanged. Lymphocyte sodium, potassium and calcium levels were generally lower than control values throughout the study but these differences were only statistically significant early in the study. Lymphocyte magnesium levels were unchanged. These findings are in contrast to those previously reported in the literature for such patients treated with conventional diuretics.

Familial occurrence of membranous subaortic stenosis (MSS) is described in three families. The defect was found in 2 siblings in two of these families, and in 3 siblings of the third family. The importance of early diagnosis and treatment of MSS is emphasized. We suggest early evaluation of first-degree relatives of patients with MSS for the possibility of this defect.