Hypertrophic subaortic stenosis with myocardial fibre degeneration

Electrocardiographic and hemodynamic correlations in patients with idiopathic hypertrophic subaortic stenosis

The ECG and Frank VCG were compared to the hemodynamic findings in 33 patients with idiopathic hypertrophic subaortic stenosis in whom cardiac catheterization had excluded concomitant valvular heart disease, congenital heart disease, or occlusive coronary artery disease. The patients were divided into two groups according to the absence (Group I) or presence (Group II) of left ventricular hypertrophy on the ECG and/or VCG. The 11 patients in Group I were found to have neither mitral insufficiency nor a resting left intraventricular gradient, and only six patients in whom mitral valve movement was visualized demonstrated systolic anterior movement of the anterior leaflet. The papillary muscles and left ventricular wall were either normal or only mildly hypertrophied in 10 of 11 Group I patients. Group II (22 patients) demonstrated either a resting left intraventricular gradient and/or mitral insufficiency in 18 patients. Twenty-one of the 22 patients showed systolic anterior movement of the anterior leaflet of the mitral valve on a cineangiogram and the papillary muscles and left ventricular wall were moderately to severely hypertrophied in 18 patients. These data suggest that specific hemodynamic and anatomic characteristics of hypertrophic subaortic stenosis may be predicted with reasonable accuracy from the ECG and VCG.

Pathology of primary cardiomyopathies

Images

Atrial fibrillation in patients with idiopathic hypertrophic subaortic stenosis

Atrial fibrillation occurred in 16 (10%) of 167 patients with idiopathic hypertrophic subaortic stenosis. The clinical and haemodynamic findings in these 16 patients are presented. Atrial fibrillation appeared late in the course of the disease, and its occurrence did not seem to be related to the severity of left ventricular outflow obstruction or to the amount of associated mitral regurgitation. In each patient the onset of the arrhythmia was accompanied by severe clinical deterioration, which often necessitated urgent medical treatment. Digitalis was administered to all 16 patients with subsequent clinical improvement in 15. Electrical cardioversion was uniformly successful in restoring sinus rhythm, but atrial fibrillation usually recurred. In each of 8 patients catheterized during atrial fibrillation, cardiac output was strikingly low (average, 1.9 l./min./m.(2)), whereas it was normal in 10 of 13 patients studied in sinus rhythm. The duration of follow-up from the onset of atrial fibrillation has averaged 5 years, and 3 of the 16 patients have died of causes related to their heart disease. Four have suffered cerebral emboli. Only 5 patients are now in stable sinus rhythm; in general, they are less symptomatic than the patients in whom atrial fibrillation has recurred.The unusually severe clinical deterioration at the onset of atrial fibrillation and the low cardiac output measured during catheterization are thought to be related to the loss of the important contribution to ventricular filling of atrial systole in patients with poorly compliant ventricles, and to the effect of an irregular ventricular rhythm on the variable nature of the outflow obstruction.

Electromechanical correlations in hypertrophic subaortic stenosis

Six of 14 patients with hemodynamically proven subaortic stenosis (SAS) showed electrocardiographic patterns consistent with myocardial infarction. Analysis of the 0.02-sec horizontal plane vector allowed discrimination between true myocardial infarction and SAS. In SAS this vector was shifted anteriorly and to the right consistent with septal hypertrophy and increased left-to-right early septal forces.

Cineangiographic studies of left ventricular contraction revealed a unique pattern also consistent with septal hypertrophy disproportionately greater than that of the ventricular free wall.

No correlation existed between maximal instantaneous vectorial voltage, and either the peak left ventricular pressure or the pressure gradient within the left ventricular outflow tract. Striking increases in vectorial forces in SAS may be related to dystrophic changes within the myocardial mass and may not be attributable to simple hypertrophy secondary to hemodynamic obstruction.

Idiopathic hypertrophic subaortic stenosis. Clinical analysis of 126 patients with emphasis on the natural history

While considerable information concerning the hemodynamic and angiographic features of idiopathic hypertrophic subaortic stenosis (IHSS) is available, data concerning the natural history of the disease are limited. The clinical courses of 126 patients with hemodynamically documented IHSS, examined repeatedly for up to 12 years, were analyzed. The older patients tended to be more severely symptomatic. Although the course was extremely variable, the patients who were asymptomatic initially tended to remain so, while those who were more disabled generally deteriorated, died, or improved spontaneously. Bacterial endocarditis occurred in three patients. Ten patients died as a consequence of the natural history of IHSS; six of these deaths were unexpected. Sudden deaths occurred usually in patients with no or mild obstruction, and in patients with both the familial and sporadic forms of the disease. Atrial fibrillation was observed in 8% of the patients, and abnormalities of atrioventricular conduction, in 30%. Absence of voltage criteria for left ventricular hypertrophy occurred more frequently in asymptomatic patients, those with mild obstruction, and those with familial IHSS. Pulmonary hypertension occurred in one third of the patients, and was associated with considerable clinical disability. Obstruction to right ventricular outflow occurred in eight patients (15%), two of whom had no associated obstruction to left ventricular outflow.