IDIOPATHIC LEFT VENTRICULAR HYPERTROPHY: A HEMODYNAMIC REAPPRAISAL

Evaluation of phentolamine as a provocative test for idiopathic hypertrophic subaortic stenosis

Intravenous injection of phentolamine potentially offers a better provocative test for aortic left ventricular outflow tract obstruction than do Valsalva's maneuver, inhalation of isoproterenol, or of amyl nitrite. In hemodynamic studies, phentolamine enhanced myocardial contractility, and decreased afterload with only induction of slight tachycardia. Phentolamine (5 mg.) was administered intravenously to five patients who had idiopathic hypertrophic subaortic stenosis, and 35 patients who had valvular dysfunctions, after which echocardiographic and phonocardiographic recordings were performed. Recordings were of high quality despite changing hemodynamics. Systolic pressures fell an average of 20 mm. Hg; no pressure fell below 90 mm. Hg; there was no notable increase in heart rate. In the five patients with typical idiopathic hypertrophic subaortic stenosis, the amyl nitrite increased the obstructive index from 39.6 +/- 12 to 51 +/- 18.9 (P less than 0.05); whereas, phentolamine increased the obstructive index to 69.8 +/- 25.6 (P less than 0.015). After a 2 week course of oral administration of 80 mg. of propranolol daily, and then either inhalation of amyl nitrite or injection of phentolamine, there was no change from the mean resting obstructive index. Phentolamine appears to be a safe, simple and specific diagnostic agent, and more potent than amyl nitrite in eliciting dynamic obstruction in IHSS; phentolamine and amyl nitrite do not affect the obstructive index in patients with beta blockade.

Idiopathic hypertrophic subaortic stenosis and ventricular preexcitation

Two patients who had idiopathic hypertrophic subaortic stenosis (IHSS) and type A ventricular preexcitation were studied and showed variations of the subvalvular flow gradients. The increase in subvalvular gradient, occurring at a time when preexcitation developed, was associated with significant increase of the systolic murmur and the systolic anterior motion of the mitral valve. In patient 1, the significant increase in subvalvular gradient during ventricular preexcitation was also confirmed by catheterization of the left side of the heart. The increase of the gradient with the development of the ventricular preexcitation was apparently due to decreased end-diastolic volume. The importance of ventricular volume considered as a variable affecting outflow tract gradient in idopathic hypertrophic subaortic stenosis is emphasized.

Situs inversus totalis associated with subaortic and subpulmonic stenosis

The unusual occurrence of total situs inversus and idiopathic hypertrophic subaortic stenosis with the demonstration of right and left heart dynamic obstruction in one patient is presented. The fact that the patient was known to have a rare abnormality (total situs inversus) and the presenting symptom being angina pectoris, may have obscured the diagnosis of IHSS and emphasized the value of comprehensive evaluation of patients. The documentation of right ventricular dynamic obstruction, in addition to obstruction of the left side of the heart, was facilitated by the use of simultaneous pressure recordings in the pulmonary artery and in the body of the right ventricle. The angina-like pain was secondary to left ventricular outflow obstruction, rather than to coronary disease.

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.

Experimental myocardial infarction. IV. Reduction of left ventricular compliance in the healing phase

Compliance of the infarcted left ventricle was studied in dogs 3-5 days after occlusion of the left anterior descending coronary artery. Compliance was assessed from postmortem pressure-volume curves and from pressure-length measurements (mercury-in-silastic segment length gauges) made both in vivo and postmortem. Postmortem pressure-volume curves showed reduced compliance compared to sham-operated animals. Postmortem pressure-length curves of infarcted and adjacent normal myocardium indicated that the diminished total compliance could be attributed to an increase in stiffness of the infarcted area. This was confirmed by in vivo end-diastolic pressure-length changes produced by transient aortic occlusion. The infarcted area was akinetic, showing neither contraction nor aneurysmal bulging. In addition, anesthetized dogs with infarcts, when compared with sham-operated animals, had similar left ventricular end-diastolic volumes (indicator dilution method), but higher left ventricular end-diastolic pressures. Taken with previous observations, which show that systolic aneurysmal bulging is uniformly present at the onset of ischemia, these results indicate that stiffening of the ischemic myocardium occurs during the first 5 days after infarction, and show that elevation of left ventricular filling pressure does not necessarily signify ventricular dilatation. The results also suggest a mechanism whereby ventricular performance may improve during recovery from acute myocardial infarction.

Left ventricular volume in aortic stenosis measured by an angiocardiographic and a thermodilution method

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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.

Impaired rate of left ventricular filling in idiopathic hypertrophic subaortic stenosis and valvular aortic stenosis

In order to determine whether there is any interference with left atrial emptying or left ventricular filling in idiopathic hypertrophic subaortic stenosis (IHSS) and aortic stenosis, the fall in pressure (y descent) of the left atrial v wave following the opening of the mitral valve was analyzed in 27 patients with IHSS and in 22 patients with valvular aortic stenosis, and the results were compared to those for 13 normal subjects and 24 patients with mitral stenosis. The y descent in 0.1 sec and the mean rate of the y descent, as well as the maximum rate of decline, were reduced in all three groups of patients, as compared to those of the normal group. The changes in IHSS were more marked than those occurring in patients with aortic stenosis or mitral stenosis. These findings in patients with IHSS and valvular aortic stenosis appear to result from reduced left ventricular compliance. It is concluded that there is an impairment of left ventricular filling in IHSS and that obstruction to ventricular inflow, as well as to outflow, contributes to the hemodynamic changes in this condition.

Effects of prompt squatting on the systolic murmur in idiopathic hypertrophic obstructive cardiomyopathy

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Ventricular volume studies in a patient with hypertrophic subaortic stenosis

Left ventricular volume studies were performed on a patient with hypertrophic subaortic stenosis utilizing cineangiocardiography. During the injection of contrast material the patient had a premature ventricular contraction followed by sinus rhythm. The ventricular volume measurements were made during the post PVC beat and subsequent sinus beats. The volume studies revealed normal end-diastolic volumes and small end-systolic volumes with an increased ejection fraction. Although the left ventricular stroke volume was greater during the post PVC beat than during subsequent beats, the simultaneous arterial systolic and pulse pressure did not rise. The elevated diastolic filling pressure, the normal end-diastolic volumes, and the failure of the end-diastolic volume to increase with a longer diastolic filling period are compatible with diastolic restriction in hypertrophic stenosis.