Idiopathic Hypertrophic Subaortic Stenosis and Mitral Stenosis

Transcription

1 CASE REPORTS Idiopathic Hypertrophic Subaortic Stenosis and Mitral Stenosis Martin J. Nathan, M.D., Roman W. DeSanctis, M.D., Mortimer J. Buckley, M.D., Charles A. Sanders, M.D., and W. Gerald Austen, M.D. ABSTRACT An instance of coexistent mitral stenosis and idiopathic hypertrophic subaortic stenosis is reported. Mitral valvulotomy and resection of hypertrophic muscle were successfully performed. The physiology of the combined lesion is discussed. M itral regurgitation is common in idiopathic hypertrophic subaortic stenosis (IHSS) [1, 31. Patients have been operated upon with the erroneous diagnosis of mitral stenosis only to find a normal mitral valve and systolic muscular obstruction to left ventricular outflow [4]. This report describes an unusual patient with coexistent IHSS and mitral stenosis, the latter probably rheumatic in origin. A 44-year-old woman was first admitted to the Massachusetts General Hospital in May, 1964, with increasing fatigue, exertional dyspnea, and paroxysmal atrial fibrillation. There was no history of rheumatic fever although a murmur had been detected eighteen years before, when she was pregnant. Her mother was 66 years old when she died of hypertensive heart disease, and her father died of a stroke. A brother was known to have had irregular heart rhythm. On physical examination there was a right ventricular tap with a loud first heart sound and a palpable second sound (Sz) that was paradoxically split. A grade 1/6 systolic murmur was heard at the apex, and a grade 2 ejection murmur was present at the left sternal border. There was a faint From the Departments of Surgery and Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Mass. Supported in part by National Institutes of Health Grant No. HE (HEPP). Accepted for publication Aug. 27, Address reprint requests to Dr. Nathan, 4300 Alton Rd., Miami Beach, Fla VOL. 18, NO. 2, AUGUST,

2 NATHAN ET AL. FIG. 1. Posteroanterior and lateral chest roentgenograms showing diffuse cardiac enlargement. The esophagus is displaced posteriorly by an enlarged left atrium. diastolic rumble at the apex, but no opening snap was heard. The chest roentgenogram showed moderate left atrial enlargement with enlargement of both ventricles and no intracardiac calcification (Fig. 1). An electrocardiogram showed biatrial enlargement and suggested an old anteroinferior myocardial infarct (Fig. 2). The clinical impression at that time was mitral stenosis and mild mitral regurgitation, with the possibility of IHSS arising on the basis of the unusual electrocardiogram. The following month a right and retrograde left heart catheterization with left ventriculography was performed. The pulmonary wedge pressure was 14 mm. Hg at rest and rose to 24 mm. Hg with exercise. There was a I I1 111 AVR AVL AVF FIG. 2. Electrocardiogram with abnormal Q waues in leads II, III, avf, and V,-V,, suggesting an old anteroinferior infarct. 192 THE ANNALS OF THORACIC SURGERY

3 CASE REPORT: Subaortic and Mitral Stenosis diastolic mean gradient of 10 mm. Hg (14 mm. Hg with exercise) across the mitral valve and a calculated minimal mitral valve area of 1.1 cm.2 There was no gradient across the aortic valve. However, when the catheter was positioned lower in the left ventricular cavity there was a variable gradient rising to as high as 60 mm. Hg across the left ventricular outflow tract. The gradient was absent following angiography and methoxamine administration and was increased by isoproterenol infusion and with a Valsalva maneuver. The radial artery tracing exhibited the typical spike-and-dome configuration of IHSS. The calculated left ventricular outflow area was 0.5 cm.2 at rest and with exercise. A 10 mm. Hg peak systolic gradient was noted across the right ventricular outflow tract which increased to 20 mm. Hg following administration of isoproterenol. The pulmonary arteriolar resistance was normal, and there was no evidence of right or left ventricular failure. The cardiac index was 2.5 liters per minute per square meter of body surface and failed to rise with exercise. Left ventriculography demonstrated systolic narrowing of the left ventricular outflow tract with hypertrophy of the left ventricular wall. There was no mitral regurgitation, and the coronary arteries were normal (Fig. 3). During the next four years she was admitted to the hospital three times with paroxysmal atrial fibrillation and mild congestive heart failure and either reverted spontaneously to normal sinus rhythm or did so following electrical cardioversion. Propranolol was added to her drug regimen to help control the arrhythmia. FIG. 3. Left uentriculogram in diastole (A) and in systole (B). There is systolic narrowing of the left ventricular outflow tract. VOL. 12, NO. 2, AUGUST,

4 NATHAN ET AL. In July, 1968, she was readmitted with atrial fibrillation and transient left-sided numbness, probably due to a small cerebral embolus. Anticoagulation with warfarin was begun. The following month the patient returned to the hospital for a cardiac operation. Through a median sternotomy, using cardiopulmonary bypass and moderate hypothermia, the aorta was cross-clamped and a longitudinal aortotomy extending into the noncoronary sinus was performed. Left coronary artery perfusion was instituted. Through the aortic orifice the hypertrophic myocardium on the interventricular septum and free ventricular wall was exposed. A generous resection of the hypertrophied muscle was performed with good resolution of the subvalvular obstruction. The left atrium was then explored through the right superior pulmonary vein, and a fibrous mitral valve typical of rheumatic mitral stenosis was found. Valvulotomy with the Tubbs transventricular dilator was performed with a satisfactory result, and the aortotomy and atriotomy were then closed. The patient was rewarmed, and bypass was discontinued without difficulty. She remained in atrial fibrillation postoperatively and was discharged on the sixteenth postoperative day after an uneventful postoperative course. She has continued to do well. Comment This patient had the typical catheterization and operative findings of IHSS, in particular a systolic pressure gradient within the body of the left ventricle and systolic muscular stenosis of the left ventricular outflow tract. At operation there was fibrous commissural adherence typical of rheumatic mitral stenosis. The small systolic gradient across the right ventricular outflow tract is not uncommonly seen in IHSS and can probably be attributed to bulging of the hypertrophied interventricular septum into the right ventricular outflow tract [I]. One of the IHSS patients reported by Braunwald and associates [I] had an 8 mm. Hg gradient across the mitral valve but also mitral regurgitation. When examined at operation, the mitral valve in this patient was normal. Teare [4] described a patient with congestive heart failure, atrial fibrillation, and an apical diastolic rumbling murmur. The electrocardiogram, however, showed 1eft ventricular preponderance. Mitral valvulotomy was performed. The valve was found to be narrowed, and a hard mass thought to be calcified thrombus was noted in the anterior ventricular wall. The patient died and at postmortem examination had findings typical of IHSS with distortion of the mitral valve by a greatly hypertrophied septum. There was no thickening of the valve itself. -Much has been written on mitral valve dysfunction in IHSS. This usually concerns the associated mitral regurgitation present in about half the patients with this disorder. The electrocardiographic pattern suggesting I94 THE ANNALS OF THORACIC SURGERY

5 CASE REPORT: Subaortic and Mitral Stenosis myocardial infarction in our patient in the absence of a history of any such episode first raised the question of associated IHSS. This electrocardiographic pattern has frequently been described in IHSS [2]. It is interesting to speculate what effect the concomitant mitral stenosis had on the pathophysiology of IHSS in this patient. Usually, any maneuver causing an increase in ventricular systolic volume or depression of the contractile state of the myocardium (e.g., hypervolemia, propranolol, general anesthesia) tends to decrease the degree of obstruction in IHSS. Conversely, those factors which increase the contractile state of the myocardium or cause reduction in ventricular systolic volume (Valsalva maneuver, isoproterenol, nitroglycerin, exercise, and premature contraction) increase the obstruction. It is possible that mitral stenosis, by leading to decreased ventricular filling, might be expected to accentuate the systolic muscular obstruction in IHSS. In addition, the mitral stenosis might have contributed to the onset of atrial fibrillation, which is a particularly deleterious rhythm in IHSS. References 1. Braunwald, E., Morrow, A. G., Cornell, W. P., Aygen, M. M., and Hilbish, T. Idiopathic hypertrophic subaortic stenosis: Clinical, hemodynamic, and angiographic manifestations. Amer. J. Med. 29:924, Frank, S., and Braunwald, E. Idiopathic hypertrophic subaortic stenosis: A clinical analysis of 126 patients with emphasis on natural history. Circulation 37:759, Menges, H., Brandenburg, R. O., and Brown, A. L. The clinical, hemodynamic, and pathologic diagnosis of muscular subvalvular aortic stenosis. Circulation 24: 1126, Teare, D. Asymmetrical hypertrophy of the heart in young adults. Brit. Heart J. 20:1, VOL. 12, NO. 2, AUGUST,