Obstructive Hypertrophic Cardiomyopathy

Melissa A. Graham-Cryan, RN; Gina Rowe, RN; Londa Hathaway, RN; Susan Biddle, RN; Dorothy Tripodi, RN; Lameh Fananapazir, MD

Disclosures

Prog Cardiovasc Nurs. 2004;19(4) 

In This Article

Abstract

Hypertrophic cardiomyopathy (HCM) is a primary disease of cardiac muscle characterized by a thickening of the left ventricular wall and often predominantly affecting the interventricular septum. This paper presents a case study of a 53-year-old female with a dynamic and obstructive form of HCM. The study includes a case presentation, clinical findings, investigations, and management. Patient findings were obtained before and after alcohol septal ablation, a novel interventional therapy. The article reviews the various forms of HCM and describes the currently available treatment modalities for obstructive HCM. Further research will be necessary to determine the comparative efficacy between past, present, and future therapies.

A 53-year-old female presented with a 10-year history of hypertrophic cardiomyopathy (HCM), increasing dyspnea and chest discomfort on exertion, postural lightheadedness, palpitations, and a functional limitation of less than one flight of stairs. Symptoms were initially treated with β blockers, which were not tolerated due to symptomatic hypotension. She was referred for further evaluation and treatment because of worsening symptoms despite taking verapamil 240 mg/day. There was a history of a congenital thyroid disorder, however, the patient was euthyroid on admission. She has three children, ages 30, 28, and 11 years, at the time of admission who are all well. There is no family history of HCM or of sudden death. She stopped cigarette smoking in 1988 and had a 14 pack-year history.

An examination of the patient revealed a regular radial pulse of 84 bpm; a blood pressure of 137/65 mm Hg; a normal jugular venous pressure; a prominent left ventricular (LV) apical impulse displaced to the anterior axillary line, fifth intercostal space; a normal first and second heart sounds and a third (S3) heart sound; a grade 3/6 systolic murmur that increased with the Valsalva maneuver and was best heard in the third intercostal space left of sternum. Her lung sounds were clear to auscultation bilaterally. The patient's peripheral pulses were present and normal.

A 12-lead electrocardiogram (ECG) is shown in Figure 1. The chest x-ray reveals a normal heart size. The ECG shows a systolic anterior motion of the mitral valve (SAM), mitral regurgitation, left atrial dimension of 48 mm (normal, <40); LV end-diastolic and end-systolic dimensions, 45 mm and 23 mm, respectively; a septum of 19 mm (normal, 6-11); an LV free wall of 10 mm (normal, 6-11); and a normal right ventricle. The cardiac catheterization revealed a mean right atrial pressure of 5 mm Hg (normal, 2-6); a right ventricular systolic pressure of 40 mm Hg (normal, 15-30); a mean pulmonary artery pressure of 20 mm Hg (normal, 10-15); a mean pulmonary artery wedge pressure of 12 mm Hg (normal, 4-12); a cardiac output of 5.7 L/min (normal, 4-8); and a cardiac index of 2.9 L/min/m2 (normal, 2.5-4.0). The simultaneous LV and aortic pressures, illustrating a dynamic (constantly changing) gradient of 90 mm Hg (abnormal LV and aortic pressures should be equal) are shown in Figure 2. The patient's angiography showed a normal epicardial left coronary artery and several large septal perforators (Figure 3). The subject's metabolic panel, complete blood count, coagulation, thyroid-stimulating hormone, and free thyroxine 4 levels were normal.

M-mode echocardiogram in obstructive hypertrophic cardiomyopathy showing systolic anterior motion of the mitral valve (SAM) (arrows indicating septum and mitral valve leaflet contact)

Illustrations of some types of hypertrophic cardiomyopathy (HCM). Panel 1. In patients with asymmetrical septal hypertrophy (ASH), the septum that separates the left ventricular cavity from the right ventricle is much thicker than the remaining walls of the left ventricle. Panel 2. Idiopathic hypertrophic subaortic stenosis (IHSS), which is the old name for the common form of obstructive HCM. In this variety, the intracavitary obstruction is caused by the movement of the mitral valve leaflet toward the septum, blocking the flow of the blood out of the heart. The area of the septum that the mitral valve touches becomes scarred. Panel 3. Apical or Japanese HCM. In this form of nonobstructive HCM, the thickest part of the left ventricle is at the tip or apex of the pump. Panel 4. Mid-cavity HCM. In this uncommon form of obstructive HCM, the obstruction is not in the outflow tract but in the middle of the ventricle. A tunnel leads into a dilated apical portion, called an aneurysm, which has thin walls. SAM=systolic anterior motion of the mitral valve

Normal epicardial left coronary artery and septal perforators

The therapeutic options of cardiac surgery, dual chamber (DDD) pacemaker therapy, and alcohol septal ablation (ASA) were discussed with the patient. The ASA procedure was chosen by the patient; ablation of the first septal branch reduced the LV outflow tract gradient from 90 to <10 mm Hg without complications. The post-procedure ECG showed an anterior septal infarct associated with a right bundle branch block (Figure 1, Panel B). The patient was discharged home after 3 days on no medications. Verapamil was restarted after discharge for episodes of atrial tachycardia. The patient reports that her symptoms and exercise tolerance are markedly improved 3 months after the ASA. The patient verbalized the ability to walk for several blocks and climb three flights of stairs before being limited by "joint pain" or muscle fatigue.

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