Internal illnesses. Hypertrophic cardiomyopathy (lecture notes)

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Internal illnesses. Hypertrophic cardiomyopathy (lecture notes)

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LECTURE № 17. Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy - hypertrophy of the walls of the left ventricle (occasionally right) without expansion of the cavity, with increased systolic function and impaired diastolic function. Hypertrophy is more often asymmetric with a predominance of thickening of the interventricular septum, not associated with increased work of the heart. Men get sick 2 times more often.

Pathogenesis. Asymmetric septal hypertrophy leads to dynamic, then fixed obstruction of the outflow tract from the left ventricle. The ability of the myocardium to relax is reduced. The diastolic function of the left ventricle worsens due to calcium overload of the cytoplasm of cardiomyocytes and a decrease in the elastic properties of the myocardium against the background of hypertrophy and cardiosclerosis. Coronary blood flow decreases due to a decrease in the lumen of the intramural arteries against the background of intima proliferation, a decrease in the density of blood vessels per unit volume of a cardiomyocyte, and the lack of complete relaxation during diastole.

Pathological anatomy. There are 4 types of hypertrophic cardiomyopathy: predominant hypertrophy of the upper sections of the interventricular septum, isolated hypertrophy of the interventricular septum throughout, concentric hypertrophy of the left ventricle, hypertrophy of the apex of the heart.

The main hemodynamic options are:

1) obstructive;

2) with permanent obstruction of the outflow tract of the left ventricle (at rest);

3) with latent obstruction (no pressure gradient at rest), obstruction occurs with increased myocardial contractions, a decrease in blood flow to the heart, a decrease in afterload (lowering blood pressure, peripheral resistance);

4) non-obstructive (no pressure gradient).

Clinic. Clinically noted are shortness of breath, aggravated by physical exertion, pain in the region of the heart, muscle weakness, dizziness, fainting, palpitations, attacks of loss of consciousness. The disease can be asymptomatic or vegetative-dystonic. There are no changes in skin color and cyanosis. Pulse of weak systolic filling. Arterial pressure is prone to hypotension, pulse amplitude remains normal or decreases.

The apex beat has a biphasic character, the second wave occurs after overcoming the obstruction. A pre-systolic impulse is possible, coinciding in time with the systole of the left atrium and the sound of the IV tone; a push is possible in the early phase of diastole at the moment of rapid filling of the left ventricle and sounding of the III tone. Double, triple, quarter apex beats represent a symptom pathognomonic for obstructive hypertrophic cardiomyopathy.

During auscultation at the apex and at the Botkin point, a systolic murmur of great variability is heard.

In the non-obstructive form, a secondary origin of cardiomyopathy is possible, since over the years the tendency to cardiac arrhythmias increases, which can be complicated by circulatory decompensation.

Additional diagnostic study. The most diagnostically significant is the ECG study. This study reveals signs of left ventricular hypertrophy; the appearance of atypical Q waves is possible - deep, narrow in leads II, III, aVF, V4, V5; in the inferolateral chest leads, deep Q waves are followed by low R waves and upright T waves; Q waves reflect a sharp thickening of the interventricular septum; possible signs of WPW syndrome, repolarization disorders, ST segment depression, T wave inversion.

To detect ventricular tachycardia, atrial fibrillation, daily Holter ECG monitoring is performed.

Echocardiography reveals changes in the thickness of the interventricular septum, which can reach 1,7-2 cm or more. Hypokinesia or akinesia (due to fibrosis), a decrease in the cavity of the left ventricle (in systole the cavities are in contact), hypertrophy of the basal sections of the interventricular septum are also detected; mitral valve calcification.

Complications. The main types of complications are ventricular fibrillation (risk of sudden death), hemodynamic collapse (during exercise), cardiac asthma, pulmonary edema.

Differential diagnostics. Should be performed with mitral valve prolapse, coronary heart disease, hyperkinetic syndrome, mitral insufficiency, isolated aortic stenosis, congestive cardiomyopathy.

Treatment. β-blockers are prescribed in high doses, which increase the filling of the left ventricle, reduce the pressure gradient and have an antiarrhythmic effect.

Calcium channel blockers are used. Verapamil has a negative inotropic effect on the myocardium, is prescribed 40-80 mg 3-4 times a day. Long-term treatment with this drug can lead to inhibition of automatism, deterioration of atrioventricular nodal conduction, and excessive negative inotropic action. You can not prescribe the drug with a large filling of the left ventricle, with orthopnea, nocturnal paroxysmal dyspnea.

Nifedipine is inappropriate, as it increases the pressure gradient due to a pronounced vasodilating effect (syncope).

Antiarrhythmic drugs are used. Cordarone is prescribed for ventricular arrhythmias: in the first week, 600-800 mg / day, then 150-400 mg daily with a two-day break every week. The effect of the drug occurs after 1-2 weeks and persists for several months after withdrawal. Disopyramide is indicated for supraventricular and ventricular tachycardia.

Physical activity is limited, alcoholic beverages are excluded, and timely antibiotic therapy is carried out for infections.

Cardiotonic agents, diuretics, nitrates, vasodilators are contraindicated in the treatment.

Of the surgical methods of treatment, excision of a part of the interventricular septum and mitral valve replacement are used.

Flow. Relatively favorable, the disease progresses slowly.

Forecast. Severe, annual mortality with obstructive form is about 1,5%, due to congestive insufficiency 0,2%.

Author: Myshkina A.A.

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