Diagnosis of hypertrophic cardiomyopathy

The diagnosis of hypertrophic cardiomyopathy is established based on family history (cases of sudden death of relatives at a young age), complaints, and results of physical examination. Information obtained through instrumental examination is of great importance for establishing the diagnosis. The most valuable diagnostic methods are ECG, which has not lost its importance even now, and two-dimensional Doppler echocardiography. In complex cases, MRI and positron emission tomography help to conduct differential diagnostics and clarify the diagnosis. It is advisable to examine the patient's relatives in order to identify family cases of the disease.

Clinical examination

In the non-obstructive form of hypertrophic cardiomyopathy, there may be no deviations from the norm during examination, but sometimes an increase in the duration of the apical impulse and the fourth heart sound are determined.

In the obstructive form of hypertrophic cardiomyopathy, signs of cardiac pathology are revealed. The most important ones include an increased prolonged apical impulse, occupying the entire systole up to the second tone (a sign of left ventricular myocardial hypertrophy), systolic tremor along the left edge of the sternum, pulsation of the carotid arteries, a fast "jerky" pulse during palpation of the carotid arteries, caused by the rapid expulsion of blood in the first half of systole, systolic murmur localized at the apex of the heart and in the third-fourth intercostal space on the left at the edge of the sternum. The murmur at the apex of the heart is explained by mitral regurgitation, in the third-fourth intercostal space - infundibular stenosis of the left ventricle. The intensity of the murmur increases in a sitting position, standing, on exhalation, during the Valsalva maneuver, i.e. with worsening of the obstruction to blood expulsion as a result of decreased pre- and afterload or increased contractility. The first heart sound at the apex is in most cases of normal sonority, and the second heart sound at the base is weakened in some patients, and the fourth heart sound is detected. Often, a disturbance of the cardiac rhythm is determined.

However, in some patients, systolic murmur is localized at the base of the heart, is not intense and is not accompanied by a weakening of the sonority of the second tone. In this case, recognition of the disease is possible using additional research methods, in particular, echocardiography.

Instrumental methods

Electrocardiography and 24-hour ECG monitoring

Interpretation of ECG data in patients with hypertrophic cardiomyopathy is often very difficult due to the polymorphism of changes. The following changes are most often detected:

• voltage signs of myocardial hypertrophy of the left ventricle and left atrium;
• disturbances in the process of ventricular repolarization - the most characteristic signs found in both non-obstructive and obstructive forms of HCM, manifested by changes in the ST-T interval; changes in the amplitude of the T wave can be of varying degrees of severity (from a moderate decrease in amplitude, especially in the left chest leads, to the registration of a deep negative G wave); conduction disturbances along the left leg of the bundle of His, in particular, the block of its anterior branch is the most common of all heart blocks;
• ventricular overexcitation syndrome in the form of shortening of the P-Q interval or the Wolff-Parkinson-White phenomenon is frequently recorded;
• registration of pathological Q waves in the left chest and (less often) standard leads is one of the typical electrocardiographic signs;
• Heart rhythm disturbances that can cause syncope and sudden death attract special attention from clinicians.

Daily monitoring of ECG data allows us to detect ventricular ectopic extrasystoles, attacks of ventricular tachycardia or supraventricular arrhythmia in most patients. Arrhythmias, especially ventricular ones, are detected much less frequently in children, although the frequency of sudden death in them is higher than in adults.

Chest X-ray

Data from X-ray examination of the heart in hypertrophic cardiomyopathy are uninformative. Some patients have a slight increase in the left ventricular and left atrium arches and rounding of the apex of the heart, possibly an increase in the vascular pattern associated with overfilling of the venous bed. In young children with hypertrophic cardiomyopathy, the cardiothoracic index fluctuates within 0.50-0.76.

Echocardiography

Of the non-invasive research methods, echocardiography is the most informative diagnostic method.

The main echocardiographic signs of hypertrophic cardiomyopathy are as follows.

• Left ventricular myocardial hypertrophy, the prevalence, localization and severity of which are very diverse. However, it has been found that the most common form of hypertrophic cardiomyopathy is asymmetric hypertrophy of the interventricular septum, occupying either the entire interventricular septum (50% of cases) or localized in its basal third (25%) or two thirds (25%). Less common is symmetric hypertrophy, as well as other variants of hypertrophic cardiomyopathy - apical, mesoventricular and hypertrophy of the posterior septal and / or lateral wall of the left ventricle.
• A decrease in the left ventricular cavity associated with myocardial hypertrophy, both during diastole and systole. This is an important morphological sign of the disease and one of the factors contributing to hemodynamic impairment due to insufficient filling of the left ventricle during diastole.
• Dilation of the left atrium.

In the obstructive form of HCM, Doppler echocardiography allows us to identify signs of obstruction of the left ventricular outflow tract:

• the systolic pressure gradient between the left ventricle and the aorta can be of varying degrees of severity, sometimes reaching 100 mm Hg or more;
• anterior systolic movement of the anterior leaflet of the mitral valve in mid-systole and contact of the leaflets with the interventricular septum;
• mid-systolic aortic valve closure;
• mitral regurgitation.

When assessing the functions of the left ventricle using echocardiography data, most patients with hypertrophic cardiomyopathy show an increase in the ejection fraction, but a violation of the diastolic function of the myocardium, characterized by a decrease in the speed and completeness of active diastolic relaxation, is considered important.

Magnetic resonance imaging

This method allows the most accurate assessment of morphological changes, the prevalence and severity of myocardial hypertrophy. The method is especially valuable for diagnosing the apical form of the disease and hypertrophy of the lower part of the interventricular septum and the right ventricle.

Positron emission tomography

Allows to identify and assess the degree of impairment of regional perfusion and myocardial metabolism.

Cardiac catheterization

Catheterization and angiocardiography were widely used in the early stages of studying hypertrophic cardiomyopathy. Currently, they are performed much less frequently: in cases of concomitant cardiac pathology, in particular congenital heart defects, and when deciding on surgical treatment of the disease.

The results of invasive research methods have shown that in young children, unlike schoolchildren and adults, obstruction of the outflow tract of not only the left but also the right ventricle is often determined. On the one hand, this is associated with the fact that children die in the first months and years of life as a result of refractory heart failure, and on the other hand, with the disappearance of obstruction of the left ventricular outflow tract as the child grows due to changes in the relationships of cardiac structures.

Differential diagnostics

When making a diagnosis, it is necessary to exclude diseases that have similar clinical manifestations, primarily acquired and congenital heart defects (aortic stenosis), essential arterial hypertension. In addition, it is necessary to differentiate other possible causes of left ventricular hypertrophy, in particular "athlete's heart".

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