Hypertrophic cardiomyopathy

The heart consists of an outer layer, the pericardium, a muscular layer called the myocardium, and an inner layer, the endocardium. The myocardium is the part that is responsible for exerting force to carry out the pumping of blood and that shapes the heart chambers, atria and ventricles.

When, for whatever reason, the walls of the ventricles increase in size and hypertrophy, that is, they become thicker, the heart is diminished in its ability to relax, which is why it cannot fill with blood correctly and the pumping of blood is impaired. the same to the circulatory stream. In these cases the patient is said to have hypertrophic cardiomyopathy.

How is it produced?

Most cases of hypertrophic cardiomyopathy are due to a genetic alteration in chromosome 14, although alterations in other chromosomes have also been described. This alteration follows an autosomal dominant inheritance pattern, although this genetic alteration can sometimes occur without a family history. In addition to causing thickening of the walls, there is usually an alteration in the organization of the muscle fibers and in the coronary arteries.

The walls of the left ventricle thicken and the myocardium slowly distends, so that it loses its elastic capacity and cannot relax adequately so that its chambers fill with blood during the diastole phase of the cardiac cycle. The most affected wall is usually the one that separates both ventricles, although sometimes the hypertrophy of the ventricular walls is symmetrical.

Likewise, it is frequent that there is an alteration of the associated mitral valve, so that the anterior part of the valve is dragged during the expulsion of the blood and makes it difficult to leave it during systole. This phenomenon is known as anterior systolic movement or SAM.

Symptoms

Hypertrophic cardiomyopathy can be suffered without the patient presenting any type of symptoms, but at the same time it is the main cause of sudden cardiac death in young people without having suffered any previous symptoms.

In case of presenting symptoms, these are due to a defect in the heart's blood pumping capacity. Patients may present with dyspnea secondary to heart failure caused by a defect in the filling capacity of the ventricle. Dyspnea is the most common symptom of this disease.

Other symptoms that patients may present are syncope, dizziness, palpitations or angina pectoris, as occurs in the case of aortic valve stenosis.

Atrial fibrillation, angina pectoris, acute myocardial infarction, or sudden death are complications of hypertrophic cardiomyopathy. Sudden death, rare in its entirety, usually affects adolescents and young people in general as a consequence of a severe ventricular arrhythmia. Family history, syncope, or asymptomatic ventricular tachycardias are poor prognostic factors.

Diagnosis

Hypertrophic cardiomyopathy should be evaluated in patients with a family history of this disease and suspected in patients who, with or without a family history, present symptoms compatible with it, especially if they are young people.

Cardiac auscultation shows a murmur in the area of ​​the left ventricle during the systole phase that increases with physical exercise, when performing a Valsalva maneuver or when standing up abruptly, while it decreases when squatting or elevating the extremities. lower.

The electrocardiogram shows nonspecific signs of enlargement of the left ventricular walls. Also, arrhythmias secondary to hypertrophic cardiomyopathy can be detected.

The chest radiograph usually does not show alterations, at most a slight increase in the size of the cardiac silhouette.

The echocardiogram will make it possible to assess the thickening of the walls of the left ventricle and quantify the severity of the impairment of cardiac function. A thickness of the wall that separates both ventricles will be appreciated greater than 15 mm, when the normal is that it has a thickness of between 8 and 11 mm. If the thickening is greater than 11 mm, it can be said that there is hypertrophy, but it cannot be said of hypertrophic cardiomyopathy. Hypertension can lead to thickening of the left ventricular septa, but without reaching the extremes of hypertrophic cardiomyopathy. The echocardiogram also makes it possible to assess the abnormal movement of the anterior leaflet of the mitral valve in the systole phase (SAM) and to quantify the proportion of blood that the heart manages to expel with each pump, which is usually between 30% and 70% normal value. Another test by which hypertrophic cardiomyopathy can be evaluated is isotopic ventriculography.

If a hemodynamic study is carried out, it will be seen that the final filling pressures in the ventricles will be elevated in the case of hypertrophic cardiomyopathy.

Treatment

The treatment of hypertrophic cardiomyopathy is based on the use of drugs that decrease the contractility of the heart, including calcium channel blockers, beta-blockers, and some antiarrhythmic drugs such as amiodarone.

In cases of severe obstruction, part of the thickened ventricular septum can be surgically resected, either by open surgery (myectomy), or by creating controlled ischemia in that part of the heart muscle. These options are used less frequently today.

In case of significant risk of sudden death, the patient may benefit from the use of a self-implantable defibrillator (ICD), a device that, connected to the heart through electrodes, monitors the heart rhythm and if it detects an alteration in the heart rate and attempts to reverse it. at a normal rate by electric shock.

Precautionary measures

Since it is a hereditary disease and most of the time it does not give symptoms, there are no specific measures to prevent it. However, if the patient has a family history of hypertrophic cardiomyopathy or sudden death, it is advisable to have regular check-ups with the cardiologist.