Hypertrophic cardiomyopathy

Content

Introduction

Introduction

Hypertrophic cardiomyopathy is a disease of the muscle tissue of the heart characterized by alterations in its structure and functioning. In particular, it concerns the left ventricle, one of the four cavities into which the heart is divided, which undergoes a thickening of the walls (hence the term "hypertrophic"). Much more rarely it affects the right ventricle.

In most people, the thickening of the wall is most pronounced in the interventricular septum, which is the portion that separates the left ventricle from the right ventricle. The cavity of the left ventricle, on the other hand, can maintain its normal size or shrink.

The thickened muscle usually contracts well and expels most of the blood very quickly; only in a small minority of people does a reduction in the contraction capacity of the heart and heart failure occur over time.

However, even if it contracts well (systole phase), in hypertrophic cardiomyopathy the heart muscle becomes stiff and relaxes shortly after contraction. This determines a smaller width of the ventricular cavity and therefore the possibility of receiving a smaller quantity of blood in the filling phase (diastole phase).

This reduced ability to fill with blood is the most frequent cause of the disorders (symptoms), such as shortness of breath or impaired exercise tolerance, which are reported by people with this disease.

Furthermore, in at least 1/3 of people with hypertrophic cardiomyopathy, during contraction, due to the thickened walls, an "obstruction to the passage of blood from the ventricle to the" aorta is created (obstructive form of hypertrophic cardiomyopathy). In these cases, the mitral valve, located between the atrium and the left ventricle, is moved forward, also contributing to the obstruction. Abnormal movement of the valve can cause blood to regurgitate into the left atrium (mitral regurgitation). The turbulent flow of blood produced by the obstruction generates a heart murmur that can be heard with the stethoscope.

Hypertrophic cardiomyopathy affects approximately 1 in 500 people and there seems to be no difference between men and women.

Causes

Causes

At the basis of the onset of hypertrophic cardiomyopathy c "is almost always a genetic mutation (modification of the DNA). Sometimes it is transmitted by a first degree family member with cardiomyopathy; at others, it develops" de novo ", so it is not inherited.

People with a family member with hypertrophic cardiomyopathy have about a 50% chance of having inherited the same mutation and, for this reason, should undergo a genetic examination and a cardiological check with electrocardiogram and echocardiogram. If the genetic test is positive, the cardiologist will suggest the checks to be performed over time and how often to do them.

There are other situations characterized by thickening of the heart walls not to be confused with hypertrophic cardiomyopathy. Among these, amyloidosis, which is found mainly in elderly people, and other very rare genetic diseases.

In the so-called athlete's hearton the other hand, the thickening of the heart walls is "benign" and is due to intense training. It can lead to suspicion of hypertrophic cardiomyopathy in very limited cases.

Symptoms

Symptoms

The disorders (symptoms) caused by hypertrophic cardiomyopathy are generally similar to those of other heart diseases and include:

  • reduced resistance to effortdifficulty exercising due to shortness of breath (shortness of breath) and fatigue due to insufficient blood pumping from the heart to the tissues through the arteries
  • chest pain, sometimes oppressive, provoked by exertion or meals
  • irregular heartbeat, sometimes consisting of pauses in the beat (extrasystole); at other times, in an accelerated and irregular heartbeat (palpitation). They can appear suddenly and be accompanied by blurring of vision. These episodes should be promptly reported to the cardiologist
  • faintingloss of consciousness (known as syncope)
Diagnosis

Diagnosis

The most typical sign of hypertrophic heart disease, when present, is constituted by an intense murmur caused by a partial obstacle to the passage of blood from the ventricle to the aorta. The turbulence of the blood perceived, listening to the chest, as a murmur may also be due to the mitral regurgitation.

In 95% of people with hypertrophic heart disease, the electrocardiogram, a test that records the electrical signals generated by the heart, is altered and shows a variety of abnormal electrical signals due to thickening of the heart muscle.

The main test to ascertain hypertrophic cardiomyopathy is the echocardiogram. Thanks to the use of ultrasound, it shows images of the heart and allows you to estimate the thickness increase of the walls of the ventricles and to identify any obstruction. Through a particular method of use of ultrasound, called Doppler, the severity of obstruction and mitral regurgitation can be assessed.

Cardiac catheterization, an invasive method that involves the introduction of a small tube (catheter) into a blood vessel until it reaches the heart, allows to obtain fundamental information on the flows and pressures inside the heart chambers and arteries. Through the injection of a contrast medium, an x-ray (angiogram) of the heart is obtained which allows to evaluate the obstruction, mitral regurgitation and narrowing of the coronary arteries due to the presence of arteriosclerotic plaques. It is a test that is performed only before cardiac surgery or to rule out coronary heart disease.

MRI is able to provide detailed images of the heart under the stimulus of a magnetic field. It is widely used in people with hypertrophic cardiomyopathy because it allows to identify, within the thickened heart walls, the presence of areas where the muscle has been replaced by fibrous tissue (scars). The larger these areas, the greater the risk of cardiac arrhythmias, which aggravate the disease over time.

Genetic testing is indicated in all people with hypertrophic cardiomyopathy. The test consists of a simple venous blood sample. The result, unlike what happens with common blood tests, is not rapid and can take up to a month or more. If the genetic mutation is identified, this happens in 60-70% of cases, it may be useful to look for the same mutation in first degree relatives (parents, siblings, children). Those who discover they have the mutation will have to undergo a cardiological evaluation; those who test negative will be able to rest assured, they will not develop the disease.

Therapy

Therapy

Pharmacological therapy involves the use of beta-blockers and / or calcium antagonists. The drugs belonging to these two classes have the property of slowing the heartbeat, allowing the ventricle to work more efficiently and to have more time to fill.

In the obstructive form of the disease, when the disorders (symptoms) are no longer controllable with drugs, the intervention of myectomy, which consists in the surgical removal of a small portion of thickened muscle from the upper part of the interventricular septum. In this way the cavity of that part of the ventricle widens and the obstruction is reduced. As an alternative to the myectomy, especially in cases where the surgery has a high risk for the person (elderly with other pathologies), it is possible to perform the "alcohol ablation of the septum. This procedure, which is performed during a cardiac catheterization, involves the injection of a small amount of alcohol into a minor branch of the coronary artery to reduce the part of the heart muscle thickened to a thin scar. Both treatments are performed. only in centers specialized in these procedures.

In a small percentage of people (5% or less) over time there may be a reduction in the force of contraction of the heart, with thinning of the walls and dilation of the cavities (“end stage”). This condition is accompanied by very serious disturbances (symptoms): shortness of breath even for minimal efforts, repeated changes in the heartbeat (arrhythmias).

In these cases, heart transplantation represents the main treatment that allows a good future life expectancy.

Prevention

Prevention

In hypertrophic cardiomyopathy the most important event to prevent is sudden and unexpected cardiac death in the absence of warning signs. It occurs in a small number of people, especially younger ones.

Hypertrophic cardiomyopathy is one of the most frequent causes of sudden athlete death. For this reason, young people with this disease cannot practice competitive and competitive sports. In Italy, cardiological control with electrocardiogram, required by law for those who must practicing competitive activities, allows to ascertain (diagnose) the disease and to prevent young people unaware of being sick from suffering sudden death during sporting activity.

Identifying people at high risk of sudden death is an important goal in assessing the disease. Based on the identification of well-defined risk factors, for example, previous cardiac arrest, recent syncope, very severe thickening of the heart, or having first degree relatives suddenly died, implantation of an automatic defibrillator as a preventative may be indicated. It is a very sophisticated device that is permanently implanted, as is the case with the pacemaker, and has proven very effective in preventing sudden death as it recognizes and interrupts the heart arrhythmias underlying this dramatic event.

Bibliography

Bibliography

Humanitas Medical Care. Hypertrophic cardiomyopathy

American Heart Association. Hypertrophic cardiomyopathy (HCM) (English)

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