Dilated 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.

On occasions and for different reasons, the myocardial walls diminish in thickness and consequently the heart chambers widen and the myocardium cannot perform its job of driving blood efficiently. When this happens, the patient is said to have dilated cardiomyopathy.

How is it produced?

The dilation of the heart chambers can respond to many causes. Most of the time it is of idiopathic cause, that is to say, unknown. In some cases there is a familial form whose inheritance pattern is unknown.

The most frequent secondary causes of dilated cardiomyopathy include:

• alcoholism
• drugs (adriamycin, cyclophosphamide, cocaine, lithium)
• infections (polio, rubella, adenovirus, HIV)
• metabolic disturbances (lack of calcium or magnesium, hyperthyroidism)
• nutritional deficits
• myocardial infiltration
• connective tissue diseases (systemic lupus erythematosus, sarcoidosis, panarteritis nodosa)
• neuromuscular diseases (Duchenne disease, Steinert disease)
• pregnancy and childbirth (rare)

The most common secondary dilated cardiomyopathy is due to alcoholism. Alcohol alters the membranes of myocardial cells and causes them to die, causing the walls to weaken and the cavities to dilate. It must be said, however, that this cause, unlike the primary ones, is reversible, so that if the patient abandons alcohol consumption and the deterioration is not very advanced, the normal pumping function of the heart can be restored in a few minutes. three years.

In general, there is a destruction of the muscle cells of the myocardium, so that the cardiac septa diminish in thickness and the cavities increase in size, allowing the entry of more blood. Being less thick, the heart cannot pump all the blood in each systole, so that with each beat there is blood that is retained and does not go out into the circulatory stream, leading to heart failure in the medium term.

Symptoms

In the initial stages, the patient does not present symptoms, but as the disease progresses, symptoms of heart failure become established, with dyspnea, orthopnea, edema and an enlarged liver. On lung auscultation, crackles are seen.

Likewise, it is common for patients to present sinus tachycardia which, as the disease progresses, can lead to atrial fibrillation.

Since the blood is trapped in the ventricles, there is a risk that thrombi will form and that these can escape into the bloodstream and cause embolisms due to obstruction of a peripheral artery.

Diagnosis

The diagnosis will be based on the suspicion of any patient who presents symptoms of heart failure such as those discussed above. On cardiac auscultation, accessory sounds and murmurs can be heard in the systole phase due to mitral valve failure due to dilation of the left ventricle. If murmurs are seen in the diastole phase of the cardiac cycle, a cardiomyopathy of hypertrophic and non-dilated origin will be suspected, as well as if the patient has arterial hypertension.

The electrocardiogram shows nonspecific changes and, if present, sinus tachycardia or atrial fibrillation.

Cardiomegaly and lung signs of pulmonary hypertension can be seen on the chest radiograph.

The echocardiogram will be the best test to diagnose and assess the severity of dilated cardiomyopathy. The dilation of the left ventricle will be appreciated, with increased diameters in the two phases of the cardiac cycle, an increase in volume in the filling phase, and a blood output of less than 30% of normal, which is known as the ejection fraction. The walls are often thinned, but can also be of normal thickness. Likewise, the echocardiogram allows us to see if there are thrombi inside the left ventricle. Another test by which dilated 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 suffering from dilated cardiomyopathy.

If an infiltrative cause, such as amyloidosis, is suspected, a myocardial biopsy may be performed, although this test is rarely performed.

Treatment

The treatment will be that of heart failure and its derived symptoms. The hydrosaline intake in the diet will be reduced and diuretics, vasodilators (especially from the ACEI group, since they have been shown to increase the survival of these patients) and digoxin will be administered on occasions.

If the dilation is significant, there are thrombi in the left ventricle, or the patient suffers from atrial fibrillation, anticoagulants will be administered to reduce the risk of thromboembolism.

In the event of severe arrhythmias, they will be treated pharmacologically or by means 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 revert it to a rhythm. normal by electric shock.

In advanced cases where the patient does not respond to treatment, a heart transplant may be possible.

Precautionary measures

Cessation of alcohol consumption is essential to be able to treat dilated cardiomyopathy due to alcoholism, since it is a potentially reversible cause. In case of suffering from a disease that can be associated with this pathology, it is advisable to carry out periodic controls and go to the specialist in case of any symptoms. A healthy diet low in fat and salt and moderate physical activity can lead to a lower risk of suffering from this disease and a better prognosis in case of suffering from it.