Dilated cardiomyopathy is the result of myocardial damage that may lead to heart failure, predominantly ventricular dilatation and systolic dysfunction. Clinical manifestations which occur most frequently are represented by dyspnea (shortness of breath), fatigue and peripheral edema. The diagnosis is based on objective clinical examination, chest radiography and echocardiogram.
Causes of dilated cardiomyopathy
The most common cause is coronary artery disease with diffuse character that causes diffuse ischemia. Viral infections can also cause dilated cardiomyopathy, the most common etiological agent is Coxsackie B virus. In patients with AIDS risk is greatly increased. Other causes: toxoplasmosis, thyrotoxicosis, beriberi disease. Toxic substances can also be incriminated: alcohol, solvents, chemotherapy.
Usually this disease affects both ventricles and rarely it can be affected just the right ventricle.
If dilatation of the heart chambers is significant thrombus may form near the walls. Acute inflammation phase and late phase of expansion may be complicated by the occurrence of arrhythmias and atrioventricular block. If the left atrium is dilated, atrial fibrillation occurs frequently.
Signs and symptoms in dilated cardiomyopathy
In general, the onset of the disease is progressive, except acute inflammation of the myocardium. Left ventricular damage causes exertional dyspnoea (shortness of breath), chronic fatigue (fatigue) due to decreased cardiac output. If the right ventricle is affected there will appear peripheral edema and distended neck veins. Approximately, one-quarter of patients with dilated cardiomyopathy shows atypical chest pain.
For diagnosis there will be made a chest radiography, electrocardiogram and echocardiogram. If chest pain is presented then the cardiac enzymes will be dosed. We must look in particular for a given cause. If a specific cause is not highlighted the following tests will be done: serum ferritin, TSH, serological tests for toxoplasma, Coxsackie. This will exclude a treatable cause.
Changes on ECG: sinus tachycardia, ST-segment depression, negative T-wave, it may be present Q-waves which mimic an old myocardial infarction, frequently there can appear a left bundle branch block.
Echocardiography can detect enlargement of the heart cavities, hypokinesia, valvular diseases will be excluded.
If after all these noninvasive investigations the diagnosis is unclear a coronary angiography should be performed, especially in patients that present chest pain or elderly patients.
Treatment of dilated cardiomyopathy
70% of patients die within 5 years, the prognosis is reserved.
Treatment is the same as for heart failure. It will be used: inhibitors of angiotensin converting enzyme, beta-blockers, spironolactone, angiotensin II receptor blockers, diuretics, digoxin, nitrates. Because the risk of thrombus formation is high it will be given prophylactically oral anticoagulation. If arrhythmias occur they will be treated with antiarrhythmic drugs. Atrioventricular block will require installation of a permanent pacemaker. In case of left bundle branch block associated with severe manifestations it will take into account the biventricular stimulation.