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Cardiomyopathy Dilated

Resulting from extensively damaged myocardial muscle fibers, dilated cardiomyopathy interferes with myocardial metabolism and grossly dilates all four chambers of the heart. This gives the heart a globular appearance. In this disorder, hypertrophy may be present.

Dilated cardiomyopathy leads to intractable heart failure, arrhythmias, and emboli. The prognosis of dilated cardiomyopathy without clinical evidence of heart failure is variable, with some patients remaining stable, some gradually deteriorating, and others rapidly declining. Once heart failure is manifest,the natural history is similar to that of other causes of heart failure.

Causes

Dilated cardiomyopathy can be inherited, but it is primarily caused by a variety of other factors, including:

• Severe coronary artery disease
• Alcoholism
• Thyroid disease
• Diabetes
• Viral infections of the heart
• Heart valve abnormalities
• Drugs that are toxic (or cause damage) to the heart

Rarely, it can occur in women after childbirth (postpartum cardiomyopathy).

When there is no known cause, the condition is called idiopathic dilated cardiomyopathy.

Signs and symptoms

In dilated cardiomyopathy, the heart ejects blood less efficiently than usual. Consequently, a large volume of blood remains in the left ventricle after systole, causing signs of heart failure both left-sided (shortness of breath, or thopnea, dyspnea on exertion, paroxysmal nocturnal dyspnea, fatigue, and an irritating dry cough at night) and right-sided (edema, liver engorgement, and jugular vein distention).

Symptoms can develop gradually, over months or years, or they can develop suddenly, such as after a viral infection or pregnancy.

Diagnosis

• Echocardiography confirms the presence of dilated cardiomyopathy.
• Exercise thallium-201 scintigraphy may suggest possible underlying coronary artery disease.
• Electrocardiography (ECG) and angiography rule out ischemic heart disease; ECG may also show biventricular hypertrophy, sinus tachycardia, atrial enlargement and, in 20% of patients, atrial fibrillation and bundle-branch heart block.
• Chest X-ray demonstrates cardiomegaly - usually affecting all heart chambers and may demonstrate pulmonary congestion, pleural or pericardial effusion, or pulmonary hypertension.

Treatment

Therapeutic goals include correcting the underlying causes and improving the heart's pumping ability with digoxin, diuretics, oxygen, and a sodium restricted diet. Other options may involve bed rest and steroids.

Vasodilators reduce preload and afterload, thereby decreasing congestion and increasing cardiac output. Acute heart failure requires vasodilation with nitroprusside or nitroglycerin LV. Long term treatment may include hydralazine, isosorbide dinitrate, angiotensin converting enzyme inhibitors, and anticoagulants.

When these treatments fail, therapy may require heart transplantation for carefully selected patients. Cardiomyoplasty, which wraps the latissimus dorsi muscle around the ventricles, assists the ventricle to effectively pump blood. A cardiomyostimulator delivers bursts of electrical impulses during systole, to contract the muscle.

In most cases, the heart failure is likely to eventually be fatal. Heart transplant is often recommended for dilated congestive cardiomyopathy due to this poor prognosis.

Prevention

• Modify risk factors that can be controlled by eating a generally well-balanced and nutritious diet, exercising to improve heart fitness.
• Eat a well-balanced and nutritious diet, exercise to improve heart fitness, stop smoking, and minimize alcohol consumption.