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Dilated cardiomyopathy

Idiopathic dilated cardiomyopathy, DCM

Overview

Dilated cardiomyopathy is a disease of the heart muscle which primarily affects the heart's main pumping chamber, the left ventricle. It is the most common type of cardiomyopathy and typically affects those aged 20 to 60. The left ventricle of affected individuals becomes enlarged (dilated) and cannot pump blood to the body with as much force as a healthy heart can. The term "cardiomyopathy" is a general term that refers to the abnormality of the heart muscle itself. Dilated cardiomyopathy might not cause symptoms, but for some people it can be life-threatening. A common cause of heart failure — the heart's inability to supply the body with enough blood — dilated cardiomyopathy can also contribute to irregular heartbeats (arrhythmias), blood clots or sudden death.

Symptoms - Dilated cardiomyopathy

Symptoms of heart failure are most common. Usually, they develop slowly over time. However, sometimes symptoms start very suddenly and are severe.

Common symptoms are:

  • The heart muscle also has difficulty contracting normally, which can lead to irregular heartbeats (arrhythmia)
  • Blood clots
  • Sudden death
  • Over time, the heart becomes weaker and heart failure can occur
  • Chest pain or pressure (more likely when you exercise)
  • Cough
  • Fatigue, weakness, faintness
  • Irregular or rapid pulse
  • Loss of appetite
  • Swelling of feet and ankles (in adults)
  • Shortness of breath (dyspnea) when you're active or lying down (or being asleep) for a while
  • Reduced ability to exercise
  • Swelling of your abdomen (ascites)

Causes - Dilated cardiomyopathy

While the cause of dilated cardiomyopathy is often unknown (idiopathic), some cases are acquired and roughly half are inherited or familial.[1][2] Familial dilated cardiomyopathy is most often inherited in an autosomal dominant pattern. Mutations in the TTN gene are found in approximately 20 percent of cases of familial dilated cardioyopathy.

Heart disease (which is caused by a narrowing of the arteries) and poorly controlled high blood pressure are the most common causes of dilated cardiomyopathy. These problems lead to a weakened and enlarged heart muscle.

There are many other causes of dilated cardiomyopathy, including:

  • Genetics
  • Congenital heart defects
  • Infections, including those caused by bacteria, viruses, fungi and parasites
  • Certain cancer medications
  • Exposure to toxins, such as lead, mercury and cobalt
  • Coronary artery disease or heart attack
  • High blood pressure (hypertension)
  • Diabetes
  • Complications of late-stage pregnancy
  • Alcohol or cocaine abuse, or medicines that can be toxic to the heart (such as drugs used to treat cancer)
  • Abnormal heart rhythms in which the heart beats very fast for a long period of time
  • Autoimmune illnesses, when the immune system attacks and destroys healthy body tissue by mistake
  • Conditions that run in families
  • Infections that involve the heart muscle
  • Heart valves that are either too narrow or too leaky (regurgitant)
  • Trace elements, such as lead, arsenic, or mercury

This condition can affect anyone at any age. However, it is most common in adult men. Dilated cardiomyopathy most commonly occurs in men, ages 20 to 60. Other risk factors include:

  • High blood pressure (hypertension)
  • Coronary artery disease
  • Damage to the heart muscle from a heart attack
  • Family history of dilated cardiomyopathy
  • Alcoholism
  • Certain chemotherapy drugs and radiation for treating cancer
  • Cocaine use
  • Viral or bacterial infections of the heart muscle
  • Metabolic disorders, such as thyroid disease or diabetes
  • Diseases that can damage the heart, including hemochromatosis and sarcoidosis
  • Obesity
  • Nutritional deficiencies of essential vitamins and minerals, such as selenium
  • Inflammation of heart muscle from immune system disorders, such as lupus
  • Metals and other toxic compounds, such as lead, mercury and arsenic
  • Neuromuscular disorders, such as muscular dystrophy
  • HIV infection

Prevention - Dilated cardiomyopathy

If you eliminate lifestyle habits that can contribute to dilated cardiomyopathy, you may prevent or minimize effects of the disease:

  • If you smoke, quit.
  • Don't drink alcohol, or drink in moderation.
  • Don't use cocaine or other illegal drugs.
  • Eat a healthy diet.
  • Maintain a healthy weight.
  • Follow an exercise regimen recommended by your doctor.

Diagnosis - Dilated cardiomyopathy

During the exam the health care provider may find:.

  • The heart is enlarged
  • Lung crackles (a sign of fluid buildup), heart murmur, or other abnormal sounds
  • The liver may be enlarged
  • Neck veins may be bulging

A number of laboratory tests may be done to determine the cause:

  • Antinuclear antibody (ANA), erythrocyte sedimentation rate (ESR), and other tests to diagnose autoimmune illnesses
  • Antibody test to identify infections such as Lyme disease and HIV
  • Iron tests on the blood
  • Serum TSH and T4 test to identify thyroid problems
  • Tests for amyloidosis

Heart enlargement or other problems with the structure and function of the heart (such as weak squeezing) may show up on these tests:

  • Echocardiogram (ultrasound of the heart)
  • Cardiac stress tests
  • Chest x-ray
  • Coronary angiogram to look at blood flow to the heart
  • CT scan of the heart
  • MRI of the heart
  • Nuclear heart scan (MUGA, RNV)

Heart biopsy, in which a small piece of heart muscle is removed, may be needed depending on the cause. However, this is uncommon.

Tests your doctor might order include:

  • Blood tests. These tests give your doctor information about your heart. They also may reveal if you have an infection, a metabolic disorder or toxins in your blood that can cause dilated cardiomyopathy.
  • Chest X-ray. Your doctor may order a chest X-ray to check your heart and lungs for abnormalities in the heart's structure and size and for fluid in or around your lungs.
  • Electrocardiogram (ECG). An electrocardiogram — also called an ECG or EKG — records electrical signals as they travel through your heart. Your doctor can look for patterns that show abnormal heart rhythm or problems with the left ventricle. Your doctor may ask you to wear a portable ECG device known as a Holter monitor to record your heart rhythm for a day or two.
  • Echocardiogram. This primary tool for diagnosing dilated cardiomyopathy uses sound waves to produce images of the heart, allowing your doctor to see whether your left ventricle is enlarged. This test can also reveal how much blood is ejected from the heart with each beat and whether blood is flowing in the right direction.
  • Exercise stress test. Your doctor may have you perform an exercise test, either walking on a treadmill or riding a stationary bike. Electrodes attached to you during the test help your doctor measure your heart rate and oxygen use. This type of test can show the severity of problems caused by dilated cardiomyopathy. If you're unable to exercise, you may be given medication to create the stress.
  • CT or MRI scan. In some situations, your doctor might order one of these tests to check the size and function of your heart's pumping chambers.
  • Cardiac catheterization. For this invasive procedure, a long, narrow tube is threaded through a blood vessel in your arm, groin or neck into the heart. The test enables your doctor to see your coronary arteries on X-ray, measure pressure in your heart and collect a sample of muscle tissue to check for damage that indicates dilated cardiomyopathy. This procedure may involve having a dye injected into your coronary arteries to help your doctor study your coronary arteries (coronary angiography).
  • Genetic screening or counseling. If your doctor can't identify the cause of dilated cardiomyopathy, he or she may suggest screening of other family members to see if the disease is inherited in your family.

Prognosis - Dilated cardiomyopathy

Heart failure is most often a chronic illness, which may get worse over time. Some people develop severe heart failure, in which medicines, other treatments, and surgery no longer help. Many people are at risk for deadly heart rhythms, and may need medicines or a defibrillator.

Treatment - Dilated cardiomyopathy

Knowing your body and the symptoms that your heart failure is getting worse will help you stay healthier and out of the hospital. At home, watch for changes in your symptoms, heart rate, pulse, blood pressure, and weight.

Limiting how much you drink and how much salt (sodium) you eat can help prevent or reduce these symptoms.

Most people who have heart failure need to take medicines. Some medicines treat your symptoms. Others may help prevent your heart failure from becoming worse or may prevent other heart problems.

Procedures and surgeries you may need are:

  • A pacemaker to help treat slow heart rates or help your heart contract in a more coordinated fashion
  • A defibrillator that recognizes life-threatening heart rhythms and sends an electrical pulse to stop them
  • Heart bypass (CABG) surgery or angioplasty to improve blood flow to the damaged or weakened heart muscle
  • Valve replacement or repair

For advanced cardiomyopathy:

  • A heart transplant may be recommended for patients who have failed all the standard treatments and still have very severe symptoms.
  • Placement of a left ventricular assist device or artificial heart may be considered.

Chronic heart failure becomes worse over time. Many people who have heart failure will die from the condition. Thinking about the type of care you may want at the end of life and discussing these issues with loved ones and your health care provider is important.

Medications:

Doctors usually treat dilated cardiomyopathy with a combination of medications. Depending on your symptoms, you might need two or more of these drugs. Drugs that have proved useful in the treatment of heart failure and dilated cardiomyopathy include:

  • Angiotensin-converting enzyme (ACE) inhibitors. ACE inhibitors are a type of drug that widens or dilates blood vessels (vasodilator) to lower blood pressure, improve blood flow and decrease the heart's workload. ACE inhibitors may improve heart function. Side effects include low blood pressure, low white blood cell count, and kidney or liver problems.
  • Angiotensin II receptor blockers. These drugs have many of the beneficial effects of ACE inhibitors and may be an alternative for people who can't tolerate ACE inhibitors. Side effects include diarrhea, muscle cramps and dizziness.
  • Beta blockers. A beta blocker slows your heart rate, reduces blood pressure and prevents some of the harmful effects of stress hormones, substances produced by your body that can worsen heart failure and trigger abnormal heart rhythms. Beta blockers may reduce signs and symptoms of heart failure and improve heart function. Side effects include dizziness and low blood pressure.
  • Diuretics. Often called water pills, diuretics remove excess fluid and salt from your body. The drugs also decrease fluid in your lungs, so you can breathe more easily.
  • Digoxin. This drug, also known as digitalis, strengthens your heart muscle contractions. It also tends to slow the heartbeat. Digoxin may reduce heart failure symptoms and improve your ability to be active.
  • Blood-thinning medications. Your doctor may prescribe drugs, including aspirin or warfarin (Coumadin), to help prevent blood clots. Side effects include excessive bruising or bleeding.

 

Devices:

Implantable devices used to treat dilated cardiomyopathy include:

  • Biventricular pacemakers, which use electrical impulses to coordinate the actions of the left and right ventricle.
  • Implantable cardioverter-defibrillators (ICDs), which monitor heart rhythm and deliver electrical shocks when needed to control abnormal, rapid heartbeats, including those that cause the heart to stop. They can also function as pacemakers.
  • Heart pumps (left ventricular assist devices, or LVADs). These mechanical devices are implanted into the abdomen or chest and attached to a weakened heart to help it pump. They usually are considered after less invasive approaches are unsuccessful.

Resources - Dilated cardiomyopathy

  • NIH
  • Mayo Clinic
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