Dilated cardiomyopathy, sometimes referred to as DCM, is characterized by impaired contractions of one or both of the heart's ventricles, the heart's main pumping chambers. DCM is responsible for approximately 45,000 hospitalizations and 10,000 deaths every year in the U.S. alone.
Definition & Facts
Dilated cardiomyopathy affects people of all ages, from infants to adults, but is most commonly found in males between the ages of 20 and 60. Cardiomyopathy is a general term referring to an abnormality of the heart muscle and may be asymptomatic. DCM is a condition that stretches or dilates the heart muscle with the disease usually starting in the left ventricle.
Dilated cardiomyopathy results in the heart not being able to pump blood as effectively as a healthy heart. The disease can contribute to arrhythmias, meaning irregular heartbeats, blood clots, and can be life-threatening, even resulting in sudden death during any stage of the disease.
Symptoms & Complaints
- A loss of the ability to exercise from lack of energy and shortness of breath.
- Swelling, or edema in the lower legs, ankles, and feet.
- Ascites, or a swelling of the abdominal region.
Dilated cardiomyopathy may often be idiopathic, meaning the exact cause of the disease cannot be determined. However, there are multiple factors that can result in the heart's ventricles becoming dilated and lessen its ability to pump blood efficiently. The most common factors leading to dilated cardiomyopathy include:
- Bacterial infections, viral infections (including viral hepatitis and HIV), parasite infection and fungal infection. Infections that have invaded the heart muscle can be especially damaging.
- Certain prescription medications used to treat cancer, such as daunorubicin and doxorubicin.
- Complications during the last 30 days of pregnancy or within five months after delivery.
- Congenital heart defects as well as previous heart attacks.
- Coronary artery disease.
- Diabetes and hypertension, or high blood pressure.
- Drug use, such as cocaine and amphetamines.
- Alcohol abuse, especially if combined with a poor diet.
- Exposure to toxins, such as cobalt, lead, mercury and other heavy metals.
- Genetics, with approximately 30 percent of patients diagnosed with dilated cardiomyopathy inheriting the disease from their parents.
- Thyroid disease.
Diagnosis & Tests
A diagnosis of dilated cardiomyopathy requires the presence of dilation along with impaired contractions of either the left or both ventricles. A physician will take the medical history of the patient as well as his or her family history and perform a physical examination, listening to the heart and lungs. Additional tests will be ordered if the doctor suspects dilated cardiomyopathy from the initial exam.
Blood tests can reveal if there is an infection, metabolic disorder or toxins in the blood that may cause DCM. A chest X-ray can detect abnormalities in size and structure of the heart and fluid in the lungs. An electrocardiogram, referred to as an EKG, shows the electrical signals traveling through the heart. An echocardiogram can reveal abnormal heart rhythms or other problems, using sound waves that produce images of the heart. It is a type of ultrasound.
If these tests show evidence of the DCM, the doctor will typically refer the patient to a cardiologist, a heart specialist, for further testing. Further testing may include an exercise stress test and a CT scan or MRI to check the heart's size and pumping ability. A cardiac catheterization may be done to examine the inside of the arteries, measure pressure in the heart, and collect a tissues sample.
Treatment & Therapy
Treatments for dilated cardiomyopathy try to address the underlying cause, if known, and to increase blood flow. Depending on symptoms, a combination of medicines may be used to treat the condition. Drug therapies that have proven useful in treating heart failure include:
- ACE inhibitors. Angiotensin-converting enzyme inhibitors work as a vasodilator to open blood vessels to improve blood flow and decrease the heart's workload by lowering blood pressure.
- Angiotensin II receptor blockers produce many of the same beneficial effects as ACE inhibitors for patients who can't tolerate ACE inhibitors.
- Beta blockers slow heart rate, reduce blood pressure, and work to prevent some of the heart-damaging effects of stress hormones.
- Diuretics, sometimes called water pills, work to remove excess fluid from the body, including the lungs to make breathing easier.
- Digoxin strengthens heart-muscle contractions while slowing the heartbeat.
- Blood-thinners, including aspirin or Wayfarin (brand name Coumadin®), to guard against blood clots.
Besides drug treatments, devices may be implanted to treat dilated cardiomyopathy. Pacemakers use electrical impulses to regulate the actions of the ventricles. Implantable cardioverter-defibrillators, called ICDs, monitor the heart's rhythm and deliver an electrical shock as needed to control abnormal heartbeats. Left ventricular assist devices, known as LVADs, are heart pumps implanted into the chest or abdomen to aid the heart in pumping blood. Finally, if none of the above treatment work, a heart transplant may be necessary.
Prevention & Prophylaxis
Maintaining a healthy weight is crucial, as being overweight requires the heart to work harder. Eating a heart-healthy diet that includes fish, whole grains, a variety of fresh fruits and vegetables, and limits salt, sugar, cholesterol, and saturated and trans fats will also help protect the heart from disease. Adequate sleep is also important, as a strong immune system will help fight infections.