If the chamber walls become weak enough, the heart can no longer perform its normal pumping action adequately. Other parts of the body compensate for this deficiency in pumping power by increasing the quantity of fluid they retain – and by producing a greater volume of blood than usual. The heart chambers then dilate (expand) to accommodate the greater blood volume.
Bodily functions remain near normal over the short term. Early on, adequate circulation is maintained. Stretching of the heart muscle tissue to accommodate the increased blood volume can initially restore some of the heart’s pumping strength: the more a muscle is stretched, the more forcefully it may contract. Over the long term, however, the effects of continuing heart enlargement are not positive. The heart compensates by increasing its rate. The less efficient heart cannot contract as well, which results in poor circulation and causes excess body fluids to accumulate in the lungs, abdomen, and legs. This fluid buildup produces breathing difficulties and swelling (edema), two common symptoms of heart failure.
Causes of Dilated Cardiomyopathy
No exact cause can be determined for more than 80% of all cases of dilated cardiomyopathy, although viral infections may be responsible. Unfortunately, viruses are very difficult to detect in laboratory samples. Because the infection may have occurred months or even years before a person shows any sign of a weakened heart muscle, the precise initiating cause is difficult to pinpoint with certainty. When the cause is unknown, the cardiomyopathy is called idiopathic.
Other cases can be traced to the following causes:
- Alcohol and other toxic substances
After years of heavy drinking, the heart can be weakened by alcohol’s toxic effect on its muscle cells. Also, heavy drinkers tend to substitute alcohol for food, which leads to nutritional deficiencies. Other toxic substances, including some chemicals and pesticides, have also been shown to weaken the heart muscle. In addition, drug abuse can also weaken the heart muscle.
- Poor nutrition
Severe deficiencies in essential vitamins and minerals – especially Thiamine (also known as vitamin B–1) – may lead to dilated cardiomyopathy.
In a rare condition called Myocarditis, the heart muscle becomes inflamed as a result of an infection by a virus, less often, by bacteria, or other infective processes. Persons may actually feel no symptoms at all, in other cases, they may feel acute chest pain and fatigue such as that associated with a bad cold or the flu. Usually, a mild case of myocarditis will disappear and cause no lasting damage. In fact, it may go completely undiagnosed. Severe cases are frequently not diagnosed until the symptoms of heart failure appear. Even a severe case may go away spontaneously, but intense bouts of inflammation usually cause progressive and irreversible heart muscle damage.
- Pregnancy and childbirth
In rare cases, a woman may develop heart muscle disease late in pregnancy or during the first few months after delivery. This is called Peripartum Cardiomyopathy. With or without having had a viral or bacterial infection, the woman develops an inflammation of her heart muscle. Researchers have not been able to determine why this happens. They do know that if the woman recovers from the disease and becomes pregnant again, she is again at risk for developing the condition.
Scientists haven’t identified an abnormal gene related to the development of dilated cardiomyopathy. However, many suspect that there may be a genetic link. They also point to instances in which the disease occurs within families. In addition, some genetic neurological disorders, such as muscular dystrophy, are associated with heart muscle impairments.
Sometimes inflammation of the heart muscle causes no immediate noticeable symptoms. At other times, the person affected may feel symptoms most often associated with the common cold or flu: chills, fever, overall aches, and weariness. When the heart becomes very enlarged, a person will feel definite symptoms. These include chest pain, extreme tiredness, shortness of breath, and swelling of the legs and ankles. All of these are early signs of heart failure.
Diagnosis of Dilated Cardiomyopathy
- A chest X–ray will show if the heart is enlarged and if there is fluid in the lungs.
- An Electrocardiogram (ECG or EKG) can show areas of the heart that are damaged or enlarged.
- Echocardiography can be used to detail the dimensions of the heart and the degree of damage.
- Angiography, a cardiac catheterization procedure, can provide a detailed view of how well the heart’s arteries, chambers, and valves have been functioning.
- A biopsy of tissue from the wall of the heart may help determine how seriously the heart has been damaged, or what process may be causing the cellular damage.
Whether an underlying cause can be identified or not, treatment is focused on relieving symptoms, as well as relieving the extra load the heart has been bearing. Lifestyle changes, medication, and/or surgery may be needed. If physicians can determine the cause of the dilated cardiomyopathy, treatment may be more specific. For example, correcting a nutritional deficiency or eliminating a toxin from the body can actually reverse the damage that’s been done to the heart. In some cases of alcohol–caused dilated cardiomyopathy, total abstinence allows the body to repair itself.
Medication for Dilated Cardiomyopathy
Drugs can help manage symptoms and improve heart action.
- Diuretics reduce excess fluid in the body.
- Vasodilators, such as Angiotensin–converting enzyme (ACE) inhibitors, relax blood vessels and help to lower blood pressure.
- Digitalis help to improve the heart’s pumping action and regulate the heartbeat.
- Calcium channel blockers or beta blockers help to regulate the heartbeat and alter the work of the heart muscle.
- Inotropic agents increase the strength of the heart’s contraction.
Surgery for Dilated Cardiomyopathy
For some patients, the amount of damage to the heart muscle is so great that medications aren’t effective – nor are additional medical options for repairing the damage promising. In those situations, selective patients, physicians may recommend that a heart transplant be considered. Patients may need the support of a heart assisting device while they await a transplant. In some cases, the device may allow recovery of heart function, eliminating the need for a heart transplant.
Persons may need to lose weight, stop smoking, get sufficient rest, restrict salt intake, or begin a moderate exercise program. Improving overall fitness can help ease the demands on the heart and improve the effectiveness of prescribed medications.