Cardiomyopathy - definition, types, symptoms and treatment
Cardiomyopathy is weakness and loss of pumping effectiveness of the HEART, usually with changes to the structure of the heart and in particular the left ventricle. Cardiomyopathy is as likely to affect people under age 40 as people over age 60 and is a leading cause of HEART FAILURE resulting in HEART TRANSPLANTATION. Genetic factors can play a role in cardiomyopathy, especially in younger people, though lifestyle factors such as nutrition and ALCOHOL consumption are also significant. Viral and bacterial infections of the heart (MYOCARDITITIS) can leave the heart MUSCLE damaged. In many situations, however, doctors do not know what causes the structural and functional changes in myocardial (heart muscle) cells that result in primary cardiomyopathy. Secondary cardiomyopathy may also develop as a consequence of other CARDIOVASCULAR DISEASE (CVD), such as ISCHEMIC HEART DISEASE (IHD) and HYPERTENSION (high BLOOD PRESSURE).
The five major types of cardiomyopathy are
Dilated cardiomyopathy
in which the heart enlarges in an attempt to compensate for damage to myocardial cells that limits the heart’s ability to efficiently pump BLOOD . Long-term ALCOHOL abuse accounts for the dilated cardiomyopathy in about a third of the people who develop it. Deficiency of vitamin B1 also damages the heart. Though uncommon in the general US population, vitamin B1 deficiency can occur with long-term, heavy alcohol consumption as well as with long-term EATING DISORDERS such as anorexia nervosa. Dilated cardiomyopathy is more common in people over age 60.
Hypertrophic cardiomyopathy
in which the walls of the heart, particularly the ventricles, thicken. Some doctors may refer to this condition as hypertrophic obstructive cardiomyopathy (HOCM) or idiopathic hypertrophic subaortic stenosis (IHSS), both of which are older terms. Hypertrophic cardiomyopathy is hereditary, the result of mutations in a number of genes that regulate proteins essential for myocardial cell contractions (notably myosin, troponin T, and alpha tropomyosin). The hypertrophy, or thickening, typically affects the left ventricle most extensively and can involve the ventricular septum to the extent that the hypertrophy creates an obstruction for the proper functioning of the aortic valve (AORTIC STENOSIS). Undiagnosed hypertrophic cardiomyopathy is a leading cause of SUDDEN CARDIAC DEATH in younger people, especially athletes.
Ischemic cardiomyopathy
which develops secondary to longstanding IHD or following extensive or repeated MYOCARDIAL INFARCTION. Ischemia results from inadequate oxygen supply to the cells, some of which die. The patches of dead muscle tissue do not contract, diminishing the heart’s effectiveness. Ischemic cardiomyopathy is more common in people over age 60 who have other forms of cardiovascular disease.
Peripartum cardiomyopathy
which develops in a woman during late PREGNANCY or in the first few months after CHILDBIRTH. It appears an inflammatory process in the body, though doctors are uncertain what sets it off. In some situations there is a clear bacterial or viral INFECTION, but most often there is no apparent reason for the INFLAMMATION. Most women fully recover from peripartum cardiomyopathy though are at increased risk for developing it again with subsequent pregnancies.
Restrictive cardiomyopathy
in which the myocardial cells accumulate deposits that cause them to lose elasticity. The loss restricts the ability of the heart to expand, reducing the ability of the ventricles to properly fill with blood. As a consequence, the heart cannot pump enough blood to meet the body’s needs. Restrictive cardiomyopathy is secondary to other health conditions such as AMYLOIDOSIS, which leaves protein deposits, and HEMACHROMATOSIS, which leaves iron deposits.
Symptoms of Cardiomyopathy and Diagnostic Path
Cardiomyopathy often does not show symptoms until the condition is quite advanced, and then the symptoms are likely to be those of other cardiovascular conditions, such as hypertension and heart failure, especially congestive heart failure. Doctors commonly discover cardiomyopathy during chest X-RAY done for other reasons.
When symptoms are present, they typically include
- shortness of breath (DYSPNEA)
- weakness and tiredness
- inability to participate in physical activities
The diagnostic path includes ELECTROCARDIOGRAM (ECG), which detects the arrhythmias typical of an overworked heart, and ECHOCARDIOGRAM, which shows the heart’s enlargement and altered function. These tests can provide definitive diagnosis for most cardiomyopathy. Other diagnostic procedures the cardiologist may recommend, depending on the kind of cardiomyopathy suspected, may include COMPUTED TOMOGRAPHY (CT) SCAN, MAGNETIC RESONANCE IMAGING (MRI), transesophageal echocardiogram (TEE), angiogram, and myocardial biopsy. GENETIC TESTING to detect mutations commonly associated with hypertrophic cardiomyopathy can help detect the potential for this condition before it manifests symptoms, allowing prophylactic interventions to delay or minimize its development.
Cardiomyopathy Treatment Options and Outlook
All forms of cardiomyopathy make it difficult for the heart to pump blood effectively. Though in the early stages of the condition the heart’s enlargement can compensate for some of the diminished STRENGTH, eventually the compensatory measures become ineffective and even counterproductive. Treatment targets improving the heart’s efficiency, usually through a combination of medications and lifestyle modifications. Medications typically include diuretics to reduce edema (fluid accumulations), antiarrhythmia medications to maintain the heart’s regular rhythm, vasodilator medications to relax the blood vessels and reduce resistance for blood flow, and medications such as digoxin (inotropic medications) to strengthen the heart’s pumping effectiveness. It also is crucial to treat any coexisting or causative cardiovascular disease such as hypertension, ATHEROSCLEROSIS, and CORONARY ARTERY DISEASE (CAD). Such measures allow the majority of people who have cardiomyopathy, particularly dilative cardiomyopathy, to enjoy normal lives.
Progressive cardiomyopathy necessitates substantial lifestyle changes and is a leading cause of disability due to cardiovascular disease. Hypertrophic, ischemic, and restrictive cardiomyopathies are most likely to be progressive. The therapeutic approach is to manage symptoms to the extent possible, making lifestyle adaptations such as reduced physical activity to accommodate diminished CARDIAC CAPACITY. Heart transplantation becomes a treatment option for people under age 65 who are otherwise healthy. Cardiomyopathy accounts for about half of heart transplantations performed in the United States. In some situations an implanted ventricular assist device (VAD) can supplement the natural heart’s function, allowing the heart to regain strength and recover from damage. A VAD also can serve as a “bridge” to support the heart while a person waits for a donor heart for transplantation. Sometimes other surgical approaches, such as removing a segment of diseased heart tissue to reduce the size of the ventricle, are successful in restoring the heart’s functional ability.
Cardiomyopathy - Risk Factors and Preventive Measures
The leading risk factors for most forms of cardiomyopathy are physical inactivity and suboptimal nutrition, which are risk factors for cardiovascular disease in general, as well as excessive alcohol consumption, genetics, and other cardiovascular disease. As with any form of cardiovascular disease, controlling lifestyle factors reduces the risk for the condition. Early GENETIC TESTING can help people who have family history of hypertrophic cardiomyopathy to determine whether they are at risk for this condition and to plan appropriate therapeutic approaches to delay its development. Most people who die suddenly because of hypertrophic cardiomyopathy do not know they have the condition. Keeping chronic cardiovascular conditions such as hypertension and atherosclerosis under control reduces the risk for secondary cardiomyopathy.
See also ALCOHOLISM; ARRHYTHMIA; BACTERIA; CARDIOVASCULAR DISEASE PREVENTION; CONGENITAL HEART DISEASE; LIFESTYLE AND CARDIOVASCULAR HEALTH; MEDICATIONS TO TREAT CARDIOVASCULAR DISEASE; MUTATION; QUALITY OF LIFE; RISK FACTORS FOR CARDIOVASCULAR DISEASE; VENTRICULAR ASSIST DEVICES (VADS); VIRUS.
