Neuromuscular Comprehensive Care Center
Muscular dystrophies are a group of diseases that affect skeletal and cardiac muscle. Four of the more common types of muscular dystrophy to affect the heart include Duchenne, Becker, Limb-girdle and some types of congenital muscular dystrophy.
The process of muscle death and replacement of cardiac muscle by fibrous and fatty material is similar to other muscles in the body. Symptoms of cardiac involvement can occur much later than symptoms of skeletal muscles, but changes can occur early. Cardiac evaluation should begin shortly after diagnosis and continue throughout life.
Muscular dystrophy can affect the pumping function and / or the electrical function of the heart. Some forms of muscular dystrophy are associated with dilated cardiomyopathy, or a condition in which the heart chamber enlarges and the muscle loses the ability to pump blood effectively to the body. Other forms of muscular dystrophy are associated with hypertrophic cardiomyopathy, or a condition in which the heart chamber thickens. Muscular dystrophies can be associated with electrical abnormalities producing an abnormal heart rate and / or rhythm. This can cause the heart to beat too fast (tachycardia) too slow (bradycardia), or in an abnormal rhythm (dysrhythmia).
Symptoms of Cardiac Dysfunction
The first symptoms of dilated cardiomyopathy, may be feelings of being overly tired, sleepiness, frequent waking during sleep and changes in weight (weight loss or weight gain). Chest pain, dizziness or palpitations are also symptoms that require investigation. Cardiologists will monitor for changes in heart rate or rhythm, fast respirations, decreased pulses, heart murmurs, enlarged liver, swelling, abdominal pain or vomiting.
Diagnostic Tests
An electrocardiogram (ECG) can be ordered to evaluate heart rate, rhythm and functions of the hearts electrical system. The ECG is a 10 second recording of the electrical activity of the heart. A Holter monitor may be ordered to record heart rate and rhythm for 24 to 48 hours. An event monitor is patient-activated and can capture heart rate and rhythm during a symptomatic event. The event monitor can be used for weeks to months, if necessary.
Echocardiography is useful to assess cardiac anatomy, size and function. As children grow, the increased body size may limit the findings of the echocardiogram. An alternate test, such as the cardiac MRI, may then be more useful.
Cardiac Treatments
If the heart is affected, medication may be prescribed depending on the type of abnormality detected. These medications may include angiotensin converting enzyme (ACE) inhibitors, beta blockers and / or diuretics.
