Understanding Heart Disease -- the Basics
Cardiomyopathy (Heart Muscle Disease)
Diseases of the heart muscle, or myocardium, are collectively referred to as cardiomyopathies. When diseased, the myocardium becomes abnormally stretched, thickened, or stiff. Among the many potential causes of cardiomyopathy are genetic heart conditions, reactions to certain drugs or toxins (such as alcohol), and viral infections. Sometimes, chemotherapy for cancer causes cardiomyopathy. Often, the precise cause of cardiomyopathy is unknown. In any event, either the heart muscle becomes too weak to pump efficiently or stiffening prevents adequate filling of the heart.
When cardiomyopathy progresses to the point of causing serious arrhythmias or heart failure, the outlook for long-term survival is poor.
Sudden death is another outcome associated with some cardiomyopathies, including hypertrophic cardiomyopathy, which results in an abnormally thickened heart muscle. Hypertrophic cardiomyopathy has claimed the lives of several prominent young athletes.
If cardiomyopathy can be detected and treated early enough, symptoms can often be controlled and heart failure averted for many years. Occasionally, cardiomyopathy is relentlessly progressive despite the best medical management, and heart transplant surgery becomes the only option for long-term survival.
Congenital Heart Disease
Should anything go wrong in the formation of the heart during prenatal development, a baby will be born with one or more congenital heart defects. Such defects are quite common, occurring in about seven of every 1,000 babies.
The exact causes of congenital heart defects are generally hard to pin down; the mother's genes and environmental factors may both contribute. Chromosome abnormalities, including the one that causes Down syndrome, have been linked to many congenital heart defects. Infections contracted during pregnancy by the mother, such as rubella, may also result in congenital heart defects for the child. Congenital heart defects range widely in their effects. Some are apparent immediately, but others do not produce noticeable symptoms until adulthood.
Among the most common congenital heart defects are septal defects, or holes in septum, the wall dividing the left and right sides of the heart. If a septal defect is big enough to cause problems, it can be patched surgically or with a minimally invasive catheter-based procedure. Another frequently seen defect is pulmonary stenosis, a condition in which the pulmonary valve is so narrow that blood flow to the lungs is restricted. With surgery, the valve can be opened or replaced. In some babies, a small fetal blood vessel known as the ductus arteriosus fails to close at birth as it should. This condition, known as patent ductus arteriosus, allows some blood that is headed for the body via the aorta to leak back into the pulmonary artery, placing the heart under added strain. This problem can also be corrected surgically or sometimes with medication.