A tumor is any type of abnormal growth, whether cancerous (malignant) or noncancerous (benign). Tumors in the heart may be
Primary heart tumors are tumors that originate in the heart. Primary heart tumors are rare, occurring in fewer than 1 of 2,000 people. Most primary heart tumors are noncancerous.
Metastatic heart tumors are cancers that developed in another organ and then spread to the heart. Most heart tumors are metastatic cancer, and most are cancers that spread from the lungs.
Both primary and metastatic tumors may develop in the tissue lining the inside of chambers of the heart (endocardium), the heart muscle (myocardium), the heart valves, or in the sac that surrounds the heart (pericardium). Tumors in the endocardium and heart valves can block blood flow through the heart or cause blood clots that can break off and go to other parts of the body (embolism). Tumors in the myocardium can affect heart function and lead to heart failure or affect the heart's electrical conduction system and cause abnormal heart rhythms. Tumors in the pericardium may squeeze (constrict) the heart, preventing it from filling properly. Chest pain and heart failure may develop.
In adults, about half of noncancerous primary heart tumors are myxomas. Myxomas usually develop in the heart's left upper chamber (atrium). They may develop from embryonic cells located in the inner layer (lining) of the heart's wall.
In infants and children, the most common type of noncancerous primary heart tumor is a rhabdomyoma. Rhabdomyomas, which typically occur in groups, usually grow within the heart wall and develop directly from the heart's muscle cells. Rhabdomyomas commonly develop during infancy or childhood, often as part of a rare disease called tuberous sclerosis.
Another common noncancerous primary tumors in infants and children are fibromas. Fibromas, which typically occur as a single tumor, usually grow within the heart muscle and develop from the heart's fibrous tissue cells.
Several other types of primary heart tumors can develop, but all are rare. Some are cancerous and some benign.
Types of Noncancerous Heart Tumors
Cancerous primary heart tumors include
Sarcomas are cancers that develop from connective tissues (blood vessels, nerves, bones, fat, muscles, and cartilage). Sarcomas develop in the right or left atrium and can block blood flow through the heart. Tumors in the right atrium can spread to the lungs.
Mesothelioma is a rare cancer that can develop in the membrane that covers the heart (pericardium), although it most often develops in the membrane that covers the lungs (pleura). Pericardial mesothelioma can spread to the spine and brain.
Lymphoma is a cancer of white blood cells known as lymphocytes. Lymphoma usually develops in the lymph nodes, spleen, and/or bone marrow. Lymphoma that develops in the heart is extremely rare. It usually occurs in people who have AIDS and grows rapidly.
Metastatic heart tumors originate in some other part of the body—usually the lungs, breasts, kidneys, blood, or skin—and then spread (metastasize) to the heart. They are always cancerous. Metastatic heart tumors are 30 to 40 times more common than primary heart tumors. About 10% of people who have lung cancer or breast cancer—two of the most common cancers—and an even larger proportion of people with melanoma have metastases to the heart.
Heart tumors may cause no symptoms, minor symptoms, or symptoms of life-threatening heart malfunction.
Noncancerous tumors can be as deadly as cancerous ones if they interfere with the function of the heart.
Major symptoms of heart tumors include
Other symptoms may include
Heart murmurs (sounds caused by turbulent blood flow through the heart) develop in about half of the people who have tumors that develop near or on a heart valve (such as myxomas and fibromas) because blood does not flow through the valve normally. Heart tumors that block the valves, compress the heart, or affect the muscular wall of the heart can lead to heart failure, causing shortness of breath and swelling of the legs. Those affecting the electrical system in the heart can cause abnormal heart rhythms, causing palpitations or fainting. If blood flow through the heart is decreased by a tumor blocking the valves or by a tumor in the pericardium compressing the heart, people may develop low blood pressure, leading to dizziness and fainting.
Heart tumors, especially myxomas and sometimes fibroelastomas, may degenerate so that pieces of them break off and travel through the bloodstream (becoming emboli). Emboli may lodge in small arteries and block blood flow. Also, blood clots that form on the surface of tumors, such as myxomas, may break off as emboli and block arteries. Symptoms due to emboli depend on where the material goes and therefore which tissues or organs are affected by the blocked artery. For example, emboli that block an artery in the brain can cause a stroke.
Primary heart tumors are difficult to diagnose because they are relatively uncommon and because their symptoms resemble those of many other disorders. Doctors may suspect a primary heart tumor in people who have heart murmurs, abnormal heart rhythms (causing palpitations, weakness, or fainting), unexplained symptoms of heart failure (causing shortness of breath, swelling of the legs, and fatigue), or unexplained fever (which may be due to a myxoma). Metastatic heart tumors are suspected when people who have cancer elsewhere in the body come to a doctor with symptoms of heart malfunction. More often, heart tumors are diagnosed when a person is undergoing testing for another medical condition, such as for difficulty breathing.
If a tumor is suspected, echocardiography is usually done to confirm the diagnosis. For this procedure, a probe that emits ultrasound waves is passed over the chest, producing an image of heart structures. If another view of the heart is needed, the probe can be passed down the throat into the esophagus to record signals from just behind the heart. This procedure is called transesophageal echocardiography.
Unlike with tumors in most other parts of the body, doctors rarely do a heart biopsy (taking a tissue sample to look at it under a microscope). Heart biopsy may be dangerous depending upon the location of the tumor, and doctors can usually tell the difference between benign and cancerous heart tumors from the results of imaging tests.
A single small noncancerous primary heart tumor can be surgically removed, usually resulting in a cure. If a large noncancerous primary tumor is significantly reducing blood flow through the heart, removal of the part of the tumor that does not grow into the heart wall may improve heart function. However, if a large part of the heart wall is involved, surgery may be impossible.
Rhabdomyomas regress without treatment in most affected newborns and usually do not require treatment.
In infants and children, a fibroma that does not affect the wall between the ventricles (septum) may be successfully removed. Tumors that affect this wall usually also affect the electrical conduction system of the heart and cannot be surgically removed. Children with this type of tumor usually die of an abnormal heart rhythm at an early age. If a fibroma is large, blocks blood flow, and has grown into the surrounding tissue, heart transplantation may be required.
Transplantation is very rarely done in either children or adults, and only people with noncancerous tumors are typically considered for heart transplantation.
Noncancerous tumors in the pericardium can be removed surgically, but cancerous tumors are not removed because they have usually already spread elsewhere in the body. If the tumor secretes fluid that interferes with heart motion, this fluid can be drained with a small plastic tube inserted by needle into the space between the pericardium and the heart (the pericardial space). Sometimes drugs are injected into the pericardial space to slow the tumor's growth or keep the fluid from building up again.