Malignant tumors or cancer can invade the heart either by spreading from other sites within the body, or, in extremely rare instances, as a primary locale. In much the same way that cancer cells affect normal tissue elsewhere in the body, cancer cells replace normal heart muscle cells, eliminating the ability of the muscle to contract. Most cardiac cancers appear in patients who have late-stage, metastasized cancer. As cancer patients live longer, this form of cancer is becoming increasingly prevalent.

	Tumor located in left atrium, as seen on an echocardiogram.

Cancer can spread directly to the heart from an adjacent structure, such as the lungs, or it can spread through the bloodstream or lymphatic channels and implant itself into the muscle or the pericardium. For example, cardiac cancer can be a manifestation of melanoma, a highly aggressive skin cancer that can spread throughout the body, seeding itself in the heart muscle and eventually growing to replace some of the original heart tissue. Or, a kidney cancer can grow up the vein called the inferior vena cava and into the heart. Cancer can also affect the heart valves and the pericardium.

Anecdotally, I've treated patients whose first sign of the spread of cancer to the heart consists of the incidental identification of a moderate amount of fluid on an echocardiogram. This spread may appear years after the patient's initial cancer treatment, and the patient may not experience any symptoms.

A much more rare and acquired disorder is the development of a benign cardiac tumor known as a myxoma. Myxomas are noncancerous tissue growths within the cardiac chambers that adhere to the walls of the heart or to the valves themselves. Physicians often identify these tumors when examining the echocardiogram of a patient who has suffered a stroke or closed artery. These conditions can arise when a piece of the tumor breaks off and either travels through the general circulation or lodges in a coronary artery. Myxomas may also be revealed as an incidental or accidental finding of an unrelated examination. The treatment for myxomas is surgical removal. The tumors typically do not recur unless a family history of multiple tumors exists.

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