A host of diseases can invade the heart. In a condition called amyloidosis, the heart begins to store abnormal proteins that are produced elsewhere in the body. These proteins can clog heart cells, possibly resulting in heart failure. An excessive amount of alcohol consumption is directly toxic to heart muscle. While small amounts of alcohol may, in fact, benefit the heart and reduce long-term coronary risk, excess alcohol takes a toll on heart function. If the disease that results is not too far advanced, ceasing to consume alcohol usage can create some reversal of existing muscular damage. Chemical deficiencies such as a lack of selenium, or excess amounts of iron, called hemochromatosis, can also cause damage to heart tissue. Hemochromatosis is associated with pigmentation of the skin, as well as diabetes. Physicians can treat all of these conditions using medical therapies.

Echocardiogram of heart damaged by alchohol abuse.

Pericardial diseases involve the pericardium, the sac that surrounds the heart. The pericardium normally serves as a protective coating around the heart. Structurally, the pericardium actually consists of two sacs, one sac within the other. A small amount of fluid fills the space between these sacs, enabling them to slide back and forth as the heart beats.

In a condition called pericardial effusion, an abnormally large amount of fluid collects within the sacs. At a certain point, the volume of that fluid begins to put pressure on the heart, preventing it from expanding properly. Pericardial effusion can occur for a variety of reasons, including viral infections and severe thyroid deficiency. Chronic infections such as tuberculosis can also result in the gradual buildup of fluid, thickening the membranes of the pericardium. As time elapses, these membranes become scarred and calcified, essentially forming a prison around the heart.

	Pericardial effusion revealed in echocardiogram.

Physicians can use medications to reduce infection-related pericardial inflammations and help reabsorb some of the fluid. They can also remove the fluid through a needle inserted directly through the chest into the sac, performed under X-ray or ultrasound guidance. For more severe cases, surgeons can open the chest and completely remove the pericardium, eliminating the source of the infection without impeding the patient's cardiac function.

Occasionally, a disease can involve both the pericardium and the myocardium, or heart muscle. Although the heart muscle may appear normal, the disease can make it stiff and noncompliant—a condition referred to as restrictive cardiomyopathy. Catheterization, echocardiography, and CT scanning can help to distinguish between the complicated relative contributions of the pericardium and the myocardium to some diseases.