When the heart muscle incurs damage or has to work extra hard for a prolonged period of time, the heart itself may become enlarged. Minor enlargement may not prevent the heart from functioning correctly, but a significantly swollen one generally struggles to pump effectively. Heart attack, cardiomyopathy (KARD-ee-o-my-AW-puh-thee), and congestive heart failure are three conditions that can cause permanent injury to and enlargement of the heart muscle. A heart attack may trigger an enlarged heart because it can scar and damage cardiac muscle, forcing the recovered heart to work harder to function properly. In primary cardiomyopathy, the heart becomes inflamed for unknown reasons. In secondary cardiomyopathy, it swells in response to another condition, such as hypertension, heart valve disease, artery disease, or congenital heart defects. These underlying situations force the heart to work harder than normal for an extended period of time, which may cause it to become enlarged. Generally, cadiomyopathy takes one of three distinct forms, each causing the heart to enlarge in a slightly different manner. Dilated (DY-lay-ted) cardiomyopathy is the most common form of this disease. It generally involves swelling and stretching of the entire heart cavity, weakened pumping, electrical conduction problems, and abnormal heart rhythms. Blood then travels more slowly through the heart, allowing blood clots to form, break loose from the inner heart walls, and travel to various parts of the body. In hypertrophic (hy-per-TRO-fik) cardiomyopathy, the heart's left lower chamber or ventricle (VEN-trik-ull) muscle becomes thick and enlarged. This can prevent adequate blood flow, cause a leaky valve, and/or instigate abnormal heartbeats or arrhythmias (a-RITH-mee-ahs). Finally, in restrictive (ree-STRIK-tiv) cardiomyopathy, an overly rigid ventricular (ven-TRIK-you-lar) muscle restricts the chamber's filling capacity, making it hard for the heart to beat and causing it to swell from continuous overexertion. If you're concerned about your heart, or have questions about enlarged hearts, contact a healthcare provider.