The heart normally pumps blood throughout the body to sustain life. Certain medical conditions may affect the heart muscles, weakening them. The muscle weakness causes the heart to pump harder in effort to supply the same amount of blood that it could at normal strength. The heart enlarges in order to compensate for its muscle weakness and to offset the negative effects of less blood flow.
High Blood Pressure
According to the National Heart, Lung and Blood Institute, blood pressure refers to the force of blood put against the arterial walls as the heart pumps it. High blood pressure, or hypertension, refers to a higher-than-normal pressure of blood on the arterial walls. High blood pressure constricts the blood vessels, and the constricted blood vessels make the heart pump harder to deliver blood to the rest of the body. The heart enlarges as a result, states MayoClinic.com.
Congenital Heart Defects
MayoClinic.com lists congenital heart defects as a cause of an enlarged heart. The American Heart Association reports hypertrophic cardiomyopathy as the most common congenital heart defect. Hypertrophic cardiomyopathy causes the heart muscle to thicken and stiffen, and this defect affects blood flow through the heart, forcing it to pump harder. In response to the constant stress put on it, the muscle mass of the left ventricle--the heart chamber responsible for pumping blood throughout the body--enlarges, or hypertrophies.
Heart Valve Disease
MayoClinic.com points out that an enlarged heart can occur if the heart valves are damaged. The heart contains four valves that keep blood flowing in the right direction. Damage to the valves can occur from rheumatic fever, a heart defect, infections, connective tissue disorders, certain medications or radiation treatments. The conditions can cause the valves to become inflamed, and this inflammation can damage them. The damage the valves incur affects how the blood flows through them. Enlargement of the heart occurs because the heart pumps harder to move more blood through the valves.
Anemia
Anemia refers to a condition in which a decrease in the production of red blood cells exists. The red blood cells carry adequate oxygen to the tissues in the body. Untreated anemia can lead to arrhythmias, or irregular heartbeats, notes MayoClinic.com. Arrhythmias occur when the heart doesn't pump blood as it normally does. The heart has to pump more blood to compensate for the lack of oxygen in the blood. The extra work the heart does to pump more blood through the body causes it to enlarge.
