Cardiomegaly (sometimes megacardia or megalocardia) is a medical condition in which the heart becomes enlarged. It is more commonly referred to simply as "having an enlarged heart". It is usually the result of underlying conditions that make the heart work harder, such as obesity, heart valve disease, high blood pressure (hypertension), and coronary artery disease. Cardiomyopathy is also associated with cardiomegaly. Cardiomegaly can be serious and can result in congestive heart failure. Recent studies suggest that cardiomegaly is associated with a higher risk of sudden cardiac death. Cardiomegaly may diminish over time, but many people with an enlarged heart (dilated cardiomyopathy) need lifelong medication. Having a family history of cardiomegaly may indicate an increased risk for this condition. Lifestyle factors that can help prevent cardiomegaly include eating a healthy diet, controlling blood pressure, exercise, medications, and not abusing anabolic-androgenic steroids, alcohol and cocaine.

Signs and symptoms

For many people, cardiomegaly is asymptomatic. For others, if the enlarged heart begins to affect the body's ability to pump blood, then symptoms associated with congestive heart failure may arise, including:

Causes

The causes of cardiomegaly are not well understood and many cases have no known cause. Lifestyle-related risk factors include tobacco use and high cholesterol, high blood pressure, and diabetes. Non-lifestyle risk factors include a family history of cardiomegaly, coronary artery disease (CAD), congenital heart failure, atherosclerotic disease, valvular heart disease, exposure to cardiac toxins, sleep-disordered breathing (such as sleep apnea), sustained cardiac arrhythmias, abnormal electrocardiograms, and cardiomegaly on chest X-ray. Research and the evidence of previous cases link the following (below) as possible causes of cardiomegaly. The most common causes of cardiomegaly are congenital (patients are born with the condition based on a genetic inheritance), high blood pressure (which can enlarge the left ventricle causing the heart muscle to weaken over time), and coronary artery disease. In the latter case, the disease creates blockages in the heart's blood supply, leading to tissue death which causes other areas of the heart to work harder, causing the heart to expand in size. Other possible causes include: In recent years, a consistent theme has occurred in rock and metal drummers dying of drug overdoses and later revealed via autopsy that they were suffering from Cardiomegaly, which may have been worsened by a mix of drug use and the toll such physical exercise takes on the heart, examples of such cases include Jimmy ‘The Rev’ Sullivan (Avenged Sevenfold) and Taylor Hawkins (Foo Fighters).

Mechanism

Within the heart, the working fibers of the myocardial tissue increase in size. As the heart works harder the actin and myosin filaments experience less overlap which increases the size of the myocardial fibers. If there is less overlap of the protein filaments within the sarcomeres of the muscle fibers, they will not be able to effectively pull on one another. If the heart tissue gets too big and stretches too far, then those filaments cannot effectively pull on one another to shorten the muscle fibers, impacting the heart's sliding filament mechanism. If fibers cannot shorten properly and the heart cannot contract properly, then blood cannot be effectively pumped to the lungs to be re-oxygenated or to the body to deliver oxygen to the working tissues of the body. An enlarged heart is more susceptible to forming blood clots in the heart lining. These clots can form elsewhere in the body, potentially disrupting blood supply to other organs.

Diagnosis

Many techniques and tests are used to diagnose an enlarged heart. These tests can be used to see how efficiently the heart is pumping, determine which chambers of the heart are enlarged, look for evidence of prior heart attacks and determine if a person has congenital heart disease. [[File:Cardiothoracic ratio.jpg|thumb|220px|Cardiothoracic ratio = where: MRD = greatest perpendicular diameter from midline to right heart border MLD = greatest perpendicular diameter from midline to left heart border ID = internal diameter of chest at level of right hemidiaphragm]]

Classification

Cardiomegaly can be classified by the main enlarged location of the heart, and/or by the structure of the enlargement. Specific subtypes include athletic heart syndrome, which is a non-pathological condition commonly seen in sports medicine in which the heart is enlarged, and the resting heart rate is lower than normal.

By enlarged location

Structure of enlargement

Dilated cardiomyopathy is the most common type of cardiomegaly. In this condition, the walls of the left and/or right ventricles of the heart become thin and stretched. In the other types, the heart's left ventricle becomes abnormally thick. Hypertrophy is usually what causes left ventricular enlargement. Hypertrophic cardiomyopathy is typically an inherited condition.

Treatment

Treatments include a combination of medications and medical/surgical procedures. Below are some of the treatment options:

Medications

Devices to regulate heartbeat

Surgical procedures

Consequences

The exact mortality rate for people with cardiomegaly is unknown. However, many people live for a long time with an enlarged heart and, if detected early, treatment can help improve the condition and prolong their lives.

Recommended lifestyle changes