Cardiomegaly (sometimesmegacardia ormegalocardia) is a medical condition in which theheart becomes enlarged. It is more commonly referred to simply as "having anenlarged heart". It is usually the result of underlying conditions that make the heart work harder, such asobesity,heart valve disease, high blood pressure (hypertension), andcoronary artery disease.Cardiomyopathy is also associated with cardiomegaly.[12]
Cardiomegaly may diminish over time, but many people with an enlarged heart (dilated cardiomyopathy) need lifelong medication.[14] Having a family history of cardiomegaly may indicate an increased risk for this condition.[15]
Lifestyle factors that can help prevent cardiomegaly include eating a healthy diet, controlling blood pressure, exercise, medications, and not abusing anabolic-androgenic steroids, alcohol andcocaine.[15]
For many people, cardiomegaly isasymptomatic. 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:[15]
Heartpalpitations – the irregular beating of the heart, usually associated with a valve
Severe shortness of breath (especially when physically active)
The causes of cardiomegaly are not well understood and many cases have no known cause. Lifestyle-related risk factors includetobacco use and highcholesterol, high blood pressure, anddiabetes. 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 assleep apnea), sustained cardiacarrhythmias, abnormalelectrocardiograms, and cardiomegaly on chest X-ray.
Research and the evidence of previous cases link the following (below) as possible causes of cardiomegaly.[citation needed]
The most common causes of cardiomegaly arecongenital (patients are born with the condition based on a genetic inheritance), high blood pressure (which can enlarge the leftventricle 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.[citation needed]
Cardiomegaly can also occur non-pathologically as part ofathletic heart syndrome (AHS) in individuals who frequently engage in high-intensityphysical exercise, for instanceendurance athletes and other individuals who exercise for more than 1 hour daily.[23] AHS is a result of physiologicalcardiac remodeling, which is a natural adaptation to frequent physical exercise and a high level ofphysical fitness.[24] Cardiomegaly due to AHS is usually benign and reversible, but it is important that athletes with suspected AHS undergoscreening to rule out potentially life-threatening underlyingheart problems.[25][26]
Within the heart, the working fibers of themyocardial tissue increase in size. As the heart works harder theactin andmyosin filaments experience less overlap which increases the size of the myocardial fibers. If there is less overlap of the protein filaments within thesarcomeres 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.[citation needed]
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.
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.[citation needed]
Cardiothoracic ratio = where:[29] 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
Chest X-ray:X-ray images help to visualize the condition of the lungs and heart. If the heart is enlarged on an X-ray, other tests will usually be needed to find the cause. A useful measurement on X-ray is the cardio-thoracic ratio, which is thetransverse diameter of the heart, compared with that of thethoracic cage.[30] These diameters are taken fromPA chest x-rays using the widest point of the chest and measuring as far as the lungpleura, rather than lateral skin margins. If the ratio is greater than 50%, pathology is suspected.[31] The measurement was first proposed in 1919 to screen military recruits. A newer approach to using these x-rays for evaluating heart health takes the ratio of heart area to chest area and has been called the two-dimensional cardiothoracic ratio.[32]
Electrocardiogram: This test records the electrical activity of the heart through electrodes attached to the skin. Impulses are recorded as waves and displayed on a monitor or printed on paper. This test helps diagnose heart rhythm problems and assess the damage to a person's heart from a heart attack.
Echocardiogram: This test uses sound waves to produce a video image of the heart. With this test, the four chambers of the heart can be evaluated.
Stress test: A stress test, also called an exercise stress test, provides information about how well the heart works during physical activity. It usually involves walking on a treadmill or riding a stationary bike while heart rhythm, blood pressure, and breathing are monitored.
Cardiac computerized tomography (CT) ormagnetic resonance imaging (MRI). These techniques create images of the heart for inspection.
Blood tests: Blood tests may be ordered to check the levels of substances in the blood that may show a heart problem. Blood tests can also help rule out other conditions.
Histopathology of (a) normal myocardium and (b) myocardial hypertrophy. Scale bar indicates 50 μm.Weight of the heart versus the body[33]
Cardiac catheterization and biopsy: In this procedure, a catheter is inserted into the groin and threaded through the blood vessels to the heart, where a biopsy of the heart can be extracted for laboratory analysis.[15]
Autopsy: Cardiomegaly is indicated if the heart weighs more than >399 grams in women and >449 grams in men.[34]
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.[35]
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.[36]
ICDs: Small devices implanted in the chest to monitor heart rhythm and deliver electrical shocks to control abnormal heartbeats. The devices can also work as pacemakers.
Valve surgery: If an enlarged heart is caused by a problem with a heart valve, surgery can remove the valve and replace it with either an artificial valve or a tissue valve from a pig, cow or deceased human donor. If blood leaks backward through a valve (valve regurgitation), the leaky valve may be surgically repaired or replaced.
Coronary bypass surgery: to address coronary artery disease, which can lead to an enlarged heart.
Left ventricular assist device: (LVAD): to help a weak heart pump, potentially while waiting for a heart transplant or as a long-term treatment for heart failure.
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.[15]
Heart failure: One of the most serious types of enlarged heart, an enlarged left ventricle, increases the risk of heart failure. In heart failure, the heart muscle weakens, and the ventricles stretch (dilate) to the point that the heart can't pump blood efficiently throughout the body.
Blood clots: If clots enter the bloodstream, they can block blood flow to vital organs, possibly causing a heart attack or stroke. Clots that develop on the right side of the heart may travel to the lungs, a dangerous condition called apulmonary embolism.
Heart murmur: Two of the heart's four valves – themitral andtricuspid valves – may become dilated and not close properly, leading to a backflow of blood. This flow creates sounds calledheart murmurs.
Cardiomegaly may be a temporary condition that can resolve on its own.
^ab"Enlarged heart".Heart and Stroke Foundation of Canada. Archived fromthe original on 2019-03-29. Retrieved2019-03-29.Types...Hypertrophic cardiomyopathy, Left ventricular hypertrophy (LVH), Intense, prolonged athletic training
^McKelvie, Robert S."Athlete's Heart".MSD Manual: Professional Version. Merck & Co.Archived from the original on 27 February 2025. Retrieved27 February 2025.
^Kumar, Neena Theresa; Liestøl, Knut; Løberg, Else Marit; Reims, Henrik Mikael; Mæhlen, Jan (2014). "Postmortem heart weight: relation to body size and effects of cardiovascular disease and cancer".Cardiovascular Pathology.23 (1):5–11.doi:10.1016/j.carpath.2013.09.001.ISSN1054-8807.PMID24121021.
^"Cor Pulmonale".The Lecturio Medical Concept Library. October 2020. Retrieved10 July 2021.
^Kaplan's Essentials of Cardiac Anesthesia. Elsevier. 2018.doi:10.1016/c2012-0-06151-0.ISBN978-0-323-49798-5.Mechanisms of Action:ACE inhibitors act by inhibiting one of several proteases responsible for cleaving the decapeptide Ang I to form the octapeptide Ang II. Because ACE is also the enzyme that degrades bradykinin, ACE inhibitors increase circulating and tissue levels of bradykinin (Fig. 8.4).
Ampanozi, Garyfalia; Krinke, Eileen; Laberke, Patrick; Schweitzer, Wolf; Thali, Michael J.; Ebert, Lars C. (1 September 2018). "Comparing fist size to heart size is not a viable technique to assess cardiomegaly".Cardiovascular Pathology.36:1–5.doi:10.1016/j.carpath.2018.04.009.PMID29859507.S2CID44086023.
Agostoni, PierGiuseppe; Cattadori, Gaia; Guazzi, Marco; Palermo, Pietro; Bussotti, Maurizio; Marenzi, Giancarlo (1 November 2000). "Cardiomegaly as a possible cause of lung dysfunction in patients with heart failure".American Heart Journal.140 (5):A17 –A21.doi:10.1067/mhj.2000.110282.PMID11054632.
Luedde, Mark; Katus, Hugo; Frey, Norbert (1 January 2006). "Novel Molecular Targets in the Treatment of Cardiac Hypertrophy".Recent Patents on Cardiovascular Drug Discovery.1 (1):1–20.doi:10.2174/157489006775244290.PMID18221071.
