Cardiomegaly

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor in Chief: Cafer Zorkun, M.D., Ph.D. [2]

Cardiomegaly is defined as an enlargement of the heart above its normal size. Cardiomegaly is generally first detected on chest X ray, and less often it is detected on routine physical examination. Cardiomegaly may be the first sign of an occult systemic or cardiovascular disease.

Cardiomegaly involves two main processes in the heart muscle. Hypertrophy causes the heart to enlarge due to thickening to the cardiac muscle, and dilation causes enlargement due to stretching of the heart muscle. Dilation occurs as a result of volume overload in the heart.

There are many causes for the condition of cardiomegaly, including medications, genetic conditions, endocrine conditions, infectious processes, toxins and iatrogenic causes.

There is a large differential for cardiomegaly, as it is a finding that is seen in many conditions. The differential can be narrowed based on the chamber of the heart affected, and whether the cardiomegaly is caused by dilation or by hypertrophy. Other physical findings, imaging studies, and laboratory findings need to be taken into consideration when determining the underlying diagnosis caused the manifestation of an enlarged heart.

The history and symptoms can suggest the underlying cause of cardiomegaly. The patient may have a history of rheumatic heart disease or congenital heart disease, or a history of alcohol abuse which may suggest dilated cardiomyopathy. Symptoms such as chest pain, or other cardiac or respiratory symptoms may help in illiciting the underlying cause.

A comprehensive physical examination with a thorough cardiac exam will reveal cardiomegaly, and may indicated the nature of the underlying cause. The body habitus of the individual needs to be taken into account when evaluating findings on cardiac examination.

Laboratory tests that should be obtained when a person is suspected or known to have cardiomegaly are: a complete blood count, thyroid stimulating hormone levels, and a blood urea nitrogen. These are common, high yield tests. Other tests can be ordered based on suspicions as to the underlying cause of the cardiomegaly, obtained through patient history and physical examination.

An EKG is a standard method of evaluating a patient with cardiomegaly. It can help to determine the cause, severity, and the specific chamber which is affected. A q wave would indicate an area of muscle death accounting for the enlargement, and ST elevation may suggest a myocardial infarction, myocarditis or pericarditis.

Cardiomegaly is easily visualized on chest x ray. Cardiomegaly is traditionally defined as a cardiothoracic ratio that is more than 0.5 on a PA film. Other findings on chest x ray can help to determine the specific chamber that is contributing most to the enlargement of the heart.

Echocardiogram recommended for those patients presenting suspected valvular disease, aberrant chamber size, ventricular function, and wall motion abnormalities.

Exercise or pharmacological stress testing may be indicated in those patients suspected of having coronary artery disease. Patients suspected of having valvular disease or coronary artery disease may need a cardiac catheterization for full evaluation following echocardiography.

There are both acute and chronic pharmacotherapies used to manage the cardiomegaly. Diuretics and ACE inhibitors are the standard therapy for chronic management of cardiomegaly. Acute therapies include digoxin, diuretics, antiarrhythmics, pre-load and after-load reducing medications.

In patients who are awaiting a transplant for end-stage symptomatic heart failure, implantable ventricular assist devices may serve as a temporary aid for compensation. Transplantation may be considered in a few cases.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Cardiomegaly involves two main processes in the heart muscle. Hypertrophy causes the heart to enlarge due to thickening to the cardiac muscle, and dilation causes enlargement due to stretching of the heart muscle. Dilation occurs as a result of volume overload in the heart.

The left ventricle can be enlarged from two broad underlying conditions: dilation and hypertrophy.

Left ventricular dilation can occurs as a result of volume overload. Conditions that cause volume overload can be further broken down as follows:

• Valvular Disease: More common underlying valvular heart disease conditions would include mitral regurgitation and aortic regurgitation.
• Congenital Heart Disease: Patent ductus arteriosus and a ventricular septal defect.
• High output states resulting in volume overload: Anemia and thyrotoxicosis.
• High stroke volume states: Complete heart block and prolonged severe sinus bradycardia.
• Can occur as a result of ischemia and remodeling.

Left ventricular hypertrophy occur due to factors that can cause the heart to work harder than normal. Cardiac hypertrophy is seen in the following condtions:

• Hypertension
• Aortic valve stenosis
• Hypertrophic cardiomyopathy
• Atheletic training

Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mugilan Poongkunran M.B.B.S [2]

Cardiomegaly is often caused by hypertension, but it can also occur as a result of other heart conditions, such as congestive heart failure. Common causes of cardiomegaly due to dilation of the myocardium (not hypertrophy) are dilated cardiomyopathy (non-ischemic cardiomyopathy) and ischemic heart disease.

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Aortic dissection
• Cardiac tamponade
• Congestive heart failure
• Myocardial rupture

• Cardiomyopathy
• Congestive heart failure
• Hypertensive heart disease
• Valvular heart disease
• Fludrocortisone
• Hypothyroidism
• Lymphadenopathy

Cardiomegaly causes developed by WikiDoc.org

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and keywords: pseudo-cardiomegaly; pseudocardiomegaly

Cardiomegaly must be distinguished from pseudo-cardiomegaly, a scenario in which the apparent size of the heart is artificially increased. Disorders and conditions which falsely increase the apparent size of the heart include straight back syndrome, a disorder in which the heart is “pancaked” or compressed; and obtaining the chest x-ray during expiration at which time the diameter of the lungs is decreased and the relative diameter of the heart and aorta is increased.

• Epicardial fat pad
• Expiration: If the chest x-ray is obtained during expiration, the lung volume will be decreased and the cardiac size and aortic size will be relatively increased. The traditional metrics used to diagnose cardiomegaly do not apply in this case.
• Kyphoscoliosis
• Mediastinal mass
• Pectus excavatum
• Pulmonary blastoma^[1]
• Straight back syndrome with pancake heart: This can cause a leftward shift of the heart on the chest x-ray. The heart can be “pancaked” or compressed.
• Thymus tumor

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Cardiomegaly (enlarged heart) can be caused by conditions that increase the workload of heart i,e to pump harder than usual or that damage the heart muscle. Established risk factors for cardiomegaly include family history of cardiomegaly, high blood pressure, high cholesterol, obesity, smoking, and coronary artery disease.

Patients have a greater risk of developing an enlarged heart if they have any of the following risk factors:

• Age: Age as an risk factor of cardiomegaly has been controversial. Some studies have shown no increase in heart size with age if hypertension and other heart diseases are carefully excluded.^[1] However elderly people are at increased risk for developing cardiomegaly because of other comorbid conditions.
• Ethnicity : African American
• Gender : Males have an increased risk than females for developing cardiomegaly.
• Alcohol: Heavy alcoholism has significant direct cardiac effects and also results in hypertensive heart disease^[2]
• Congenital heart disease: Genetic condition that affects the structure of heart increases the risk for developing cardiomegaly, especially when the condition is not treated at early stage of life.
• Family history of heart disease: A family history of cardiomyopathy increases the risk of deveopling cardiomegaly.
• High blood pressure: Blood pressure >140/90 mmHg results in remodeling of left ventricular myocardium.^[3]
• Hyperlipidemia: Lipid and lipoprotein abnormalities are common in the general population and are regarded as a modifiable risk factor for cardiovascular diseases due to their contribution to atherosclerosis.
• Obesity: Excess weight contributed significantly to formation of structural and geometric changes of left ventricle and left atrium.
• Physical exercise: Intense, prolonged endurance and strength training can cause the heart to adapt to the extra workload.
• Tobacco smoking: Smoking tends to increase blood cholesterol levels and contributes to the risk of developing heart disease.
• Valvular heart disease : Valves may be damaged by a variety of conditions leading to stenosis, regurgitation or prolapse. Any of these conditions may cause the heart to enlarge.

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