The term cardiomegaly usually refers to an enlarged heart as seen on imaging tests, usually the chest X-ray. The heart is composed of four chambers, and an enlargement of any of the chambers can result in cardiomegaly.
A patient with an irregular heartbeat, such as atrial fibrillation, can have a severe enlargement of the heart’s atrial chambers. This can result in cardiomegaly without necessarily affecting the heart function. Patients with sleep apnea or COPD can have an enlargement of the right ventricle and the right atrium. This can result in cardiomegaly without necessarily affecting the overall left ventricular heart function. When all 4 chambers of the heart are enlarged, it is called pancardiomegaly. On occasion, accumulation of fluid around the heart into the pericardium, or envelope, of the heart can cause cardiomegaly.
In most cases, however, hypertension or coronary artery disease affects the left ventricle and results in cardiomegaly. The two main types of cardiomegaly affecting the left ventricle are both referred to as cardiomyopathies. It’s either a dilated type cardiomyopathy, with or without a reduced left ventricular function, or a hypertrophic type of cardiomyopathy, with or without a reduced left ventricular function.
What causes cardiomegaly?
Hypertension is a very common cause of cardiomegaly. By increasing the workload on the heart, the left ventricle adapts by developing hypertrophy and an increase in wall thickness. Over time, the heart wears out and becomes larger and weaker. Another very common cause of cardiomegaly is coronary artery disease. Built-up plaque inside the artery can interrupt the blood supply to the heart muscle and cause damage to the heart or a scar. Subsequently, the heart remodels and becomes larger and weaker in proportion to the amount of scar created by this blocked artery.
The heart has four valves, and any malfunction of these valves can cause the cardiomegaly. When the aortic or mitral valves are leaking, the left ventricle adapts to the increased volume load by getting larger. This results in cardiomegaly. If the aortic valve is narrow, this results in an obstruction to the left ventricle which develops hypertrophy and cardiomegaly. When the mitral valve is narrow, the obstruction to the blood flow results in an increase in left atrial pressure and enlargement of that chamber, causing cardiomegaly.
There can be some congenital or familial type of cardiomyopathy resulting in enlargement and weakening of the left ventricle. Sometimes a viral infection affects the left ventricle, resulting in cardiomyopathy and cardiomegaly. Sometimes, the cause of the cardiomyopathy is not known and is called idiopathic. On rare occasions, amyloidosis can cause deposits of abnormal protein into the heart muscle. This can result in hypertrophy or an increase in the thickness of the muscle, which can lead also to cardiomegaly.
Disease of the lungs can lead to cardiomegaly. When the pressure in the lungs increases, it can lead to enlargement of the right ventricle and cause cardiomegaly. As mentioned earlier, any irregular heartbeat, whether it consists of atrial fibrillation/flutter or ventricular arrhythmias such as PVC (premature ventricular contraction) or ventricular tachycardia, can cause cardiomegaly. This can occur either by an enlargement of the atrial chambers or the left ventricular chamber when heart failure develops.
Sometimes, cardiomegaly can be transient. Alcohol, for example, can lead to enlargement and weakness of the left ventricle, resulting in cardiomegaly. Upon cessation of alcohol use, the heart can become normal again. Cardiomegaly seen in athletes results more from an adaptive mechanism while the heart function is preserved. Pregnancy causes an increase in plasma volume which can result in transient cardiomegaly. Sometimes, however, pregnancy can lead to cardiomyopathy and weakness of the heart muscle with resulting cardiomegaly, which can be permanent.
What is the cardiomegaly workup?
The workup for cardiomegaly starts with a visit to your doctor. By taking a history, the doctor can be clued into a possible cause of cardiomegaly. These could include hypertension, coronary artery disease or heart attack, an infectious cause, or familial history. The physical exam can also provide some clues as to what is the cause of the cardiomegaly, particularly if it is secondary to a right or left-sided congestive heart failure, a valvular problem, or an irregular heartbeat.
Following this, medical professionals perform an ECG, or electrocardiogram, which can reveal the presence of LVH, or left ventricular hypertrophy, as seen in hypertension or valvular problems, right ventricular hypertrophy as seen in patients with chronic pulmonary disease, signs of a scar or a previous heart attack, or the presence of an irregular rhythm such as atrial fibrillation or PVC’s.
One of the best methods for working up cardiomegaly is the echocardiogram. This non-invasive method uses ultrasound and can take under 30 minutes. The echocardiogram can scan the heart and show moving pictures that depict the structure and function of the heart. It shows accurate information on the heart pumping function and heart chamber sizes. An echocardiogram also provides highly accurate information on heart valve function. It can help identify leaky or tight heart valves. Echo will also show whether there is a pericardial effusion, or fluid around the heart, and whether the accumulation of fluid is critical and necessitates immediate removal. It can also help measure the atrial size.
Other imaging techniques such as cardiac CT (computed tomography) or cardiac MRI (magnetic resonance imaging) aid in the workup of cardiomegaly. These techniques are more expensive and usually require an injection of contrast. Cardiac CT uses ionizing radiation. With high resolution, it can provide thin slices of the heart structure, including the coronary arteries, all non-invasively. With special software, it can also provide information regarding the significance of coronary blockages. Cardiac MRI is a non-ionizing imaging technique that also can provide useful information about cardiomegaly. It can help characterize the type of cardiomyopathy such as amyloidosis. It can also provide information about the viability of the heart muscle after a heart attack.
How do you treat cardiomegaly?
The treatment of cardiomegaly depends on the underlying cause.
In high blood pressure, careful blood pressure control is key and can sometimes lead to a regression of cardiomegaly. For those who have suffered a heart attack and other cardiomyopathies, the process of remodeling can be somewhat attenuated by taking medicines such as ACE inhibitors or angiotensin receptor-neprilysin inhibitors and beta-blockers. This can lead to the improvement of heart function and regression of cardiomegaly. In valve disease, treatment at the appropriate time, prior to the onset of full-fledged failure, can often lead to regression of the cardiomegaly.
When the right side of the heart is enlarged and weakened by a massive blood clot to the lungs, the removal and dissolution of the clot can reestablish normal pressure to the right ventricle and resolution of the cardiomegaly. When the pressure in the lungs is chronically elevated, such as seen in patients with chronic obstructive lung disease from long term smoking, the resulting cardiomegaly is not likely to regress. Sometimes cardiomegaly improves when patients stop smoking or when patients with sleep apnea are adherent to their CPAP machine.
In patients with pericardial effusion or fluid around the heart, the removal of that fluid by pericardiocentesis or by surgery will result in a rapid resolution of the cardiomegaly. When the accumulation of fluid is relatively small, anti-inflammatory drugs such as colchicine can be successful.
In conclusion, if one of your imaging studies reports that you have cardiomegaly, you need to follow up with your doctor. He may decide that you need further investigation or that your treatment needs to be adjusted.