What Is Left Atrial Enlargement?

Left atrial enlargement is a dilation of the heart's left atrium. Sometimes referred to as left atrial dilation or left atrial hypertrophy, this condition is most often seen in obese individuals or in those who have an abnormal heart rhythm called atrial fibrillation. It is commonly a side effect of other heart related issues such as hypertension, irregularities in the heart muscle, and congestive heart failure.

The left atrium is the area of the heart that receives oxygenated blood pumped from the lungs. Once the left atrium takes in the fresh blood, it is conveyed through a valve to the left ventricle and into the rest of the body. The left ventricle can also experience enlargement, a medical condition known as left ventricular hypertrophy.

One of the most common reasons for developing left atrial enlargement is high blood pressure, or hypertension, which is a frequent side effect of obesity. Hypertension can also result from an individual's genetic makeup. When blood pumps through the left atrium at an elevated rate of speed, the heart has to work considerably harder to accommodate the increased flow of blood. This can lead to left atrial enlargement and dilation of the ventricles.

The left atrium can also become expanded and compromised by irregularities in the muscle of the heart itself. This condition is known as cardiomyopathy. In most cases, the heart muscle has become notably thicker, and blood must work more diligently to pass through the smaller space, causing an enlargement of the left atrium.

Congestive heart failure can also produce left atrial enlargement. The hearts of those with this condition do not efficiently pump and transmit blood to the rest of the body, which compromises the integrity of the atriums and ventricles. When the left atrium widens as a result of congestive heart failure, enlargement ensues.

In the majority of instances, left atrial enlargement can be detected with an electrocardiogram, or ECG. An ECG monitors and gauges the electrical activity of the heart. Any abnormalities in an ECG reading can indicate heart problems, and a reading that displays a noticeable flux in the P wave — the main line of measurement in an ECG — typically means the patient has left atrial enlargement.

Depending on the cause, the condition may be treated in its early stages with medication. If genetic deformities are present, surgery may be necessary to treat the enlargement. As a first line of treatment, many patients are given blood thinners to attempt to eradicate the issue without major surgery.