What is right atrial enlargement?

Right atrial enlargement describes an increase in the size of the upper chamber, or atrium, on the right side of the heart. In adults, conditions that lead to enlargement of the right atrium usually also cause the corresponding lower chamber, or ventricle, to grow in size. Since blood travels from the right side of the heart directly to the lungs, an enlarged right atrium can be associated with conditions that increase blood pressure in the lungs, such as chronic obstructive pulmonary disease. Some types of congenital heart disease also cause enlargement of the right atrium by allowing blood to pass from the left side of the heart to the right or to flow back from the ventricle to the atrium. The study of heart disease is known as cardiology.

Some babies are born with a heart defect where a hole connects the right atrium of the heart to the left. Since the two sides of the heart are normally completely separate, this leads to problems. Blood from the left atrium passes into the right atrium, increasing the volume inside the heart chamber. Over time, the increased load forces the right atrium to enlarge. This enlargement stretches the tricuspid valve between the right atrium and the right ventricle so it no longer closes properly, forcing blood back into the atrium and further increasing its load.

Finally, the increased blood flow to the right side of the heart can lead to increased pressure in the lungs, causing damage to the pulmonary blood vessels. Enlargement of the right atrium can also disrupt the pacemaker cells located within the atrium, leading to irregular heartbeats. An irregular heartbeat is associated with the risk of forming a blood clot, which could travel to a blood vessel in the brain and cause a stroke. Congenital heart defects are usually treated by heart surgery.

Sometimes, in what is known as cor pulmonale, existing lung disease causes back pressure on the heart. The right ventricle becomes enlarged due to the increased pressure within the pulmonary artery. This leads to distortion of the tricuspid valve, and blood leaks back into the right atrium, which also becomes enlarged. In the case of lung diseases that affect the heart, treatment depends on the individual disease. The overall goal of treatment is to reduce the load on the heart.

Enlargement of the right atrium can be recognized on an electrocardiogram, also known as an EKG or ECG, which records the electrical activity of the heart by placing electrodes on the chest. Almost always, evidence of right ventricular enlargement is also seen, apart from the case of tricuspid valve stenosis. This is where the tricuspid valve becomes damaged during an episode of rheumatic fever, leading to narrowing of the valve, or stenosis. The narrow atrial outlet reduces the enlargement of the right atrium while the right ventricle does not receive enough blood. Tricuspid stenosis usually doesn't need treatment, but rarely, severe symptoms can be treated with heart surgery.

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