What is Right Atrial Enlargement?

Right atrial enlargement describes an increase in the size of the upper chamber, or atrium, on the right-hand side of the heart. In adults, conditions which 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, right atrial enlargement can be associated with diseases which raise blood pressure in the lungs, such as chronic obstructive pulmonary disease. Some types of congenital heart disease also cause an 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 into 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 through 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, resulting in blood leaking back into the atrium and adding to its load even more.

Eventually, the increased flow of blood in the right side of the heart may lead to higher pressure in the lungs, causing damage to the pulmonary blood vessels. Right atrial enlargement can also disrupt the pacemaker cells situated inside the atrium, giving rise to irregular beating of the heart. 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 via heart surgery.

Sometimes, in what is known as cor pulmonale, existing lung disease causes back pressure in the heart. The right ventricle becomes enlarged due to raised pressure within the pulmonary artery. This leads to distortion of the tricuspid valve, with blood subsequently leaking back into the right atrium, which also enlarges. In the case of pulmonary diseases affecting the heart, the treatment depends on the individual disease. The general aim of treatment is to reduce the load on the heart.

Right atrial enlargement can be recognized in 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 in the case of tricuspid valve stenosis. This is where the tricuspid valve is damaged during an episode of rheumatic fever, causing narrowing of the valve, or stenosis. The narrowed atrial outlet leads to right atrial enlargement while the right ventricle does not receive enough blood. Tricuspid stenosis does not usually need treatment but, rarely, severe symptoms can be treated through heart surgery.