Left atrial enlargement (LAE) or left atrial dilation refers to enlargement of the

left atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

(LA) of the heart, and is a form of

cardiomegaly Cardiomegaly (sometimes megacardia or megalocardia) is a medical condition in which the heart is enlarged. As such, it is more commonly referred to simply as "having an enlarged heart". It is usually the result of underlying conditions that make t ...

Signs and symptoms

Left atrial enlargement can be mild, moderate or severe depending on the extent of the underlying condition. Although other factors may contribute, left atrium size has been found to be a predictor of mortality due to both cardiovascular issues as well as all-cause mortality. Research suggests that left atrium size as measured by an echo-cardiograph may be linked to cardiovascular disease. However, studies that have found LAE to be a predictor for mortality recognize the need for more standardized left atrium measurements than those found in an echo-cardiogram.

Causes

In the general population,

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...

appears to be the most important

risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often use ...

for LAE. LAE has been found to be correlated to body size, independent of obesity, meaning that LAE is more common in people with a naturally large body size. Also, a study found that LAE can occur as a consequence of atrial fibrillation (AF), although another study found that AF by itself does not cause LAE. The latter study also showed that the persistent type of AF was associated with LAE, but the number of years that a subject had AF was not. See p. 2560 Left ventricular filling pressure, LAV, and AF. Obstructive sleep apnea (OSA) may be a cause of LAE in some cases. When an OSA event occurs, an attempt is made to breathe with an obstructed airway and the pressure inside the chest is suddenly lowered. The negative intrathoracic pressure may cause the left atrium to expand and stretch its walls during each OSA event. Over time, the repetitive stretching of the left atrium may result in a persistent left atrial enlargement. See section 5.1.

Diagnosis

E307 (CardioNetworks ECGpedia) (cropped)

LAE is suggested by an electrocardiogram (ECG) that has a pronounced notch in the

P wave A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any ...

. However, if atrial fibrillation is present, a P wave would not be present. In any case, LAE can be diagnosed and measured using an

echocardiogram An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound of the heart. It is a type of medical imaging of the heart, using standard ultrasound or Doppler ultrasound. Echocardiography has become routinely used in th ...

(ECHO) by measuring the left atrial volume (LAVI). Characterizing the size of the left atrium according to its volume is preferred over a single linear dimension since enlargement can be different for different directions. For example, because of the smaller distance in the

thoracic cavity The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. There ...

between the

sternum The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...

and spine, compared to the other directions, less room exists for enlargement of the left atrium along the

anteroposterior axis Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

. By approximating the shape of the left atrium as an

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

, its volume can be calculated from measurements of its dimensions along three perpendicular directions. Indexing the left atrial volume to

body surface area In physiology and medicine, the body surface area (BSA) is the measured or calculated surface area of a human body. For many clinical purposes, BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adi ...

(volume/BSA) is recommended by the

American Society of Echocardiography The American Society of Echocardiography (ASE) is a professional organization of physicians, cardiac sonographers, nurses and scientists involved in echocardiography, the use of ultrasound to image the heart and vascular system. The organization w ...

and the European Association of Echocardiography. The values for volume/BSA in the following table are the best validated, and are the same for both men and women.

References

{{Heart diseases Cardiomegaly