Echocardiography

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An echocardiogram. Image shows that the human heart has four chambers. Posterior view - left side of the heart to the left. Right side-up - heart's apex at bottom. The trace in the lower left shows the cardiac cycle and the red mark the time in the cardiac cycle that the image was captured.

An abnormal echocardiogram. Image shows a mid-muscular ventricular septal defect, typical position and size found in a new-born child. The trace in the lower left shows the cardiac cycle and the red mark the time in the cardiac cycle that the image was captured. Colours are used to represent the velocity of the blood.

The echocardiogram is an ultrasound of the heart. Using standard ultrasound techniques, two-dimensional slices of the heart can be imaged. The latest ultrasound systems now employ 3D real-time imaging.

The standard echocardiogram is also known as a transthoracic echocardiogram, or TTE. In this case, the echocardiography transducer (or probe) is placed on the chest wall (or thorax) of the subject, and images are taken through the chest wall. This is a non-invasive, highly accurate and quick assessment of the overall health of the heart. A cardiologist can quickly assess a patient's heart valves and degree of heart muscle contraction (an indicator of the ejection fraction). The TTE is a popular test which keeps improving with more and more advances in the field.

Another method to perform an echocardiogram is to insert a specialised scope containing an echocardiography transducer (TOE probe) into the patient's esophagus, and record pictures from there. This is known as a transesophageal echocardiogram, or TEE. The advantages of TEE over TTE are clearer images, since the transducer is closer to the heart. Some structures are better imaged with the TEE. These structures include the aorta, the pulmonary artery, the valves of the heart, and the left and right atria. While TTE can be performed easily and without pain for the patient, TEE may require light sedation and a local anesthetic lubricant for the esophagus. Unlike the TTE, the TEE is considered an invasive procedure.

In addition to creating two-dimensional pictures of the cardiovascular system, the echocardiogram can also produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using doppler ultrasound. This allows assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), and calculation of the cardiac output as well as the ejection fraction.

Echocardiography was the first medical application of ultrasound. Echocardiography was also the first application of contrast enhanced ultrasound. This technique uses gas-filled microbubble contrast agents to improve the delineation between tissue and blood. It can also be used with Doppler ultrasound to improve flow-related measurements.

Echocardiography is usualy performed by medical doctors or cardiac sonographers.

See also

• Medical imaging
• Medical ultrasonography
• Contrast enhanced ultrasound