Echocardiography

From Wikipedia, the free encyclopedia

Image:Echocardiogram 4chambers.jpg Image:Ventricular Septal Defect.jpg 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.

In addition to creating two-dimensional pictures of the cardiovascular system, the echocardiogram can also produce accurate assessment of the velocity of blood and cardiac tissue at any arbitrary point using Pulsed or Continuous wave 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 intravenous contrast enhanced ultrasound. This technique injects gas-filled microbubbles into the venous system to improve tissue and blood delineation. Contrast is also currently being evaluated for its effectiveness in evaluating myocardial perfusion. It can also be used with Doppler ultrasound to improve flow-related measurements.

Echocardiography is usually performed by cardiologists or cardiac sonographers.

1 Transthoracic echocardiogram
2 Transesophageal echocardiogram
3 See also
4 External links

[edit] Transthoracic echocardiogram

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 commonly used to help diagnose endocarditis. Diagnostic findings by the Echocardiogram include definitive evidence of vegetation or thrombus on valves or other endocardiac structures, abscesses, or disruption of a prosthetic heart valve.

The TTE is highly accurate for identifying vegetations, but the accuracy can be reduced in up to 20% of adults because of obesity, chronic obstructive pulmonary disease, or chest-wall deformities. Transesophageal echocardiography, if available, may be more accurate than TTE because it excludes the variables previously mentioned and allows closer visualization of common sites for vegetations and other abnormalities. Transesophageal echocardiography also affords better visualization of prosthetic heart valves.

[edit] Transesophageal echocardiogram

Another way to perform an echocardiogram is to insert a specialised scope containing an echocardiography transducer (TEE probe) into the patient's esophagus, and record pictures from there. This is known as a transesophageal echocardiogram, or TEE (TOE in the United Kingdom). The advantages of TEE over TTE are usually clearer images. The transducer is closer to the heart and doesn't have the ribs and lungs to deflect the ultrasound beam. 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. Children are anesthetized. Unlike the TTE, the TEE is considered an invasive procedure.

In some centers, sedation is used to ease the discomfort to the individual. The use of local anesthetic agents and sedation can decrease the gag reflex, making the ultrasound probe easier to pass into the esophagus. The transducer and cable are then coated in a lubricant, placed in the patient’s mouth, and then passed down the patient's throat. The individual is instructed to swallow while the probe is being passed down, to prevent it from going into the trachea. Although the placement of the thumb-wide transducer is uncomfortable, there are very few complaints of gagging from the patient once the transducer is in the correct location.