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A standard echocardiogram is also known as a transthoracic echocardiogram (TTE), or cardiac ultrasound. 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 or cardiac physiologist can quickly assess a patient's heart valves and degree of heart muscle contraction (an indicator of the ejection fraction). The images are displayed on a monitor, and are recorded either by videotape (analog) or by digital techniques.
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|CC Patrick J. Lynch and C. Carl Jaffe, Yale University, 2006.|
An echocardiogram can be used to evaluate all four chambers of the heart. It can determine strength of the heart, the condition of the heart valves, the lining of the heart (the endocardium), and the aorta. It can be used to detect a heart attack, enlargement or hypertrophy of the heart, infiltration of the heart with an abnormal substance. Weakness of the heart, cardiac tumors, and a variety of other findings can be diagnosed with an echocardiogram. With advanced measurements of the movement of the tissue with time (tissue doppler), it can measure diastolic function, fluid status, and ventricular dyssynchrony.
The TTE is highly accurate for identifying vegetations (masses consisting of a mixture of bacteria and blood clots), but the accuracy can be reduced in up to 20% of adults because of obesity, chronic obstructive pulmonary disease, chest-wall deformities, or otherwise technically difficult patients. TTE in adults is also of limited use for the structures at the back of the heart, such as the left atrial appendage. Transesophageal echocardiography 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.
"Bubble contrast TTE" involves the injection of agitated saline into a vein, followed by an echocardiographic study. The bubbles are initially detected in the right atrium and right ventricle. If bubbles appear in the left heart, this may indicate a shunt, such as a patent foramen ovale, atrial septal defect, ventricular septal defect or arteriovenous malformations in the lungs.