A transthoracic echocardiogram (TTE) is the most common type of echocardiogram, which is a still or moving image of the internal parts of the heart using ultrasound. In this case, the probe (or ultrasonic transducer) is placed on the chest or abdomen of the subject to get various views of the heart. It is used as a non-invasive assessment of the overall health of the heart, including a patient's heart valves and degree of heart muscle contraction (an indicator of the ejection fraction). The images are displayed on a monitor for real-time viewing and then recorded. Often abbreviated "TTE", it can be easily confused with transesophageal echocardiography which is abbreviated "TEE". Pronunciation of "TTE" and "TEE" are similar, and full use of "transthoracic" or "transesophageal" can minimize any verbal miscommunication.
Details A TTE is a clinical tool to evaluate the structure and function of the heart. All four chambers and all four valves can be assessed by TTE, but the quality and visibility of these structures varies from person to person. Other structures visible on TTE include the aorta, the pericardium, pleural effusions, ascites, and inferior vena cava. It can be used to diagnose a heart attack, enlargement/hypertrophy of the heart, infiltration of the heart from an abnormal substance (e.g. amyloidosis), weakness of the heart, and cardiac tumors. With advanced measurements of the movement of the tissue with time (Tissue Doppler), it can measure diastolic function, fluid status, and ventricular dyssynchrony. 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 vegetation and other abnormalities. Transesophageal Echocardiography also affords better visualization of prosthetic heart valves and clots within the four chambers of the heart. This type of Echocardiogram may be a better option for patients with thick chests, abnormal chest walls, chronic obstructive pulmonary disease and the obese. However, transthoracic is often superior to transesophageal for visualization of the apex of the left ventricle (e.g., left ventricular thrombus) and visualization of the ventricular size of mechanical 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, it may indicate a shunt, such as a patent foramen ovale, atrial septal defect, ventricular septal defect or arteriovenous malformations in the lungs. If a doctor deems it necessary, a stress TTE may be performed. It can be accomplished by either exercising on a bike or treadmill, or by medicine given through an IV along with a contrast agent to make the bodily fluids show up brighter. It allows a comparison between the heart at rest and the heart when it is beating at a faster rate. (Transthoracic Echocardiogram, n.d.) There are some risks associated when having an echocardiogram performed. It is possible that the images will not show up clearly enough, which can cause a misdiagnosis.
Indications There are numerous indications for a TTE:
Non-specific symptoms if cardiac etiology is suspected: Fatigue Dyspnea Heart failure Heart murmur or known valve disease Chemotherapy (cardiotoxic) Chest pain for evaluation of wall motion abnormalities Congenital heart disease Endocarditis Hypoxemia for shunt evaluation
Examination
A typical TTE examination is done by either a cardiologist or a cardiac sonographer. It is a non-invasive test that can be done in many settings that include clinic exam room, inpatient rooms, and exam rooms dedicated to echo imaging. Examination involves using an echo probe at various positions or windows to obtain views of the heart (thus capturing images/videos for later playback while formally "reading" the study to come up with the findings). Examination is usually done while lying flat and tilted onto the left side to bring the heart into better view. Ultrasound gel is used to improve the acoustic windows and increase quality of the captured images. Overall, an uncomplicated TTE exam takes less than 30 minutes. Limited studies (i.e., looking at only specific structures) can be done as a follow-up exam to a full study, or can be done as "point of care" to answer specific questions in the appropriate setting. For example, critically ill patients often have "bedside ultrasounds" performed to assess particular questions the treating team has about their status. This could be looking for cardiac tamponade and acute valve regurgitation. Often, this may include examination of other organ systems such as lungs for effusions or the focused assessment with sonography for trauma. Interpretation of the exam can be done by anyone trained in reading echocardiograms. However, this is often limited to cardiologists for "formal reading" of these studies. Anesthesiologists can perform intra-operative TEEs during surgical cases and they interpret their own studies. Anyone performing a bedside or "point of care" echocardiogram is expected to interpret their own study as it is performed. Pocket-sized TTE devices are growing in popularity.
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