Transesophogeal Echocardiogram (TEE)
Echocardiogram is an image of the heart using ultrasound. An ultrasound beam is transmitted into the body using a device known as transducer. The echo received from the body is processed by the echocardiograph to give an image of the heart. Transesophageal echocardiogram (TEE) is obtained by introducing a special type of transducer through the throat into the food pipe (esophagus) and stomach. Usual echocardiogram is obtained by placing the transducer on the chest (transthoracic echocardiogram or TTE). Lungs may overlap the heart intermittently in TTE, interfering with the image quality. In TEE as the transducer is in the esophagus, there is no interference by the overlapping of lungs. Esophagus is just behind the heart so that the distance which the ultrasound beam has to travel to reach the heart is also small. For both these reasons, the images obtained by TEE has much superior quality compared to TTE. TEE is very useful in picking up small clots and vegetations (infective material) on heart valves. This helps in treatment of potentially life threatening diseases like infective endocarditis.
What are the novel applications of TEE?
Now that advanced real time three dimensional (4D) imaging is possible with modern TEE probes, cardiac surgeons can have better planning of the surgery. They can obtained ‘surgeon’s view‘ from the device even before opening the heart, which helps them a lot. Monitoring of heart function during surgery with TEE is almost routine in all open heart surgical centers. Assessment of result of surgical repair of heart valves and other structural defects can be done even before closing the chest wall using intraoperative TEE (TEE during surgery). Conventional TTE is difficult with open chest wall. This gives the surgeon an opportunity to revise the surgical procedure if needed and saves a repeat procedure of opening up of the chest again.
Is there any disadvantage for transesophageal echocardiogram?
The most important disadvantage is the semi invasive nature. Some feel it uncomfortable to have the long transducer introduced through the throat. Those with obstructions or diseases of the esophagus can have complications when the device is introduced. So the operator should be well trained in the procedure and in interpretation of the images. Supporting personnel to monitor the patient during procedure is also necessary.