Transesophageal Echocardiography (TEE)

Transesophageal Echocardiography (TEE)

Transesophageal Echocardiography (TEE) is a specialised form of echocardiographic study using an echo probe held at the tip of an endoscope like device.  As the esophagus is very close to the heart, higher quality images are obtained. Interference by air in the lungs, which is usual for transthoracic echocardiography (TTE) is also avoided. As the imaging is in the near field, higher frequency transducers can be used, providing better image resolution. TEE imaging frequency is of the order of 5 – 10 MHz. TEE is very useful for imaging the posterior structures of the heart like the left atrium. Clots in the left atrial appendage can be seen well on TEE. Small vegetations of infective endocarditis are also better seen on TEE than on TTE. Mitral valve morphology and regurgitant jets can be imaged well on TEE.

Intraoperative TEE is an important application being increasingly used by cardiac surgeons to assess the results of surgical repair. Since it does not interfere with the operative field, results of procedures like mitral valve repair can be assessed soon after restarting the heart even before closure of the chest wall. TTE does not permit intra operative evaluation during open heart surgery.

Intraoperative TEE is being increasingly used in important non cardiac surgery to supplement hemodynamic monitoring as it provides a real time visual assessment of cardiac function. This is more important in those with pre-existing cardiovascular disease. Yoo MC and colleagues have reviewed the advantages and disadvantages of perioperative use of TEE for liver transplantation surgery [1].

TEE is also being used in the cardiac catheterisation laboratory to evaluate results of procedures like device closure of atrial and ventricular septal defects. The proper seating of the device and potential impingement on surrounding vital structures can be accurately assessed by TEE during the interventional procedure without compromising the sterile operating field.

Potential risk of transesophageal echocardiography

Presence of esophageal varices is a potential risk for TEE as there is risk of gastrointestinal bleeding. But a study evaluating 14 patients with grade 1 or 2 esophageal varices and no recent bleed, did not document any serious complications after TEE. Transgastric TEE views were avoided in these patients [2].

References

1. Yoo MC, West JM, Eason JD,Vanatta JM. The Advantages and Disadvantages of Perioperative Transesophageal Echocardiography during Liver Transplantation. J Anesthe Clinic Res. 2012; 4:331.
2. Spier BJ, Larue SJ, Teelin TC, Leff JA, Swize LR, Borkan SH, Satyapriya A, Rahko PS, Pfau PR. Review of complications in a series of patients with known gastro-esophageal varices undergoing transesophageal echocardiography. J Am Soc Echocardiogr. 2009 Apr;22(4):396-400.