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CON: Transesophageal Echocardiography (TEE) should be used routinely in all high risk noncardiac surgery
John E. Ellis, MD
Transesophageal echocardiography (TEE) provides useful information on cardiac structure and function. It can diagnose ischemia, aortic pathology, and valvular disturbances. However, just because it can do these things does not mean that patients benefit from routine use. Limitations include difficulty in using TEE continuously outside of the operating room; the cost; diversion from vigilance and common tasks; and false positive results resulting in unnecessary therapies. Most importantly, the benefits provided by routine TEE may well not be cost-effective. Even though years ago we showed that persistent TEE myocardial ischemia was associated with poor outcome after major vascular surgery,1 the San Francisco group has shown that such ischemia is not an independent predictor of adverse events,2 if more common clinical indicators such ischemic ECG changes and preoperative cardiac risk factors are considered. Indeed, in my practice, a large number of patients present with recent echocardiography, stress echo, or thallium scanning, with estimation of LV function. In patients with normal LV function to begin with, intraoperative TEE may be relatively uninformative. Indeed, even preoperative echocardiography may be limited in its ability to predict preoperative risk.3 Unlike cardiac surgery, where TEE may actually guide surgical management4,5 (aortic cannula placement, mitral regurgitation, coronary sinus cannulation, etc.), rarely does the same hold true in major vascular procedures. While TEE is an excellent tool for diagnosis of thoracic dissection,6 most patients will have been imaged and diagnosed before coming to the operating room. In some cases, though, TEE may help surgeons to choose a deployment site during endovascular thoracic aneurysm (TAA) repair.7 Other specialized but rare uses may include detection of caval and atrial thrombi.8 In my practice, I reserve TEE for evaluation of cardiac structure and function in patients who are doing poorly. I would estimate that after several years of routine use in abdominal aortic aneurysm (AAA) patients, I now use TEE in approximately 10-20% of routine AAA patients. Situations in which I use TEE today include rupture, where rapid assessment of contractility and volume status may be helpful before invasive monitoring can be instituted. Additionally, in those with supraceliac clamps or those with severe cardiac, pulmonary, and/or renal dysfunction, I may consider its use. Indeed, the group at Mt. Sinai in New York showed that TEE resulted in changes in management in only 15% of patients undergoing noncardiac surgery.9 Of course, this number will depend on the severity of illness of the patients studied. A Swiss group found a similar number (20% of patients had changes in therapy); only in lung and liver transplant patients was care routinely changed by TEE.10 The majority of AAA repair done at our institution today is of the endovascular variety; in these cases we generally provide sedation while surgeons use local anesthesia. This anesthetic technique makes TEE nearly impossible. As endovascular techniques improve, we can expect more and more major vascular surgery to be performed without the need for general anesthesia. Recent series and registries suggest that endovascular repair of aortic aneurysms (both abdominal and thoracic) is associated with lower mortality than traditional open repair.11 Therefore endovascular techniques make TEE both less needed and less practical. Of course, when the rare endovascular catastrophe occurs, TEE may be used to guide initial resuscitation,12 since it can be rapidly placed. As mentioned previously, however, TEE may provide useful anatomic information during thoracic stent placement. In our patients undergoing AAA repair, we place a large-bore central line, and occasionally float a pulmonary artery catheter. Therefore, in major vascular surgery, we rarely make the choice of central monitoring vs. TEE; rather TEE is an adjuvant. Measurement of contractility and valvular function with TEE is more straightforward than assessment of filling and diastolic function. Unless one has a dedicated ultrasonographer to measure filling velocities,13 one will still need invasive monitoring to avoid overfilling the heart. This is particularly true in the elderly and those with LVH, where compliance is low and TEE may not help the clinician appreciate excessive fluid administration. Ischemia monitoring is limited by the difficulty of quantitative analysis, particularly when baseline abnormalities, conduction defects, and or paced rhythms exist. TEE is not benign. Complications include esophageal tear, bleeding from esophageal varices,14 infection, and swallowing difficulties. Admittedly, these complications are rare, but they still may occur.15 In short, I do not believe the evidence supports the utility of routine use of TEE in major vascular surgery. However, I do use it my practice to help guide the resuscitation of unstable patients. Additionally, it may be useful in the management of patients with thoracic aortic pathology.16 References
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