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Synopsis: New segmented wall motion abnormalities detected by TEE during coronary bypass surgery without cardiopulmonary bypass that persist at the end of surgery identify a group with increased postoperative morbidity.
Source: Moises VA, et al. J Am Soc Echocardiogr 1998;11:1139-1144.
The practical value of monitoring left ventricular function during coronary bypass surgery by transesophageal echocardiography (TEE) is uncertain. However, coronary surgery performed without cardiopulmonary bypass may represent a unique opportunity for intraoperative TEE. Thus, Moises and colleagues evaluated their experience with 27 patients undergoing coronary bypass surgery without cardiopulmonary bypass who had intraoperative TEE monitoring. Transthoracic echocardiography was performed one day prior to surgery and on the seventh post-operative day. During 48 coronary artery clampings, new segmented wall motion abnormalities were observed in 31 (64%). Half had recovered by the end of the operation and one-third showed partial recovery of wall motion, but five (17%) did not recover. The latter five segments were still abnormal at seven days, as were two of the 10 with partial recovery. Those with persistent new wall motion abnormalities at seven days had higher enzyme levels, more electrocardiographic abnormalities, and more clinical events than those without new segmental wall motion abnormalities at seven days post-operatively. Moises et al conclude that new segmented wall motion abnormalities detected by TEE during coronary bypass surgery without cardiopulmonary bypass that persist at the end of surgery identify a group with increased post-operative morbidity.
Comment by Michael H. Crawford, MD
In this small study, new persistent segmental wall motion abnormalities detected during coronary surgery without cardiopulmonary bypass seemed to be of clinical significance. Since the heart is beating and not protected by cardioplegia during coronary artery clamping, transient wall motion abnormalities would be expected depending on the duration of occlusion and other factors such as collaterals. The paper gives no details on factors that may predict the development of wall motion abnormalities, but, clearly, their persistence is associated with myocardial ischemia or infarction. Also, the complications noted in patients with persistent wall motion abnormalities, namely heart failure and atrial fibrillation, were related to reduced left ventricular function.
At this point in the development of coronary surgery on the beating heart, it would appear that TEE provides clinically useful information about left ventricular function, canula position, etc., to justify its routine use. Also, it may contribute to new knowledge about mechanisms of myocardial damage during this type of surgery (ischemia, infarction, stunning). Along these lines, Moises et al point out that coronary contrast echo may add information about the integrity of the microvasculature after revascularization. One practical note is that Moises et al believe it is important to use transgastric as well as transesophageal planes to visualize as much of the left ventricle as possible.