| Summary: | Two features of off-pump coronary artery bypass (OPCAB) can lead to hemodynamic instability: transient occlusion of coronary arteries during distal anastomosis construction and displacement of the heart to provide access to distal coronary arteries. The position of the heart during OPCAB trans-esophageal echocardiography (TEE) can often provide an indication as to how much compression of the right or left ventricle has occurred. If either chamber is not filling, repositioning of the heart will be necessary. Close observation of the heart with TEE during periods of coronary occlusion may facilitate detection of worsening cardiac function as evidenced by weakening contraction, ventricular dilatation, or increasing mitral or tricuspid regurgitation. Haemodynamic changes are more pronounced with displacement of the heart to access posterior coronary arteries than anterior vessels. Cardiac manipulations during off-pump coronary artery bypass grafting (OPCABG) can lead to haemodynamic instability. This, along with distal anastomosis causing transient occlusion of coronary arteries, may cause transient hypotension with increased filling pressures. TEE is more helpful in this scenario. In these patients, TEE helps differentiate between cardiac dysfunction and secondary to myocardial ischemia in which regional wall motion abnormalities will be present from a much more common scenario where the increase in filling pressure is secondary to extra cardiac compression and provides the ability to detect mitral regurgitation (MR) with a color-flow Doppler, as well as assess right heart function.
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