Effects Of Manipulating The Aorta

Coronary artery disease is often considered a component of systemic vascular disease. The same risk factors that contribute to coronary artery disease, such as smoking, diabetes, hypertension, and hyperlipidemia, also contribute to carotid artery disease and atherosclerotic changes in the aorta; this is especially true for the ascending aorta. Atheroma in the aorta can present with calcified plaques or with "cheeselike" soft plaques, which can be disrupted (dislodged) during: (1) cannulation of the

Mammory Vessel Heart Surgery
Fig. 1. Totally aortic nontouch technique in off-pump three-vessel coronary artery bypass grafting surgery via left minithoracotomy; the inflow vein grafts come from the distal left subclavian artery in addition to in situ left internal mammary artery graft.

ascending aorta for cardiopulmonary bypass, (2) cross-clamping in general, or (3) side-clamping of the ascending aorta for attachment of proximal anastomoses of bypassed grafts.

The mobilized plaques can then cause microembolization or macroembolization of brain vessels, resulting in neurological deficits. Multiple episodes of microembolic events have been documented by transcranial Doppler studies during routine CABG surgery. The number of microembolic signals is reported to be related to the extent that the ascending aorta is manipulated (17). Nevertheless, calcified areas of the aorta (or porcelain aorta) can be identified by palpation and thus avoided during surgery, whereas soft plaques are typically unnoticed until they are disrupted during surgical manipulation. The incidence of plaque formation in the ascending aorta can be as high as 30% (18).

Several methodologies have been described to avoid disrupting plaques when working in the region of the ascending aorta. For example, topical ultrasound devices have been used to identify hidden plaques, especially the soft types. In addition, a single aortic cross-clamp technique has been shown to reduce the risk of plaque disruption during conventional CABG surgery (19). Similarly, aortic cross-clamping or side-clamping can be avoided by using proximal anastomotic devices during OPCABG. Totally aortic "nontouch" techniques have been described that can be applied during OPCABG by using: (1) bilateral in situ internal mammary arteries; (2) sequential grafts; (3) in situ gastroepiploic arteries; (4) radial artery Y or T grafts from internal mammary arteries; (5) radial artery or vein grafts from innominate, subclavian, axillary arteries; or (6) descending thoracic aorta. Currently, nontouch techniques during OPCABG are gaining popularity, especially in high-risk patients (Fig. 1). Nevertheless, given limited patient num bers and short follow-up times, the long-term graft patency rate for the procedures remains unknown.

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