Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3711_Библиотеки_им_академика_М_И_Перельмана

Cardiopulmonary bypass (CPB) (Fig. 18.1) is utilized for providing circulatory support in ascending aortic aneurysms (aortic annulus to innominate artery). If the involvement is restricted to the aortic root or ascending aorta alone, then CPB is sufcient. When aneurysmal disease involves the arch, or arch repair is anticipated, circulatory arrest is gener­ally required. There are multiple approaches to circulatory arrest including deep hypothermia without cerebral perfusion and varying degrees of hypothermia with cerebral perfusion. The best strategy for cerebral protection is currently under debate and is a focus of active investigation. Options include deep hypothermia (18–22 °C), moderate hypothermia (22– 26°C), and mild hypothermia (26–30 °C). Cannulation for arch disease depends on the cerebral perfusion strategy. Direct aortic cannulation with dual-stage right atrial cannula can be used in selective antegrade cerebral circulation via direct arch vessel ostia once circulatory arrest is initiated (Fig.18.2). Multiple techniques are available in clinical prac­tice for cerebral perfusion: (1) retrograde cerebral perfusion, (2) selective unilateral antegrade cerebral perfusion via right axillary perfusion, and (3) direct bilateral antegrade cerebral perfusion via ostia of the arch vessels (Fig.18.2). When com­paring antegrade versus retrograde cerebral perfusions during deep hypothermic circulatory arrest, there is no difference in 30-day mortality or stroke in the postoperative period [1]. When comparing deep hypothermic circulatory arrest to moderate hypothermic arrest, there are shorter cross clamp

The patient is positioned supine and a roll is placed between the scapulae to allow greater exposure to the sternum and medias­tinum. The neck should be extended which is particularly help­ful for patients with large body habitus. The arms are tucked to the side. Body hair is clipped, and the patient is prepped from the angle of the mandible to feet. Care is taken to stay midline while performing the sternotomy. The sternal periosteal vessels are coagulated, and vancomycin paste is applied to the sternal edges. Although the utility of vancomycin applied to sternal edges is highly debated, several studies have found signicant reduction in supercial and deep wound infections [4–7]. A sternal retractor is used to expose the anterior mediastinum. The thymus is separated midline up to the innominate vein. The pericardium is opened from the diaphragmatic pericardium up to the superior pericardial reection and transversely at the superior and inferior portion of the pericardium. If the arch is uninvolved, there is minimal dissection needed onto the arch of the aorta. Circumferential dissection of the aorta is carried out in preparation for replacement with graft.

Root repair can be performed in many fashions, with com­posite replacements being more common compared to valve­sparing procedure. Composite mechanical prosthesis is generally chosen for younger patients with few comorbidities.

The aortic root anastomosis is completed with composite conduit with 2–0 polyester suture pledgeted horizontal mattress sutures. The suture line is dried and Bioglue may be applied to the suture line particularly in friable tissues. The right and left coronary buttons are sized and location on the conduit chosen for the anastomoses. It is imperative to have sufcient mobility on both coronary buttons to ensure a tension- free anastomosis. The ostial sites are then opened with a high-temperature cautery pen. If a biologic conduit is being used such as homograft or xenograft root, a 4mm punch is used to create the ostial sites. The left coronary button is rst anastomosed followed by the right coronary button.

Survival from proximal aorta and arch aneurysms is variable. Elective replacement of the proximal aorta carries a mortality rate of 1–3.4%, whereas it is up to 15.4% for nonelective cases [8, 9]. There are many factors that contribute to mortality including urgency of the case, age, ventricular function, arch surgery, concomitant coronary surgery, pulmonary disease, nonsinus rhythm, female sex, NYHA >II, and renal dysfunc-

Elective proximal aortic surgery can be accomplished rela­tively safely with good outcomes. However, the commonly encountered complications include cerebrovascular acci­dent, temporary neurologic dysfunction, hemorrhage, and pulmonary and renal dysfunction. The occurrence of a com­plication contributes not only to length of stay but mortality.

disseminated intravascular coagulation has been described in aortic aneurysms [12]. Ultimately, abnormalities in the clot­ting cascade lead to increased transfusions. Cardiopulmonary bypass induces a proinammatory state. Its utilization, par­ticularly with prolonged bypass times, can lead to end-organ damage along with coagulopathy. Visceral injury from car­diopulmonary bypass can be caused by hypoperfusion [13].

Stroke is a complication of aortic surgery and varies depending on urgency of the intervention. The majority of strokes are embolic [14]. The length of cerebral ischemia is correlated to increased rates of stroke. There have been decreased rates of stroke with the combination of hypother­mia, cannulation strategies, and antegrade cerebral perfusion.

proximal clamp site is not feasible, circulatory arrest is man­datory for construction of the proximal anastomosis [27]. The same cannulation strategy can be used but in conjunc­tion with deep hypothermic circulatory arrest (DHCA) and subsequent total body retrograde perfusion, enabling a uni­form strategy for all TAAA repairs [28].

Numerous strategies have been implemented to reduce the risk of spinal cord ischemia associated with TAA and TAAA repair.

Some of the methods used for spinal cord protection addi­tionally aid in preventing ischemic injury of the abdominal viscera. These include permissive hypothermia and sequen­tial aortic clamping in the repair of any TAAA.Additionally, cold crystalloid selective renal perfusion and selective perfu­sion of the celiac and superior mesenteric axes are frequently employed in extent I and II TAAA repairs [42]. This is accomplished utilizing balloon-tipped catheters and a sepa­rate arterial inow circuit from the bypass pump to perfuse the celiac and superior mesenteric vascular beds with oxy­genated blood, particularly during the reattachment of proxi­mal thoracic aortic segmental arteries.

The patient is placed in a modied right lateral decubitus position with padding of all pressure points and a right axil­lary roll to protect the axillary nerve (Fig.18.6). The hips are rotated obliquely to the left to allow access to the right groin, if necessary. The right knee is exed, and the left kept straight, with padding between the legs to avoid stretch on the left femoral nerve. A beanbag is used to maintain this position and the table is exed just above the iliac crest. The eld is prepped to include the left chest including the axilla superiorly and the spine posteriorly. The entire abdomen and both groins are prepped.