End-organ malperfusion and ischemia is not uncommon in acute DeBakey Type I dissection. Traditionally, proximal aortic repair has been undertaken first, and remaining end-organ ischemia, if any, has been managed postoperatively. However, if arterial obstruction is judged static, rather than dynamic, and unresolving ischemia is anticipated, it may be ju.jpgied to address ischemia without delay, i.e., intraoperatively, to mitigate its effects.
The patient, a previously healthy 61-year-old man, was admitted to another hospital with sudden chest pain and left leg ischemia: pain, numbness, pulselessness and loss of motor control. A computed tomography (CT) scan demonstrated acute aortic dissection Stanford Type A/DeBakey Type I with subtotal occlusion of the right carotid artery (Fig. 1) and left external iliac artery (Fig. 2). Clinically, the dissection was classified as Penn Ab . Suspecting static occlusion, due to local false lumen thrombosis, rather than dynamic occlusion, due to mobile dissection flap, it was decided to address the malperfusion of the left leg directly. At operation, simultaneously with sternotomy and cannulation, a femoro-femoral crossover bypass using an 8-mm Dacron graft was performed (Fig. 3), with immediate restoration of peripheral regional tissue saturation as monitored by near-infrared spectroscopy (INVOSTM, Covidien, Boulder, CO, USA). In addition, a prophylactic three-compartment fasciotomy of the lower leg was carried out. Arterial cannulation was performed in the only nondissected peripheral vessel, the left subclavian artery (Fig. 1), using an 18 French Fem-Flex II (Edwards Lifesciences LLC, Irvine, CA, USA) cannula introduced by modified Seldinger technique . The ascending aortic repair was carried out in a standard fashion, using a supracoronary straight 28-mm tube-graft with a side-arm, a hemiarch distal anastomosis during deep hypothermia (18°C), and circulatory arrest followed by side-arm recannulation, reperfusion, and rewarming. Apart from implantation of a permanent pacemaker due to intermittent AV-block, the postoperative course was uneventful. At radiological follow-up three months postoperatively, the ascending aortic repair is satisfactory, the right carotid artery is patent with less false lumen thrombosis, the left external iliac artery remains subtotally occluded (Fig. 4), and the crossover bypass is widely patent with a right-to-left flow verified by duplex sonography.
The treatment of leg malperfusion and ischemia at presentation has regularly been postponed until after the ascending aortic repair . In cases of dynamic obstruction, it is reasonable to assume that dissection repair and reestablishment of preferential true lumen blood flow is sufficient to restore leg perfusion, and ischemia can resolve. However, if the obstruction is static (or combined), delaying intervention until after aortic repair may only propagate further ischemic damage, contributing to the increased mortality and morbidity associated with end-organ ischemia [1,4]. Performing a simultaneous crossover bypass is a quick and simple solution with high success rate. The only modification of the dissection operation is refraining from femoral arterial cannulation. The described strategy of selective leg perfusion  adds no further benefit in a similar situation, still mandating a revascularization of the affected leg in a postponed or secondary procedure. Endovascular treatment using bare metal stent or stent-graft would either delay the aortic repair (if performed preoperatively), delay leg reperfusion (if performed postoperatively), or demand a hybrid operating suite for the two procedures to be performed simultaneously, along with the cost of the device(s), the need for antithrombotic medication, and the risk of future secondary intervention.
Although outside of manufacturer instructions for use, peripheral INVOSTM tissue saturation monitoring is quick, simple, and probably satisfactory in assessing immediate revascularization outcome and limb reperfusion .