Comment
Paraplegia, gastrointestinal complications and acute kidney injury are serious complications of TAAA repair1,2. The use of distal aortic perfusion, SVP and renal perfusion was very important to reduce these complications. And LHB was the most common maneuver to provide distal perfusion. With LHB, the bypass perfusion is started before clamping the aorta, and distal perfusion is maintained during the whole period of aortic occlusion. So it provides marginal safety during the cross-clamp period4. Our technique is different from LHB method. The downstream organs including visceral, renal and spinal cord are ischemic (about 10 minutes) during the proximal anastomosis. As soon as the anastomosis is completed, the downstream organs restore perfusion.
LHB method was performed under mild hypothermia4, while our technique was under normothermia. And LHB method can reduce proximal blood pressure and afterload to the heart during proximal anastomosis, which has the detrimental effect on the heart. But LHB circuit is very expensive, and this method carries some risks for its technical difficulty. And LHB could only provide non-pulsatile flow to viscera. The strategy of SVP in our technique was not via LHB. This strategy could directly provide pulsatile flow from heart to visceral organs through the bypass mentioned previously (Figure 2C). During SVP period, the lower body and the viscera received double perfusion from the heart and the roller pump. Interestingly, in arterial cannula connected to graft, the pulsatile flow from the heart to the viscera (flow 1) has opposite direction to the flow from the roller pump to the lower body (flow 2). Therefore, the direction of blood flow in the cannula depends on rate or pressure of two flows. If the rate of flow 1 is greater than that of flow 2, the flow from the roller pump could only directs to the viscera, while the flow from the heart perfusates both the viscera and the lower body. If the rate of flow 1 is lesser than that of flow 2, the lower body receives bilateral blood supply from the heart and the roller pump, while the viscera could only receive blood flow from the roller pump. In addition, our strategy has avoided some complicated produre related to LHB and decreased the medical expenses to great extent. Overall, it provided a safe and effective repair of giant TAAA, with satisfactory visceral organ protection.
Conflict of interest: none declared.