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.