Deep hypothermic circulatory arrest (“circ arrest”) is often required for partial or total aortic arch reconstructions. At this point in the surgery, there is no blood flow anywhere. Because of systemic cooling to ~18°C, we mitigate the anaerobic and calcium-mediated apoptotic pathways that are implicated in neuronal dysfunction and can safely perform surgery for short circ arrest periods.

Antegrade cerebral perfusion (ACP) with end-to-side axillary artery anastomosis with Gelweave graft

If a longer circ arrest period is expected, unilateral antegrade cerebral perfusion (ACP) is a technique that maintains brain perfusion and relies on collateralization through the Circle of Willis to perfuse the contralateral left brain. In one approach, a chimney graft (ie, 8 mm Gelweave) is sewn to the right axillary artery and perfused with an arterial cannula that connects to the cardiopulmonary bypass (CPB) circuit. Initially, this cannula perfuses the entire body through the graft with ~50 cc/kg/min of flow.

After the heart is arrested with cardioplegia and moderate systemic hypothermia is obtained, a clamp is placed proximally on the innominate artery and flow is lowered to ~ 10 cc/kg/min. Now the arterial cannula is only able to perfuse down the right arm and up the right vertebral/carotid systems into the brain. For this reason, a right radial arterial line pressure serves as a surrogate for cerebral perfusion pressure.

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  1. Whats your opinion on some Surgeons choice to only cool to 28C or 24C for DHCA? Do you think theres a big difference between 18C and 24C?
    Also how did they come up with these flows? Why 10cc/kg/min?

    • I’m not sure exactly where the 10 cc/kg/min came from, but it makes sense that it’ll be lower than the traditional 50 cc/kg/min which is often used for full, systemic perfusion since with ACP, only the right arm and brain are being perfused. As far as temperature, I know that 18-20C is generally regarded as safe, but cooling to that degree comes riddled with the usual issues of DHCA (not to mention a longer re-warming). Here’s a paper that suggests moderate hypothermia (24C) + ACP may provide superior neuroprotection to DHCA at 18C alone.

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