Deep Hypothermic Circulatory Arrest for Aortic Arch Surgery: A Global Brain Ischemia Situation

 Mitch Keamy reviews some pretty interesting material on aortic arch dissection. Surgery for this is a full time affair at Penn.

I am especially interested in the deep hypothermic circulatory arrest used for this because it’s a great example of survivable human brain ischemia. My colleagues in cardiac anesthesia are particularly interested in brain protection during cardiac surgery and I am interested in brain protection in all situations. So I have taken a bit of an interest in this. (Click on all figures to expand)

Some observations:

Here is the number of DHCA cases that my colleagues do annually:

 

 

 
Some pretty good program growth here.

 

 

 

 

 

Here is the distribution of time of DHCA for aortic arch repair. John Augoustides gave me this figure:

       

 

 

 

 

 

 I forgot to mention that one way to help the brain tolerate this is to provide a bit of backwards blood flow from the vena cava up thru the brain and out the carotids. This means we can sample the blood coming out of the ischemic brain.

 

This figure from data collected by Albert Cheung and colleagues suggests that after about a half hour to an hour time’s up:

 

 

NSE is neuron specific enolase and S100 is S100, both are putative biomarkers of brain injury and in this case they were collected directly from the DHCA brain outflow.

 

 

 

Yes this is interesting but maybe the biomarkers were elevated by the bypass itself. So Hetal Hosalkar, John Augoustides, myself  and others organized an effort to compare in vs out suggesting that the brain by 20 minutes of DHCA is putting out S100(* p<.05):

 

 

 

 

    In regular CABG surgery we were able to show that

the postop release of biomarkers of brain injury varied according to genotype. Here we demonstrate that having the ApoeE4 genotype results in higher levels of S100.

 

Maybe it makes for worse neuro outcome, but we did not measure that:

 

 

 

 
Despite the above data,  the patients generally do remarkably well after such a big operation. I worry that there may be some fairly subtle neurocognitive effects that vary with genotype. This material is taken from the preliminary data of a grant I am working on.  I am just dying to know if this model can be used to make generalizable inferences about variations in genotypes and their impact on human brain ischemia, using SNP technology. It is taking so long to get it funded this may be a literal description (the dying part).  Much of it is already published and can be found by searching on the names Augoustides, Kofke, Cheung, and Bavaria (an incomplete list of people at Penn working on this).

This is what I’ll look like by the time this stuff gets funded:

 

 

 

Comments

[mkeamy]

This is really good stuff! What is your sense of the value of retrograde flow on duration of protection?

[andrew kofke]

According to my colleague yianni augoustides:

The Penn practice is to institute DHCA with routine RCP for a maximum duration of 40-45 minutes. If longer DHCA times are required, then typically we employ antegrade cerebral perfusion.

However, this practice varies significantly at high-volume centers around the world.

[esteban]

very nice your blog