Re: [HSF] BT shunt – neonate

[ICHFNO at aol.com]

Interesting question as well as some interesting responses.  The issue of 
over-circulation is the Achilles Heal of neonatal shunt operations.  Although 
shunt size is the predominant determinant of over-circulation in a  normal 
pulmonary arterial bed (anatomically normal distal run-off), there are  several 
other factors that will either augment or decrease flow through the  shunt, and 
therefore determine if you have over-circulation or not. 
 
It is far easier to deal with the medication and physiologic  determiners of 
increased shunt flow than it is to try and decrease shunt flow  when you have 
inserted a shunt that is too large. 
 
Our goal has been to have a room air saturation between 75%-  85% when we are 
done. As such we do not use shunts in neonates bigger than 3.5  unless the 
child is over 4 kgs. I would agree that a 3.0 is more likely to  develop 
thrombosis, but that is also to some degree a technical issue, there is  less room 
for less than perfect when inserting a 3.0. They will generally last  up to six 
months if they are performed flawlessly  and the child is  maintained on ASA 
post-operatively. All our shunts receive 10 mg/kg of ASA  within 4 hours 
post-op. We have no experience with Plavix.
 
Having said all this our routine is;
 
3.0 for children 3.0 kgs or less
3.5 for children 3.1 to 4.0 kgs
4.0 for children 4.1 and up.
 
There is rarely an indication for a 5 in a neonate. 
 
If the pCO2 is maintained at or near physiologic range, acid  base status 
will usually be normalized.
It is far better to put in a smaller shunt and augment  pulmonary blood flow 
via pulmonary vasodilatation than it is to put in a big  shunt and try to deal 
with massive over-circulation.
 
 
Outside the neonatal age group, i.e., 30 days or so, this  changes, and will 
depend upon the child's anatomy, age, and defect that requires  shunting. But 
the same point remains, over-circulation can be  dangerous.

 
WNovick



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