[HSF] Re: [HSF ] OPCAB pitfall

[Ben Bidstrup]

The rationale is (prior to the suggestion that there was a potential 
hypercoagulable state after OPCAB) that there is not the foreign 
surface activation seen with CPB. This is a powerful stimulus for 
activation not only via the extrinsic cascade but also the intrinsic. 
Evidence of this is multitudinous - raised levels of F1.2 and TAT 
during CPB as I and others have shown.
Without that stimulus, and short periods of stasis in the coronary 
alone would in theory cause less problem. But for some reason that is 
not the case.
Does so called full dose create problems. In its own right  - no. It 
has a short half life  1 hour or so, so after 2-3 hours, it will be 
effectively all gone even if not reversed. Have you ever seen a 
patient start bleeding after giving the heparin?
OPCAB is more than meets the eye. Poston and his colleagues have 
shown by measuring  trans cardiac generation of coagulation that 
there is a local hypercoagulable state. There may also be changes in 
runoff, not always measurable by flow measurements over time  which 
can also contribute to graft occlusion.
The ACT will tell if there is inhibition of clot formation. The 
actual number will depend on the  test you are using. They were not 
all created equal. But most accept > 200 seconds as being adequate 
(250  is possibly better). That is still a large dose of heparin. 
Most vascular surgeons just use 10000 units and do not always measure 
ACT.




>Nand
>
>What is the logic for using half dose heparin - I have never quite 
>understood it? Also what is the scientific basi for such a practice? 
>I believe it spins from vascular surgery but they are using much 
>bigger tubes. How do you control for adequate anticoagulation (what 
>ACT etc?). What do you see as the disadvantage of 'full' 
>heparinization?
>
>Thanks
>
>Ani
>   ----- Original Message -----
>   From: nand kejriwal<mailto:nkkejriwal at gmail.com>
>   To: OpenHeart-L at lists.hsforum.com<mailto:OpenHeart-L at lists.hsforum.com>
>   Sent: Friday, February 02, 2007 6:12 AM
>   Subject: Re: [HSF] Re: [HSF ] OPCAB pitfall
>
>
>   He also gave half dose heparin.
>
>   Ani
>
>   I use half dose dose heparin and do nor reverse unless bleeding is a problem
>   in ICU. Do all OPCAB surgeons use full dose (3-4mg/kg) heparin ?
>
>   nand
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-- 
Ben Bidstrup FRACS FRCSEd FEBCTS
Consultant Cardiothoracic Surgeon