[HSF] Targeted Renal Therapy
Ani Anyanwu
anianyanwu at hotmail.com
Sat Apr 14 19:42:33 EDT 2007
Thank you for your comments Murtaza. I too would be keen to know Dr Salerno's thoughts. My understanding though is that ischemia is a relative phenomenon and occurs when the demand (primarily of oxygen) exceeds the supply. If indeed the metabolic rate of the heart is such that most oxygen is not utilized even though blood is going through it, will this be defined as ischemia? Probably the cells have used whatever oxygen they need (which will not be much). When we give cold blood cardioplegia, we often see it going in bright red at one end and coming our dark at the other so surely some of the oxygen has been taken away? I suspect Prasanna may have some coronary sinus sampling data to support that the heart is indeed utilizing the oxygen. Of course one does not know what this all means - maybe the real benefit (if any) of continuous cold blood perfusion lies in maintaining tissue hypothermia rather than preventing ischemia.
I am not sure though that we need mega amounts of K to keep a continually cold perfused heart arrested. I suspect that provided it is kept cold (by the continued cold perfusate) it is unlikely to beat (and if it does it defeats your argument that cardiac cell mechanisms stop working when they are below 16 degrees Celsius). Certainly I have never seen an explanted donor heart beat when taken out of the ice bucket, but as the heart warms (before the clamp is removed) one sometimes will see some fine fibrillation.
The ideal I agree is no doubt warm or tepid perfusion but the question is whether, for those who like it cold, background continuous perfusion offers any advantage over intermittent cardioplegia.
Ani
----- Original Message -----
From: murtaza chishti<mailto:cmurtaza at hotmail.com>
To: OpenHeart-L at lists.hsforum.com<mailto:OpenHeart-L at lists.hsforum.com>
Sent: Saturday, April 14, 2007 1:37 PM
Subject: Re: [HSF] Targeted Renal Therapy
dr Anyanwu
congrtulaions on successful surgery of this very sick patient. certainly,
continuos perfusion is better than intermittent perfusion. There are two
things that must be taken cognizance of, though.
1) temperature in the cardiac capillaries needs to be 16-20 degrees cel
before any significant amount of oxygen gets released. So contineous
perfusion must mean warm perfusion( or tepid) , or else the very purpose of
preventing ischemia and subsequent reperfusion injury is defeated. i wonder
if you moniter myocardial temp. Blood delivered at 4 deg probaly ends up
being at 12 degrees in the capillaries.
2)keeping a contineously perfused heart arrested means large amounts of K+
and perhaps other additives like glucose, with attendent problems of their
own, and ,therefore, comes at a price which could be significant. the point
is if you are perfusing cotineously , is arrest
' really necessary in someone with normal coronaries.A case could be made
for (tepid)arrest in some one with coronary artery disease if you argued
that retrograde plegia is about 25% nutritive.
i look forward to dr. salerno' post on this
murtaza chishti
EHIRC DELHI.
>From: "Ani Anyanwu" <anianyanwu at hotmail.com<mailto:anianyanwu at hotmail.com>>
>Reply-To: OpenHeart-L at lists.hsforum.com<mailto:OpenHeart-L at lists.hsforum.com>
>To: <OpenHeart-L at lists.hsforum.com<mailto:OpenHeart-L at lists.hsforum.com>>
>Subject: Re: [HSF] Targeted Renal Therapy
>Date: Sat, 14 Apr 2007 07:55:27 -0400
>
>
>I used targeted renal therapy for first time earlier this week. Patient was
>50 year old with dilated cardiomyopathy EF ranging between 8 and 12%,
>severe pulmonary hypertension who underwent triple valve surgery (was not
>transplant candidate). His preoperative creatinine ranged from 1.9 to 2.6.
>His renal arteries were off-set by 5cm so was not possible to cannulate
>them both with single catheter so left a unilateral catheter in left renal
>artery and infused 0.4 mcg.kg/min of fenoldapam for 24 hours. He was never
>oliguric post-operatively and his creatinine did not 'bump' as they usually
>do. Maybe has nothing to do with catheter - will try on some more patients
>before forming opinion, but I know Hal seems to be convinced it may be
>beneficial.
>
>Another thing I did differently is to apply Salerno's logic and perfuse
>this very sick heart continuously during clamping via cannulae sutured into
>the coronary ostia so that the heart was never ischemic during the case
>(other than for very brief period when placing cannulae) . That way without
>ischemia there could be no ischemic injury and also no reperfusion injury
>and must say for a heart which barely moved before I was impressed by
>function coming off. No IABP even. I think this makes sense and I will do
>it more on sick ventricles. I have not gone all the way yet though and was
>not bold enough to leave the heart warm and beating - I arrested the heart
>and ran cold (4 degrees) blood through the case - also packed heart with
>slush (yes - some archaic surgeons like me still use topical cooling!).
>
>Ani
>
>
>Hgrmd at aol.com Hgrmd at aol.com
><mailto:openheart-l at lists.hsforum.com?Subject=[HSF<mailto:openheart-l at lists.hsforum.com?Subject=[HSF>] Targeted Renal
>Therapy&In-Reply-To=>
>Mon Jan 22 07:26:45 EST 2007
>
>
>--------------------------------------------------------------------------------
>
>Dear Ahmed,
> To be honest, I found out about TRT from the rep coming by my office
>last
>Wednesday. I've read some of the brochures he left. From what I've seen,
>there's really nothing concrete about its efficacy, only a few case
>reports.
>Apparently, intraop testing has shown that the GFR is increased by 25%
>with
>the infusion. All I know is it's fairly straight forward to insert, and
>seems
>to have little downside. Look at their website _www.flowmedica.com_
>(http://www.flowmedica.com<http://www.flowmedica.com/<http://www.flowmedica.com<http://www.flowmedica.com/>>) .
>Hal
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