[HSF] Provocative

Fri Jun 1 10:23:12 EDT 2007

Flow measurements have been routine in my practice, and I would have
difficulty in operating on coronary patients without flow measurements.
The reason is that, despite experience, from time to time, a perfect
anastomosis of LIMA-LAD has not flow. The usual reaction is that the
probe is broken. This occurred to me last week.

Regarding what to look for. LIMA flow is diastolic. I tend to pay more
attention to the flow characteristics, ie, diastolic flow than to the
amount of flow itself.  When the flow is marginal or low, I usually go
ahead and perform other grafts, and at the end return to the LIMA-LAD to
determine whether the flow and flow characteristics have changed.
Another important observation is that, usually the surgeon can predict
whether the amount of flow is going to be large or small, depending on
the coronary angiography and operative findings. If I expected high
flows (size of the artery, degree of stenosis, and amount of
collaterals), and found low flows, my threshold to redo the anastomosis
is different than if I expected low flows.

Please remember that lack of flow, low flows, or systolic flows may be
due to other problems other than the distal anastomosis. In the LIMA, it
can be due to distal anastomotic problems, obstruction of the LIMA
somewhere along its length, and other problems. Same for veins. One
cannot assume that lack of flow is due to distal anastomotic problems.

In the RCA one usually finds some systolic and diastolic flows. Areas of
the myocardium with low pressures, such as aneurismal areas, will have
components of systolic flows.

The size of the probe may have something to do with the characteristics
of flow. I use Cardiosonics (Neoprobe) flowmeter, which has the
advantage of one probe fitting all sizes of coronary grafts. This allows
me to measure flows with different sizes of probes, and this may have an
effect on flow characteristics.

Finally, it is important to measure flow in all grafts before and after
protamine, prior to closure of the sternotomy. Anastomotic problems
usually lead to occlusion of the graft after protamine, and the flow
characteristics change. 

Once the surgeon starts to measure flows during coronary surgery, it
becomes more and more difficult to practice without these devices that
measure flows. Furthermore, a print out of flows in each graft is part
of the medical records of the patient.

I hope that some of these hints will help. The book on flows describes
on great details most of the circumstances surrounding problems with
flow and flow measurements.

Tomas   

age-----
From: openheart-l-bounces at lists.hsforum.com
[mailto:openheart-l-bounces at lists.hsforum.com] On Behalf Of Donald Ross
Sent: Thursday, May 31, 2007 11:09 PM
To: OpenHeart-L at lists.hsforum.com
Subject: Re: [HSF] Provocative

Aren't there some juicy bits on coronary flows you could share with us?
Don
On 31/05/2007, at 11:09 PM, Salerno, Tomas wrote:

> This is not a paper. It is a book. Unfortunately I cannot PDF it.
>
> Sorry.
>
> Tomas
>
> -----Original Message-----
> From: openheart-l-bounces at lists.hsforum.com
> [mailto:openheart-l-bounces at lists.hsforum.com] On Behalf Of Michael
> Firstenberg
> Sent: Thursday, May 31, 2007 7:41 AM
> To: OpenHeart-L at lists.hsforum.com
> Subject: RE: [HSF] Provocative
>
> Ding ding ding foul.
> Dr Salerno you forgot a key rule of the forum of if you quote your own
> paper (particularly something hard to find) you must supply the pdf  
> - or
> at least part of it in pdf.
>
>
>
> Michael Firstenberg <msfirst at gmail.com>
>
> -----Original Message-----
> From: "Salerno, Tomas" <TSalerno at med.miami.edu>
> To: OpenHeart-L at lists.hsforum.com
> Sent: 5/31/2007 6:24 AM
> Subject: RE: [HSF] Provocative
>
> Recommended reading:
>
> Intraoperative Graft Patency Verification in Cardiac and Vascular
> Surgery
> Editors D'Ancona, Karamanoukian, Ricci, Salerno, Bergsland.
> Futura Publishing 2001
>
>
> Tomas
>
> -----Original Message-----
> From: openheart-l-bounces at lists.hsforum.com
> [mailto:openheart-l-bounces at lists.hsforum.com] On Behalf Of Mark
> Levinson
> Sent: Wednesday, May 30, 2007 11:36 PM
> To: OpenHeart-L at lists.hsforum.com
> Subject: Re: [HSF] Provocative
>
>
> On May 25, 2007, at 12:34 AM, Ajit Damle wrote:
>
>>
>> 1.  How many of you record the flow in the OR note? Is it the
>> standard of
>> care in US?
>
> For many years, I measured flows, but I noticed that sometimes the
> data was
> either unhelpful, or confusing.     One thing I did for years was
> measure flow
> in the LIMA before removal of the cross clamp, and then after weaning
> from the pump.
> Invariably, the flows were much higher when the cross clamp was still
> on.    It was not
> unusual to see a LIMA go from 120 cc/min to 30 cc/min after release
> of the clamp.
> To me, this always implied 1) a correct anastomosis, and 2)
> competitive flow.
>
> However, when trying to use this experience for OPCAB, it is more
> confusing.
> I do not snare the proximal in OPCAB, so I don't have a baseline
> without competitive
> flow.  So, is 30 cc/min a great graft with competitive flow, or a
> poor graft in the setting
> of minimal competitive flow?
>
> I have tried to use the pulsatility index, but I find if I measue the
> same vessel over and over,
> I get different P.I. values, so this is not absolutely helpful.     I
> look at the diastolic waveforms now,
> but I can't re-explore the graft just based on my limited
> interpretation of these waves.
>
> In the few cases where I could tell a graft was bad, the audible
> waveform sounded like
> a hammer strike rather than a swishing flow signal.    This was
> helpful in 3 cases (all 3
> were kinks after resuming ventilation and resolving with tacking).
>
>>
>> 2.  Do you stipulate the perfusion pressure at the time of your
>> record?
>
> No, I don't     But I try not to make conclusion when the presssure
> is lower than
> what the patient will experience awake (120/80).     If the patient
> is hypotensive,
> the flows are taken during a non-physiologic period, and I remeasure
> when the
> pressure is normal.
>
>> 3  Is it mandatory, or do you do anyway,  include these in the OR
>> note?
>
> No, I do not believe flows are mandatory.    In some cases, they can
> encourage you
> to re-clamp and re-graft a vessel that is perfectly fine, but grafted
> to a small target, or
> one with diffuse disease, or competition.
>
>>
>> 4.  What do you accept as good flow vs bad flow"?
>>
>
> I get nervous below 10 cc/min or with a bad sounding audible
> waveform....
>
>>
>>
>> On on-pumps, where is (usually) quality of anastomosis is not in
>> question,
>> how do you interpret the numbers?
>>
>
> It can be subjective.   Yes, we tend to believe a number and try to
> make that
> number correlate with something, especially by plugging the number
> into a
> database and then running an analysis.
>
> However, there are pitfalls of measuring flows.    If the probe does
> not fit the vessel
> snugly, the flows are down.   If the probe is at a bad angle to the
> flow, the values are less.
> If the pressure is down, if the probe is turned around, then the
> results are spurious.
>
> I know that if I put the probe on 5 different times, I get 5
> different values.    What does this mean?
> I sometimes don't know.    So, if the graft is mechanically perfect,
> and the heart is doiing great, I
> don't measure.    If there is unusually contractility, arrythmias,
> filling pressures, I start looking
> and measure flows.    But I rarely need to revise a graft.  I usually
> find something besides a bad
> distal.    Usually a kink.
>
> Hope this helps.
>
>
> Mark
>
>
>>
>>
>> I do want to elicit the response from American surgeons  regarding  
>> the
>> medico-legal implications.
>>
>>
>>
>> Thanks!
>>
>>
>>
>> Ajit Damle
>>
>>
>>
>>
>>
>> Also,
>>
>>
>>
>> How  many of American surgeons routinely measure the flow, with what
>>
>> device, what criteria?
>>
>>
>>
>> Thans, guys, I nees help
>>
>>
>>
>> Ajit Damle
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: openheart-l-bounces at lists.hsforum.com
>> [mailto:openheart-l-bounces at lists.hsforum.com] On Behalf Of Donald
>> Ross
>> Sent: Thursday, May 24, 2007 6:40 PM
>> To: OpenHeart-L at lists.hsforum.com
>> Subject: [HSF] help with flow probe
>>
>>
>>
>> We have just acquired a Medistim flow  probe ( partly in response to
>>
>> Thomas's credo ) and I have a few questions for the experts.
>>
>> What is the lower limit of flow which would trigger a re-anastomosis?
>>
>> Is this level modified by the size of the target artery?
>>
>> If the flow is at this low level for arterial grafts, would you wait
>>
>> for a while and retest incase the low flow is due to arterial spasm?
>>
>> Do you ever inject dilators in such a graft?
>>
>> Do you always test with proximal occlusion?
>>
>> Can you actually determine whether a coronary lesion is significant
>>
>> enough to support an arterial graft by comparing flow with and
>>
>> without proximal coronary occlusion.
>>
>> Would you ever replace such graft with a SVG?
>>
>> Thanks,
>>
>> Don
>>
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> Mark M. Levinson, MD
> Founder, Editor-in-Chief,
> The Heart Surgery Forum
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