Some background info on the IMA's

1. Intrinsic disease of the IMA is exceedingly rare (I think below 1%, but
definately below 2%)

2. It is important to rule out significant disease in the ipsilateral
Subclavian artery (bilats SBP's images, of proximal segments of sub
arteries where possible with duplex).

3. The IMA is the "conduit of choice" for coronary artery bbypass
grafting, having superior longevity to the
saphenous vein (the saphenous vein has been dissapointing in long term
patency). It can be used with it's anatomic origin in tact ( or pedicled
 which is useful when the aorta is heavily calcified)
or as a free graft. It is conveniently accessed during sugery from the
same exposure as requireed by the CABG.

4. The current trend in coronary artery bypass grafting is toward all
arterial reconstruction due to the
above stated findings. Popular arterial conduits include the right
gastroepiploic artery (minimal intrinsic disease, can be left with it's
anatomic origin intact, also known as pedicled, and anastamosed to
post/inferoir surfaces of the heart or used as a free graft) and the
radial artery.


      Literature that compares preharvest US findings in conduits with
thier long term patency is sorely lacking. In cardiology/thoracic surgery
literature, excellent longterm patency rates are described for the IMA
andf RGEA with no preoperative scanning. We are more often asked to scan
IMA's here when a SBP difference is detected, but that is not to say that
we are not also asked to scan in patients without an SBP difference. I
have
an Application note from HP written by Linda Freeland On imaging the IMA.
In it she describes imaging the IMA from it's origin through the fifth
intercostal space. It is not clear to me from what Joe wrote wether he
scans at a specified space or all spaces through space five. This would
seem to be a bit extensive to me given the low incidence of intrinsic
disease in the IMA and the limits imposed on the scan by acoustic
shadowing from the ribs. We tend to scan from space 3 through five.
     When reporting findings from mapping any conduit pre-harvest I always
suggest being
descriptive. The descision to harvest is up to the surgeons, and will
vary according to many variables including the size of recipient vessel
and vascular bed to be perfused. As Joe said, measure vessel diameter,
and obtain a duplex waveform. We report peak systolic velocities and
RI's. The RI's are really to assess if the vessel has the characteristic
high resistance waveform commonly seen in a normal artery perfusing
skeletal muscle. Close to 1.0 is good. If the Flow in the IMA suggests
reduced pulsatility/flow c/w intrinsic or inflow disease, and or the
ipsilateral sub artery has disease I would throw out a red flag, otherwise
I remain descriptive.

Sorry so long
Tina WOods.