Transcript Arterial Conduits in CABG

Arterial Conduits in
CABG
Ayman Abdul-Ghani
June 2003
CTC - Liverpool
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35 - yr history of CABG.
Better outcome with technical
refinements, myocardial protection
and search for better conduits.
Vein grafts:
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Early post-operative events:
– Thrombosis
– Hypercoagulable state
– Technical reasons
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upto 2.5 yras post op: Intimal
Hyperplasia
3 years or more: Atherosclerotic
Post-op antiplatelets/lipid lowering
agents.
Why Arterial Patency is
better:
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Vasoconstrictor effects of leukotrienes
less effective in IMA compared to SVG.
Antithrombotic properties of vein graft
endothelium less well developed than in
arterial grafts - less secretion of NO and
PGI-2 by vein graft endothelium
Intimal proliferation
Graft-coronary discrepancy - eg.smaller
proximal diameter, stasis + clot.
Other Alternative veins:
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Lesser Saphenous vein: acceptable in
70%,difficult to harvest,many
valves,concomitant sinus dilatations
that disrupts laminar flow, lots of
branches, anecdotal results on long
term patency.
Brachial vein,cephalic,basilic:arm veins
are small and thin walled, difficult to
use, abnormal due to previous iv,prone
to aneurysmal dilatation,segmental
stenosis-1 yr patency 57%-66%, 6 yr
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Umbilical Vein:Gluteraldehydeprepared, off the shelf, difficult to
contour around the heart, 1 yr patency
50%.
Cryopreserved allograft sahenous
veins:off the shelf 1-4 yr patency 1547%,last resort, life saving
procedures, to be replaced.
Arterial Grafts:
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Intimal Hyperplasia and
atherosclerosis RARE.
Long term failure is usually due to
progressive athersosclerosis in CA.
ITA:
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Gold Standard.
Superiority of ITA to LAD disclosed in
1986 - Loop and colleagues from the
Cleveland Clinic.
Lytle and associates: Two ITA grafts
are better than one.
ITA:
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Resistant to atherosclerosis (well
formed internal elastic lamina,
perivascular lymphatic drainage,fewer
muscle cells in the media, biochemical
differences compared with SVG.
3% are atherosclerotic at origin.
Use of papaverine !
ITA:
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Longer operative time, post-op
bleeding,sternal healing with bilateral
use.
Uncommon problems: steal from
proximal branches, atherosclerosis,
fistulization to the lung, severe
tortuosity and atherosclerosis.
Currently Best graft available.
Radial artery:
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First used for CABG by Carpentier &
associates 1973.
Abandoned soon due to strong
tendency to spasm.
Revived in 1990’s by Acar & colleagues
with the use of Ca channel blockers.
Radial artery:
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Thicker wall than ITA.
Ideal diameter.
Rarely affected by atherosclerosis.
When to use it ?
Contraindiction: positive Allen’s test.
Others: Raynaud’s,Buerger’s disease,
subclavian bruit, planned AV fistula.
Radial artery:
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Long term patency results.
Use of Calcium channel blockers.
Harvest/ enblock with fat and
concomitant veins, temporary
occlusion proximally, stump pressure
measurement !
The Allen Test:
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1929.
Thromboangiitis obliterans.
6% UA originates from RA.
3% incomplete deep palmar arch.
53% incomplete superficial palmar
arch.
1% significant loss to SPA, 3%
significant loss to DPA with sacrifice of
RA.
The Allen Test:
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1929.
Thromboangiitis obliterans.
6% UA originates from RA.
3% incomplete deep palmar
arch.
53% incomplete superficial
palmar arch.
1% significant loss to SPA,
3% significant loss to DPA
with sacrifice of RA.
Right Gastroepiploic
artery:
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Early 1980’s.
Lumen-to-outer media distance is
slightly less than ITA.
Less elastic tissue.
Fewer smooth muscle cells in media.
Initially strict indications: no other
conduit available, now used more.
Propensity to spasm. In vitro studies,
rings develop three times the force of
ITA.
Right Gastroepiploic
artery:
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Too small for use as a bypass graft in
only 1.4 % in USA.
Contraindications: previous gastric
resection, morbid obesity,
atherosclerosis of the descending
aorta and celiac axis.
Harvest is time consuming, Emergency
!
Long term patency !
Right Gastroepiploic
artery:
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Atherosclerosis is rare.
Difficult to angio, spasm !
Use: avoid BIMA, near occlusion to
RCA or PDA, anastomosis of SVG to
GEA in calcified ascending aorta (no
touch tech.).
Correct orientation.
Inferior epigastric Artery:
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Harvest: different side of ITA.
Athersclerosis near orifice of IEA in
small percentage.
Patency rate: 57-86% at 25 months.
Patch of pericardium or SV at proximal
end improved patency.
Decreased patency with small
coronaries, not to use in DG or small
OM
Better patency reported with
anastomses to ITA pedicle
Splenic artery:
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Used in early years of CABG.
Patency 1-2 yr reported up to 90%.
Very difficult to harvest, tortuosity.
42% evidence of atherosclerosis in
vessel wall.
Significant incidence of pancreatitis.
Left gastric artery:
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Three cases reported by one surgeon.
Lateral costal artery:
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Found in 27% of cadavers.
Traverses 6 intercostal spaces.
Originates from ITA,SCA or supreme
ICA.
Histologically identical to ITA.
Can be used as free or pedicled graft.
Subscapular artery:
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Origin: axillary artery.
Bifurcates to thoracodorsal and
circumflex scapular arteries.
Can be dissected in Lt. Thoracotomies
for re-do CABG.
Used as free graft from descending
aorta to CA.
8% have atherosclerotic disease.
Few reported cases.
Other grafts:
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Dacron: no new intima formation,
thrombogenic.
PTFE - Perma flow graft: 32%
patency at 2 years, Aorta-SVC fistula.
Diffuser-reducer cone at venous end,
cautious optimism and pharmacologic
agents.