Arterial Conduits in CABG

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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.

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Vein grafts

• Early post-operative events
• Thrombosis
• Hypercoagulable state
• Technical reasons
• upto 2.5 yras post op Intimal Hyperplasia
• 3 years or more Atherosclerotic
• Post-op antiplatelets/lipid lowering agents.

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Why Arterial Patency is better

• 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.

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Other Alternative veins

• 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,basilicarm 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 10

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• Umbilical VeinGluteraldehyde-prepared, off the
  shelf, difficult to contour around the heart, 1
  yr patency 50.
• Cryopreserved allograft sahenous veinsoff the
  shelf 1-4 yr patency 15-47,last resort, life
  saving procedures, to be replaced.

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Arterial Grafts

• Intimal Hyperplasia and atherosclerosis RARE.
• Long term failure is usually due to progressive
  athersosclerosis in CA.

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ITA

• 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.

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ITA

• 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 !

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ITA

• 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.

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Radial artery

• First used for CABG by Carpentier associates
  1973.
• Abandoned soon due to strong tendency to spasm.
• Revived in 1990s by Acar colleagues with the
  use of Ca channel blockers.

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Radial artery

• Thicker wall than ITA.
• Ideal diameter.
• Rarely affected by atherosclerosis.
• When to use it ?
• Contraindiction positive Allens test.
• Others Raynauds,Buergers disease, subclavian
  bruit, planned AV fistula.

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Radial artery

• Long term patency results.
• Use of Calcium channel blockers.
• Harvest/ enblock with fat and concomitant veins,
  temporary occlusion proximally, stump pressure
  measurement !

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The Allen Test

• 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.

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The Allen Test

• 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.

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Right Gastroepiploic artery

• Early 1980s.
• 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.

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Right Gastroepiploic artery

• 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 !
• Calcium Channel blockers start in theatre !

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Right Gastroepiploic artery

• 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.

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Inferior epigastric Artery

• 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

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Splenic artery

• 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.

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Left gastric artery

• Three cases reported by one surgeon.

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Lateral costal artery

• 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.

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Subscapular artery

• 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.

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Other grafts

• 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.

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