different conduits used in cabg

1. Dr.Ramprasath

3. Arterial Conduits
Autologous
 Internal thoracic artery
 Right gastroepiploic artery
 Inferior epigastric artery
 Radial artery
 Splenic artery
 Gastroduodenal artery
 Left gastric artery
 Intercostal artery
Nonautologous
 Bovine internal thoracic artery

4. Venous Conduits
Autologous
Greater saphenous vein
Short (lesser) saphenous vein
Upper extremity veins (cephalic and basilic)
Nonautologous
Umbilical vein
Greater saphenous vein homografts

5. Conduit Options ?
 How to decide about ?
 Life expectancy of individual?
 Elective or emergency?
 Age ?
 Target vessel in Angio ?
 Co-morbidities?

6. Cleeveland clinic study
 Comparison of Saphenous Vein and
Internal Thoracic Artery Graft Patency by
Coronary System(1972-1999)
Joseph F. Sabik, III, MDa,*
, Bruce W.
Lytle, MDa
, Eugene H. Blackstone,
MDa,b
, Penny L. Houghtaling, MSb
, Delos M.
Cosgrove, MDa

7.  LIMA - 93%, 90%, and 88%
 GSV - 78%, 65%, and 57%
CONCLUSIONS: Internal thoracic arteries
demonstrate better patency than
saphenousveins except when grafting
moderately stenosed right coronaryarteries.
When bypassing right coronary arteries with less
than70% stenosis, saphenous veins may be a
better choice.

8.  LIMA Patency 96.4% at 1 year,
89.1% at 5 years, and
88% at 10years.
(The Journal of Thoracic and Cardiovascular
Surgery, Vol 90, 668-675,barner et al)

9. Angiographic patency of
grafts
Conduit 1 yr 5 yr 10yr 15 yr
LIMA 99 95-98 85-95 88
RIMA 98 95-98 80-85 65
RA 96 79 67
RGEA 95 63
IEA 79
GSV
Current 80-95 73 55-75 32-40
Historic 80-95 75 45

10. 2011 ACCF/AHA Guideline for
Coronary Artery Bypass Graft
Surgery
Bypass Graft Conduit:
Recommendations
CLASS I
1. If possible, the left internal mammary artery (LIMA) should be used
to bypass the left anterior descending (LAD) artery when bypass of the
LAD artery is indicated . (Level of Evidence: B)
Journal of the American College of Cardiology Vol. 58, No. 24, 2011
© 2011 by the American College of Cardiology Foundation and the American Heart
Association, Inc. ISSN 0735-1097/$36.00
Published by Elsevier Inc. doi:10.1016/j.jacc.2011.08.009

11. CLASS IIa
1. The right internal mammary artery (IMA) is probably indicated
to
bypass the LAD artery when the LIMA is unavailable or
unsuitable as
a bypass conduit. (Level of Evidence: C)
2. When anatomically and clinically suitable, use of a second IMA
to
graft the left circumflex or right coronary artery (when
critically
stenosed and perfusing LV myocardium) is reasonable to
improve
the likelihood of survival and to decrease reintervention .
(Level of Evidence: B)

12.  CLASS IIb
1. Complete arterial revascularization may be reasonable
in patients
less than or equal to 60 years of age with few or no
comorbidities.(Level of Evidence: C)
2. Arterial grafting of the right coronary artery may be
reasonable
when a critical (90%) stenosis is present. (Level of
Evidence: B)
3. Use of a radial artery graft may be reasonable when
grafting
left-sided coronary arteries with severe stenoses (70%)
and rightsided arteries with critical stenoses (90%) that
perfuse LV myocardium . (Level of Evidence: B)

13. CLASS III: HARM
1. An arterial graft should not be used to bypass
the right coronary artery with less than a
critical stenosis (90%)

14. Date of download:
1/29/2013
Copyright © The American College of Cardiology.
All rights reserved.
From: Long-term patency of saphenous vein and left internal mammary artery grafts after coronary artery bypass surgery:
Title and subTitle BreakResults from a Department of Veterans Affairs Cooperative Study
J Am Coll Cardiol. 2004;44(11):2149-2156. doi:10.1016/j.jacc.2004.08.064
Plot of time to development of 50% to 99% stenosis in internal mammary artery (IMA) and single saphenous vein graft (SVG) to the left anterior
descending coronary artery (LAD). The number of patients at each time point is listed in the figure. *p < 0.001 (IMA vs. single SVG to LAD). CABG =
coronary artery bypass grafting.
Figure Legend:

15. Date of download:
1/29/2013
Copyright © The American College of Cardiology.
All rights reserved.
From: Long-term patency of saphenous vein and left internal mammary artery grafts after coronary artery bypass surgery:
Title and subTitle BreakResults from a Department of Veterans Affairs Cooperative Study
J Am Coll Cardiol. 2004;44(11):2149-2156. doi:10.1016/j.jacc.2004.08.064
Plot of time-related graft patency (or freedom from graft occlusion) for saphenous vein grafts (SVG) to the left anterior descending (LAD),
circumflex (CX), and right coronary (RCA) arteries. The number of patients at each time point is listed in the figure. *p < 0.001 (LAD vs. CX and/or
RCA). CABG = coronary artery bypass grafting.
Figure Legend:

16.  LIMA is Gold standard
 Radial is good
 GSV is acceptable
 Gastro-epiploic better to know
 Re-Do ???? conduit

17. LIMA

18. Anatomy
Origin: from the inferior aspect of the
first part of subclavian artery,
opposite the thyrocervical trunk.
This origin is 2cm above the sternal
end of clavicle
Course:
 Above the first costal cartilage, it
runs downwards, forward and
medially behind the sternal end of
the clavicle
(Related posteriorly to subclavian vein,
phrenic nerve)
 Below the first costal cartilage, the
artery runs vertically down upto its
termination in the 6th
IC space – 2 cm
lateral to edge of sternum.
 Terminates by dividing into the
superior epigastric and
musculophrenic arteries

19. Branches:
1. Pericardiophrenic artery – arises
at the root of neck and
accompanies the phrenic nerve.
= supplies pericardium and
pleura
2. Mediastinal arteries – irregular
branches supply the thymus,
mediastinal fat
3. Two anterior intercostal arteries
per space in upper 6 spaces
4. Perforating branches to the
anterior chest wall. In females
2,3,4 perforators supply the
breast
5. Superior epigastric artery enters
the rectus sheath at the 7th
cartilage
6. Musculophrenic artery runs
down and laterally behind the
costal cartilages and gives
anterior intercostal arteries.

20. Relationships
Anteriorly – upper 6 costal cartilagesand the internal intercostal muscles of
the spaces
Posteriorly – sternocostalis muscle

21. Features of IMA suitable as coronary
conduit
1. Internal elastic laminae has fewer and smaller fenestrations
2. Muscular media has numerous elastic laminae
3. Media has fewer smooth muscle cells
4. Intact endothelium produces EDRF and prostacyclin
5. Arterial conduit – it is used to arterial pressures = lesser intimal hyperplasia
6. Live graft with vasa vasorum
7. Adaptabilty to increased flow demand
8. Pedicle graft – so no proximal anastamosis
9. Anatomical location – suitable for coronary grafting
10. Suitable diametre – 3.5 mm matches coronary
11. Wont be missed - Anterior chest wall has numerous collateral blood supply

22. The histology of the ITA
 lined with typical arterial endothelium
 Internal elastic lamina has fewer and smaller
fenestrations.
 The media is between the internal and
external elastic laminae - contains fewer
smooth muscle cells and 5-9 elastic
lamellae.
 The proximal and distal 10 to 20 percent contains
fewer lamellae, and usually none are distal to the
bifurcation.
 The adventitia contains dense collagen
fibers and transits to loose alveolar tissue
that contains vasa vasorum that do not
penetrate the media.
 Wall thickness is about 200 µm, which is well
under the 350 µm that can be nourished by
diffusion from the lumen.
The elastin layers appear
black, muscle is red and
collagen blue.

24. EDRF
Endothelium derived relaxing factor (EDRF = Nitric oxide)
The ITA endothelium releases more prostaglandin I2 (prostacyclin) and shows
greater NO-mediated vasodilation than does saphenous vein.

25.  Extraluminal release of NO causes relaxation of vascular smooth muscle.
 Intraluminal NO inhibits platelet aggregation and adhesion and
promotes platelet disaggregation as well.
 Downstream travel of NO from the ITA may cause coronary vasodilation.
 Because NO inhibits mitogenesis and smooth muscle proliferation, the
chemical may inhibit development of atherosclerosis in the ITA.
 Activated neutrophils cause more vasoconstriction in saphenous vein
than in the ITA.
Histamine is a potent stimulus for NO release. Serotonin-induced
vasoconstriction is inhibited by NO.
from platelets, mast cells, and endothelium - implicated in coronary spasm,
may contribute to venous graft spasm
but are unlikely to cause ITA spasm

26. Harvesting
 Intra-thoracic ,Extra thoracic
 Along with tissue or skeletionised
 Methods to overcome spasm?
 Papaverine in blood or saline?
1 to 2 mg/ml- extraluminal
0 .5 mg/ml- intraluminal
 Avoid hydrostatic dilatation

27. Grafting strategy
 LIMALAD
 LIMA  LCX ,RIMA LAD
 Use as Free graft when damaged
 Flow should be good (30-150 ml/min)
 Diseased aorta- svg hood or pericardial patch

28.  Presumed difficulty of Dissection
 Fragility of the ITA,
 limitations of flow through the arterial
conduit, and
 Restricted versatility.

29. Caution regarding the use of the internal mammary artery:
1) Diabetics, Immunocompromised and CRF
2) Extremely old patients (life expectancy <10yrs)- most likely not
benefit.
3) Atherosclerotic subclavian arteries.
4) Patients requiring emergency surgery for cardiogenic shock-
increased time
5) Severely calcified or extremely tiny target coronary artery
would minimally benefit
6) Heavy dose radiation to chest
One of the major problems with IMA grafts is – chance of spasm in
the perioperative period which can result in acute infarction.

30. Patency
LIMA to LAD = 92 to 97 percent at 1 year,
88 to 96 percent at 5 years
88 to 93 percent at 10 years.
Right ITA patency is less by 5 to 10 percent
(but if only grafts to the LAD are considered, patency is comparable for the two conduits)
The failure rate for ITA grafts is 0.5 to 1.0 percent per year between years 1
and 10. Beyond the tenth year only anecdotal data are available.
Data from: Loop FD, Lytle BW, Cosgrove DM, et al, N Engl J Med 1986; 314:1.

31. FACTORS INFLUENCING CONDUIT
PATENCY
 Intimal fracturing and thrombosis,
 Profound spasm with secondary thrombosis,
 Faulty anastomotic technique,
 severe coronary disease, and
 competitive coronary flow causing
thrombosis

32. Radial artery

33. Radial Artery
 1973, Carpentier yielded encouraging results
with 90% patency at 1 to 10 months.
 Curtis et al of the radial artery grafts Studied
between 7 and 19 days postoperatively were
patent, only 26% of the grafts were patent at
2 to 12 months after operation.
 Fisk et al who found that of the 48 radial
artery grafts studied after 1 to 24 weeks, 50%
were not patent, whereas simultaneously
placed GSV grafts had a patency rate of 77%.

34. Radial artery
 Muscular media thicker &
devoid of elastic fibres
 Check for completeness of arch
 Papaverine ,low dose milirinone
short term amlodipine (possati
et al 2003,108.1350-4)
 ? Benefit of diltiazem

35.  Grafting strategy- Y graft, T Graft, vein hood
 Patency 5 year – 78%-96%
10 year- 88 %
 Compititive coronary flow – 80% stenosis is
cut-off , better if 90 % stenosed target.
Ann Thorac Surg 2002;73:143-148
The radial artery in coronary surgery: a 5-year experience—clinical and angiographic
results,6446 patients
James Tatoulis, FRACS
*a
, Alistair G. Royse, FRACSa
, Brian F. Buxton, FRACSa
, John A. Fuller,
FRACPa
, Peter D. Skillington, FRACSa
,John C. Goldblatt, FRACSa
, Robin P. Brown,
FRACSa
, Michael A. Rowland, FRACSa

36. Right Gastroepiploic artery
 Histology similar to Radial
 Less atherosclerosis
 Cruciate incision in diaphragm

37.  Perrault et al with 51 right
gastroepiploic in situ grafts with a
patency rate of 90% in 31 patients
prior to hospital discharge.At 1 year-
80% .
 Mills et al showed 82% patency at 11
months .
 Suma et al 10 year patency 87%
 In Re-do surgery when no other
option it can be an alternative

38. Great saphenous vein
 Media is composed of smooth muscle cells
 Wall is too thick for intraluminal nutrition
 Devoid of vasavasorum SM death
replaced by fibrosis after few years its rigid
tube

39.  NO production by native endothelium is less
more so if regenerated
 Patency
1 year- 80-90%
5 year- 70%
10 year- 40- 60 %
15 year- 32%

40. Technical issues to improve
patency Mark the vein
 Minimal handling
 Harvest with pad of fat
 Don`t divide until its needed
 Distension with blood better

41.  Try to maintain
lumen uniformity

42.  Adequate anastamosis
 Try to match the proximal and distal calibre
while anastamosing ( > 50% diffrence not
good)

43. Postoperative Antiplatelet
Therapy:
Recommendations CLASS I
If aspirin (100 mg to 325 mg daily) was not
initiated preoperatively, it should be initiated
within 6 hours postoperatively and then
continued indefinitely to reduce the occurrence
of SVG closure and adverse cardiovascular
events . (Level of Evidence: A)
 CLASS IIa
For patients undergoing CABG, clopidogrel 75
mg daily is a reasonable alternative in patients
who are intolerant of or allergic to aspirin. (Level
of Evidence: C)

44. Future-eSVS mesh

47. Other alternatives
 Cephalic vein
 Inferior epigastric

49. Patency Assessment confounded
certain facts:
(1) alternative conduits are used only in
circumstances in which the ITAs and GSVs are
unavailable;
(2) used in the least favorable site
(3) there is a lack of uniformity in
obtaining long-termfollow-up angiograms to
determine the reliable patency rates for each
alternative conduit; and
(4) it is possible that surgeons are as
unfamiliar with the use of alternative conduits as
they are with theITA and GSV.

51. NEW STRATEGIES TO IMPROVE
GRAFT PATENCY
 Transfer of the endothelial-type nitric oxide
synthase gene
 Fibroblast growth factor- inside PTFE
 Therapeutic angiogenesis

52. Conclusion
 In the usual clinical cardiac surgery practice, if
one becomes familiar with the expanded use
of the ITAs,lower extremity veins, and
possibly right gastroepiploic artery, the other
conduits are rarely needed.
 Think of future Re-do ,conserve conduits

53. In the future, the search for
an ideal coronary bypass conduit
"off the shelf`` will continue
to evolve.

54. Thank