Coronary Artery Bypass Graft

1. Coronary Artery Bypass Graft Joshua Paul Aronson March 20, 2003 5.22J Biotechnology & Engineering Professors J. Essigmann and R. Langer TA: Jyoti Agarwal Cover PageCover Page

2. Go over history, summarize slide, don�t readGo over history, summarize slide, don�t read

3. Chronic angina Unstable angina Acute myocardial infarction Acute failure of percutaneous transluminal coronary angioplasty (PTCA) Severe coronary artery disease Indications for surgeryIndications for surgery

4. Most common arteries bypassed: Right coronary artery Left anterior descending coronary artery Circumflex coronary artery

5. Saphenous vein used for bypassing right coronary artery and circumflex coronary artery Internal mammary artery (IMA) used for bypassing left anterior descending coronary artery Patency rate over 90% after 10 years If more veins are needed, alternative sites such as upper extremity veins can be used Patency rate as low as 47% after 4.6 years

6. Conduit removed Median sternotomy Sternum divided using electric saw Cold potassium cardioplegia Cardiopulmonary bypass Cannulation of: Ascending aorta Femoral artery Right atrium Heparin administered to minimize clotting

7. Bypass of arteries: Incision in target artery: Anastamosis of graft with artery:

9. Positive: Relief of angina in 90% of patients 80% angina free after 5 years Survival about 95% after 1 year Low chance of restenosis Negative: 2-3 days in ICU, 7-10 day total hospital stay 3-6 month full recovery time 5-10% have post-op complications High cost ($25,000-$30,000) Long time on CPB Depression of the patient's immune system Postoperative bleeding from inactivation of the blood clotting system Hypotension

10. Minimally invasive surgery does not use CPB Smaller incision Emerging as a replacement for conventional CABG Starting in 1990�s, MIDCAB has gained popularity Usually conducted for LIMA to LDA grafts

11. Additionally, MIDCAB: Reduced need for blood transfusions, if any Less time under anesthesia: patients are moved out of intensive care more quickly Less pain and discomfort Up to 40% savings over conventional CABG (under $20,000 compared to over $30,000)

12.

13. Small portion of front of 4th rib removed LIMA clipped and dissected MIDCAB retractor and LIMA stabilizer facilitates grafting

14. LAD exposed Anastamosis preformed with assistance of mechanical stabilizer

15. MIDCAB in-hospital and 1 year results (n=174) This study conducted at Washington Hospital Center by a single surgical team Clinical results improved with each operation performed

16. New instruments must be developed Requires highly skilled surgeon and learning curve for surgeons limits number performed Small incision Beating heart Blood in field Can only be used with patients having blockages in one or two coronary arteries on the front of the heart Attempts at operating on other arteries have been moderately successful, but requires even greater skill and practice

17. Uses CPB Balloon catheter system for aortic occlusion and cardioplegic arrest 5-8 cm left anterior thoracotomy incision No sternotomy!!!

18. LIMA harvested using specialized retractor Aorta drawn into operating field

19. Aorta clamped, anastamosis performed

20. Benefits: Bloodless field Heart arrested allows more accurate anastomoses than MIDCAB Smaller incision than CABG No sternotomy Drawbacks Uses CPB Technically very difficult

21. Arterial Revascularization Therapy Study (ARTS) 2001 Percentage requiring second revascularization: 16.8% in stenting group 3.5% in CABG group Event-free survival at one year: 73.8% of stent group 87.8% of CABG Costs for the initial procedure $4,212 less for stenting Difference reduced during follow-up because of the increased need for repeated revascularization After one year, the net difference in favor of stenting was $2,973 per patient.

22. Stent or Surgery Study (SOS) 2001 Death rate for CABG in this study unusually low

24. CABG results in a lower restenosis rate as compared with stenting Drug-eluting stents will narrow this difference Due to repeat treatment, costs for stents and surgery are approximately equal after 2 years Minimally invasive surgeries (MIDCAB and port-access) will result in fewer complications from surgery and a shorter hospital stay This leads to lower costs for surgery, essentially removing the cost advantage of stenting Diabetics have a substantially better response to CABG than to angioplasty and stenting

25. Currently, stenting is recommended over surgery for one-vessel disease In the future, drug-eluting stents will probably be used Minimally invasive surgeries could be used in place of stents in diabetic, and other high-risk patients For more than one-vessel disease, surgery is substantially better at preventing restenosis and so will likely continue to be used in the future Minimally invasive surgeries will expand and replace most conventional CABG procedures

26. References: Cohen, Robbin G, et al. Minimally Invasive Cardiac Surgery. St. Louis: Quality Medical Publishing, Inc, 1999. Gravlee, Glenn P, at al. Cardiopulmonary Bypass: Principles and Practice. Philadelphia: Lippincott Williams & Wilkins, 2000. Holmes Jr, David R. �Debate: PCI vs CABG: a moving target, but we are gaining,� Current Controlled Trials in Cardiovascular Medicine. December 2001 Vol 2 No 6. Harlan, Bradley J, et al. Manual of Cardiac Surgery. New York: Springer-Verlag, 1995. Mehran, R, et al. �One-Year Clinical Outcome After Minimally Invasive Direct Coronary Artery Bypass,� Circulation. December 2000 Vol 102 Issue 23 Pages 2799-2802 Salerno, Thomas A, at al. Beating Heart Coronary Artery Surgery. Armonk: Futura Publishing Company, Inc, 2001. Serruys, Patrick W, et al. �Comparison of coronary-artery bypass surgery and stenting for the treatment of multivessel disease,� New England Journal of Medicine. April 12, 2001 Vol 344 No 15. Stables, RH, et al. �Coronary artery bypass surgery versus percutaneous coronary intervention with stent implantation in patients with multivessel coronary artery disease (the Stent or Surgery trial): a randomised controlled trial,� The Lancet. September 28, 2002 Vol 360 Issue 9338 Pages 965-970. American College of Cardiology Medscape.com TCTMD.com WebMD.com