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CORONARY ARTERY BYPASS
Paul J. Corso, M.D., FACS, FACC
Chief Cardiovascular Surgery, Washington Hospital Center
Coronary Revascularization - Surgical
Historical Review:• 1946 Vineberg IMA implant into cardiac muscle• 1954 Murray Experimental anastomosis (IMA/SVG)• 1962 Sabiston First CABG (SVG to RCA)• 1964 Garrett First CABG to LAD without pump• 1967 Kolessov Lima-LAD, thoracotomy• 1968 Favaloro Initial experience with SVG with pump• 1970 Johnson Expanded experience CABG• 1972 Ankeney USA 1st Single graft series w/o CPB
Classic Procedure (Same Operation For All)
1. Sternotomy2. IMA Harvest3. SVG4. Cannulation for CP Bypass5. Arrest Heart6. Anastomosis Heparin
7. Wean From Bypass 8. Reverse heparin and
Stop Bleeding
21st Century CABG
1. On pump with sternotomy
2. Off pump with sternotomy
3. Small incisions on pump4. Small incisions off pump
CORONARY ARTERY BYPASS GRAFTING WITHOUT CARDIOPULMONARY BYPASS
Complications of cannulation/clamping
• Bleeding – aorta and atrium• Dissection• Embolization
CORONARY ARTERY BYPASS GRAFTING WITHOUT CARDIOPULMONARY BYPASS
Consumption of coagulation factors
Platelet damage Bleeding
Leukocyte damage (pyrogen) Fever
Leukocyte & platelet-mediated
endothelial damage Edema (increased
Complement-induced increased interstitial H2O)
vascular permeability
Bradykinin Vasoconstriction
Platelet & fibrin microemboli Organ dysfunction
CPB – Causes of Neurological Abnormalities
• Platelet micro-emboli• Air emboli• Atherosclerotic emboli
• Aortic cross clamping• Aortic cannulation• Proximal graft placement
COMPLICATIONS OF CABG
1.Death2.MI3.CVA 4. Infection5.Bleeding
70% Related to use of CP Bypass
Bleeding is a Significant Aspect of CABG
•300,000 Operations
•46% received blood and/or blood products
•2.5% returned to OR for bleeding
SOURCE – STS Database
Complications of Blood Transfusion
Death! – “With non-leukocyte reduced transfusions in randomized trials, multiorgan failure and death may occur in up to 10% of transfused intensive care unit patients versus 5% in recipients of leukocyte reduced blood transfusions” => at least 5% of patients may die as a result of blood transfusions!!!Leukocyte-related target organ injury in 2 to 5%Transfusion-related acute lung injury (TRALI) may be the most common complication!!
Intraoperative RBC Tx Increases Risk of Low Output Failure
8004 Patients, Northern New England Cardiovascular Disease Study Group
Included only patients with <=3 units RBCs
nadir hematocrit associated with LOF (p<.02)
RBC TX also INDEPENDENTLY associated with LOF (p=0.047)!!
Surgenor, et al. Circulation 2006;114:43-48
Adverse outcomes of Blood transfusion after cardiac surgery
Vamvakas et al Transfusion 2000
Prolonged need for mechanical ventilation Habib et al Ann thorac surg 1996
Impaired wound healing Chmell et al J surg onc 1996
Multiple organ system failure Tran et al Nephro
Trans 1994
Prolonged length of stay in hospital
Vamvakas et al Trans 2000
Increased postoperative mortality Watering et
al Circ 1998
Transfusion in CABG is associated with Reduced long term Survival Blackstone et al Ann Thorac Surg 2006 Cleveland Clinic
10,289 patients from 1995 to 2002Blood transfusion rate of 49%, Platelets in 9 %,FFP in 2.5 % and Cryo in 0.5 %Risk adjusted: Increased early hazard at 6 months (p< 0.0001) and late hazard at 10 years ( p<0.0001)
Decreased survival is “dose dependant” i.e. no. of unitsUnadjusted risk: 5-year survival in non-transfused vs. transfused was 80 % and 63 %
Transfusion in coronary artery bypass grafting is associated with reduced long-term survival. Colleen Gorman Koch, Liang Li, Andra I Duncan, Tomislav Mihaljevic, Floyd D Loop, Norman J Starr, Eugene H Blackstone. Ann Throac Surg 2006;81(5):1650-7.
Landmark observational study – 10,289 isolated CABG patients
Outcomes: Blood Transfusion
Morbidity and mortality risk associated with red cell and blood-component transfusion in isolated coronary artery bypass grafting. Colleen Koch, Liang Li, Andra Duncan, Tomislav Mihaljevic, Delos Cosgrove, Floyd Loop, Norman Starr, Eugene Blackstone. Crit Care Med 2006;34(6):1-9.
First large-scale study (10,949 patients) to closely examine isolated CABG surgery related transfusions and outcomes
Each unit of packed red blood cells transfused was associated with an increased risk of:
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% H
igh
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Mortality Renal Intubation Infection Cardiac Neurological Overall
Associated risk of red blood cell transfusions
Outcomes: Blood Transfusion
Predictors of Postoperative Bleeding – The Big 6
1) Advanced age2) Small body size or preoperative anemia (low
RBC volume)3) Anti-platelet & anti-thrombotic drugs.4) Prolonged operation (CPB time) – high
correlation with OR type.5) Emergency operation6) Other co-morbidities (CHF, COPD, HTN, PVD,
renal failure, etc.)
Ferraris VA, et al. STS Guidelines. Ann Thorac Surg. 2005;79:1454-61.; Ferraris VA, et al. Ann Surg. 2002;235:820-7.
Does Aspirin Cause Increased Postoperative Bleeding
21 studies reviewed the effect of aspirin on postoperative bleeding.
5 of 6 randomized trials showed increased bleeding due to aspirin (Level A evidence).
Evidence less convincing in 15 observational studies (Level B or C evidence).
Ferraris VA, et al. STS Guidelines. Ann Thorac Surg. 2005;79:1454-61.
Postoperative Bleeding and Aspirin
Can estimate the amount of bleeding after operation due to aspirin
200-400cc of increased chest tube blood loss
0.5 to 1.0 unit of blood transfusion due to aspirin.
Lower doses of aspirin protect just as well and are associated with less bleeding.
Ferraris VA, et al. STS Guidelines. Ann Thorac Surg. 2005;79:1454-61.
STS Evidence-Based Workforce
Blood conservation writing group
Writer Organization
Victor A. Ferraris, M.D., Ph.D. (Chair, Blood Conservation Taskforce)
University of Kentucky
Suellen P. Ferraris, Ph.D. University of Kentucky
Sibu P. Saha, M.D., M.B.A. University of Kentucky
Constance K. Haan, M.D. University of Florida
B. David Royston, M.D. Harefield Hospital, UK
Charles R. Bridges, M.D., Sc.D. (Chair, Evidence-Based Workforce)
University of Pennsylvania
Robert S.D. Higgins, M.D. Rush Presbyterian, St. Luke’s Medical Center
George J. Despotis, M.D. Washington University
Blood Conservation Interventions – Class I Recommendations: “Is Recommended”
Identify high risk preoperatively.
High dose aprotinin; Low-dose aprotinin
Lysine Analogs
Cell saver
Blood transfusion algorithm w/ point-of-care testing.
Multimodality approach.
Ferraris VA, et al. STS Guidelines on blood conservation. Ann Thorac Surg, May 2007;83:S27-89
Blood Conservation - Class IIA Recommendations: “Is Reasonable”
Preoperative EpogenIntervention in Patients with thrombocytopeniaAutologous predonationOff pump BypassAlternatives to Blood samplingTotal Quality Management Discontinue plavix 5 to 7 days preopRBC Transfusion for Hemoglobin < 6: Higher trigger in elderly, CVA, cardiac dysfunction, ischemiaBlood component transfusion for clinical bleeding
Ferraris VA, et al. STS Guidelines on blood conservation. Ann Thorac Surg, May 2007;83:S27-89
Mangano & co-workers Conclusion
‘Association between aprotinin & serious end-organ damage indicates that continued use is not prudent. In contrast, the less expensive generic medications, EACA & TXA, are safe alternatives.’
Mangano, 2006, NEJM
‘…data mostly representing level A evidence suggests that high-dose aprotinin has an acceptable risk-benefit profile and is indicated for blood conservation (class I, level A) in patients at increased risk for bleeding.’
Aprotinin – Workforce on Evidence Based Surgery Response NEJM
Ferraris, Bridges and Anderson, 2006, NEJM
Evidence-Based Blood Conservation Strategies: Pennsylvania Hospital
Top 4Preoperative interventions
Epogen: Hgb =16 ideallyLimit anti-thrombotic & anti-platelet drug effect.
Limit blood loss during operationHigh-dose aprotinin or anti-fibrinolyticsMeticulous hemostasisSpeed of operationPerfusion strategies (minipump)
Salvage & sequester blood (not as helpful in high-risk)Cell saver, pump salvage, RAP, AAP, etc.Normovolemic Hemodilution (predonation)
Manage blood resources (process of care variables)Multimodality approach including postop epogen/ironTransfusion algorithm & point-of-care testing.
PAH Cardiac Surgery Blood Conservation Protocol
Pre Operative measures
Consult Bloodless Medicine Team for all patients
Outpatients seen by Bloodless Medicine on the same day of Cardiac visit
Erythropoetin administration:
40,000 U SQ weekly (caution in renal failure, cancer)
In selected cases, acute Coronary syndromes may be stabilized with stenting culprit vessel and elective CABG/Hybrid approach
Courtesy of Dr. Bridges
PAH Cardiac Surgery Blood Conservation protocol
Pre operative measures
Avoid daily labs in the Inpatients awaiting surgerySerum Ferritin levels in all patientsBloodless Medicine will decide the need for Ferrlecit 125 mg IV/day 3 timesAngio - Seal recommended for all patients who may need surgery in the next 48 hrs ( blood loss upto 1 to 2 gms Hb from cath site reported)Vitamin K 10 mg oral for selected patients pre operatively
Courtesy of Dr. Bridges
PAH Cardiac Surgery Blood Conservation protocol
Manage risk factors for transfusion
Coumadin – normalize INR preoperatively; convert to Lovenox as neededStop Lovenox 24-48 hrs prior to surgeryAspirin (low risk patients/Jehovah’s witnesses), Plavix to discontinue for 5 to 7 daysCelebrexGinka and other herbal supplementsGarlic, Vitamin E, Saw PalmetoNo Alcohol for at least 1 week Pre operative anemia – major risk factor for transfusion
Courtesy of Dr. Bridges
PAH Cardiac Surgery Blood Conservation Protocol
Intra operative measures
Trasylol ( Aprotinin) to be used in high risk patients ex: Plavix, combined procedures, aortic surgery, JW
Auto donation: ( Normovolemic hemodilution)
Red cell volume > 900 - 1 unit
Red cell volume > 1100- 2 units
Red cell volume > 1400- 3 units
“One sponge technique”
Blood returned to the patient after cardiopulmonary pass
Fibrillatory arrest for redo AVR patients with patent IMA
Courtesy of Dr. Bridges
PAH Cardiac Surgery Blood Conservation Protocol
Intra Op measures- Bypass circuit
Miniature Cardiopulmonary Bypass CircuitsCELL SAVER ONLY Leg elevation, chair position improves venous drainageAntegrade and Retrograde primingSmaller venous line 3/8 as opposed to ½ - less prime‘Follow through’–retrieve all blood from bypass circuitFull rewarming to 36 deg before weaning bypass
Courtesy of Dr. Bridges
1. Reduces systemic inflammatory
response syndrome and preserves
platelet function. Aprotinin enhances
this effect
2.Decreases Blood Loss
3.Avoids Reduced Graft Patency of
Off Pump Bypass
4.Applicable to all situations
Best Strategy: Optimize Cardiopulmonary Bypass Technology
Low Prime Circuits: Benefits
Reduced Priming VolumeReduced hemodilution
Decreased blood component usage
Reduced foreign surface areaLess contact activation (systemic inflammatory response)
Demonstrated safety and efficiency
Proven results regarding clinical factors that influence patient outcomes (nadir HCT/Frequency of blood transfusions)
Confirmed cost avoidance
Low impact to surgical technique
Procedure independent – can by utilized on all procedures requiring CPB
Summary – Low Prime Circuits
PAH Cardiac Surgery Blood conservation Protocol
Intra Op measures–Hemostatic agents
Thrombin, Gelfoam, Surgicel for sternum
Bio Glue and Fibrin glue ( ex Tissel) as needed
‘Point Of Care Testing’ to be evaluated
Courtesy of Dr. Bridges
PAH Blood Conservation Program
Post op measures – bleeding patients
Coagulation profile- Protamine as needed
Correct temperature
Replace volume with 5% Albumin
Positive Airway Pressure
Cryoprecipitate
Early re exploration
Courtesy of Dr. Bridges
PAH Cardiac Surgery Blood Conservation Protocol
Post op measures – Minimize labs
Avoid routine labs
Use peripheral lines
Small “pediatric” tubes
Stable patients – labs on alternate days
Courtesy of Dr. Bridges
Conclusions
A multimodality approach to blood conservation is essentialGuidelines are useful to help guide therapy and reduce variability in practice.Aprotinin is an important adjunct to a comprehensive cardiac surgery blood conservation program in high risk patients, Jehovah’s witnesses, and other “transfusion free” cardiac surgery patientsThe avoidance of blood transfusion in cardiac surgery patients decreases costs, morbidity and is likely to decrease mortality as well.