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:

0

10

20

30

40

50

60

70

80

90

100

% H

igh

er R

isk

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.