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Off pump coronary surgery: benefits and indications

An article from the e-journal of the ESC Council for Cardiology Practice

The development of off pump coronary surgery aims to decrease the incidence and/or severity of adverse outcomes due to extracorporeal circulation. Clinically, off pump surgery has shown improved outcomes in patients at risk for cardiopulmonary bypass and aortic cross-clamping.Cardiologists can suggest off-pump surgery when the patient profile fits yet the determining factors for on or off-pump coronary surgery ultimately lie with the surgeon, as they are obtained through preoperative work up and intraoperative findings.



“Off-pump” or "beating heart" coronary bypass surgery, also known as OPCAB (for "Off-Pump Coronary Artery Bypass), differs from conventional Coronary Artery Bypass Grafting (CABG) in that the cardiopulmonary bypass pump (extracorporeal circulation) is not employed.

1 - Benefits

Cardiopulmonary bypass and cardioplegia provide :

• a motionless field which facilitates manipulation of the heart,
• stabilises the anastomotic site guaranteeing the quality of the anastomosis, and
• providing myocardial protection during cross-clamping.

However, blood contact through the cardiopulmonary bypass circuit for prolonged periods induces a systemic inflammatory response and impaired hemostasis.

Biologically, on pump CABG has been shown to produce a more significant elevation of the following biochemical, cellular, and molecular inflammatory markers as compared to OPCAB:

• Complement, activated through the classical and alternate pathways [1,2]
• Tumor necrosis factor a, C-reactive protein, elastase [3]
• Interleukin-6, interleukin-8, interleukin-10 [3]
• Leukocytes [3]
• Urinary hypoxanthine, xanthine and malondialdehyde as markers of oxidative stress [4]
• Disturbances in hemostasis after on pump CABG have been demonstrated by lower platelet counts, lower plasminogen and higher 
•  D-dimer levels after surgery [5].
On-pump CABG is also associated with 
• Microembolisation of gas and particles from blood constituents and lipids as they are cycled through the cardiopulmonary bypass circuit [6].

The development of OPCAB was based on decreasing the incidence and/or severity of these adverse outcomes by eliminating extracorporeal circulation. Clinically, OPCAB has indeed shown improved outcomes with benefits including:

• Reduced inflammatory response
• Lesser renal dysfunction [7,8]
• Reduced incidence of stroke [9,10] and cognitive problems [11]
• Lesser coagulopathy and blood transfusion requirement
• Reduced morbidity and mortality [12,13]
• Reduced length of intensive care and hospital stay

2 - Indications

Having passed a significant learning curve (for the surgeon, anesthetist, and theatre staff), multiple bypasses by OPCAB covering all coronary territories are possible with current technology including stabilising devices and intracoronary shunts.

There are two essential techniques available in OPCAB depending on the number and location of the coronary vessels that need to be bypassed.

The MIDCAB approach is performed through a mini thoracotomy mainly for anteriorly located single or two-vessel disease.

The midline sternotomy approach as for conventional CABG.

In general, indications for OPCAB include:

• Coronary artery disease requiring surgical revascularisation
• High risk or contraindications for cardiopulmonary bypass and aortic cross-clamping:
• Severely atheromatous or heavily calcified aorta
• Aortic disease with risk of dissection, rupture or embolisation
• Poor quality target vessels including intramyocardial vessels, diffusely diseased vessels and calcified coronary vessels
• Hemodynamic instability
• Impaired left ventricular function
• Recent myocardial infarction
• History of transient ischemic attacks or cerebrovascular accidents
• Impaired renal function or need for dialysis in patients with chronic renal failure
• Patients who refuse blood transfusions 
• Elderly patients, patients with respiratory problems or other systemic disease considered high risk surgical patients because of their reduced functional capacity and the presence of co-morbidities.

Figure 1 provides a decision-making algorithm to choose between on-pump and off-pump approaches [14].

Figure 1. Decision-making algorithm (AV = atrioventricular; PDA = posterior descending artery; PLA = proximal left ascending artery; RCA = right coronary artery) Reprinted from Annals of Thoracic Surgery, 81,Brown JM, et al. Off-Pump Versus On-Pump Coronary Artery Bypass Grafting in Consecutive Patients: Decision-Making Algorithm and Outcomes: 555-561, Copyright (2006), with permission from the Society of Thoracic Surgeons.

 The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.

References


1. Kirklin J.K., Westaby S., Blackstone E.H., et al. Complement and the damaging effects of cardiopulmonary bypass. J Thorac Cardiovasc Surg 1983;86:845-857.

2. Edmunds L.H., Jr Inflammatory response to cardiopulmonary bypass. Ann Thorac Surg 1998;66(5 Suppl):S12-S16.

3. Schulze C., Conrad N., Schutz A., et al. Reduced expression of systemic proinflammatory cytokines after off-pump versus conventional coronary artery bypass grafting. Thorac Cardiovasc Surg 2000;48:364-369.

4. Gerritsen W.B.M., van Boven W.J.P., Driessen A.H.G., et al. Off-pump versus on-pump coronary artery bypass grafting: oxidative stress and renal function. Eur J Cardiothorac Surg 2001;20:923-929.

5. Casati V., Gerli C., Franco A., et al. Activation of coagulation and fibrinolysis during coronary surgery: on-pump versus off-pump techniques. Anesthesiology 2001;95:1103-1109.

6. Taggart DP, Westaby S. Neurological and cognitive disorders after coronary artery bypass grafting. Curr Opin Cardiol. 2001; 16: 271–276.

7. Ascione R, Lloyd CT, Underwood MJ, et al. On-pump versus off-pump coronary revascularization: evaluation of renal function. Ann Thorac Surg. 1999; 68: 493–498.

8. Arom KV, Flavin TF, Emery RW, et al. Safety and efficacy of off-pump coronary artery bypass grafting. Ann Thorac Surg. 2000; 69: 704–710.

9. Brown PP, Mack MJ, Simon AW, et al. Outcomes experience with off-pump coronary artery bypass surgery in women. Ann Thorac Surg. 2002; 74: 2113–2119.

10. Sharony R, Bizekis CS, Kanchuger M, et al. Off-pump coronary artery bypass grafting reduces mortality and stroke in patients with atheromatous aortas: a case control study. Circulation. 2003; 108 (suppl II): II-15–II-20.

VolumeNumber:

Vol5 N°25

Notes to editor


Prof. Nawwar Al-Attar, FRCS, PhD, FETCS
Hôpital Bichat, Paris, France
Web editor of the Working Group on Cardiovascular Surgery

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.