List the theoretical advantages and disadvantages of coronary bypass grafting with and without cardiopulmonary bypass
Coronary artery bypass grafting off bypass is now widely performed. There are numerous techniques for getting access to the grafts and heart (eg. limited thoracotomy, video assisted).
(a) Theoretical advantages include:
• Avoidance of the effects of extracorporeal circulation including .. coagulation/kalikrein activation, microembolus of air and platelet clumps to cerebral circulation
• Avoidance of aortic cannulation with attendant risks of arterial embolisation of air or atheroma
• Avoidance of atrial cannulation with attendant risk of atrial injury respectively
• Avoidance of the effects of cardioplegia including K load. fluid load, coronary air embolus
• Avoidance of risks of aortic cross clamping including atheroembolism. myocardial ischaemia
• Decreased costs (less equipment, less staff)
(b) Theoretical disadvantages include:
• Potential for myocardial ischaemia without the protection of cold cardioplegia during grafting.
• Unfavorable operating conditions with a beating heart increasing the risk of anastamotic bleeding, suboptimal revascularisation and myocardial ischaemia
[Information on graft patency, morbidity, mortality and quality of life from proper trials is not yet available]
Current status and future directions of minimally invasive cardiac surgery. Current Opinion in Cardiology 1999,14(5); 419·
Minimally invasive coronary bypass: a dissenting opinion. Circulation 98(6);495-7
There is little to add to the college answer. It is rare for references to be included with it, and I will link to these papers below. The second one is available for free as full text, from Circulation.
I will quote from it:
"... just because something can be done by some surgeons does not mean that it should be done by all surgeons. "
A comparison of conventional and off-bypass CABG appears as a brief summary in the Required reading section. Additionally, LITFL have this article ("Cardiothoracic Surgery Literature Summaries") where two of the more influential on-vs-off-pump trials are thoroughly dissected. Put simply, the advantages and disadvantages are as follows:
Advantages of off-pump CABG:
Disadvantages of off-pump CABG:
These are the references used by the college in their answer:
Goldstein, Daniel J., and Mehmet C. Oz. "Current status and future directions of minimally invasive cardiac surgery." Current opinion in cardiology 14.5 (1999): 419.
Bonchek, Lawrence I., and Daniel J. Ullyot. "Minimally Invasive Coronary Bypass A Dissenting Opinion." Circulation 98.6 (1998): 495-497.
These are the subsequent studies which answer this question:
Khan, Natasha E., et al. "A randomized comparison of off-pump and on-pump multivessel coronary-artery bypass surgery." New England Journal of Medicine350.1 (2004): 21-28.
Afilalo, Jonathan, et al. "Off-pump vs. on-pump coronary artery bypass surgery: an updated meta-analysis and meta-regression of randomized trials." European heart journal 33.10 (2012): 1257-1267.
Zhang, Busheng, et al. "Comparison of Graft Patency Between Off-Pump and On-Pump Coronary Artery Bypass Grafting: An Updated Meta-Analysis." The Annals of thoracic surgery 97.4 (2014): 1335-1341.