Coronary artery bypass grafting (off pump and via cardiopulmonary bypass)

Coronary artery bypass grafting may be indicated when a coronary angiogram shows >50% stenosis in the presence of any of the following:

• severe angina which is unresponsive to medical therapy
• marked S-T depression of exercise ECG
• left main stem stenosis
• severe triple vessel disease
• angina with left ventricle dysfunction

Procedure:

• heart is cooled and stopped
• blood is pumped and oxygenated extracorporeally - although off pump coronary artery surgery is increasingly being performed in the UK (see note 2).
• at one end the graft is attached to the coronary artery, distal to the stenosis
• in the case of a saphenous vein bypass the other end is attached to the aorta
• where possible the internal mammary artery should be used as this offers longer term patency
• after grafting, antithrombotic drugs are used to prevent reocclusion
• there is no significant difference between the type of drug administered, but aspirin may be the best choice since it is associated with fewer adverse reactions
  
  

Note 1: NICE have stated that if it is clinically considered appropriate to undertake either coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI), the availability of stents should push the balance of clinical decision-making towards PCI (1).

Note 2: Increasingly that off-pump coronary artery bypass surgery is being performed in the UK. In this procedure CABG is performed on a beating heart. The rationale behind this procedure is that some of the morbidity of CABG procedures relates to the use of cardiopulmonary bypass (CPB). NICE state (3) that "Current evidence on the safety and efficacy of off-pump coronary artery bypass grafting (CABG) is adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance, consent and audit.."

Reference:

1. NICE (May 2000). Coronary artery stents in the treatment of IHD.
2. Treasure T, Anderson J (1993). Coronary Artery Surgery. Medicine International, 21(10), 397-400
3. NICE (January 2011). Off-pump coronary artery bypass grafting