Introduction

Coronary artery bypass grafting (CABG) is the commonest cardiac operation performed. Its purpose is to relieve angina and help prevent myocardial infarction by bypassing narrowed or occluded coronary arteries. This is done by suturing a pedicled arterial graft (such as a left internal mammary artery [LIMA]) or a free graft (such as a segment of saphenous vein or a radial artery) to the affected coronary artery downstream from the lesion. A pedicled LIMA brings its blood supply with it from the subclavian artery. A free graft needs to be joined to a nearby source of oxygenated arterial blood, usually the ascending aorta.

Most CABG is done on cardiopulmonary bypass with cardioplegic cardiac arrest, but it is possible to achieve good results without cardiopulmonary bypass on the beating heart. This chapter deals with specific problems that may be encountered after CABG.

Myocardial ischaemia

The heart should not be is chaemic after CABG. If the electrocardiograph shows is chaemic changes, this may indicate:

• myocardial damage owing to

◦ poor protection during surgery or

◦ compromise of a coronary artery;

• incomplete revascularization, leaving a segment of myocardium still ischaemic;

• a technical graft problem (such as thrombosis, occlusion or kink); or

• spasm of a coronary artery.