What is the technique for cardiopulmonary bypass in coronary artery bypass grafting (CABG)?

Updated: Dec 04, 2019
  • Author: Rohit Shahani, MD, MS, MCh; Chief Editor: Karlheinz Peter, MD, PhD  more...
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Answer

The first step in cardiopulmonary bypass is to cannulate the aorta and right atrium. The aortic area selected for cannulation must be soft and nonatherosclerotic. To insert the aortic cannula, unfractionated heparin is given, and the systolic blood pressure is lowered to below 100 mm Hg. At this point, two purse-string sutures are placed into the aorta, and the aortic adventitia within the diameter of the purse-string sutures is divided. An aortotomy is performed with a scalpel, the cannula is placed, and the purse-string sutures are tightened around it.

The aortic cannula is then secured to a rubber tourniquet with a heavy silk tie. Once in place, the cannula is de-aired and connected to the arterial pump tubing, where its position in the aorta can be confirmed by watching the pattern of tube filling. The venous cannula is inserted into the right atrial appendage in a similar fashion, with the end of the cannula positioned in the inferior vena cava. Adequate anticoagulation is confirmed by assessing the activated clotting time; once this is done, cardiopulmonary bypass can be commenced.

The aorta is cross-clamped distal to the cannula, and cold cardioplegia solution is infused via the aortic cannula (some centers also cool the patient). Retrograde cardioplegia may also be administered via the coronary sinus, especially in the patient who is undergoing repeat CABGs and has few or no patent grafts for adequate perfusion with antegrade cardioplegia. Compared with crystalloid cardioplegia, blood cardioplegia is associated with a lower incidence of intraoperative mortality, postoperative myocardial infarction, shock, and conduction defects.


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