Nifedipine and cardiopulmonary bypass

The management of the period after hypothermic cardiopulmonary bypass has been compared in a group of patients maintained on nifedipine therapy, a group who had the drug withdrawn at least 24 hours prior to cardiac surgery, and a control group who had never received calcium antagonists. Patients in the drug withdrawal group were significantly more likely to need vasodilator intervention than the treated (p less than 0.001) or the control (p less than 0.05) groups. Although nifedipine withdrawal appeared to reduce the need for inotropic support, compared to treated (p less than 0.001) and control groups (p less than 0.005), this may be at the cost of increasing systemic vascular resistance. This observation, coupled with reports of a rebound phenomenon following abrupt withdrawal of calcium antagonist therapy, suggests that nifedipine should be continued up to the time of surgery.