[Efficacy of prophylactic nifedipine therapy during aortocoronary vein bypass interventions. Drug concentration with oral or intravenous nifedipine administration; hemodynamics and plasma catecholamines].

To assess the usefulness of prophylactic nifedipine in coronary artery surgery, in this study nifedipine plasma concentrations were determined in patients, who had been given 10 mg nifedipine orally before operation. Furthermore, plasma and tissue concentrations of nifedipine were measured in patients receiving a nifedipine infusion. In this group of patients the efficacy of nifedipine, based on changes in hemodynamics and plasma catecholamines was also investigated. Patients with normal global left ventricular function (LVEDP less than 15 mm Hg, EF greater than 0.5) undergoing coronary artery bypass grafting (CABG) operations were included in this study. The preoperative antianginal therapy was continued until the time of surgery, the last beta-adrenoceptor blocker was given on the day of surgery. A standardized premedication and anesthesia (fentanyl-flunitrazepan infusion) was given to all patients. Hemodynamic parameters were obtained using indwelling arterial, venous and pulmonary artery thermodilution catheters. The high-pressure-liquid-chromatography (HPLC) method was used to measure plasma catecholamines as well as plasma and tissue nifedipine concentrations. Eight patients received 10 mg nifedipine orally one hour prior to anesthetic induction. Plasma nifedipine concentration (Figure 1) showed a wide interindividual scattering at anesthetic induction (25 +/- 38 ng/ml) in this group and they decreased to low, noneffective levels during surgical stimulation (12 +/- 12 ng/ml) and aortic cannulation (8 +/- 8 ng/ml). 24 patients with a nifedipine infusion of 0.30 micron/kg/min prior to extracorporeal circulation (start: following intubation, termination: at aortic cannulation) were compared to a control group of 24 patients with respect to hemodynamics, plasma catecholamines, anesthetic requirements and need for additional vasodilator and vasopressor therapy.(ABSTRACT TRUNCATED AT 250 WORDS)