[Hypotension controlled with ATP in orthopedic surgery: incidence of atrio-ventricular conduction disorders].

: Adenosine triphosphate (ATP) has been effectively used for induced hypotension in man. Atrio-Ventricular (A-V) conduction disturbances have been observed after adenosine bolus injection and during continuous ATP i.v. infusion. The present perspective investigation was designed to determine the incidence of A-V conduction disturbances during ATP-induced hypotension. Thirty-five normotensive healthy patients (ASA I-II) with no preoperative therapy were subjected to the same anesthetic technique for orthopedic surgery. Premedication consisted of diazepam and atropine. Anesthesia was induced with thiopental and fentanyl followed by atracurium for intubation. The maintenance anesthesia consisted of isoflurane (1.5% inspired)-N2O (60%) in oxygen and incremental doses of fentanyl; the lungs were mechanically ventilated. Dipyridamole (0.15 mg kg-1) was given 15 min prior to ATP-infusion. ATP was administered by an infusion pump at a dosage of 0.025-0.05 mg kg-1 min-1. The ECG was recorded with a Mingograph 34 tape-recorder using 3 pregelled electrodes positioned to give an effective V6 lead pattern. MAP was reduced by 25% and HR increased by 6%. The mean duration of ATP-induced hypotension was 75 min +/- 50 and the mean dose of ATP infused was 200 mg +/- 161. Six patients (17%) showed A-V conduction disturbances. There was a I A-V Block (AVB) in 2 cases, a II AVB in 2 cases and a III AVB in 2 cases. In every case the arrhythmia disappeared spontaneously or after ATP-infusion suspension.(ABSTRACT TRUNCATED AT 250 WORDS)