Cardiac electrophysiologic effects of articaine compared with bupivacaine and lidocaine.

Articaine is a local anesthetic structurally different from lidocaine and bupivacaine in that it contains a thiophene ring. We compared its cardiodepressant effects with those of lidocaine and bupivacaine in a randomized, blinded study using the isolated rabbit heart preparation. The hearts were removed quickly from thiamylal anesthetized/killed animals. The right septal wall was placed in a warm, aerated, Tyrode's solution-perfused chamber. The effects of the three local anesthetics on action potentials from the Purkinje fiber (PF) and ventricular muscle (VM) tissues were determined. Bupivacaine (17.4 microM) and articaine (141 microM) depressed action potential overshoot, amplitude, and maximal rate of depolarization (Vmax) by similar amounts. Bupivacaine's effects persisted significantly longer than articaine and lidocaine (P < 0.05). Rate-dependent decreases in steady-state (SS) Vmax were obtained with all three drugs. At their highest concentrations, bupivacaine (17 microM) and lidocaine (85 microM) produced decreases in SS Vmax from the first Vmax response. However, articaine (141 microM) increased SS Vmax at 1 and 2 Hz and only decreased SS Vmax at 3 Hz. During superfusion of a "bolus concentration" of the local anesthetics, bupivacaine blocked PF-VM conduction significantly longer than either articaine or lidocaine (P < 0.001). Articaine, at ten times its observed clinical blood concentration was significantly less cardiodepressant in these in vitro experiments than bupivacaine at five times its observed clinical blood concentration.