The effects of lidocaine on the electrical and mechanical activity of the heart

Abstract The effects of lidocaine on the contractile force of the heart, impulse transmission and pacemaker rate have been investigated in the experimental animal. In the dog, lidocaine has a negative inotropic effect on the isovolumic left ventricle even in the presence of paired stimulation. This effect is dose-related and minimal when the dose is less than 2 mg./kg. Lidocaine has a negative chronotropic effect on automatic pacemakers of the ventricles and, to a lesser extent, of the atria. However, under conditions of increased vagal activity, a vagolytic effect capable of increasing the rate of the S-A node was demonstrated. Large doses of lidocaine prolong A-V conduction, the site of action probably being the region of the A-V node. The effect on interatrial and intraventricular conduction is minimal with doses in the therapeutic range for man.