Hemodynamic effects of antiarrhythmic drugs: negative inotropy versus influence on peripheral circulation

The negative inotropic effect of nearly all antiarrhythmic drugs is one of the major drawbacks in antiarrhythmic therapy. This is particularly important in patients with reduced left ventricular function. In the clinical setting, different compounds have been described to depress cardiac function to a variable extent. The results are not uniform. In an experimental model, the hemodynamic effects of different drugs in the intact circulation as well as under isovolumic conditions in vivo after short cross-clamping of the aorta were tested. The results indicate that all antiarrhythmic compounds with the exception of class III drugs have a similar negative inotropic action on the heart muscle. However, the drugs have different effects on peripheral resistance, thus influencing cardiac afterload. These differences seem to be responsible for the different hemodynamic effects of the drugs observed clinically.