Optimization of atrio-ventricular delay in patients with dual-chamber pacemaker.

Development and advances in heart pacing over the last nearly half a century allowed to save numerous lives by providing pacing support in bradycardia and complete heart block. Nevertheless, long-term follow up of patients with implanted pacemaker showed unfavorable remodeling of the heart, both from hemodynamic as well as electrical standpoint. The optimal programmed pacemaker setting, apart from the optimal place for ventricular stimulation, is essential to obtain the best hemodynamic and the clinical after-effects of the stimulation of the heart and to minimize potential unfavorable effects. In patients with dual-chamber pacemaker (DDD) the correct function of the left ventricle of the heart depends mainly on the electric delays between the stimulated chambers. Atrio-ventricular delay (AVD) during dual-chamber pacing influences left ventricle contraction function through preload modulation. Improperly programmed AVD in the DDD pacemaker can have unfavorable hemodynamic results. Various methods have been developed during last few decades (right heart catheterization, ventriculography, peak endocardial acceleration, echocardiography, and impedance cardiography), however only echocardiography and reocardiography are currently in general use. There should be noticed too, that also the application of special algorithms present in modern pacemakers allowing for dynamic changes of the time of the delay represents certain alternative to individual AVD optimization.