Influence of right ventricular stimulation site on left ventricular function in atrial synchronous pacing

In 14 patients with 3rd degree AV block, one pacing lead was implanted in the right ventricular apex, the septal electrode was attached to that site exhibiting the smallest QRS complex. During atrial synchronous ventricular pacing, AV delay was optimized individually for each stimulation site. Phase distribution of left ventricular contraction and systolic function were randomly determined for each pacing site by radionuclide ventriculography. Decreased QRS duration was correlated with less dyssynergy of contraction and with an increase in systolic function. In atrial syncronous pacing, this can be obtained if the pacing site is optimized by surface ECG guidance and the AV delay is adapted individually.