In 15 patients, aged 55.6 +/- 3.7 years with normal LV-function, the comparison of hemodynamic results as induced by ventricular pacing (VP) (at 110, 140 and 170 bpm) versus atrio-ventricular pacing (AVP) (AV-sequences: 30, 130 and 230 msec) revealed the following: VP with increasing rates inversely proportionally compromised AO-pressure by an average of -7, - 19 and -28% respectively, and cardiac output (CO) by an average of -2, -12 and -26% respectively. However, AVP with an AV-sequence of 130 msec, at the same 3 basic rates, clearly proved hemodynamically superior in comparison, in that AO-pressure dropped significantly (by an average of -13%) only at 170 bpm, an CO even showed tendencies to increase at 110 and 140 bpm (by an average of +17 and +7% respectively), finally decreasing by a mere -11% at 170 bpm only. Pacing, when using AV-sequences of 30 and 230 msec, resulted in an impairment of AO-pressure and CO of the same range as during VP at equal rates. Thus, beneficial hemodynamic results, AVP versus VP, have been proven also for rapid-rate pacing in normal ventricles, provided the AV-sequence is optimal (130 msec for the present patient group) but not in any incoordinate range of AV-sequences (as for instance 30 and 230 msec), with which beneficial atrial transport function cannot be achieved.