The purpose of this study is to evaluate the directions, reliability and long-term results of ventricular programmable pacemakers (PPM's). One hundred and ten PPM's, types Cordis and Medtronic, were implanted in 60 patients (pts) with intermittent or paroxysmal 2 degrees, 3 degrees a-v block and in 50 pts with S.S.S., mostly symptomatics, with a follow-up of 45 months. We did not observe either spontaneous or wrong reprogrammations nor circuit failure. In 92% of pts with Omni-Stanicor Cordis PM's, the stimulation was effective at the "lower" current amplitude, hence a longer life of the generator. Eighteen pts (16.3%) needed to raise ventricular rate (average 65 bpm): 6 pts for dizziness, syncopes or cardiac failure; 2 pts to control ventricular arrhythmias; 10 pts for a stable bradycardia lower than 50 bpm. In 11 pts with bradyarrhythmia due to S.S.S., cardiac output (CO) was measured both with thermodilution and echocardiography ("mitral valve echogram", being "r" of the two methods = 0.92), in spontaneous rhythm (63.3 +/- 3.13 bpm) and increasing artificially heart rate to 74.8 +/- 3.0 bpm; CO decreased from 4.65 +/- 0.13 l/min to 3.58 +/- 0.09 l/min, likely for the loss of atrial pumping. Similar results were obtained in other pts evaluated only with echocardiographic method after PM implantation: some of these underwent a further echocardiographic haemodynamic evaluation after 15 days of constant ventricular pacing at a mean rate of 75 bpm, with a different behaviour among them. This emphasizes the utility of PPM's in preserving spontaneous rhythm until bradycardia reaches dangerous levels and also the usefulness of echocardiography to evaluate, haemodinamically, the paced patient's ventricular performance.