[Permanent endocardiac atrial pacing and sensing. Preliminary experience with screwing catheters]

25 patients affected by sick syndrome (SSS) and normal AV conduction (15), SSS with AV conduction defects (6) and complete AV block (3) were treated respectively by means of atrial pacing. AV sequential pacing and atrial triggered-ventricular pacing. In the cases for atrial pacing and sensing, the Medtronic mod. 6957 screwing lead has been utilized. The technique resulted very simple and safe. The average atrial threshold was 1.4 +/- .05 V. (1.95 +/- 0.75 mA). The average total impendance was 740 +/- 240 ohm and the average atrial potential 2.7 +/- 1.43 mV. Two cases of early displacement of the lead were observed (due to the operator poor familiarity with the new lead). Temporary sensing defect was observed in two patients and promptly abolished by steroid therapy. No exit block was observed. The patients have been followed for an average period of six months. All the leads are sensing and pacing correctly.