SINGLE-LEAD VDD PACING - MULTICENTER STUDY

Optimal treatment for patients with AV block and normal sinoatrial nod e (SA) function entails atrial sensing and ventricular pacing (VDD mod e). Single-lead VDD pacing preserves AV synchrony, precludes the need to insert two leads, and makes the implanter's work simpler and quicke r. Our objectives were to verify the performance of the Thera(TM) VDD pacing system (Medtronic, Inc., Minneapolis, MN, USA), and evaluate th e effectiveness of its atrial sensing and ifs ventricular sensing and pacing. In 165 patients, 150 adults (mean age 62 +/- 18 years) and 15 children (mean age 7 +/- 5 years) with 1 degrees - 3 degrees AV block and normal SA node function, a Thera VDD system (Models 8948 or 8968) was implanted. Intraoperative ventricular electrical measurements were not significantly different fi om those of VVI pacemakers. The mean a mplitude of the atrial signal during implantation was 4.1 +/- 1.9 mV. Optimal atrial signals during implantation were usually obtained in th e mid or lower part of the right atrium by using a special technique. Adequate atrial measurements remained stable throughout 24 months. The re was no difference between serial measurements of atrial signal ampl itudes at predischarge and during follow-up visits. Reposition of the lead was done in 2 patients (1.4%), and reprogramming to VVI in 7 pati ents: due to atrial fibrillation in 3 (1.8%) and due to atrial underse nsing in 4 patients (2.4%). Thera VDD pacing is reliable and eas to ma nage with dependable atrial sensing and ventricular pacing. The surviv al rate of VDD pacing at 2 years was 96%.