The implantation of VDD pacemakers with a single electrode--a comparative study. The experience of the last 5 years]

OBJECTIVE: To compare the epidemiological characteristics and immediate results of all first single lead VDD pacemaker (PM) implantations with those of an equal number of dual chamber DDD PM, implanted during a 5-year period in a tertiary-care hospital. POPULATION AND METHODS: A total of 41 patients (pts) (25 males, mean age of 69.0 +/- 11.8 years) underwent a VDD PM implantation, from 30-11-92 to 15-9-97. This group was compared with an equal number of patients (28 males, mean age of 69.9 +/- 7.31 years) with a DDD PM implanted in the same period, selected by a criterion of immediate temporal proximity of procedure. For each patient we collected the clinical and electrocardiographic (ECG) indications for PM implantation, parameters of atrial (AS) and ventricular (VS) sensing and ventricular pacing (VP), X-ray exposure time (XRT) and complications. RESULTS: In the VDD group, 46.3% of the patients had syncope, 51.2% had complete AV block on the ECG, and 14.6% were PM-dependent. Analyzed procedure-related parameters were as follows: P-wave amplitude: 2.1 +/- 0.6 V; AS threshold: 1.2 +/- 0.7 V; R-wave amplitude: 9.1 +/- 3.3 V; VS threshold: 7.0 +/- 2.0 V; VP thresholds: 0.68 +/- 0.24 mA, 0.43 +/- 0.12 V (for a spike duration of 0.5 ms); ventricular impedance: 644.9 +/- 132.0 ohm; XRT; 7' 43" +/- 8' 23". There were two minor complications, for an incidence of 4.9% (one local hematoma and a vagal reaction). In the DDD group the clinical and ECG characteristics were similar, but there was a 22.0% prevalence of sinus-node dysfunction, VS 0% in the VDD group). The P-wave amplitude and AS threshold were significantly (p < 0.005) better (2.8 +/- 0.9 V and 2.8 +/- 0.9 V respectively). The other parameters were similar to those of the VDD group. CONCLUSIONS: The immediate results of VDD PM implantation are good and comparable with those of DDD PM, although with worse acute AS parameters.