ABSTRACT
Single lead atrial synchronous ventricular pacing [VDD] is used increasingly in place of conventional dual chamber pacing [DDD] for patients with atrioventricular [AV] block and preserved sinus node function. Compared to the latter, VDD pacemakers provide similar haemodynamic benefits derived from atrial synchronous pacing, with the added benefit of an easier implant procedure. To review the use, safety and efficacy of long-term VDD compared to DDD pacing in our locality. A study of all patients with atrioventricular block and normal sinus node function implanted with DDD and VDD pacemakers over a 10-year period [26 DDD, 15 VDD] at the cardiology department of Assiut University Hospital was performed. Data on complications, atrial sensing performance and maintenance of atrioventricular synchrony during implant and at subsequent follow-up visits were obtained from a prospectively maintained registry and analysed. The pacing period was 5.3 +/- 2.6 in DDD vs 2.9 +/- 1.8 years in VDD group [P=0.02]. The implant time was significantly reduced in VDD compared to DDD patients [60 +/- 26 vs 84 +/- 20 min., P< 0.05]. The implant P wave was significantly higher in DDD than VDD pacing [3.92 +/- 1.53 vs 2.71 +/- 1.30 mV, P<0.01], but was comparable at pre-discharge and last follow-up visit [1.93 +/- 1.0 vs 1.47 +/- 0.65, 1.75 +/- 1.0 vs 1.18 +/- 0.82 mV], P>0.05 for both. The total complication rate was comparable in DDD and VDD groups [24% vs 26% P>0.05]. The total AF rate was 12% in DDD patients vs 13.3% in VDD patients, P>0.05. However, it was persistent in12% of DDD vs 6.6% of VDD patients, P<0.01. Atrial under-sensing occurred in 4% of DDD vs 13.3% of VDD patients, P>0.01. At the last follow-up visit, 88% DDD vs 86.6%VDD patients were maintained on the original mode. Maintenance of AV synchrony was also comparable in the 2 groups [88% in DDD vs 80% in VDD, P>0.05]. VDD pacing systems can provide excellent long-term performance in AV block patients with normal sinus node function. They are as safe and effective in maintaining a physiological A V synchronous pacing mode as DDD systems with decreased implantation time and decreased rate of persistant AF