ATRIAL LEAD IMPLANTATION DURING ATRIAL-FLUTTER OR FIBRILLATION

In patients with sinoatrial disease, unexpected atrial flutter (Af) or fibrillation (AF) is a common problem during implantation of atrial-b ased pacing systems. As an alternative approach to blind atrial lead p lacement, lead positioning could be optimized by atrial electrogram ma pping. It was the object of this study to evaluate if atrial lead impl antation according to this approach and during ongoing arrhythmia is r easonable or if it should be postponed until restoration of sinus rhyt hm ISR). Twenty-nine consecutive patients (group II with sick sinus sy ndrome received a dual-chamber pacemaker during an episode of Af (n = 11) or AF (n = 18). All but two atrial leads were of the screw-in type and had bipolar sensing. Atrial lead position was optimized by mappin g the electrogram under fluoroscopy to find locations with high potent ial amplitudes. The patients were followed for 15.1 +/- 9.8 months, an d atrial sensing threshold (AST), atrial pulse width threshold (PWT) a t 2.0 V, the pacing mode programmed, and the clinical outcome (OUT) we re recorded. The control group consisted of 30 patients (group II) who equally had a history of AF or Af, but were in SR during implantation . The atrial peak-to-peak potential (APEAK) after final lead placement was lower for AF (median value 2.5 mV, lower-upper quartile: 12.7-3.2 mV) as compared to Af (3.8 mV, 2.7-4.9 mV, P < 0.05) and SR (4.1 mV, 3.3-6.2 mV, P < 0.001). There was a correlation (P < 0.01) between APE AK during Af/AF and the postoperative AST immediately after restoratio n of SR. No lead in any group had to be corrected due to improper sens ing in the postoperative course. Median chronic AST was 2.8 mV (2.0-4. 0 mV)in group I and 4.0 mV (2.8-4.0 mV)in group II. Median chronic PWT at 2.0 V was 0.15 ms (0.12-0.26 ms) in group I and 0.15 ms (0.09-0.20 ms) in group II. There was no significant difference in chronic AST a nd PWT between both groups. All but two patients in group I preserved SR as the basic rhythm. A stable SR was observed in 10 of 29 patients, intermittent Af/AF was documented in 17 of 29 patients, seven of whom were asymptomatic. There was no significant difference in OUT between group I and II. Hence, sinus rhythm is not a prerequisite of atrial l ead implantation. Mapping the Af or AF waves appears to be useful to g uide lead placement and to achieve sufficient sensing and pacing condi tions after conversion to sinus rhythm.