Atrial lead implantation during atrial flutter or fibrillation?

Far-Field R-Wave Reduction with a Novel Lead Design: Experimental and Human Results

INTRODUCTION

The purpose of this study was to examine a bipolar screw-in lead (NL), specially designed to reduce unwanted far-field R-wave (FFRW) signal detection in an acute human setting. The results were compared with animal experiments.

METHODS

The newly designed lead with a center-to-center distance between the anode and cathode electrodes of 3.23 mm, corresponding to an inter-electrode spacing of 1.1 mm was implanted in nine canines with a follow-up of 6 months. Sensing of P waves, FFRW signals, pacing threshold, and impedance was measured at regular intervals. As a result of the positive outcome with the animal study, an acute human experiment was performed. In patients scheduled for conventional dual chamber pacemaker implantation, the NL was compared to a Tendril Model 1388T bipolar screw-in lead (St. Jude Medical, CRMD, Sylmar, CA).

RESULTS

Utilizing a tip-to-ring distance of 1.1 mm, the optimum P wave to FFRW ratio was found in animal experiments. In the acute human tests in 15 patients, the mean P-wave voltage of the 1388T lead of 3.30 +/- 1.54 mV was slightly larger than that of the NL, at 2.55 +/- 1.11 mV, but did not differ significantly (P = 0.13). The FFRW voltage of the 1388T lead was 0.62 +/- 0.37 mV and was significantly greater from that of the NL, at 0.10 +/- 0.08 mV (P < 0.0001). Pacing thresholds and pacing impedances were comparable.

CONCLUSION

Animal testing results were reproducible in the acute human test setting. The lead reduced the paced FFRW signal amplitudes significantly, allowing for high atrial sensitivity settings but without sensing the FFRW. A robust P-wave signal could be retained.

Atrial lead placement during atrial fibrillation. Is restitution of sinus rhythm required for proper lead function? Feasibility and 12-month functional analysis

Unexpected atrial fibrillation (AF) during implantation of an atrial pacemaker lead is sometimes encountered. Intraoperative cardioversion may lengthen and complicate the implantation process. This study prospectively investigates the performance of atrial leads implanted during AF (group A) and compares atrial sensing and pacing properties to an age- and sex-matched control group in which sinus rhythm had been restored before atrial lead placement (group B). Patient groups consisted of 32 patients each. All patients received DDDR pacemakers and bipolar, steroid-eluting, active fixation atrial leads. In patients with AF at the time of implantation (group A), a minimal intracardiac fibrillatory amplitude of at least 1.0 mV was required for acceptable atrial lead placement. In patients with restored sinus rhythm (group B), a voltage threshold < 1.5 V at 0.5 ms and a minimal atrial potential amplitude > 1.5 mV was required. Patients of group A in whom spontaneous conversion to sinus rhythm did not occur within 4 weeks after implantation underwent electrical cardioversion to sinus rhythm. Pacemaker interrogations were performed 3, 6, and 12 months after implantation. In group A, implantation time was significantly shorter as compared to group B (58.7 +/- 8.6 minutes vs 73.0 +/- 17.3 minutes, P < 0.001). Mean atrial potential amplitude during AF was correlated with the telemetered atrial potential during sinus rhythm (r = 0.49, P < 0.001), but not with the atrial stimulation threshold. Twelve months after implantation, sensing thresholds (1.74 +/- 0.52 mV vs 1.78 +/- 0.69 mV, P = 0.98) and stimulation thresholds (1.09 +/- 0.42 V vs 1.01 +/- 0.31 V, P = 0.66) did not differ between groups A and B. However, in three patients of group A, chronic atrial sensing threshold was < or = 1 mV requiring atrial sensitivities of at least 0.35 mV to achieve reliable atrial sensing. Atrial lead placement during AF is feasible and reduces implantation time. However, bipolar atrial leads and the option to program high atrial sensitivities are required.