Active fixation of endocardial pacing leads: the preferred method of pediatric pacing

Effectiveness of Excimer Laser-Assisted Pacing and ICD Lead Extraction in Children and Young Adults

BACKGROUND

High capture thresholds, decreased electrical sensing, and lead fractures continue to be a problem in children undergoing transvenous pacing. The clinician must therefore decide at the time of pacing system revision to either abandon chronically implanted transvenous pacing leads or extract them.

METHODS

We report our experience using an excimer laser-assisted (LA) strategy for removing chronically implanted pacing (36) and implantable cardioverter/defibrillator (ICD) (7) leads in children and young adults. The study population consisted of 25 patients, in whom 29 procedures were performed. The patients ranged in age from 8.4 to 39.9 years, median age was 13.9 years, at the time of the extraction procedure. In all procedures, a Spectranectics locking stylet and excimer laser sheath were used to assist in lead extraction.

RESULTS

Lead removal was complete for 39 (91%) leads, and partial for four leads. In two patients, the pacing lead tip was retained and in two, the ring electrode from a bipolar pacing lead was left in situ. All ICD leads were removed completely. Two major complications occurred--cardiac perforation and tamponade (1), and thrombosis of the left subclavian/innominate vein (1). LA extraction facilitated the implantation of new pacing or ICD leads in three patients with obstructed venous access.

CONCLUSIONS

Removal of pacing and ICD leads using an excimer LA technique was highly successful. Lead removal was complete in 91%. The most common indication for lead removal in our study was lead fracture. Complications were few, but may be significant.

Comparison of mid-term clinical experience with steroid-eluting active and passive fixation ventricular electrodes in children

Although active fixation ventricular leads seem to have advantages over passive fixation leads, this study compares the follow-up results of active and passive fixation leads in children. We evaluated the implantation and follow-up data of 41 children with active (Accufix II DEC, group 1) (n = 20) or passive (Membrane E, group 2) (n = 21) fixation, steroid-eluting ventricular leads. All but one of the patients in group 1 completed the 12-month follow-up. The mean follow-up period in group 2 was 10.4 +/- 2.9 months (range 3-12 months, median 12 months). In both groups the mean pacing threshold was measured as 0.51 +/- 0.09 V versus 0.48 +/- 0.15 V (P > 0.05) at 0.5-ms pulse width, mean R wave amplitude as 9.9 +/- 2.5 mV versus 9.4 +/- 3.2 mV (P > 0.05), and mean impedance as 557 +/- 92 omega versus 664 +/- 160 omega (P < 0.05), respectively, at implantation. After the first week of pacing, mean threshold values in group 1 were significantly lower than those of group 2 (P < 0.01 and P < 0.05, respectively). During the follow-up period, lead impedance measurements did not show a significant difference between the two groups. In one patient from group 1, the lead (by unscrewing) was removed easily because of pacemaker pocket infection. No lead dislodgement or helix deformation occurred in group 1. Nevertheless, in one patient from group 2, the lead was extracted at 4-month postimplantation because of lead displacement. We conclude that the steroid-eluting active fixation lead (Accufix II DEC) have advantages of easier implantation and lower acute and chronic stimulation thresholds compared to the passive fixation lead (Membrane E). Therefore, Accufix II DEC is superior to Membrane E, and it is a better first choice in children with an implanted single chamber ventricular pacemaker.

Long-term superiority of steroid elution in atrial active fixation platinum leads

Steroid elution reduces the acute increase in stimulation threshold particularly in active fixation leads. The aim of this study was to investigate the long-term efficacy of steroid elution in atrial screw-in leads compared to conventional lead design. Two different bipolar active fixation platinum lead designs were implanted. Leads were similar except for the presence (group S, n = 66) or absence (group N, n = 68) of steroid elution. Patients received dual chamber pacemakers with the following atrial leads in consecutive order: Medtronic 4058 M (group N, n = 30), Medtronic 4068 (group S, n = 40), Vitatron IMS 13 (identical to 4058 M, group N, n = 38), and Vitatron IMX 13 (identical to 4068, group S, n = 26). The mean follow-up period was 40.7 +/- 16.1 months (range 10 to 84 months). Stimulation thresholds, pacing impedances, P wave potentials, and sensing threshold were assessed for both groups immediately, 10 days, 6 weeks, and 3 months after implantation followed by 6-months intervals. Energy thresholds, chronaxie-rheobase products, and energy consumption of atrial pacing were calculated. Chronic values were deduced from the most recent measurement performed in an individual patient. Within the first 10 days after implantation, atrial voltage threshold at pulse duration of 0.4 ms increased from 0.91 +/- 0.42 to 2.06 +/- 0.45 V in group N (P < 0.001). Less increase was observed in group S (0.83 +/- 0.39 to 1.08 +/- 0.53 V, P = 0.003). Atrial voltage thresholds remained markedly lower in steroid-eluting leads during whole follow-up (1.12 +/- 0.49 V in group S vs 1.58 +/- 0.71 V in group N, P < 0.001). Chronic energy consumption was markedly reduced in group S (4.0 +/- 2.7 microJ) compared to group N (9.8 +/- 7.5 microJ, P < 0.001). An atrial voltage threshold below 1.25 V at 0.4 ms was achieved in 92.3% of patients of group S allowing programming of an output of 2.5 V. Such low outputs were feasible in only 49.3% of patients in group N (P < 0.001). Chronic P wave amplitudes did not differ significantly between groups (3.27 +/- 1.81 mV in group N vs 3.24 +/- 1.18 mV in group S, P = 0.91). Steroid elution diminishes the increase of stimulation thresholds of nonsteroid atrial active fixation platinum leads resulting in a long-term reduction of energy consumption. Thus, use of steroids can be recommended for general use in atrial active fixation lead designs.

Long-term clinical experience with a steroid-eluting active fixation ventricular electrode in children

In this study, the first study performed in pediatric patients, we assessed the safety and efficacy of a steroid-eluting active fixation ventricular electrode in 18 children. Our study shows that steroid-eluting active fixation leads are safe and effective in children, and suggests that these leads with their easy implantation and low chronic threshold values may be considered as the first choice in this age group.

Lead extraction in young patients with and without congenital heart disease using the subclavian approach

Pacemaker lead removal using interlocking stylets and dilator sheaths has greatly reduced the need for major surgical intervention when lead extraction is required. Previous reports have shown the utility of this method in older patients, most of whom have anatomically normal hearts. The purpose of this study is to report the results of this technique in young patients with and without congenital heart disease. There were 13 patients (M:F = 7:6) aged 9-26 years (median 13). Congenital heart disease was present in 8 of 13 patients. A total of 17 leads required removal; they had been implanted for 54 +/- 24 months (range 19-94). Leads were removed from the left subclavian vein (13) or right subclavian vein (4) only. Seventeen of 18 leads were completely removed and one partially retained in the left subclavian vein. New leads were implanted from the same vein in 11 of 13 patients. Interlocking stylets and metal or flexible dilator sheaths were used in all cases except two. There was one surgical complication: a late wound dehiscence, which was easily managed. No patient required a transfusion, and there was no structural damage noted in any patient on the postoperative echocardiogram. We conclude that lead removal using interlocking stylets and dilator sheaths from the subclavian approach is an effective technique that can be used in young patients, including those with congenital heart disease.

Steroid elution improves the stimulation threshold in an active-fixation atrial permanent pacing lead. A randomized, controlled study. Model 4068 Investigators

BACKGROUND

Prior work suggests that the addition of a steroid-eluting reservoir to a passive-fixation permanent pacemaker lead improves the stimulation threshold; however, no large randomized study has addressed this tissue. Over the last several years, there has been an increase in enthusiasm for the use of active-fixation permanent pacemaker leads for various reasons in spite of the generally accepted notion that active-fixation leads have higher stimulation thresholds.

METHODS AND RESULTS

This multicenter, randomized, controlled study examined the difference in performance between a standard active-fixation atrial lead (Medtronic model 4058) and a steroid-eluting lead (Medtronic model 4068). Stimulation thresholds were obtained in a four-point strength-duration fashion. Evaluations of sensing and impedance were performed as well. These evaluations were performed at implantation, at weeks 1 through 4, and at weeks 6, 12, 24, and 52. Stimulation thresholds were significantly better in the steroid lead than in the nonsteroid lead at each measurement point from 1 week to 12 months. The mean 1.6-V stimulation threshold at 12 months was 0.19 +/- 0.2 ms in the steroid lead and 0.41 +/- 0.30 ms in the control lead. No acute peaking was observed with the steroid lead, whereas significant peaking was observed with the control lead. There was no difference in long-term sensing or impedance.

CONCLUSIONS

Inclusion of a steroid-eluting reservoir in an active-fixation permanent pacing lead improved stimulation thresholds in both the subacute and chronic periods and therefore should extend pulse-generator longevity.

A new steroid-eluting screw-in electrode

A new lead design was tested that combined a small microporous steroid-eluting electrode with an insulated, exposed helix for active fixation. This lead (model 5078, Medtronic, Inc., group I, n = 10) was compared to a conventional model (model Y 60 BP, Biotronik) with a larger surface of polished platinum-iridium, equipped with a fixed, noninsulated screw but without steroid elution (group II, n = 10). The two lead models were studied in the atrial position of dual chamber pacing systems, which all had a tined ventricular lead (model 5024, Medtronic, Inc.), with essentially the same steroid-eluting tip as the new active fixation lead design. Sensing and pacing data were recorded acutely and during 1 year of follow-up, via the telemetry of a Relay pulse generator (Intermedics, Inc.). Intraoperatively, unfiltered atrial electrogram amplitudes did not differ between groups (group I: 7.12 +/- 2.56 mV vs group II: 6.42 +/- 1.87 mV; P > 0.05), nor did sensing thresholds 1 year after implantation (group I: 5.33 +/- 1.70 mV vs group II: 4.26 +/- 1.40 mV; P > 0.05). Atrial pacing thresholds as measured during surgery at a pulse width of 0.5 msec were lower in group I (0.49 +/- 0.15 V) than in group II (0.68 +/- 0.19 V; P < 0.05). From day 5 through day 360 of follow-up, the difference in atrial pacing thresholds was highly significant (P < 0.01), with a smaller peaking of early thresholds and a much lower scattering of data for the steroid screw-in leads than for controls.(ABSTRACT TRUNCATED AT 250 WORDS)