Long term transvenous ventricular pacing in adults with congenital abnormalities of the heart and great arteries

Right ventricular electrode lead implantation via a persistent left superior vena cava. An improved technique

Persistent left superior vena cava occurs in approximately 0.5% of the population. This may complicate pacemaker implantation by making lead insertion difficult and causing lead instability through the left cephalic vein and the subclavian vein approach. We used a wide loop technique in the right atrium and successfully advanced the lead in the right ventricle apex. A persistent left superior vena cava does not preclude successful lead placement.

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.

Implantation of a dual chamber pacemaker in a patient with persistent left superior vena cava

A patient underwent dual chamber pacemaker implantation by puncture of the left subclavian vein. During the procedure we observed persistence of the left superior vena cava. An active fixation atrial lead was required to prevent instability induced by the odd course of the electrode and produced excellent long term pacing and sensing.

Endocardial pacing in infants and children 15 kg or less in weight: medium-term follow-up

Twenty-four children 15 kg or less in weight (range 2.8-15 kg) underwent implantation of a permanent pacemaker using the transvenous technique of lead placement. During a follow-up period of 2 months to 6 years 1 month (median 3 years 6 months) eight children suffered complications, six of which necessitated reoperation. These included: lead fracture in two, infection in two, transient myocardial dysfunction in one, generator migration in one, premature battery depletion in one, and threshold rise in one. A loop of redundant ventricular lead positioned in the atrium at the time of implant is successfully unravelling in all children. One child died during the follow-up period of a pneumonia unrelated to her pacemaker. The other children are growing and developing normally and the cosmetic appearance has proved acceptable in all cases.

Pacemaker system failure and other events in children with surgically induced heart block

Of 1,193 consecutive pediatric (less than 18 years) patients undergoing intracardiac repair from 1975 to 1984, 38 (3.2%) developed surgically induced complete heart block and were treated by permanent pacemaker implantation. Anomalies included complete atrioventricular septal defect = 9 (24%), simple ventricular septal defect = 9 (24%), atrioventricular discordant connection = 8 (212), tetralogy of Fallot = 7 (182), and other complex anomalies = 5 (13%). There were no hospital deaths. follow-up was 100% complete. There were six late deaths = 16%. Actuarial survival was 79 + 9% at 10 years. None of the late deaths were related to disturbance of cardiac rhythm or pacemaker system failure. Twelve patients (32%), required 27 reoperations for various types of pacemaker system failure. Indications for reoperation included: lead failure (44%). Pulse generator failure (44%), and wound sepsis (12%). Actuarial freedom from any pacemaker related reoperation was 50 + 16% at 48 months and 25 + 15% at 96 months. Only first reoperation was found to be an incremental risk factor for subsequent reoperation (p = 0.03). Surgical heart block has been neutralized as a risk factor for hospital death after repair of congenital cardiac defects. The risk of the development of surgical heart block now approaches zero, as indicated by a decreased incidence (1 of 401 = 0.25%) in our institution from 1985 to 1987, as compared to the era 1975 to 1984 (p = 0.001).