Epicardial corkscrew lead fracture: an underreported cause of pacing failure?

Long-term performance of bipolar epicardial atrial pacing using an active fixation bipolar endocardial lead

Bipolar epicardial leads are not yet widely available for atrial use. Since September 1986, we have used a bipolar active fixation endocardial lead (Cardiac Pacemakers model number's 4266, 4268, and 4269) as a bipolar epicardial atrial lead by attaching the corkscrew tip to the atrial surface and imbricating atrial tissue around the more proximal electrode. A total of 77 bipolar epicardial atrial leads have been implanted using this approach in 72 patients with congenital heart disease (ages 3 months to 38.7 years; mean 8.9 +/- 8.8 years). Indications for atrial pacing included AV block (n = 46), sinus node dysfunction (n = 17), and antitachycardial pacing (n = 9). Indications for epicardial pacing included the presence of an intracardiac right to left shunt (n = 33), concomitant cardiac surgery (n = 26), surgeon preference (n = 7), and lack of transvenous access to the atrial endocardium (n = 6). Follow-up (median 23 months; mean 28.0 +/- 23.1 months; range 1-78 months) data beyond 1 month postimplantation were available for 44 leads. Atrial sensing was > or = 2.0 mV for 26 leads (59%) with sensing possible at > or = 0.75 mV for 42 leads (95%). Threshold data were available at 5 V for 37 leads and at 2.5 V for 36 leads with mean pulse width thresholds measuring 0.21 +/- 0.33 ms and 0.34 +/- 0.34 ms, respectively. Two leads failed (high capture thresholds at 5 days [n = 1], lead fracture at 42 months [n = 1]; one of which was replaced. Four additional leads were replaced electively (marginal thresholds [n = 1], intermittent phrenic nerve stimulation [n = 1], damaged during subsequent surgery [n = 1], clinically irrelevant insulation break [n = 1]) concomitant with additional cardiac surgery. Until a commercially available lead is developed and released, improvisation with a bipolar active fixation endocardial lead as a bipolar epicardial atrial lead is a reasonable approach to providing bipolar atrial sensing and pacing in patients for whom endocardial pacing is contraindicated.

Is Epicardial Dual Chamber Pacing a Realistic Alternative to Endocardial DDD Pacing? Initial Results of a Prospective Study

Seventeen patients, in whom an epicardial (n = 7) or a transvenous DDDM pacemaker system had been implanted between June 1988 and October 1990, were followed up for pacemaker and lead related complications, pacemaker longevity, and electrophysiological lead parameters. The mean follow-up interval was 18 +/- 12 months, maximum 34 months. There were no differences in chronic atrial and ventricular sensing thresholds between epicardial and endocardial stimulation, nor were there any differences concerning lead related complications between the two pacing modalities. However, atrial as well as ventricular chronic stimulation thresholds were significantly higher with epicardial stimulation resulting in a twofold increase in atrial energy consumption and a threefold increase in the ventricular energy consumption. Thus, in one patient with an epicardial DDD system, the pacemaker had to be replaced prematurely because of battery depletion. It is concluded that epicardial DDD stimulation can be reliably performed as far as atrial and ventricular sensing is concerned, but that the energy requirements of available myocardial leads are not satisfactory for making optimal use of modern pacemaker capability.

Pacemakers in children: an update

This report reviews recent pacemaker technological advances as they apply to infants, children, and adolescents. Indications for pacemaker implantation in children have evolved since the 1984 Joint Task Force Guidelines. Recent data show that pacemaker implantation should be strongly considered in patients who have (1) asymptomatic congenital complete AV block with a mean heart rate less than 50 beats/min or other evidence of junctional instability; (2) congenital AV block with long QT interval; or (3) congenital long QT syndrome with bradyarrhythmias, or when conventional beta-blocker therapy is unsuccessful. Permanent pacemaker implantation is not necessarily an effective prophylactic measure against sudden death in patients following their operation who are receiving drug therapy for atrial tachyarrhythmias, and so is not absolutely indicated. New developments in lead technology have made transvenous lead systems more feasible for pediatric use. Because epicardial leads are required for small infants and for cosmetic reasons in some older children, design improvements are needed to enhance epicardial lead performance. Rate-responsive pacing is an acceptable alternative to dual-chamber pacing for augmenting exercise tolerance, and for children with sinus node dysfunction it is the preferred pacing mode. Pacemakers with automatic antitachycardia capabilities and with noninvasive electrophysiology features are valuable in children with atrial tachyarrhythmias. New data suggest that chronic atrial pacing also may be effective in controlling atrial tachyarrhythmias. New developments in pacemaker systems for the young parallel those for the older population, but differences between adult and pediatric patients demand ongoing increased participation by pediatric cardiologists.

Comparison of two myoepicardial pacemaker leads: follow-up in 80 children, adolescents, and young adults

Although several types of commercially available epicardial leads exist, few postimplantation data have been reported. To compare "screw-in" (6917-35) leads with "stab-on" leads (4951-35) from the same manufacturer, we reviewed the records of 80 young patients (age 8 days to 29 years) who underwent ventricular epicardial pacemaker implantation from 1973 to 1986. Follow-up for the 57 patients with the 6917-35 model ranged from 3 months to 17 years (median 6.5 years) and for the 23 patients with the 4951-35 model 9 days to 4.25 years (median 2.0 years). Actuarial life table analysis revealed significantly (P less than 0.001) fewer 4951-35 leads were functioning at each of 1-5 years after implant, compared to the 6917-35 leads. Analysis of available threshold pulse width data revealed no difference (P = 0.08) acutely (6 weeks after implant), but a significantly (P = 0.05) higher mean threshold for the 4951-35 leads was found chronically. No significant correlation was found for lead failure with age, underlying heart disease, lead site (i.e., left or right ventricle), or surgical approach. Using the sutureless, stab-on technique, the 4951-35 lead is associated with higher thresholds and lower survival rate when compared to the 6917-35 lead.

Cardiovascular computed tomography (cine CT) of abnormal left ventricular wall motion due to epicardial pacing electrodes

A patient with an abnormal cardiac silhouette on chest X-ray was studied by fast cardiovascular computed tomography (cine CT). The location of epicardial pacing electrodes and their relationship to myocardial wall motion abnormalities were examined. This eliminated the need for cardiac catheterization.

Morphological changes in human myocardium during permanent pacing

We have reviewed 74 cases of patients with permanent pacing, using different types of pacing leads in order to determine what morphological changes are produced by this therapy. Macroscopic examination of the heart was performed and slides at the implantation site reviewed when available. Severe chronic inflammation, scarring and a myocardial response were the prominent findings. From a strictly morphological aspect, the initial trauma at implantation time, the chronic foreign body reaction and myocardial response to chronic trauma, are both much less significant in endovenous than in epimyocardial pacing.