Cardiac pacing in premature infants and neonates: steroid eluting leads and automatic output adaptation

Temporary epicardial pacing in an extremely low-birth-weight infant with congenital atrioventricular block

Congenital atrioventricular block is a rare, but severe occurrence in the newborn can be related to various cardiac malformations or to maternal autoimmune diseases, particularly systemic lupus erythematosus. We report an extremely low-birth-weight infant affected by congenital heart block, due to positive anti-RO/SSA and anti-LA/SSB antibodies of the mother, with progressively increasing respiratory distress syndrome and heart failure. The infant was successfully treated with an external constant-current, single-chamber ventricular (VVI) temporary epicardial pacing, placed on the second day of life, at the weight of 810 g. After this treatment, cardiac failure resolved and respiratory assistance could be rapidly stopped. A single-chamber, rate-responsive, permanent pacemaker was placed at 3 months of life with steroid-eluting, epicardial-pacing leads. We emphasize that early extrathoracic temporary epicardial pacing is able to resolve heart failure in an extremely low-birth-weight infant.

Ventricular pacing threshold variations in the young

Ventricular Capture Management (VCM) is a Medtronic Kappa pacemakers (PM) feature that automatically measures pacing threshold through detection of the evoked response after a pacing stimulus. The aim of this study was to evaluate the range of variation of ventricular pacing threshold in pediatric patients with endocardial and epicardial pacing leads. Thirty-one patients (median age 6.5 years) were implanted with a Kappa 901 PM for atrioventricular block or sinus node dysfunction. Congenital heart defects (CHD) were present in 58% of patients. Ventricular leads were epicardial in 52% of patients. VCM was programmed to automatically measure threshold every 2 hours. In a median follow-up of 12 months, 27,110 threshold measurements, 72% of which were successful, have been taken in 94% of patients. Measurement success was 99% in the endocardial leads group (age at implantation 12 +/- 6 years) and 31% in epicardial leads (age 4 +/- 5 years) (P < 0.05). Main reasons for unsuccessful measurements were high heart rate and, in a patient with an endocardial lead, competition with intrinsic rhythm. Undersensing or oversensing of the evoked responses was not detected. In all successful VCM measurements, epicardial pacing and CHD contributed to stability of thresholds (multivariate analysis). Pacing threshold showed specific circadian patterns: higher thresholds were found between 00.00 and 06.00 a.m., but the variation was low, 0.03 +/- 0.01 V. In conclusion, children and young patients show stable ventricular thresholds, especially in presence of CHD, and epicardial leads are at least as stable as endocardial leads. Ventricular pacing threshold showed a circadian variability similar to that described in adults, that does not seem to influence VCM functioning and PM programming.

Approach to congenital heart disease in the neonate

Congenital heart disease in the newborn is a unique and complex problem faced by both pediatricians and cardiologists as it requires skillful handling and balancing of both neonatal issues as well as cardiac physiology. Babies with cyanotic and acyanotic heart disease are physiologically different from each other and management has to be tailored to the individual diagnosis and clinical status. Rapid diagnosis and appropriate management is the key to reducing mortality and morbidity in this fragile patient population. The following review deals with the common presentations of heart problems in a newborn baby and methods of diagnosis, investigative modalities, recent advances and approach to management.

Permanent epicardial pacing in pediatric patients: seventeen years of experience and 1200 outpatient visits

BACKGROUND

The purpose of this study was to evaluate the long-term outcome of all pediatric epicardial pacing leads.

METHODS AND RESULTS

All epicardial leads and 1239 outpatient visits between January 1, 1983, and June 30, 2000, were retrospectively reviewed. Pacing and sensing thresholds were reviewed at implant, at 1 month, and at subsequent 6-month intervals. Lead failure was defined as the need for replacement or abandonment due to pacing or sensing problems, lead fracture, or phrenic/muscle stimulation. A total of 123 patients underwent 207 epicardial lead (60 atrial/147 ventricular, 40% steroid) implantations (median age at implant was 4.1 years [range 1 day to 21 years]). Congenital heart disease was present in 103 (84%) of the patients. Epicardial leads were followed for 29 months (range 1 to 207 months). The 1-, 2-, and 5-year lead survival was 96%, 90%, and 74%, respectively. Compared with conventional epicardial leads, both atrial and ventricular steroid leads had better stimulation thresholds 1 month after implantation; however, only ventricular steroid leads had improved chronic pacing thresholds (at 2 years: for steroid leads, 1.9 muJ [from 0.26 to 16 mu]; for nonsteroid leads, 4.7 muJ [from 0.6 to 25 muJ]; P<0.01). Ventricular sensing was significantly better in steroid leads 1 month after lead implantation (at 2 years: for steroid leads, 8 mV [from 4 to 31 mV]; for nonsteroid leads, 4 mV [from 0.7 to 10 mV]; P<0.01). Neither congenital heart disease, lead implantation with a concomitant cardiac operation, age or weight at implantation, nor the chamber paced was predictive of lead failure.

CONCLUSIONS

Steroid epicardial leads demonstrated relatively stable acute and chronic pacing and sensing thresholds. In this evaluation of >200 epicardial leads, lead survival was good, with steroid-eluting leads demonstrating results similar to those found with historical conventional endocardial leads.

Applications of pacing strategies in neonates and infants

Pacing in neonates and infants continues to be challenging due to size constraints, growth potential, and the need for life long pacing. Indications for permanent pacing in pediatric patients have been difficult to determine due to the lack of data from controlled studies and multicenter trials. Temporary pacing has been useful to restore cardiac output in pediatric patients quickly and efficiently. Methods of temporary pacing include transcutaneous, transesophageal, transvenous, and epicardial. Permanent pacemaker implantation can be accomplished by transvenous or epicardial approaches, but the use of transvenous pacing in neonates and infants offers no advantages over epicardial pacing. Transvenous pacing in infants is often prohibitive due to size and growth constraints as well as the subsequent risk of skin erosion and venous thrombosis. Smaller pulse generators, multiprogrammable features, and steroid-eluting epicardial leads are a few of the technological advances that have made pacing in neonates and infants easier and safer. Data supporting the use of pacing systems in very young patients are sparse. Pacing 'indications' should be viewed as guidelines until such data can be accumulated.