[Pacemaker therapy in infants (author's transl)].

Since April 1974 until January 1978 permanent pacemakers were implanted in 21 children. The patient age at the time of operation averaged 4.5 years; the youngest patient was 3 months old. Indications for pacemaker implantation were: congenital total a-v block (TAVB) (n = 4), sick syndrom (S-S-S) (n = 4), postoperative TAVB (n = 13). Cardiac failure was present in all patients despite optimal medical treatment. Pacemakers were implanted under general anesthesia and intubation. The stimulation electrodes were positioned by the transvenous route in 16 subjects and by direct fixation upon the ventricle and the atrium in 5 patients. 5 children obtained an atrial triggered, 14 patients R-inhibited demand pacemaker and 2 subjects an asynchronous pacemaker. After a mean observation time of 16.4 months mean pacemaker function is normal in 14 patients. 6 children died 1 to 33 months after implantation despite functioning pacemakers because of congestive heart failure. Pacemaker malfunction was observed in 4 patients. The type of malfunction induced: failure of the impulse generator (n = 2), dislodgement of the electrode (n = 2), threshold increase (n = 1). In 5 children generators were changed 9 to 36 months (m = 23 plus or minus 10) after implantation because of battery depletion. The use of the pacemakers in small children is connected with several specific problems: 1. Application of large generators is hazardous because of impending perforation and secondary infection. 2. Until now miniaturization of pacemakers decreases function time and therefore implies frequent surgical intervention. 3. Stretching and dislodgement of transvenous electrodes may occur due to growth of the child. 4. Threshold increase may limit the life-span of myocardial electrodes. 5. Physiological changes in natural frequency requires changes in stimulation rate. 6. To guarantee normal physical activity demand related adaptation of heart rate is necessary. Because of these reasons a pacemaker system for children should have the following criteria: low weight, small wolume, high energy capacity, atrial or programmable stimulation, a thin elastic perhaps coiled electrode.