T. Davies et al., DO PERMANENT PACEMAKERS NEED AN INSULATIVE COATING - RESULTS OF A PROSPECTIVE RANDOMIZED DOUBLE-BLIND-STUDY, PACE, 20(10), 1997, pp. 2394-2397
During conventional manufacturing of implanted pulse generators (IPGs)
, an insulative coating is often applied to prevent local muscle stimu
lation and myopotential sensing in unipolar pacing. This can limit the
orientation of the IPG into ifs pocket, be a potential source of musc
le stimulation via coating scratches, and result in an increase in IPG
production costs. We hypothesized that advances in the design and con
struction of current IPGs and leads obviates the need for an insulativ
e coating of the IPG. Using a double-blind prospective randomized desi
gn, 39 patients were implanted with either coated or uncoated otherwis
e identical IPGs (19 dual, 20 single chamber). All testing wets done i
n unipolar and bipolar mode in both channels. A strength-duration curv
e for muscle stimulation was constructed for all patients with muscle
stimulation. Myopotential sensing was established during isometric exe
rcise. At 6-month follow-up when tested in unipolar mode, 3 of 15 (20%
) patients with coated IPGs and 3 of 20 (15%) with uncoated IPGs had m
uscle stimulation at 5.0 V/1.5 ms or lower (P = NS). No patients in ei
ther population had muscle stimulation at their normally programmed ou
tput. Myopotential sensing occurred in all patients in unipolar mode a
t a mean of 2.29 +/- 1.3 mV and 2.73 +/- 1.14 mV for coated versus unc
oated, respectively (P = NS). The statistical power of these negative
observations wets 80%. An insulative coating for pacemakers does not a
ppear to alter sensing performance or cause a significant difference i
n the occurrence or characteristics of muscle stimulation.