Cd. Gottlieb et al., EFFECTS OF HIGH AND LOW SHOCK ENERGIES ON SINUS ELECTROGRAMS RECORDEDVIA INTEGRATED AND TRUE BIPOLAR NONTHORACOTOMY LEAD SYSTEMS, Journal of cardiovascular electrophysiology, 7(3), 1996, pp. 189-196
Introduction: The purpose of this investigation was to prospectively e
valuate the voltage- and time-dependent characteristics of a biphasic
defibrillator discharge on the amplitude of the rate sensing electrogr
am recorded from two ''integrated'' and one true bipolar nonthoracotom
y lead system. Prolongation of redetection time has been noted after a
failed first shock with nonthoracotomy lead systems. However, a prosp
ective evaluation of the time- and voltage-dependent effects of biphas
ic shocks on electrogram amplitude with clinically utilized lead syste
ms has not been systematically performed. Methods and Results: Five- t
hen 30-J R wave synchronous biphasic discharges were delivered during
the supraventricular rhythm through three nonthoracotomy lead systems
(Medtronic Transvene, Ventritex TVL, and CPI Endotak C 60 Series). The
R wave amplitude was measured immediately postshock and for up to 1 m
inute. Amplitude changes were compared with preshock baseline value. A
5-J discharge had minimal effect on the R wave amplitude recorded fro
m the three lead systems; however, 30 J resulted in significant diminu
tion in R wave amplitude recorded from the integrated bipolar leads (i
n the Endotak lead to a greater extent than the TVL lead) with minimal
effects on the Transvene lead. Following a 30-J discharge, the time c
onstant for R wave recovery was 4.2, 14.9, and 153 seconds for Transve
ne, TVL, and Endotak 60 leads, respectively. Conclusion: There are vol
tage- and time-dependent reductions in postshock R wave amplitude. Int
egrated bipolar systems appear more affected than the ''true'' bipolar
lead evaluated. This may be due, in part, to lead design, distance of
distal defibrillating surface from rate sensing cathode, and the inco
rporation of the defibrillating surface as the rate sensing anode. The
influence of postshock R wave diminution on subsequent redetection re
mains speculative but may have implications for subsequent lead develo
pment.