TY - JOUR
T1 - Multiple spatially distributed stimulators and timing programs for entrainment of activation during ventricular fibrillation
AU - Gu, Yiping
AU - Patwardhan, Abhijit
PY - 2002
Y1 - 2002
N2 - Activation sequences during ventricular fibrillation (VF) display complex pattern and fast rate. Recent evidence suggests that even during VF an excitable gap may exist. Existence of excitable gap lead us to hypothesize that it should be possible to entrain activation patterns during VF by using spatially distributed and temporally phased pacing strength stimuli. We describe here the electronics hardware and software that were developed to test our hypothesis. Eight biphasic stimulators were designed and fabricated, each addressable via a TTL input and thus independently triggered. To minimize electrical interference from stimulus pulses the stimulators were optically isolated. A program written in C was used to deliver TTL inputs to time the sequence of stimulation. The parameters that could be varied were, pulse intensity, polarity, and duration, inter pulse interval and activation pattern cycle length. Restitution's of action potential duration, conduction velocity, and complex activation patterns make the timing of stimulators complex. To aid in optimal timing of these stimulators, we used a Luo-Rudy ionic model of cellular activation to simulate VF in a matrix of 400 × 400 cells. Entrainment of activation was verified using animated displays of activation sequences. Using results of simulation we verified the function of our stimulators experimentally using electrically induced VF in canines and by using electrograms recorded from 121-electrode patch. Our results show that the developed hardware and software can be used to deliver distributed stimuli in a flexible and effective pattern, which may aid in development of approaches for treatment of VF.
AB - Activation sequences during ventricular fibrillation (VF) display complex pattern and fast rate. Recent evidence suggests that even during VF an excitable gap may exist. Existence of excitable gap lead us to hypothesize that it should be possible to entrain activation patterns during VF by using spatially distributed and temporally phased pacing strength stimuli. We describe here the electronics hardware and software that were developed to test our hypothesis. Eight biphasic stimulators were designed and fabricated, each addressable via a TTL input and thus independently triggered. To minimize electrical interference from stimulus pulses the stimulators were optically isolated. A program written in C was used to deliver TTL inputs to time the sequence of stimulation. The parameters that could be varied were, pulse intensity, polarity, and duration, inter pulse interval and activation pattern cycle length. Restitution's of action potential duration, conduction velocity, and complex activation patterns make the timing of stimulators complex. To aid in optimal timing of these stimulators, we used a Luo-Rudy ionic model of cellular activation to simulate VF in a matrix of 400 × 400 cells. Entrainment of activation was verified using animated displays of activation sequences. Using results of simulation we verified the function of our stimulators experimentally using electrically induced VF in canines and by using electrograms recorded from 121-electrode patch. Our results show that the developed hardware and software can be used to deliver distributed stimuli in a flexible and effective pattern, which may aid in development of approaches for treatment of VF.
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M3 - Article
C2 - 12085620
AN - SCOPUS:0036041658
SN - 0067-8856
VL - 38
SP - 295
EP - 299
JO - Biomedical Sciences Instrumentation
JF - Biomedical Sciences Instrumentation
ER -