Simulation Results and Analysis of Electric Field Distribution in Myocardial Tissue under Circular Electrode Electric Pulse Ablation / 中国医疗器械杂志

As a new energy source for atrial fibrillation ablation, electric pulse ablation has higher tissue selectivity and biosafety, so it has a great application prospect. At present, there is very limited research on multi-electrode simulated ablation of histological electrical pulse. In this study, a circular multi-electrode ablation model of pulmonary vein will be built on COMSOL5.5 platform for simulation research. The results show that when the voltage amplitude reaches about 900 V, it can make some positions achieve transmural ablation, and the depth of continuous ablation area formed can reach 3 mm when the voltage amplitude reaches 1 200 V. When the distance between catheter electrode and myocardial tissue is increased to 2 mm, a voltage of at least 2 000 V is required to make the depth of continuous ablation area reach 3 mm. Through the simulation of electric pulse ablation with ring electrode, the research results of this project can provide reference for the voltage selection in the clinical application of electric pulse ablation.

Design and implement of a multi-channel electrophysiological stimulation software / 国际生物医学工程杂志

Objective To design and implement a universal multi-channel software for neural electrophysiological stimulation experimental platforms. Method The layered design of software and hardware was adopted for the logical architecture to avoid excessive reliance on specific hardware. On the premise of ensuring compatibility with existing devices, an extensible control algorithm based on the .NET Frameworks platform was developed to realize multi-channel, feedback-controlled program-controlled stimulus output. The proposed software was designed with a user-friendly interface and stimulating/recording switch function, and could dynamically change stimulation programs and switch electrodes during the experiment process. Results The results showed that the software could control the stimulators steadily and generate random stimulation protocols and synchronization control signals according to the user-supplied dynamical parameters, including electrodes, amplitudes, and intervals. In the stimulation sequence, the switching delay between two electrodes was around 600 ms level. Conclusion The software has good compatibility with existing equipment systems. It can achieve multi-channel, real-time, feedback-controlled program-controlled stimulation according to the characteristics and needs of multi-lead neural electrophysiological stimulation researches. It has the functions of dynamically changing the stimulation program and switching electrodes during operation. This software provides tools for the study of the mechanism of network-level neural network feedback loops.

Effect of Stimulus Waveform of Biphasic Current Pulse on Retinal Ganglion Cell Responses in Retinal Degeneration (rd1) mice

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an 8x8 multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than 10 microA and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to 500 micros (30 microA), changing the intensities (or duration) from 2 to 60 microA (60 to 1000 micros). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.

Responses of Cultured Neuronal Network to Electric Pulses Stimuli with Different Intervals / 航天医学与医学工程

Objective To analyze the activities of cultured neuronal network in response to electric pulses stimuli with different intervals. Method Pairs of electric pulses with different intervals were added to rat hippocampal neurons cultured on multi-electrode arrays (MEA) substrate. Result The second response duration of the network increased with the decrease of the interval between two pulses. It was typical that the second duration after pulses with 10 ms interval increased greatly and it could be divided into two stages, i.e. quick response (within 10 ms) and slow response (near or beyond 100 ms). However, following pulses with 100 ms interval,there is practically no relation between the two responses; the second response duration was shorter and the number of spikes was fewer and their amplitudes were lower, which is similar to the result of single electric pulse stimulus. Conclusion The activity of cultured neuronal network was different in response to different electric stimulation patterns. Compared with spontaneous firing, the activity of the network is potentiated or depressed respectively after different stimulations.