Simulation Analysis And Experimental Study Of Ablation Catheter Positioning Signal In Cardiac And Respiratory Interference

Objective:Research an ablation catheter positioning signal processing method, to eliminate cardiac and respiratory motion interference and obtain the catheter location information.Method:First, we researched the ablation catheter positioning signals in cardiac and respiratory motion interference according to the positioning principle, then we presented the catheter positioning signal’s mathematical model and its signal processing method. We used a research technique route of software simulation analysis combined with hardware experiments. We adopted Matlab(?) simulated the catheter positioning and its signal processing, and then designed the corresponding hardware circuit. In the hardware design, we chose the modular design concept, and divided into three steps—EDA simulation, bread board experiment, welding circuit board test. In order to test the stability and reliability of the hardware circuits, we implemented the in vitro thoracic cavity electric field simulation experiment. To obtain the closest to the human body’s thoracic cavity environment, we implemented two animal experiments, Through the animal experiments could verify whether the proposed positioning signal’s mathematical model and the signal processing solution is correct.Results:1. The catheter positioning signal can be seen as an amplitude modulation (AM) signal, the carrier signal is electric drive signal, and the modulating signal is cardiac and respiratory motion, the mid-value of the positioning signal’s envelope is the catheter location information which relative to the surface electrode, this is the mathematical model.2. Proposed a new method to obtain the location information of the catheter, that is let the positioning signal through a band pass filtcr(BPF), change the three directions superimposed signal into one direction signal, then extract the envelope and its mid-value of the signal after BPF.3. In software simulation and analysis, we adopted three methods to extract the envelope, they were Hilbcrt transform, square demodulation, and the extremal curve fitting. Two methods of extract mid-value were adopted, they were low pass filter (LPF) and Matlab’s own "median" function.4. On the hardware side, band-pass module using3-order DABP structure; envelope demodulation module using the analog multiplier to complete; the median extraction module using3-Order MFB structure. The hardware circuits achieved the desired results after the EDA simulations, bread board experiments, welding circuit board tests.5. The in vitro thoracic cavity electric field simulation experiment showed that the proposed positioning signal’s mathematical model and the signal processing solution is correct, and the hardware circuits were stability and reliability. Through the animal experiments, we verified that in vivo the catheter positioning signal is consistent with the proposed catheter positioning signal’s mathematical model and the signal processing solution is feasible.Conclusions:After the software simulation and analysis, hardware experiments, simulate in vitro thoracic cavity electric field experiment, we trusted that the proposed catheter positioning signal’s mathematical model and the signal processing solution is correct, the signal processing solution could eliminate the cardiac and respiratory motion interference and obtain the catheter’s correct location information.