Algorithm Research On Detecting Heart Refractory Period Applied To Nano-knife And It's Embedded System Implementation

As a new type of tumor ablation technology for non-thermal energy,Nano-knife plays an increasingly good role in the treatment of liver cancer,pancreatic cancer and other malignant tumors.However,studies have shown that the high-pressure pulse released by Nano-knife treatment can greatly interfere with the generation and conduction of ECG signals,increasing the probability of intraoperative complications such as arrhythmia.For this reason,heart synchronizers are needed for real-time heart detecting,which are matched with the instrument,to ensure the Nano-knife treatment pulse will be released during the effective refractory period of the heart.Therefore,it is important to identify the effective refractory period of the heart accurately,and make timely guide for Nano-knife to releasing high-pressure pulses in terms of reducing the risk of intraoperative complications.In this paper,the problem of detecting the effective refractory period of the heart was converted into the R wave real-time detection.The MIT-BIH arrhythmia database and QT database are used as sample libraries to study this problem.The main research results are as follows:1)The preprocessing of ECG signal and related parameters were designed.The theoretical delay of the filtering preprocessing was controlled within 15ms on the premise that the detection effect was not affected.Meanwhile,a step concerning low threshold zeroing processing was added in preprocessing to further highlight the R wave characteristics and simplify the calculation.2)Combining Pan&Tompkins algorithm and slope method,an improved real-time detection algorithm of R wave was proposed.The interference of QS,Qr,rS,rSr' and other special ECG waveforms was excluded on refractory positioning during the detection process.Through moving window average method and dynamic threshold method,each heartbeat cycle was divided into effective signal segment and suspected noise segment,which reduces the misjudgment rate.The positive prediction degree of this algorithm is 99.88% and the average delay is 13.02ms,which has achieved the expected effect.3)In order to verify the effectiveness of the algorithm mentioned under actual conditions,a set of ECG signal acquisition and analysis system has been developed,and more stringent refractory detection restrictions have been put forward according to the actual situation of Nano-knife surgery.Finally,the function of the device was tested,which proves that the device can accurately identify the effective refractory period of the heart in real time.