Research And Experimental Device Of Low Energy Defibrillation Method

Sudden Cardiac Death (SCD) is the leading cause of cardiovascular disease death. Ventricular Fibrillation (VF) is considered as the most malignant arrhythmia notorious as the causative rhythm disturbance of asystole and subsequent SCD. VF is an extremely turbulent, disorganized electrical activity of the heart, and if this mortal rhythm is not remedied promptly, death usually ensues in a short time. The only reliable therapy for VF is the electrical defibrillation. Despite of its effective life-saving capability, conventional defibrillation requires strong shocks with high energy responsible for several serious adverse effects and great pains the patients are exposed to and this dilemma impels scholars and researchers to lower the energy requirement of defibrillation. However, apart from adopting Direct Current (DC) in substitution for Alternative Current (AC) as the means of energy delivery and replacing the monophasic waveform with biphasic waveform as the defibrillation waveform, other endeavors of energy optimization have not yielded satisfying reduction and far from painless defibrillation.There are currently four low-energy defibrillation strategies available:1.Utilizing defibrillation-effective waveform;2.Minimizing the impedance of shock pathway;3.Improving the homogeneity of defibrillation electrical field;4.Pacing-defibrillation, among which the last one is considered as the most promising method. Nevertheless, existed pacing-defibrillation studies were energy-economic instead of defibrillation-efficient. Aiming at solving the flaws of current pacing-defibrillation research, a low-energy defibrillation scheme is proposed by synthesizing of all four low-energy defibrillation strategies. It delivers a train of overdrive pacing biphasic impulses superior over the monophasic ones to the heart through multi-electrode array deployed evenly on the heart surface, generates homogenous electrical filed and gradually terminates the VF, resulting low-energy defibrillation.To verify the said proposal, studies in silico were done as the preliminary in order to avoid performing redundant animal experiments. A cardiac electrical filed emulator was created based on the ANSYS software using the finite element method (FEM). After reliability and fidelity of the heart model were confirmed by comparison between numeric results and clinical data, simulations of defibrillation via electrode array placed on the ventricular epicardium were performed and suggested that: electrical impulse discharges through evenly distributed electrodes on the heart surface could bring along better defibrillation outcomes than the conventional implantable cardioverter defibrillator did; in addition, subsequently delivered dual defibrillation shocks produced more ideal defibrillation results than the single shock did. A suggested animal experiment protocol was provided taking advantage of the computational optimal electrode configurations.The depolarization threshold of electric quantity was studied by both theoretical analysis and patch clamp experiments. Results indicated that as long as the cell received adequate charge, it inevitablely entered the refractory phase, thus it is reasonable to defibrillate using several impulses instead of one.The machine for proposal verification was designed and built, which is compose of two subsystems:stimulation delivery system and biphasic impulse generator. It provides the functions required by the animal experiments:1. Multiple independent outputs up to64channels;2. Arbitrary output combinations;3. Availability of multiple impulses;4. Biphasic waveform;5. Manipulable impulse width;6. Manipulable cycle length of stimuli.Concise review of cardiac mapping technology is stated before introducing the actuality of mapping/stimulation system and its significance. Integration of developed128-channel mapping system and electrophysiological stimulator was realized in the manner that ensures no overlapping between mapping and stimulations, which forms the suitable platform for low-energy defibrillation trialsIn conclusion, a low-energy defibrillation scheme utilizing whole ventricular epicardial electrode array is proposed and verified by FEM simulations and patch clamp experiments. To meet the needs of animal experiments, a program-controlled multichannel electrophysiological stimulator is designed, built and integrated with existed mapping system. This paves the way for relevant animal experiments.