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1.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2614-2617, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018542

RESUMO

The main goal of this research is to evaluate the defibrillation efficacy with the high-frequency waveform on ventricular fibrillation in small animals. A biphasic defibrillator with adjustable frequency was designed for this study. This custom-designed defibrillator can be adjusted to generate four different frequencies of 125, 250, 500, and 1000 Hz. Six rat hearts were induced VT/VF by electrical induction using the waveform of these four frequencies. Success VT/VF-induction by applying those four frequencies were recorded and observed by optical mapping. The results showed that the VT/VF-induction success rate is increasing along with higher frequencies. The VT/VF-induction success rate is 16% in 125Hz and 250 Hz, 33% in 500 Hz, and 100% in 1000 Hz with S1-S2 protocol at 100 ms coupling interval. Also, using optical mapping technique, shock-induced optical potential showed that only high-frequency waveform exhibited the largest tissue responses in the middle position of the heart. In conclusion, high-frequency (1000Hz) defibrillation waveform has the highest defibrillation efficacy comparing to other lower frequencies used in this study.


Assuntos
Coração , Fibrilação Ventricular , Animais , Desfibriladores , Eletricidade , Masculino , Ratos , Registros , Fibrilação Ventricular/terapia
2.
PLoS One ; 15(5): e0232529, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32357163

RESUMO

Electrical defibrillation is a well-established treatment for cardiac dysrhythmias. Studies have suggested that shock-induced spatial sawtooth patterns and virtual electrodes are responsible for defibrillation efficacy. We hypothesize that high-frequency shocks enhance defibrillation efficacy by generating temporal sawtooth patterns and using rapid virtual electrodes synchronized with shock frequency. High-speed optical mapping was performed on isolated rat hearts at 2000 frames/s. Two defibrillation electrodes were placed on opposite sides of the ventricles. An S1-S2 pacing protocol was used to induce ventricular tachyarrhythmia (VTA). High-frequency shocks of equal energy but varying frequencies of 125-1000 Hz were used to evaluate VTA vulnerability and defibrillation success rate. The 1000-Hz shock had the highest VTA induction rate in the shorter S1-S2 intervals (50 and 100 ms) and the highest VTA defibrillation rate (70%) among all frequencies. Temporal sawtooth patterns and synchronous shock-induced virtual electrode responses could be observed with frequencies of up to 1000 Hz. The improved defibrillation outcome with high-frequency shocks suggests a lower energy requirement than that of low-frequency shocks for successful ventricular defibrillation.


Assuntos
Cardioversão Elétrica/métodos , Taquicardia Ventricular/terapia , Fibrilação Ventricular/terapia , Animais , Modelos Animais de Doenças , Eletrodos , Fenômenos Eletrofisiológicos , Feminino , Ventrículos do Coração/fisiopatologia , Técnicas In Vitro , Modelos Cardiovasculares , Ratos , Ratos Sprague-Dawley , Taquicardia Ventricular/fisiopatologia , Interface Usuário-Computador , Fibrilação Ventricular/fisiopatologia , Função Ventricular , Imagens com Corantes Sensíveis à Voltagem/instrumentação , Imagens com Corantes Sensíveis à Voltagem/métodos
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