Banca de QUALIFICAÇÃO: JIMENA GABRIELA SILES PAREDES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : JIMENA GABRIELA SILES PAREDES
DATA : 03/02/2020
HORA: 14:30
LOCAL: sala S24, Térreo, Bloco Delta, Campus SBC da Fundação Universidade Federal do ABC, localizada na Alameda da Universidade, s/n, Bairro Anchieta - São Bernardo do Campo, SP.
TÍTULO:

The influence of cardiac ablation on the electrophysiological characterization of rat isolated atrium

PÁGINAS: 80
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Biomédica
SUBÁREA: Bioengenharia
ESPECIALIDADE: Processamento de Sinais Biológicos
RESUMO:

The study and characterization of electrophysiological parameters calculated from atrial electrograms allow the understanding of myocardial characteristics and their propagation of electrical activity. In this project, the electrical activity of the isolated atrium of rats was studied through electrical and optical mapping performed respectively in the epicardium and endocardium after epicardial ablation in different duration strategies (0.5 s, 1 s, 1.5 s , 2 s, 3 s and 4 s). Methods: After ablation of the atrial bell node, the atrium was electrically stimulated by a rectangular pulse with a repetition rate between 5 Hz and 5.5 Hz. The electrical activity of the epicardium was acquired by 8 electrodes spaced equidistantly in a circular catheter with 0.2 mm in diameter (100 KHz). Simultaneously, endocardial electrical activity was acquired by optical mapping with a CCD camera (868 Hz, 82x82 pixels, 16μm × 16μm pixel size). Experimental procedures were performed by the collaborators of this project at the Institute of Biomedical Engineering of the Karlsruhe Institute of Technology. For each protocol, 4-second electrograms were analysed offline using the Matlab software (MathWorks, R2019a). Pre-processing: Unipolar epicardial signals were resampled to 5 kHz and filtered by a high-pass filter with 0.5 Hz cut off frequency (order 2, Butterworth) and a notch at 50 Hz. Optical electrograms were filtered through a filter. Gaussian The analyses were performed in the time and frequency domain. In the time domain, the calculated metrics were: optical action potential duration (OAPD30, OAPD50 and OAPD70), isochronous maps, conduction velocity (for optical signals) and time and delay between activations (optical and electrical signals). Frequency analysis was performed by Fourier in discrete time (4 s segments, Hanning window, 5x zero padding and 0.05 Hz frequency step) to identify the dominant frequency in the spectrum, defined as the highest peak frequency. The organization index (OI) was calculated as the area of the dominant frequency and its harmonics over the total spectrum area. Results: The morphology of the optical and electrical electrograms were altered as the ablation time increased making it difficult to identify activation and repolarization times. In addition, the peak-to-peak amplitude (p = 0.001, F = 2501.6) and the time between activations (p = 0.001, F = 13070) also decreased, with ablation time of 4 s having the greatest impact on these variables ( p = 0.001, F = 85.58). OAPD30, OAPD50 and OAPD70 were 14 ms, 20 ms and 30 ms respectively. After 4 s of ablation, these values were reduced to 8 ms, 10 ms and 10 ms, respectively. The isochronous maps show the propagation of wave fronts with conduction velocity of 862.39 mm / s. The ablated areas altered the propagation pattern and their conduction velocity was reduced to 4.92 mm / s. The delay between the optical and electrical signals was 42 ms. The FD and OI decreased with increasing ablation time (6.7 Hz and 0.8 for baseline vs. 5.4 Hz and 0.4 for 4 s) implying fractional electrograms. Conclusion: Through the characterization of traditional metrics applied to the electrical and optical electrograms, it was possible to identify the important changes of the ablated regions, especially for long ablation times.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 2188954 - ERICK DARIO LEON BUENO DE CAMARGO
Membro Titular - Examinador(a) Externo à Instituição - ILIJA UZELAC
Membro Titular - Examinador(a) Externo à Instituição - EMILIANO HORACIO MEDEI - UFRJ
Membro Suplente - Examinador(a) Interno ao Programa - 1671296 - HARKI TANAKA
Membro Suplente - Examinador(a) Interno ao Programa - 1760474 - PATRICIA APARECIDA DA ANA
Membro Suplente - Examinador(a) Externo ao Programa - 1640114 - MARCELA SORELLI CARNEIRO RAMOS