Browsing by Author "Zhang, Hong"

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Accelerating sino-atrium computer simulations with graphic processing units
(2015-01-01)
Zhang, Hong
;
Xiaoa, Zheng
;
Lin, Shien-Fong
;
分子醫學與生物工程研究所
;
Institute of Molecular Medicine and Bioengineering
Sino-atrial node cells (SANCs) play a significant role in rhythmic firing. To investigate their role in arrhythmia and interactions with the atrium, computer simulations based on cellular dynamic mathematical models are generally used. However, the large-scale computation usually makes research difficult, given the limited computational power of Central Processing Units (CPUs). In this paper, an accelerating approach with Graphic Processing Units (GPUs) is proposed in a simulation consisting of the SAN tissue and the adjoining atrium. By using the operator splitting method, the computational task was made parallel. Three parallelization strategies were then put forward. The strategy with the shortest running time was further optimized by considering block size, data transfer and partition. The results showed that for a simulation with 500 SANCs and 30 atrial cells, the execution time taken by the non-optimized program decreased 62% with respect to a serial program running on CPU. The execution time decreased by 80% after the program was optimized. The larger the tissue was, the more significant the acceleration became. The results demonstrated the effectiveness of the proposed GPU-accelerating methods and their promising applications in more complicated biological simulations.
Influence of Capacitive Coupling on High-Fidelity Non-Contact ECG Measurement
(2020-08-01)
Wang, Ting-Wei
;
Zhang, Hong
;
Lin, Shien-Fong
;
分子醫學與生物工程研究所
;
電機工程學系
Non-contact electrocardiogram (ECG) measurement is an advanced sensing technique that uses capacitive electrodes to detect cardiac signals through non-conductive fabrics. However, the capacitive coupling is a significant factor that affects signal-to-noise ratio (SNR) of non-contact ECG, including skin-electrode active area, material, and thickness of the non-conductive fabric. This study aims to develop a high-fidelity non-contact ECG system to evaluate the influence of capacitive coupling on ECG measurement. In this study, a polymer foam with low surface resistance (0.05 Omega/inch(2)) was designed for improving the capacitive-coupling interface between the curved body and electrode sensing surface. The system recorded excellent non-contact ECG of 29.8dB, and the accuracy of heart rate was 99.5% compared to wet-contact ECG measurement. The SNR exponentially attenuated with decreasing skin-electrode capacitance by the combined evidence of theoretical calculation and experimental results. The proposed system generates distinguishable ECG signals (SNR>0dB) at the skin-electrode capacitance above 85pF and maximum through-thickness of cotton-based cloth of 1.2mm. In conclusion, this study evaluated the influence of capacitive coupling on non-contact ECG measurements and established a lower bound of the coupling capacitance for satisfactory signal quality. Future studies may investigate whether the coupling capacitance can be further reduced.
Proarrhythmic risk and determinants of cardiac autonomic dysfunction in collagen-induced arthritis rats
(2016-11-29)
Lin, Ting-Tse
;
Sung, Yen-Ling
;
Wu, Chih-En
;
Zhang, Hong
;
Liu, Yen-Bin
Backgrounds: Patients with rheumatoid arthritis (RA) have increased risk of sudden cardiac death (SCD), which is two-fold higher than general population. The driving cause of SCD was considered due to lift-threatening arrhythmia where systemic inflammation acts as the pathophysiological basis linking RA to autonomicdysfunction. Methods: To assess the sympathetic over-activity of "inflammatory reflex", we measured heart rate variability (HRV) in a rat collagen-induced arthritis (CIA) model, whose arthritis is induced in Lewis rats by intradermal injection of emulsion of type II collagen. Single-lead electrocardiogram (ECG) was recorded for 30 min every two days. Time and frequency-domain parameters, detrended fluctuation analysis (DFA), deceleration (DC) and acceleration capacity (AC) were analyzed. Results: Compared with 9 control rats, many of HRV parameters of 9 CIA rats revealed significant different. At the beginning of arthritis, LF/HF was significant higher than controls (1st week: 2.41 +/- 0.7 vs. 1.76 +/- 0.6, p < 0.05; 2nd week: 2.24 +/- 0.5 vs. 1.58 +/- 0.5, p < 0.05) indicating intensive inflammatory reflex at the initial phase of inflammation but no significant difference was observed in the following recover phase. The similar trend of DFA parameters was noted. However, the DC appeared progressive lower despite of no significant increase of the LF/HF compared with controls since 4th week. Conclusions: We observed sympathetic over-activation of inflammatory reflex during early stage of arthritis in CIA rats. The ongoing decline of DC indicated advanced cardiac autonomic dysfunction regardless of remission of acute arthritis.
Proarrhythmic risk and determinants of cardiac autonomic dysfunction in collagen-induced arthritis rats
(2016-11-29)
Lin, Ting-Tse
;
Sung, Yen-Ling
;
Wu, Chih-En
;
Zhang, Hong
;
Liu, Yen-Bin
Backgrounds: Patients with rheumatoid arthritis (RA) have increased risk of sudden cardiac death (SCD), which is two-fold higher than general population. The driving cause of SCD was considered due to lift-threatening arrhythmia where systemic inflammation acts as the pathophysiological basis linking RA to autonomicdysfunction. Methods: To assess the sympathetic over-activity of "inflammatory reflex", we measured heart rate variability (HRV) in a rat collagen-induced arthritis (CIA) model, whose arthritis is induced in Lewis rats by intradermal injection of emulsion of type II collagen. Single-lead electrocardiogram (ECG) was recorded for 30 min every two days. Time and frequency-domain parameters, detrended fluctuation analysis (DFA), deceleration (DC) and acceleration capacity (AC) were analyzed. Results: Compared with 9 control rats, many of HRV parameters of 9 CIA rats revealed significant different. At the beginning of arthritis, LF/HF was significant higher than controls (1st week: 2.41 +/- 0.7 vs. 1.76 +/- 0.6, p < 0.05; 2nd week: 2.24 +/- 0.5 vs. 1.58 +/- 0.5, p < 0.05) indicating intensive inflammatory reflex at the initial phase of inflammation but no significant difference was observed in the following recover phase. The similar trend of DFA parameters was noted. However, the DC appeared progressive lower despite of no significant increase of the LF/HF compared with controls since 4th week. Conclusions: We observed sympathetic over-activation of inflammatory reflex during early stage of arthritis in CIA rats. The ongoing decline of DC indicated advanced cardiac autonomic dysfunction regardless of remission of acute arthritis.