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Spectral analysis of signal averaging electrocardiography in atrial and ventricular tachyarrhythmias
(2017)
Background: Targeting complex fractionated atrial electrograms detected by automated algorithms during
ablation of persistent atrial fibrillation has produced conflicting outcomes in previous electrophysiological
studies. The aim of the investigation was to evaluate atrial and ventricular high frequency fractionated electrical
signals with signal averaging technique.
Methods: Signal averaging electrocardiography (ECG) allows high resolution ECG technique to eliminate
interference noise signals in the recorded ECG. The algorithm uses automatic ECG trigger function for signal
averaged transthoracic, transesophageal and intracardiac ECG signals with novel LabVIEW software (National
Instruments, Austin, Texas, USA). For spectral analysis we used fast fourier transformation in combination with
spectro-temporal mapping and wavelet transformation for evaluation of detailed information about the frequency
and intensity of high frequency atrial and ventricular signals.
Results: Spectral-temporal mapping and wavelet transformation of the signal averaged ECG allowed the
evaluation of high frequency fractionated atrial signals in patients with atrial fibrillation and high frequency
ventricular signals in patients with ventricular tachycardia. The analysis in the time domain evaluated
fractionated atrial signals at the end of the signal averaged P-wave and fractionated ventricular signals at the end
of the QRS complex. The analysis in the frequency domain evaluated high frequency fractionated atrial signals
during the P-wave and high frequency fractionated ventricular signals during QRS complex. The combination of
analysis in the time and frequency domain allowed the evaluation of fractionated signals during atrial and
ventricular conduction.
Conclusions: Spectral analysis of signal averaging electrocardiography with novel LabVIEW software can
utilized to evaluate atrial and ventricular conduction delays in patients with atrial fibrillation and ventricular
tachycardia. Complex fractionated atrial electrograms may be useful parameters to evaluate electrical cardiac
arrhythmogenic signals in atrial fibrillation ablation.
Simulation-based degradation assessment of lithium-ion batteries in a hybrid electric vehicle
(2017)
Simulation-based degradation assessment of lithium-ion batteries in a hybrid electric vehicle
(2017)
The electrical field (E-field) of the biventricular (BV) stimulation is important for the success of cardiac
resynchronization therapy (CRT) in patients with cardiac insufficiency and widened QRS complex.
The aim of the study was to model different pacing and ablation electrodes and to integrate them into a heart
model for the static and dynamic simulation of BV stimulation and HF ablation in atrial fibrillation (AF).
The modeling and simulation was carried out using the electromagnetic simulation software CST. Five
multipolar left ventricular (LV) electrodes, four bipolar right atrial (RA) electrodes, two right ventricular (RV)
electrodes and one HF ablation catheter were modelled. A selection were integrated into the heart rhythm model
(Schalk, Offenburg) for the electrical field simulation. The simulation of an AV node ablation at CRT was
performed with RA, RV and LV electrodes and integrated ablation catheter with an 8 mm gold tip.
The BV stimulation were performed simultaneously at amplitude of 3 V at the LV electrode and 1 V at the RV
electrode with a pulse width of 0.5 ms each. The far-field potential at the RA electrode tip was 32.86 mV and
185.97 mV at a distance of 1 mm from the RA electrode tip. AV node ablation was simulated with an applied
power of 5 W at 420 kHz at the distal ablation electrode. The temperature at the catheter tip was 103.87 °C after
5 s ablation time and 37.61 °C at a distance of 2 mm inside the myocardium. After 15 s, the temperature was
118.42 °C and 42.13 °C.
Virtual heart and electrode models as well as the simulations of electrical fields and temperature profiles allow
the static and dynamic simulation of atrial synchronous BV stimulation and HF ablation at AF and could be used
to optimize the CRT and AF ablation.
Background: The electrical field (E-field) of the biventricular (BV) stimulation is essential for the success of cardiac resynchronization therapy (CRT) in patients with cardiac insufficiency and widened QRS complex. 3D modeling allows the simulation of CRT and high frequency (HF) ablation.
Purpose: The aim of the study was to model different pacing and ablation electrodes and to integrate them into a heart model for the static and dynamic simulation of BV stimulation and HF ablation in atrial fibrillation (AF).
Methods: The modeling and simulation was carried out using the electromagnetic simulation software. Five multipolar left ventricular (LV) electrodes, one epicardial LV electrode, four bipolar right atrial (RA) electrodes, two right ventricular (RV) electrodes and one HF ablation catheter were modeled. Different models of electrodes were integrated into a heart rhythm model for the electrical field simulation (fig.1). The simulation of an AV node ablation at CRT was performed with RA, RV and LV electrodes and integrated ablation catheter with an 8 mm gold tip.
Results: The RV and LV stimulation were performed simultaneously at amplitude of 3 V at the LV electrode and 1 V at the RV electrode, each with a pulse width of 0.5 ms. The far-field potentials generated by the BV stimulations were perceived by the RA electrode. The far-field potential at the RA electrode tip was 32.86 mV. A far-field potential of 185.97 mV resulted at a distance of 1 mm from the RA electrode tip. AV node ablation was simulated with an applied power of 5 W at 420 kHz at the distal 8 mm ablation electrode. The temperature at the catheter tip was 103.87 ° C after 5 s ablation time, 44.17 ° C from the catheter tip in the myocardium and 37.61 ° C at a distance of 2 mm. After 10 s, the temperature at the three measuring points described above was 107.33 ° C, 50.87 ° C, 40.05 ° C and after 15 seconds 118.42 ° C, 55.75 ° C and 42.13 ° C.
Conclusions: Virtual heart and electrode models as well as the simulations of electrical fields and temperature profiles allow the static and dynamic simulation of atrial synchronous BV stimulation and HF ablation at AF. The 3D simulation of the electrical field and temperature profile may be used to optimize the CRT and AF ablation.