Some factors affecting bubble formation with catheter-mediated defibrillator pulses

Area of Science:

• Biomedical Engineering
• Cardiovascular Science
• Electrophysiology

Background:

• Bubble formation during defibrillation can impede energy delivery and alter waveform characteristics.
• Understanding factors influencing bubble generation is crucial for optimizing defibrillator performance.

Purpose of the Study:

• To investigate the influence of defibrillator energy, electrode surface area, interelectrode distance, and electrode polarity on bubble formation.
• To assess the impact of bubble formation on current and voltage waveforms during defibrillator pulse delivery.

Main Methods:

• Damped sinusoidal discharges from a standard defibrillator were delivered to anticoagulated bovine blood using various catheter configurations.
• Bubble volume was quantified, and gas composition analyzed via mass spectrometry.
• Parameters varied included energy (5-360 J), electrode surface area, interelectrode distance (1-20 cm), and electrode polarity.

Main Results:

• Bubble volume increased linearly with defibrillator energy and inversely with electrode surface area.
• Anodal catheter discharges produced significantly more bubbles (3.30 ml) than cathodal discharges (0.070 ml) at 200 J.
• Bubble formation showed minimal variation with interelectrode distance (1-20 cm).
• Presence of bubbles distorted current and voltage waveforms, particularly at higher energies.

Conclusions:

• Defibrillator energy and electrode polarity are key determinants of bubble formation.
• Anodal discharges are more prone to bubble generation than cathodal discharges.
• Bubble formation negatively impacts defibrillator waveform fidelity and may affect therapeutic efficacy.