Transthoracic cardiac stimulation thresholds for short pulses

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Cardiac Electrophysiology

Background:

• Ventricular fibrillation (VF) is the primary cause of death from electric shock.
• Understanding electrical thresholds is crucial for safety and medical applications.

Purpose of the Study:

• To review literature and develop a model estimating VF risk from short-duration electrical pulses.
• To determine current and charge thresholds for cardiac stimulation and VF induction.

Main Methods:

• Literature review of applicable results.
• Development of an estimation model for VF risk.
• Calculation of transthoracic current and charge thresholds for various pulse durations (1 ms and 0.1 ms).

Main Results:

• For 1 ms pulses, predicted thresholds for cardiac stimulation were 1.12 A and 1.12 mC.
• For 0.1 ms pulses, predicted transthoracic current and charge thresholds were 10.9 A and 1.09 mC.
• In humans, 0.1 ms pulses require at least 0.5 mC for single cardiac capture.

Conclusions:

• Transthoracic charge thresholds for repetitive ventricular responses are significantly higher than for single responses.
• The transthoracic charge threshold to induce VF with 0.1 ms pulses in adult humans is expected to exceed 1 mC.
• This model aids in assessing electrical safety and understanding cardiac stimulation parameters.