Vagus nerve stimulation modulates parasympathetic cardiac tone to treat refractory epilepsy and heart failure. Accidental continuous current delivery can trigger bradycardia or asystole. This paper outlines formal mathematical proofs verifying that the stimulation state machine never violates cardiac refractory safety limits.
By expressing safety invariants in Linear Temporal Logic (LTL), the SPIN model checker exhaustively verified 14 million state transitions, proving that pulse delivery duration can never exceed 60 seconds without mandatory rest periods.
An auxiliary R-wave detection channel gates VNS pulses, ensuring stimulation is delivered only during ventricular refractory phases to completely prevent arrhythmia induction.