Formal Modeling and Verification of Rate Adaptive Pacemakers for Heart Failure

Cardiovascular Implantable Electronic Devices (CIEDs) are routinely implanted to treat various types of arrhythmia. However, conventional pacing algorithms may not be able to provide optimal treatment for the patients with Heart Failure (HF) and evidence suggests negative outcomes. In this paper, we introduce a formal pacemaker model that can restore heart-lung synchronization, which may bring therapeutic benefits to the patient with chronic HF. We use valued Synchronous Discrete Timed Automata (SDTA) to describe the timing requirements of the device, which is then translated into Promela for formal verification through a set of rules which are defined to maintain the synchronous semantics. The safety-critical properties are then verified using the model checker SPIN. We show that the SDTA model can be verified more efficiently than conventional approaches with pure Timed Automata (TA). Animal test results show that the pacing rates are synchronized with the respiratory cycles. In particular, the functional safety is ensured under various respiratory conditions. This work yields, for the first time, a formal model of pacing device to reinstate heart rate variability for HF patients.