Cardiac safety profile for random complex waveforms (2017)

Type of publication:
Journal article

Pratt H, Andrews C, Panescu D, *Lake B.

39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Seogwipo, 2017, pp. 3712-3718.

A rigorous method for assessing the Ventricular Fibrillation (VF) risk of a Random Complex Waveform (RCW) has not been previously available. Real-life hazardous events motivated us to develop such method. An RCW is observable and recordable. It consists of multiple different components randomly added one to the other. Assessment for VF risk exists for non-random waveforms, particularly VF thresholds for 50/60 Hz alternating currents, but not for RCWs.
We developed a method which considers exposure to a segment of an RCW. It transforms complex segment exposure to values which can be compared with AC root-mean-square (rms) magnitude/duration curves, for determination of VF risk. Human contact could occur for any given time duration within the segment. The current of most risk is the greatest found for all possible instances of that duration. This is termed the “Probable Current” (PC) for that duration. All possible exposure durations in the waveform segment are considered, giving a set of PCs, thus allowing the plotting of a PC curve. The PC set is compared with a criterion for VF risk, termed the Justified Current (JC) curve.
The theory is presented. Demonstrations and examples are given. Code is shown for generating the PC curve.
VF risk can be found for an RCW using the rigorous algorithm presented.
The VF for RCWs has not been considered previously. A rigorous statement of a method for VF risk assessment allows extension from regular waveforms to RCWs.