Longer action potential duration in the Purkinje network than in the ventricular myocardium delays retrograde activation of the human His‐Purkinje system

times at short S1S2 CIs during programmed electrical stimulation, a phenomenon discovered in 1978. At short S1S2 CI during programmed electrical stimulation, longer APD in the HPS than in the myocardium can lead to entry points into the HPS further away from the myocardial S2 stimulus site and promote reentrant arrhythmias. This is new knowledge regarding the retrograde activation of the human conduction system. The mechanism of delayed retrograde activation was determined using a state-of-the-art computer model of the human ventricles coupled to a robust model of the HPS. As a result, this study developed a new and extensive set of HPS parameters that future computational studies can use and build upon to simulate retrograde activation of the human ventricles.