# Temporary Pacing Simulator: A Training Tool for Clinicians
## 3 Experimental Results
### Pacing Failure Scenarios
Figure 23 illustrates a scenario of ventricular oversensing generated by the TCPS. Despite the TCPS being set to pace in VVI mode at a rate of 90 bpm, if the failure mode dropdown menu is set to oversensing, the TCPS disregards all other settings and reverts to displaying the patient's baseline signals--in this case, SR with VEs. As a result, the ECG signal shows no pacing spikes and exhibits irregular RR intervals, reflecting the underlying arrhythmia that the TP fails to correct due to the oversensing error. Similarly, the TCPS can generate atrial oversensing which inhibits the pacing spikes to the atria as shown in Figure 24. However, oversensing can also be localized in both atria and ventricles, leading to distinct challenges in each chamber. In the DDI pacing mode, both atrial and ventricular oversensing can occur simultaneously, leading to a scenario where both chambers are affected by inappropriate inhibition of pacing. This scenario is simulated by the TCPS as shown in Figure 25. When oversensing is present in both chambers pacing spikes are not delivered to any of the chambers and the TCPS reverts the signal to its baseline rhythm. Figure 17: Example of the signal displayed when the user selects the SR baseline rhythm and chooses the DOO pacing mode with a pacing rate of 80 bpm, while also selecting VLOC from the failure mode dropdown menu. Figure 19: Example of the signal displayed when the user selects the SR with LBBB baseline rhythm and chooses the VVI pacing mode with a pacing rate of 80 bpm, while also selecting “undersensing” from the failure mode dropdown menu. In undersensing failure mode, the TCPS shows pacing spikes erroneously superimposed on the T-waves. These inappropriate spikes occur due to the TP’s failure to correctly sense the heart’s intrinsic activity, leading to the delivery of pacing stimuli during the repolarization phase. Figure 18: Example of the signal displayed when the user selects the SR baseline rhythm and chooses the DOO pacing mode with a pacing rate of 80 bpm, while also selecting ALOC from the failure mode dropdown menu. Figure 21: DDI Pacing with Ventricular Undersensing: This figure illustrates the signal output when the user selects a sinus rhythm (SR) baseline and sets the pacing mode to DDI at a rate of 80 bpm. The user inputs a value for the ventricular sensitivity threshold and clicks the ”Insert V Sensitivity Threshold” button. The TCPS compares this input to a generated maximal ventricular sensitivity threshold. In this scenario, the system fails to detect ventricular activity, triggering the failure mode to switch to undersensing. A warning message is displayed, notifying the user of ventricular undersensing due to the inputted threshold. Figure 20: DDI Pacing with Atrial Undersensing: This figure depicts the signal output when the user selects a sinus rhythm (SR) baseline and sets the pacing mode to DDI at a rate of 80 bpm. The user inputs a value for the atrial sensitivity threshold and clicks the ”Insert A Sensitivity Threshold” button. The TCPS compares this input against a generated maximal atrial sensitivity threshold. In this scenario, the system fails to detect atrial activity, causing the failure mode to switch to undersensing. A warning message is displayed, notifying the user of atrial undersensing due to the inputted threshold. Both oversensing and undersensing errors, whether in the atria, ventricles, or both (as in the case of DDI pacing mode), underscore the critical need for precise sensing mechanisms in TP devices to ensure effective heart rhythm management. Figure 23: Example of the signal displayed when the user selects the “SR with VEs” baseline rhythm and chooses the VVI pacing mode with a pacing rate of 90 bpm, while also selecting “oversensing” from the failure mode dropdown menu. In oversensing failure mode, the TCPS reverts to the patient’s baseline rhythm, ignoring any pacing settings configured by the user. As a result, the ECG signal shows no pacing spikes and exhibits irregular RR intervals.