Training Convolutional Neural Networks on Simulated Photoplethysmography Data: Application to Bradycardia and Tachycardia Detection

Figures

• 

  FIGURE 1. Synchronous ECG and PPG signals together with heart rate during (A) bradycardia ( <40 bpm) and (B) tachycardia ( >120 bpm). The ECG-based annotation is marked with a red dashed line. The signals are extracted from the PhysioNet/CinC Challenge 2015 Database.

• 

  FIGURE 2. ECG and PPG signals with much reduced or no periodic pulsations during tachycardia. The ECG-based annotation is marked with a red dashed line. The signals are extracted from the PhysioNet/CinC Challenge 2015 Database.

• 

  FIGURE 3. Block diagram of the method proposed for detection of bradycardia and tachycardia, including information on the datasets used for training, validation, and testing.

• 

  FIGURE 4. Examples of poor-quality PPG segments excluded after signal quality assessment, with the largest spectral peak at (A) 0.4 Hz and (B) 5 Hz, i.e., both frequencies outside the 0.6–3 Hz range.

• 

  FIGURE 5. Examples of PPG signal segments and related scalograms: (A) real and (B) simulated signals in bradycardia, (C) real and (D) simulated signals in tachycardia. Since most of the power of a PPG signal is confined to lower frequencies, the vertical scale of the displayed scalograms is upper limited to 10 Hz. The annotation is marked with a red dashed line. The real signals are extracted from b124s and v837l of the Physionet/CinC 2017 Challenge Database, whereas the simulated signals are generated using A07531 of the Physionet/CinC 2017 Challenge Database and RRt3 of the Spontaneous Ventricular Tachyarrhythmia Database 1.0. The PPG signals have been normalized to [0,1] to facilitate comparison.

• 

  FIGURE 6. (A) Bradycardia and (B) tachycardia detection performance for a CNN trained with simulated PPGs at different SNRs. The results are based on test set II.

• 

  FIGURE 7. ROCs of CNN-based detection of (A) bradycardia and (B) tachycardia using test sets I and II.

• 

  FIGURE 8. Outputs of the CNN-based and reference detectors for (A) bradycardia and (B) tachycardia detection on test set II, with signal quality assessment.