Pulse-wave and transit-time analysis
Go beyond pulse rate into the shape and timing of the pulse — characterize each PPG pulse waveform, and, when ECG and PPG are recorded together, measure pulse transit / arrival time as a surrogate for cuffless blood pressure.
Research question
What do the PPG pulse-wave morphology and the ECG-to-PPG timing reveal about vascular state, and how do they track over a recording or across a cohort?
Who this is for
- Vascular and cuffless-BP researchers using PPG (and paired ECG)
- Wearable / digital-health teams characterizing pulse-wave features
- Studies linking pulse shape and transit time to outcomes
Data requirements
| Data | Required | Purpose |
|---|---|---|
| PPG waveform | Yes | Pulse-wave morphology |
| ECG waveform (time-synchronized with the PPG) | For PTT/PAT | R-peak → pulse timing |
PTT requires the ECG and PPG to share a clock (same device, or aligned files).
Workflow
Upload PPG (+ ECG) → Preprocess → PPG morphology → (paired) Pulse transit time → Interpret
Step 1 — PPG pulse morphology
Upload a PPG dataset and run Analyze pulse shape in the PPG morphology panel. Per pulse it delineates foot → systolic peak → dicrotic notch → next foot and reports:
| Output | Description |
|---|---|
| Amplitude | Systolic peak minus foot (a.u.) |
| Rise / decay time | Foot→peak and peak→next-foot |
| Pulse width | Width at half amplitude |
| Pulse area | Area above the foot baseline |
| Dicrotic notch | Detection rate across pulses |
Step 2 — Pulse transit time (paired ECG + PPG)
With a synchronized ECG in the same study, preprocess it, then open the Pulse transit time panel on the ECG dataset, pick the PPG run, and compute:
- PAT — R-peak → PPG foot.
- PTT (to peak) — R-peak → PPG systolic peak.
- The percentage of beats matched (use
offset_secif the clocks aren't aligned).
Step 3 — Interpret (optional)
Interpretation cites pulse-morphology and PTT metrics; high motion or low match rates are flagged as caveats.
Expected outputs
- Per-pulse PPG morphology with recording-level summaries
- PAT / PTT per beat and summarized (median, SD, match rate)
- Grounded interpretation citing pulse-wave and timing metrics
Example insight
Median PAT is 210 ms with low beat-to-beat variability and a consistently detected dicrotic notch, indicating good-quality pulses suitable for downstream cuffless-BP modeling.
Caveats
R-to-PPG timing includes the cardiac pre-ejection period, so it is a pulse arrival time, not a pure vascular transit time. PTT also needs time-synchronized ECG and PPG.