Pulse Transit Time (PTT) is the time that it takes a pulse pressure waveform to propagate through the length of the arterial tree. This pulse pressure waveform occurs when blood is ejected from the left ventricle, and it moves with a greater velocity than the forward movement of the blood itself. PTT is used to estimate blood pressure.
PTT can be derived from calculations on electrocardiogram (ECG) and photoplethysmography (PPG) signals. Measuring PTT involves calculating the time between the R-peak of the ECG and a reference point on the pressure pulse wave measured using PPG.