Fig. 2

Example of measured aortic arch (black) and abdominal aorta (dashed red) pressure waveforms. Thin lines represent tangent line along maximum pressure gradient and horizontal lines along minimum pressure point for each of the waveform. The green crosses represent the identified ‘foot’ of the pressure waveforms at times t1 and t2 for aortic arch and abdominal pressure, respectively. Transit time can be seen as the difference (t2–t1) between these time points