Electrocardiogram R-wave is an Unreliable Indicator of Pulse Wave Initialization

Pulse wave velocity (PWV) measurements are commonly used to evaluate a patient’s arterial , an indicator of cardiovascular dysfunction. PWV is usually calculated by measuring the pulse time (PTT) over a known distance through the arteries. In an experimental study on animals, it is forward to measure the PTT using two pressure catheters a known distance apart in the central . However, in a clinical setting it is uncommon for such a direct invasive method to be used. This aims to identify whether a surrogate measure of PTT could be found without the need for an device and without being additionally invasive. The aim is to use the time between the R-wave an electrocardiogram (ECG), and the pulse wave passing one pressure catheter (rPTT), both of which common in critical care. The analysis was performed using data from four porcine experiments (Pietrain Pigs, 20-29kg) in which ECG, aortic arch pressure and abdominal aortic pressure were simultaneously over a range of induced hemodynamic conditions including recruitment (RM), fluid admission and dobutamine admission. From the measured data, the correlation rPTT and PTT was calculated for each pig and condition. The overall results showed varied across the pigs (r2 = 0.07 to 0.79). The variability is suspected to be due to two main causes, first being pig specific response to the interventions. The second cause leading to poor correlation is to be the pre-ejection period (PEP), the time following the ECG R-wave but before ejection of from the ventricle. The analysis showed that rPTT was an unreliable measure of PTT and a poor .