Sam's research focused on developing novel haemodynamic measurement technologies by investigating the relationship between aortic central blood flow (Q
), and pressure (P
through the parameters that link them such as peripheral resistance (R
), total compliance (C
) and pulse wave velocity (PWV
To address current methodologies shortcomings, Sam used a unique mix of numerical and clinical data for establishing proofs of concept for protocols that are subsequently
validated in clinical settings. This approach also enabled him to investigate the haemodynamic mechanisms at play in cardiovascular diseases.
During his PhD, he tackled the following challenges:
- Aortic pressure can hardly be acquired during MRI scanning while this is the preferred imaging modality to assess cardiac anatomy and mechanics. Sam developed
an innovative protocol to obtain the central blood pressure waveform from MRI-acquired aortic flow waveform (Am J Phys, 2015 ; J Biomech, 2016).
- Haemodynamic mechanisms behind pulse pressure increase in hypertension are still disputed. Validation of a three-element Windkessel with in silico and in vivo
data enabled to identify and separate the main arterial and cardiac determinants to elevated pressure: total arterial compliance dominates in determining the contribution of arterial tree, while ventricular dynamics
account for a relatively large proportion of the increased pulse pressure in hypertesion (Hypertension, 2017).
- Continuous monitoring of cardiac output requires specialist equipment and invasive access while non-invasive alternatives does not provide accurate estimates of beat-to-beat
variations despite the value such information would have in intensive care units. A protocol to estimate within-patient variations in cardiac output from
non-invasive and readily available measurements of aortic pressure and pulse wave velocity has been developed.
As a Biomechanical Engineer Research Fellow, Sam conducted research on the clinical translation of his protocols.