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Osian Llwyd


Postdoctoral Researcher

  • Stroke Association Research Fellow
  • Clinical Vascular Scientist

My research focuses on assessing how blood flow is controlled by the brain and in developing an optimal technique that can be used for future studies and use within patients.  Reactivity of cerebral blood flow (cerebrovascular reactivity, CVR) to carbon dioxide (CO2) depends on endothelial function and is impaired in cerebral small vessel disease and haemodynamically significant large vessel stenosis, and is likely a key pathophysiological factor and therapeutic target.  Its use in clinical practice, large cohorts and in clinical trials is limited by a lack of well-validated, standardised and easily applicable methods.

My Stroke Association Research Fellowship (awarded September 2021) focuses on validating and optimising methods for assessing cerebrovascular function within the extracranial vessels (Duplex CVR2). Simultaneous recordings of blood flow velocity within the intracranial (middle cerebral artery) and extracranial arteries (internal carotid artery) together with beat-to-beat blood pressure, heart rate and end-tidal CO2 will be used to evaluate the suitability of cerebrovascular reactivity for future studies.  I am also an investigator in: (i) the OXVASC population-based study that is identifying physiological indices that predict the future risk of stroke and cognitive impairment; (ii) the OXHARP trial that studies the effects of phosphodiesterase inhibitors on cerebrovascular physiology in patients with cerebral small vessel disease.

In 2021 I completed the Scientist Training Programme (STP) and an MSc in Clinical Science to become a Clinical Scientist specialising in the Vascular Sciences.  Competent in the use of ultrasound for various routine and complex vascular investigations, I contribute to providing a diagnostic service to the trust on a range of patients who are suspected of having vascular disease.  I was awarded a 2020-2021 research/innovation grant by the Society for Vascular Technology (SVT) of Great Britain and Ireland to buy equipment and consumables for the final year MSc project that investigated the feasibility of assessing cerebrovascular reactivity using carotid Duplex ultrasound (Duplex-CVR).

Before Oxford, I have been fortunate to gain a wide range of research experience in the cardiovascular sciences, having worked and collaborated with several prominent research groups:


  • CHiASM (Cerebral Haemodynamics in Ageing and Stroke Medicine) research group (University of Leicester), with Professors Thompson G. Robinson and Ronney Panerai, studying how brain blood flow control can inform the diagnosis and treatment of individual acute ischaemic stroke patients.
  • Professors Damian Bailey (University of South Wales) and Phillip Adrian Evans (Swansea University), investigating new methods of measuring the strength and structure (fractal dimension) of coagulating blood.
  • Professor Andrew Halestrap (University of Bristol), investigating the efficacy of the mitochondrial permeability transition pore (mPTP) modulator, TRO40303, in limiting ischaemia-reperfusion injury.
  • Professor Gary Baxter (Cardiff University), PhD supervisor, where I investigated the involvement of CaMKII in myocardial ischaemia-reperfusion injury.
  • Professor Henning Wackerhage (Technical University of Munich), MSc supervisor at the University of Aberdeen, investigating how exercise affects health and fitness at the molecular level, in particular myostatin (TGF-β) and AMPK.

Recent publications

More publications