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Q&A with Dr Lewan Parker
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Q&A with Dr Lewan Parker

Identifying microvascular dysfunction as a novel mechanism of poor health in heart failure patients.

Dr Lewan Parker is a Heart Foundation Postdoctoral Fellow within the School of Exercise and Nutrition Science at Deakin University. Dr Parker has dedicated his research career to exploring exercise, biology, biochemical processes, bone metabolism, and microvascular (small blood vessel) function. These factors play an important role in managing blood sugar and overall health and disease. Dr Parker’s current Heart Foundation research is focused on Identifying microvascular dysfunction as a novel mechanism of poor health in heart failure patients.

What are you currently researching?

My Heart Foundation research project aims to determine how muscle microvascular dysfunction (poor blood flow through the smallest blood vessels in the body) contributes to exercise intolerance (difficulty exercising) and poor glycaemic (blood sugar) management in people with heart failure with type 2 diabetes. By using modern biochemical and ultrasound imaging techniques, we will directly measure small blood vessel function in muscles, heart function, large artery function, and how blood sugar levels respond to both exercise and eating a meal. These measures will be performed before and after a three-month home-based high-intensity interval exercise training program. Exercises in the program are tailored based on the participants unique situation that are suitable for their lifestyle. Examples of exercises we recommend in the program include walking, jogging, running (depending on the fitness of the individual), but also activities that can be performed at home such as cycling (if a gym bike is available), high-knee jogging on the spot, or aerobic steps (if there are stairs nearby, or something the participant can safely step up and down from in their house). This will allow us to determine whether exercise training can reverse potential defects of small blood vessels, and improve management of blood sugar levels, exercise tolerance and overall quality of life for people with heart failure and type 2 diabetes.

What difference will your research make to people’s cardiovascular health in Australia?

Many people with heart failure with type 2 diabetes are unable to exercise which is linked to worsening of blood sugar levels and faster disease progression. But we don’t yet completely understand why difficulty exercising and problems managing blood sugar levels affect these people.  Our initial findings suggest that the small blood vessels in muscle are just as important. In many cases they may be more important than the heart for regulating exercise tolerance and blood sugar levels. However, current treatment strategies are largely targeted at improving the heart. As such, we aim to provide evidence and highlight to the general public, clinicians and other researchers, that small blood vessel health is just as important as heart health. This will then enable us to develop new treatments to improve patient care and quality of life. We hope to further show that exercise training, and remotely delivered home-based high-intensity exercise rehabilitation, is an effective intervention for improving muscle small blood vessel function, exercise tolerance, and blood sugar management.

Are there any achievements or discoveries from your research you can share with us?

Our team recently published findings from a study where we investigated how eating a meal containing high-sugar alongside fats and protein) would change muscle blood flow through small blood vesselsin healthy adults. This recent work highlighted that eating this type of meal in healthy adults leads to decreases in blood flow through small blood vessels in muscles.  This effect can last for up to two hours after eating. This occurred despite a normal increase in large artery blood flow following the meal. These findings are important, as our other research has shown that small vessel blood flow in muscles normally increases after eating a normal balanced meal (for example, a meal containing low to moderate levels of sugar). The findings suggest that high-sugar ingestion, even in healthy individuals, impairs blood flow through small blood vessels in muscles. This may be related to poor blood sugar management and long-term small blood vessel problems observed with diseases such as diabetes and cardiovascular disease. Importantly, we recently showed that these small blood vessel problems could be helped by doing exercise (such as cycling) before a meal (PMID: 33191527). In some cases, this type of activity provided muscle microvascular benefits for up to 24 hours after exercising. This project pioneered the way for exercise to be used as a potential treatment for skeletal muscle small blood vessel blood flow problems. We are now looking into this further in our Heart Foundation funded research program.

How important was funding from the Heart Foundation for your work?

This fellowship has allowed me, for the first time, to commence a large-scale clinical trial in people with heart failure with type 2 diabetes. As part of this fellowship, I am now working alongside world-leading cardiologists, endocrinologists, sonographers and exercise physiologists at Deakin University and the Baker Heart and Diabetes Institute - including supervisor Associate Professor Michelle Keske (Deakin University Research Fellow) and mentors Professor Ralph Maddison (Deakin University Research Fellow) and Professor Thomas Marwick (Director and Chief Executive of the Baker Heart and Diabetes Institute). This fellowship and project have enabled me to learn state-of-the-art, specialised ultrasound and biochemical imaging techniques which only a few laboratories world-wide have optimised for use in humans. Through the new application of these techniques and by adopting an approach that involves many specialities (combining cardiology, sonography, endocrinology, and exercise physiology), this fellowship has allowed me to investigate whether small blood vessel problems in muscle impacts exercise ability, blood sugar levels and quality of life.

Do you have a message for Heart Foundation supporters?

I am deeply honoured to have received my Heart Foundation funding opportunity which recognises my research team’s hard work and significant contribution to the scientific and wider community. The ongoing support and generosity of the Heart Foundation and its donors and supporters has allowed myself, and many others, to follow our desire to improve health and quality of life through robust research. This research leads to real-world health outcomes and changes in health policy, regulations and guidelines.

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