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A new option for hypertension treatment, on the horizon

Written by Nadia Norcia

For some groups of individuals with high blood pressure – such as those with drug-resistant hypertension or those who are pregnant – current treatments for reducing blood pressure are limited.  

But researchers may have a whole new treatment therapy technique to target and treat hypertension that may be an option in the future.

Newly-published pre-clinical research from scientists at Sunnybrook Research Institute suggests that focused ultrasound – a breakthrough non-invasive surgical technique – when targeted to a specific location in the midbrain, can inhibit neuron activity to reduce blood pressure for potential long-lasting treatment.

When left untreated, hypertension (or high blood pressure) is a fatal condition. Currently, it is treated with diet and lifestyle changes, and systemically-delivered medications that act on the central nervous system to lower the heart rate, relax and open up the blood vessels, help rid the body of excess salt and water, or alter enzyme secretion.

For patients with drug-resistant hypertension, or for those who are pregnant, many treatment options are ineffective and unsafe.

Previous research looked at an alternative approach using deep brain stimulation – an invasive neurosurgical procedure – to stimulate a specific region of the midbrain in a handful of patients. The results were promising, but the procedure has been associated with potential infections and hemorrhage.

That’s where focused ultrasound comes in.

Acclaimed in the medical and scientific world as “scalpel-free brain surgery”, FUS has crossed over from research into successful clinical treatment of some brain conditions, non-invasively.

With its additional ability to safely open the blood-brain barrier (BBB) non-invasively – a world-first research breakthrough scientists continue to plough forward in their investigations of FUS as a treatment option for other health conditions controlled by the brain, such as is the case in this new study published recently in the journal Brain Stimulation.

We’ve shown in pre-clinical work that by targeting the periaqueductal grey (PAG) region of the brain we can cause direct neuromodulation of central brain activity, which reduces blood pressure for six hours following a single 10-minute ultrasound sonication,” says Dr. Harriet Lea-Banks, lead author of the study, and junior scientist in the Hurvitz Brain Sciences Program at Sunnybrook Research Institute.

Lowering high blood pressure into the normal range was extended to nine days with the addition of a second component: introducing nanodroplets tiny liquid droplets – containing anesthetic medication that are injected into the bloodstream, and triggered with five daily treatments of ultrasound to the brain,” adds Dr. Lea-Banks, also an assistant professor in the Department of Medical Imaging at University of Toronto.

Ultrasound causes the nanodroplets to evaporate, locally releasing the anesthetic drug in a time-controlled fashion, within that specific area of the brain. This approach was shown to extend the time that neuron activity was modified and blood pressure was reduced, and prevent off-target effects, such as general sedation; increasing its reliability.

“This work builds on our previous success with FUS and out of a need for a new alternative strategy for hypertension management,” says Dr. Kullervo Hynynen, senior author of the study, VP of Research at Sunnybrook Research Institute, and a pioneer of focused ultrasound.

This study has shown that transcranial FUS offers a non-invasive tool to stimulate the VLPAG and trigger the delivery of an anesthetic agent; both approaches show the ability to modify central brain activity to achieve sustained reduction of hypertensive blood pressure into the healthy range, while offering the potential for real-time treatment monitoring.”

Based on the results of the research, the authors suggest it may be feasible to develop a FUS device that would allow the control of hypertension initially in a hospital setting, and eventually in the patient’s home for cost-effective, long-lasting treatment.    

“This work has implications for developing a new non-invasive and long-lasting treatment for hypertension that has greater safety and broader applicability than current treatment options for vulnerable patient populations,” adds Dr. Hynynen, also a professor in the Department of Medical Biophysics at University of Toronto.

“We’re looking forward to investigating this option further, and are optimistic the results will add another tool to the clinical toolbox for controlling and reducing hypertension.”

About the author

Nadia Norcia

Nadia Norcia is a communications advisor at Sunnybrook Health Sciences Centre.

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