Implant offers alternative to high blood pressure drugs

A team working at Frenchay Hospital in Bristol has shown that the device, similar to a cardiac pacemaker, can provide a surgical alternative to blood-pressure drugs.

The team successfully used the deep-brain-stimulation technique, usually applied for mental illnesses and neurological conditions such as Parkinson’s, on a 55-year-old man when drugs were unable to control his high blood pressure following a stroke.

The team, led by Dr Nikunj Patel from Frenchay’s Department of Neurosurgery and senior clinical lecturer at the university, used magnetic resonance imaging (MRI) to precisely position the device in the brain.

‘It’s a technique that we’ve developed in Bristol that is unique in the world,’ Patel told The Engineer. ‘Using this method we’re able to ensure quite significant rates of accuracy – in 97 per cent of cases within a millimetre.’

The procedure uses plastic guide tubes made by Renishaw to implant an electrode device in the brain about 9cm from the skull, avoiding the use of metal that could interfere with the MRI scan.

This is connected like a pacemaker to a battery unit in the chest that can be replaced as required every few years.

Patel discovered the device’s ability to reduce blood pressure when attempting to treat the patient’s severe pain following his stroke. The pain returned several months after the operation, but the blood pressure remained low.

His blood pressure was controlled for three years of follow-up and, at one point, anti-hypertension drugs were used to tackle a slight increase, but the drug was successfully withdrawn once the pressure fell back again. Turning the stimulator off also led to an increase in pressure.

‘We know exactly what area of the brain we’ve targeted,’ said Patel. ‘I would have predicted the possibility of modulating one’s blood pressure and heart rate, but no one knew whether this ever extended beyond a certain period.’

Roughly five per cent of the global adult population suffers from drug-resistant hypertension, he added, although surgery of this kind would usually only be used as a last resort after other treatments failed.

Patel is now doing further research to establish exactly how the process works and plans to trial it with a larger number of chronic patients later this year.