September 3, 2013

expert reaction to high blood pressure and carotid body denervation

A paper in Nature Communications demonstrated a technique – carotid body denervation – that lowered blood pressure in rats.

Dr Tim Chico, Senior Clinical Lecturer and honorary Consultant Cardiologist, University of Sheffield/Sheffield Teaching Hospitals, said:

“This is an exciting and innovative approach to a major health problem. Current treatments for high blood pressure have serious drawbacks; noone likes taking multiple tablets and medics are often guilty of not explaining properly why treatment is needed and what benefits might be expected. This study was not performed in humans, so more work will be needed to assess its effectiveness and safety before it can be considered for use in patients. However, it may be an important step towards a surgical procedure to be used alongside, or even replace drug treatment. It’s worth remembering high blood pressure can be preventable with a better lifestyle, so although we need new treatments, it’s unfortunate that these treatments simply address the consequences of a poor diet, lack of exercise, and being overweight.”

Professor Tony Heagerty, Professor of Medicine, Institute of Cardiovascular Sciences, University of Manchester, said:

“It has been known for a considerable period of time that a large number of patients with high blood pressure have an increase in sympathetic nervous system activity.  There is also evidence for a decrease in parasympathetic nervous activity so overall there is an imbalance in terms of autonomic nervous traffic.  Investigations into animal models of high blood pressure have suggested that interfering with the autonomic nervous system is associated with large falls in blood pressure and indeed 40 years ago a treatment for severe forms of high blood pressure was introduced which involved cutting some of the sympathetic nerves in the abdomen and pelvis in order to try and control blood pressure.  This fell out of fashion and wasn’t always successful.  Most recently there have been some intriguing interventions using denervation of the renal sympathetic nerves and this has become extremely popular although it is still under trial.  In addition, there has been the development of devices to stimulate the barrow receptors and lower blood pressure on a consistent basis.  Both renal denervation and barrow receptor stimulation are now being used to treat human hypertension.

“Here, Professor Paton and his colleagues have used another approach which is to interfere with the innovation of the carotid body which is one way of modulating autonomic nervous function and in animals they have demonstrated a fall in blood pressure.  If this were to be translated into humans it again would offer another possibility for interfering with nervous system traffic and lowering pressure.  In addition, it adds to the accumulating body of evidence which suggests that many cases of hypertension are produced by this over-activity of the sympathetic nervous system which may in fact be genetically determined as well as manifesting itself in the appropriate environment.

“Obviously there would need to be some work done perhaps in larger animals before this is attempted in humans but it is another interesting development in terms of an approach to long term control of blood pressure which would then potentially avoid the use of drugs which have to be taken on a daily basis for many years as the treatment of hypertension is lifelong after diagnosis.”

‘The carotid body as a putative therapeutic target for the treatment of neurogenic hypertension’ by Fiona D. McBryde et al. will be published in Nature Communications on Tuesday 3 September 2013.