Columbia University in New York has successfully tested a technique that can deactivate (at least partially) the nerves responsible for an uncontrolled rise in blood pressure.
High blood pressure, which resists medication and is not affected by lifestyle changes (like cutting down on salt, losing weight and physical activity) is a serious problem, especially for the elderly, because the heart becomes fatigued over time and can become diseased. Hypertension also increases the risk of stroke and kidney damage.
It has been discovered that this type of imbalance is often caused by overactive nerves that regulate the function of the renal arteries and, when overstimulated, they cause a rise in blood pressure that is very difficult to control. This is why attempts to intervene on these nerves, with various devices or surgical techniques (which are still mostly experimental) have increased in recent years. But of course, drugs are also (and mainly) used to control hypertension. They act in different ways, dilating blood vessels, removing excess fluid or blocking hormones that increase pressure (and none of these drugs directly target the renal nerves).
However, patients may soon also be offered a new, minimally invasive approach, called ultrasound Renal Denervation (uRDN), in which the nerves responsible for increased pressure are deactivated in a very precise way, by inserting a special catheter inside the blood vessels of the surrounding areas, and then emitting ultrasound with a frequency and 'intensity' that can destroy the nerves themselves. The catheter is inserted into a vein in the leg or wrist, and then fed to the kidney area. This type of surgery does not require general anaesthesia and appears safe and effective, although its appropriateness must be strictly evaluated on a case-by-case basis.
Studies in the USA and Europe
uRDN, which has been studied for a few years, has been tested with good results on around 500 patients by interventional cardiologists at Columbia University in New York and other experts at several European centres. The results of the study (divided into three 'branches') were then published in the scientific journal JAMA Cardiology. The success of the trial convinced the researchers to apply to the US Food and Drug Administration (the body that governs drugs and other medical therapies) for the authorisation needed to use the special devices. The FDA will make a final decision on this therapy in the coming months.
The ‘right’ blood pressure values
What results were obtained? Two months after the procedure, the blood pressure of those treated with uRDN fell by an average of more than 8.5 millimetres of mercury (the unit used to measure blood pressure), while that of the control group (i.e., patients who had undergone the same procedure, but without actual nerve ablation) had fallen by 2.9 mm.
These differences proved very similar in the various branches of the study, which included patients with differing levels of hypertension. Furthermore, the number of patients whose blood pressure fell to levels considered to be non-threatening was twice as high in the treated group as in the control group. When medication has a limited effect, and the heart is in danger of becoming too fatigued, the researchers argue, it might be worthwhile to using ablation as well, if regulatory bodies (starting with the FDA) give the go ahead.
