Renal denervation is often mentioned nowadays in blood pressure related social media. Hypertension sufferers hope it provides a reliable alternative to blood pressure lowering medication. Dr Bryan Williams, the President of the International Society of Hypertension, in the exclusive interview below elaborates on the significance of this innovative treatment, its current and future adoptions.
However, first, I would like to explain what it is, elaborate on its origins, on the most notable research and researchers.
What renal denervation is
Renal denervation is a minimally invasive, catheter-based procedure which uses radiofrequency or ultrasound energy to disrupt the function of renal sympathetic nerves. These nerves are part of the sympathetic nervous system, running along the renal artery and playing a critical role in regulating blood pressure.
How it is performed
The procedure is typically performed by an interventional cardiologist or radiologist. Local anesthesia is used to numb the groin area, and a catheter is introduced into the femoral artery. The catheter is then carefully guided to the renal arteries using fluoroscopic imaging, a type of real-time X-ray.
Once the catheter is correctly positioned, short bursts of radiofrequency or ultrasound energy are delivered to the renal artery walls. This energy generates heat, damaging the surrounding sympathetic nerves and thus reducing their ability to signal. This, in turn, is thought to decrease the overactivity of the sympathetic nervous system, a key driver of resistant hypertension.
The whole procedure usually lasts about one to two hours. As it’s minimally invasive, recovery time is generally short, with most patients being discharged from the hospital within 24 hours.
Who has developed it
The technique of renal denervation was first introduced by Medtronic, a global leader in medical technology, in the 2000s. Its development was based on the clinical observation that kidneys play a vital role in managing blood pressure, supported by the intricate neural network that extends from the brain to the kidneys.
The most notable study in this field was the SYMPLICITY HTN-3 trial, sponsored by Medtronic. This randomized, blinded, multicenter clinical trial conducted in the US aimed to validate the safety and efficacy of renal denervation in resistant hypertension. However, the initial results in 2014 didn’t meet the primary efficacy endpoint, causing a temporary setback in the widespread adoption of this procedure.
Despite these results, subsequent studies and technological advancements led to better outcomes. A significant breakthrough came from the SPYRAL HTN-OFF MED trial, also sponsored by Medtronic, published in 2018. This trial, alongside others like the RADIANCE-HTN SOLO trial, renewed confidence in renal denervation. The SPYRAL HTN-OFF MED trial demonstrated significant blood pressure reductions in patients off antihypertensive medications.
By 2021, advancements in ultrasound-based renal denervation techniques brought new hope to the field, with companies like ReCor Medical leading the way. This technological evolution opened the door to more clinical trials aimed at proving the efficacy and safety of renal denervation in managing resistant hypertension.
New stakeholders
According to the report by MedTech Dive, Chinese companies Symap Medical and Shanghai Golden Leaf Medtech Co., Ltd. have made a significant leap in the field of hypertension treatment. Clinical trials of their renal denervation systems – a technique for blood pressure control – have met primary endpoints, suggesting both safety and effectiveness. The SyMapCath I catheter by SyMap Medical, despite showing no superiority over a sham treatment, demonstrated a reduced need for additional medications or higher doses. The Netrod system by Shanghai Golden Leaf significantly outperformed the placebo control, reducing blood pressure by 25mmHg compared to 6mmHg in the control arm. These developments may bring competition for U.S. companies Medtronic and ReCor Medical, who have been rehabilitating the reputation of renal denervation in the western market .
Most recent developments
At the UCL, researchers have developed a torpedo-like device that uses ultrasound waves to lower high blood pressure. The diminutive device, when placed in the renal artery, zaps nerves in the artery walls, resulting in a significant drop in blood pressure. This new approach could provide an effective alternative for hypertension management, targeting the misfiring nerves in the kidneys .
President of the International Society of Hypertension: “Renal denervation lowers blood pressure and is safe in experienced hands”
The Chair of Medicine at University College London (UCL), Professor Bryan Williams also serves as the Director of Research at UCLH and the Director of the NIHR at the UCLH Biomedical Research Centre. He specializes in acute medicine and hypertension, while also being an integral part of the senior director team and board of directors at UCLH. Recognized globally as a leading authority in the realm of hypertension, Professor Williams’ clinical practice and research focuses primarily on high blood pressure. He is particularly intrigued by complex and challenging cases of blood pressure management and hypertension among younger individuals.
He has held significant leadership roles in the field, including the Chairmanship of the European Council on Hypertension of the European Society of Cardiology from 2016 to 2018, and the Presidency of the British and Irish Hypertension Society between 2001 and 2003.
As the President of the International Society of Hypertension, Dr Bryan Williams has kindly agreed to answer my questions about the significance, the adoption, and the future of renal denervation:
Renal denervation is often discussed in social media by hypertension patients as a functioning alternative to blood pressure lowering medications. Is it?
There is now solid evidence that renal denervation lowers blood pressure and is safe in experienced hands. The blood pressure lowering looks to be similar to that achieved with a single blood pressure lowering drug, but this will vary and sone patients may not respond at all and others may get a bigger response – it has not been possible in advance how good the response will be. Guidelines up to now have not formally recommended renal denervation for routine treatment, or indeed at all. The latter is likely to change in the light of the new evidence for specific indications especially when other treatment options have been exhausted.
You have recently expressed satisfaction on ‘the collation of data from these well-constructed studies of ultrasound-based renal denervation’, with regards to the sound wave torpedoes, developed at the UCL. What challenges would be there to solve before we can see such a solution enter clinical practice?
The main challenge will be cost effectiveness relative to drug treatment which is generally inexpensive.
How long does it usually take from this research phase to the time when wide patient groups may benefit from renal denervation? In the wider context, as the President of the International Society of Hypertension, how do you see the future of blood pressure treatments?
The time to adoption varies – it has been a long haul for renal denervation because the early pivotal studies did not show benefit on blood pressure in resistant hypertension. This was a set back and it has taken time to recover / the newer data looks more consistent and effective at blood pressure lowering which in part will reflect operator user experience and better technology that the early iterations as well as better patient selection and control of background therapy.
There are also many new drugs in development for hypertension which is exciting to see.
