24 November 2015
A clinical trial underway at Royal Brompton Hospital aims to significantly improve treatment for patients with atrial fibrillation(AF) by removing some of the heart’s nerve endings.
The procedure, which is being carried out for the first time ever, uses an innovative imaging technique to identify the exact locations of a branch of nerves, known as the sympathetic nervous system, that are thought to have a role in causing AF. The nerve endings are then targeted for catheter ablation treatment, which uses radiofrequency energy to destroy areas of heart tissue.
AF is a heart condition that causes an irregular and often abnormally fast heart rate. It affects up to 800,000 people in the UK and can cause palpitations, tiredness, breathlessness and dizziness. The way the heart beats in AF reduces its efficacy, which can lead to low blood pressure and heart failure, as well as blood clots that may cause a stroke.
In the ongoing trial, ‘A Pilot Study on the Role of Ganglionated Plexus Ablation for Catheter Ablation of Atrial Fibrillation’, led by consultant electrophysiologist Dr Sabine Ernst at Royal Brompton Hospital, participants are injected with a dye and scanned with a high-resolution nuclear camera, called the D-SPECT. This shows up the areas in their hearts where the sympathetic nerves end. These nerve endings are known as the ganglionated plexi.
The image from the nuclear camera is then merged with a standard 3D image of the heart from a CT scan and used as a guide during catheter ablation. During a standard catheter ablation to treat AF, the pulmonary veins (PVs) that bring oxygenated blood back to the heart are electrically isolated, which stops them being able to send electrical signals to start the AF. Participants in the trial have both their PVs and sympathetic nerves treated with catheter ablation because the sophisticated imaging technique allows the location of the nerves to be pinpointed.
The aim of the new treatment is to adjust the activity of the sympathetic nervous system. The nerves are meant to act in tandem with the parasympathetic nervous system - together they form the autonomic nervous system, which regulates body processes like heartbeat and digestion and is known to play a role in AF. Once the sympathetic nervous system works in a more balanced way with the parasympathetic side, this in turn reduces AF.
The patients involved in the study will be followed up for 12 months, having regular tests including electrocardiograms (ECGs) to check their heart rhythms. After six months, the nuclear imaging scan is repeated to show how many areas of sympathetic nerve endings are still in the heart and how active they are.
Commenting on the trial, Dr Ernst said:
“Standard catheter ablation in patients with paroxysmal (‘on-off’) atrial fibrillation has a 60 to 75 per cent success rate. We believe that treating these sympathetic nerve endings as well as the patient’s pulmonary veins could increase the benefits of catheter ablation significantly. This method may potentially mean that many AF patients do not have to undergo repeat procedures, or experience unpleasant symptoms such as recurrent palpitations.
“Initial results associated with this new technique have been promising. Of the small number of patients treated, most have returned to a normal heart rhythm and have seen their symptoms disappear. This method tries to reduce the activity of the sympathetic nervous system so it works in a more balanced way with the parasympathetic nervous system. The trial will help establish the best way to carry out this technique to ensure just the right level of adjustment is achieved for each patient.”
One of the first patients treated on the trial was Tony Crook, a father of two from St Albans. The 55-year-old chartered accountant was diagnosed with AF in October 2014, after experiencing chest pains while emptying the dishwasher.
Despite Tony rarely suffering from symptoms of AF, having only briefly experienced chest pains a handful of times before, tests at his local hospital found he was in AF most of the time.
Tony’s consultant referred him to Dr Sabine Ernst at Royal Brompton for an ablation treatment. He was advised that his condition was such that he would develop heart failure within two years without any treatment.
He underwent the procedure to ablate his damaged heart tissue and his nerve endings in April. Subsequent follow-up tests have showed that his heart is now in normal sinus rhythm and his six-month scan found that none of his sympathetic nerve endings are active in his heart anymore.
“I’m really pleased I took part in the trial and avoided developing heart failure – it’s given me a new lease of life. I am completely drug free, and I am back enjoying life with peace of mind knowing that my children do not need to worry about me. This time last year I was at a very high risk of a stroke, which could have been devastating for my young family, but now that risk has totally disappeared.”
The pilot trial will involve 20 patients who have been diagnosed with AF. It is part-funded by Spectrum Dynamics, who make the D-SPECT camera.
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