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Arrhythmia services

Diagnosing and treating disturbances in heart rhythm

Coronavirus: arrhythmia services update

We know that this is a concerning time for lots of people.  Even through the coronavirus situation, we remain committed to providing you and your family the best, and safest, care possible.

We are changing how we work in the cardiovascular team, so that we can continue providing the best care possible for current and new patients, both in and out of our hospital. These changes are designed to help keep everyone as safe as we can during this challenging time.

Please see our frequently asked questions page and the links below for further details on changes we are making, and contact details for your clinical team.


To reduce the risk to our patients, whilst still ensuring they get the care they need, our team of consultants and nurses are carefully reviewing every single patient's medical history and test results. Following these detailed reviews, they can find which patients need to be seen in person, which patients could have a 'virtual' review, and which patients could safely have their appointment postponed.

We are currently working to contact every patient regarding any changes. We understand that you may have waited some time for an appointment, and we apologise that your appointment may be changed. 

After our detailed review, one of the following may happen:

  • in some cases, we are changing appointments to a telephone consultation, and in certain circumstances, a video appointment. This prevents you from having to travel to the Trust
  • some patients may be discharged back to their GP and we will write to you if this is the case. If you have been discharged back to your GP, it is because it is safe to do so. If your situation as changed, please let us know
  • some appointments may be deferred without a future date being arranged at this stage. If we defer your appointment, this is because we believe it is safe to do so. You will remain on our waiting list and we will contact you in due course. If your symptoms have changed and you think you should be seen, please contact your team so we can give you the help and treatment you need.

We understand that this is a concerning time, and we apologise that we have had to change your appointment. If you have not heard from us within three days of your scheduled appointment please contact us by emailing or by calling 020 7188 4931.

If you are worried about your health or feel that you are getting worse, or you are unable to email, please call uson 020 7188 4931 so that we can give you the help and treatment you need. Our phone lines are very busy and there may be a wait for your call to be answered.

It is possible that you are seen in more than one service. If your query is specifically about your heart rhythm condition or implanted cardiac device, you should direct that query as outlined below.

Heart rhythm service

Visit our team page for the full list of Arrhythmia consultants. If you are under their care, then you are a patient of the heart rhythm service.

Please contact the team by emailing or calling 020 7188 4931. You are likely to receive the quickest response by using an email query.

Contact us by email for: 

  • concerns regarding your heart rhythm health or symptoms which cannot be answered by your GP
  • concerns regarding an increase in the frequency or severity of your palpitations, please let us know
  • you do not need to notify us if you are self-isolating for a suspected COVID-19 infection.

For patients with an implanted pacemaker or defibrillator

If you have a query, please use your usual mode of access to the pacemaker service, as found on your pacemaker ID card: 020 7401 9249 or

COVID-19 does not affect the function of your pacemaker. We have carefully reviewed the case notes for all patients with implanted devices, and have identified all patients in whom replacement of their pacemaker battery is needed in the next three months. These procedures have been prioritised and these patients will already have been contacted by the pacemaker team if this applies.

Contact us by telephone on 020 7188 4931:

  • if you urgently need to discuss your clinical condition
  • if you don't have access to email or our website
  • if you leave a message on this number it may be a few days before we are able to respond to your query.

We can arrange for a doctor to call you if needed. If you are unwell, please contact 111, speak with your GP or go to your local hospital as needed. The heart rhythm team can be easily reached by the on call teams in your local hospital to help with your care.

Frequently asked questions (FAQs)

Visit our frequently asked questions page for answers to queries we have been receiving.


We are doing everything we can to support GPs and your patients during the coronavirus (COVID-19) situation. If you need advice from our clinical team, please use the current advice and guidance channels, including e-RS advice and guidance for written communication, or Consultant Connect to speak to a senior clinician immediately.

e-RS referrals

We would encourage you to contact our clinical team through advice and guidance before making a referrals. We are vetting all referrals. We will be contacting urgent patients but we are not currently booking routine patients and so there may be a significant delay before seeing your patient. Please consider this before making any referral as our capacity to see new patients is very limited.

Consultant Connect

Please use the following number to contact one of our clinical team (if using Consultant Connect this will be one number for all services):

What are arrhythmias?

Arrhythmias are disturbances in cardiac (heart) rhythm and are very common.

There are many different types of arrhythmia, including simple extra beats and more sustained rapid beats. Disturbances of rhythm can also sometimes cause slow heart beats. 

The symptoms experienced are varied. Some people may notice simple ‘skips and jumps’, others rapid heart beats. Sometimes dizziness or less commonly blackouts may occur.

About us

We run specialist arrhythmia clinics at both Guy's and St Thomas'. We also provide regular pacemaker and defibrillator clinics to support the arrhythmia clinics.

All our clinics are run by a consultants known as electrophysiologists, who treat patients with arrhythmias. 

Find out how imaging is transforming care for cardiac patients

At Guy's and St Thomas’ cardiologists are working to improve the way they use imaging to diagnose and treat patients with cardiac disorders, such as arrythmia.

  • How imaging is transforming care for cardiac patients – video transcript

    Prof Mark O’Neill: One of the challenges facing us today is applying a new paradigm to the management of our patients with cardiovascular disease. With our diagnostic capabilities we can personalise our investigation of a patient and subsequently personalise the treatment of that patient.

    Prof Reza Razavi: By not only looking at the patient's history and their ECGs but actually by looking at the substrate at what's going on inside the heart we can have a some idea of which patients are likely to respond and which might not.

    Prof Aldo Rinaldi: We can use data that's been derived from magnetic resonance imaging or even CT scanning imaging now and this can give us an idea of the patient's anatomy by using computer modelling we can test whether a patient will respond to therapy so we're moving much more towards the sort of precision or targeted approach in individual patients try to improve response. 

    Prof Mark O’Neill: Guy's and St Thomas' is one of the largest teaching hospitals, university hospitals, in the United Kingdom based in the centre of London there has in fact been a St Thomas' Hospital based on the Southbank of the Thames since the 12th century. The clinical and intellectual atmosphere here is unique together with my colleagues in bioengineering and advanced cardiovascular imaging including MR physics we have the ability to answer very quickly questions which we ask. All under one roof. We're seeking to expand the boundaries of how diagnostic imaging can inform therapeutic intervention in patients with heart rhythm disturbances, to understand why a particular patient on a particular day suffers a rhythm disturbance which could potentially be fatal. In the United Kingdom at least 1.5 to 2 percent of our population suffers with atrial fibrillation therefore it's very important for us to find better ways to manage this condition in a more cost-effective way. The current interventions we use seek to ablate or destroy in a controlled way clearly defined cardiac tissue. Advanced cardiac imaging allows us to assess atrial structure. It's important for us to understand which parts of the atrium are the sites that we should target and also how safely can we target them. Sitting here within the XMR environment, we have the ability to take a patient on the morning of their procedure, perform a scan to assess their atrial structure and function, and then to tailor our procedure according to that individual patient's anatomy and depending on where we see sites with scar or abnormal tissue or sites with thick or thin atrial tissue.

    Prof Aldo Rinaldi: Cardiac resynchronisation therapy is an extremely powerful treatment. But approximately a third of patients don't respond to this treatment. By looking for areas of scar, by looking for areas of late electrical or mechanical activation and by using that data and taking it into the catheter lab to actually guide the procedure at the time, we hope to be able to then make a bespoke treatment for the patient to guide the lead to the optimal position in that patient's heart to improve the response to therapy. We were also able to develop in conjunction with our biomedical engineers here, biophysical models derived from MRI and electrical input. We can actually test in silicone what the response to a patient's treatment will be before we actually give it to the patient. There are several studies and programmes we're undertaking in conjunction with other centres in the UK and Europe actually to validate these models. Also we want to make the models more sophisticated and require less invasive data. We want them to be quicker as well so we hope to be able to now create this in hours to minutes in the future.

    Prof Reza Razavi: When we are looking at patients with ventricular tachycardia, cardiac MR allows us to image the shape and size of the ventricle in its function but particularly it allows us to image the scar and the areas around the scar, the border zone, or the grey zone, but getting that information into the cardiac catheterisation laboratory is difficult. That is why we're pursuing doing these procedures inside the MR scanner where we can both observe the substrate accurately but also accurately to target it by tracking our device to do the ablation, the catheter into the right part of the substrate. We can ablate arrhythmias in patients inside an MR scanner for atrial flutter but doing this for ventricular tachycardia is much harder. We have developed the technologies working with Siemens Healthcare and Imricor to be able to do this in an animal model and a next step over the coming year or two for us is to translate that into studies in patients.

    Prof Mark O’Neill: Almost every patient we see is interested in understanding better why they have suffered the problem they have suffered. Therefore every patient who comes into hospital contact with a doctor or a nurse is offered the opportunity, if appropriate, to participate in a research study.

    Dr Ronak Rajani: The UK's National Health Service indicates that all patients should have access to clinical research should they wish to be involved in research. We do screening of patients as they attend their clinics and patients are identified if they have specific pathological conditions or clinical disease states and if these conditions match up to current research studies they are approached for inclusion into these research studies. The transition of clinical data acquisition will ultimately be dependent on the publication and dissemination of our research findings but we are already starting to see that patients are benefitting from some of the work that's being conducted on our site.

    Prof Mark O’Neill: With the support of the infrastructure provided by the NHS, King's College London and our in-house services in bioengineering medical physics, cardiovascular imaging and interventional cardiac electrophysiology we hope that our work using imaging technology to assess arrhythmia substrate in patients will lead to earlier identification of patients for whom intervention is appropriate and better interventions in those patients.


Support websites


Please visit the main Trust coronavirus (COVID-19) page for more information.


Email: gst-tr.cardiology 

Watch our videos about anticogulation medication

Find out more about atrial fibrillation