Dr Beeton's Perspectives

Our ICD Education Day on 5 April was the best attended ever in the excellent new Chertsey House at St Peter's Hospital.  Sister Aideen Ryan delivered training on Basic Life Support with supervised practice.  Remember:  Make sure it is safe.....Call for help 999.......Then central chest compressions to 'Stayin' Alive'. Oh! And make sure they aren't just sunbathing. 

  

Christina Tewkesbury presented the history of defibrillators and how we can tell when ICD batteries are running out.  Defibrillators have evolved from large unreliable pieces that need to be transported in a van to implantable devices with reliable and predictable battery dynamics.  The 'bottom line' is that the Pacing Clinic can tell with a good safety margin when the ICD unit needs to be replaced.  Dr Para Dhillon explained the practice of ICD replacement operations (also called box change, battery change or generator change).  These operations are sometimes thought to be easier than the first insertion, but in truth the challenges are just different and need to be managed by an experienced team.

After lunch, there was a Q&A session with questions from ICDC members about driving with ICDs, exercise with ICDs,  twitching from ICDs and hypertrophic cardiomyopathy and ICDs.  The DVLA 'at a glance' site is a very good summary about driving regulations.  Driving restrictions vary from 1 week for a replacement to 2 years if there have been ICD shocks that are not amenable to treatment with drugs or procedures, but most restrictions are between 1-6 months.  Check the DVLA site for details. Download the 'At a glance' guide here and see Chapter 2 Cardiovascular Disorders.

Exercise with ICDs is covered elsewhere on this website, but Graham Skelding's advice to 'live your life, but know your limits' is correct.  Most people have not heard of hypertrophic cardiomyopathy (HCM) and people who are given the diagnosis are often shocked and feel that they have an exceedingly rare condition.  It is not that rare and at St Peter's we will see a few HCM patients every week.  It is a genetic and often inherited condition caused by a gene defect causing the heart muscle to become too thick.  This can cause abnormal heart rhythms which is why some patients with HCM need ICDs.  There is more information on the Cardiomyopathy Association website.

Diaphragmatic twitches tend to occur with biventricular ICDs and biventricular pacemakers.  These are three-lead devices with one lead used to pace the left ventricle.  This lead has to pass around the back of the heart close to a nerve called the phrenic nerve which supplies the diaphragm.  The pacing lead can stimulate the phrenic nerve to cause twitching of the diaphragm which can feel like a hiccup.  Sometimes the twitching only happens in certain positions such as lying on one's side.  It doesn't mean that the device isn't pacing the heart, but is often uncomfortable so we try to avoid twitching.  The first thing to do is tell the Pacing Clinic and they can change the direction and strength of electrical current to try prevent it stimulating the phrenic nerve.  If that doesn't work and the twitching isn't causing much discomfort then no further action is needed.  If the twitching is uncomfortable then we decide if the left ventricular lead (the third lead usually) is essential to the pacemaker or ICD function.  If it isn't then we would usually replace it when the battery requires changing, which may be in some years.  If the left ventricular lead is essential then we need to arrange another ICD operation to try implant a new lead, in a different position that doesn't cause twitching.

Graham Skelding spoke about the objectives of ICDC and recent highlights.  I join him in thanking all who contributed to the day with a special mention for Ian Clement who is leaving for a deserved promotion.  I always appreciate the efforts of the 'Food and Drink' sub-committee and thank ICDC for the tin of special biscuits which are now a distant pleasant memory.

New members always welcome. Keep an eye on the website for more information, and details of forthcoming events, or email us.


Dr Ian Beeton

Consultant Cardiologist, Ashford and St Peter's Hospitals NHS Foundation Trust
Patron, ICDC Surrey




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