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OXFORD ICD GROUP
A REVIEW OF ARRHYTHMIAS ..
Patient Perspective Paper 11
These notes are a patient’s view on the subject following a talk given to the Oxford ICD Group by Laura Richmond
from the Barts and the London Cardiovascular Biomedical Research Unit. You might like to refer to the various
booklets on the subject and these are amongst the stock of information, which I hold and are listed on our website.
I must emphasise once again that notes such as these are very much my personal interpretation and I apologise but
take no responsibility for any inaccuracy. If you are worried in any way concerning your own position, please
consult your own doctor or consultant. Remember that you have an ICD which monitors you for certain conditions
every second of every day, particularly for the very dangerous VF fibrillation.
What is an arrhythmia?
A cardiac arrhythmia is when the heart beats too fast, too slowly or irregularly,
because of faults within the heart’s electrical system. They are caused by or arise from a range of conditions
including heart failure, blackouts, sudden cardiac arrest, stroke or cardiomyopathy. In some cases a damaged heart,
as a result of scarring from a heart attack, may cause the problems or in other cases a patient may have completely
healthy hearty arteries, valves or heart muscle and yet the “electrics” are faulty. Arrhythmias can occur in the upper
chambers (atria) or the lower cambers (ventricles) of the heart.
Detection and monitoring of Arrhythmias.
The ideal is of course the ICD itself. This normally has two wires –
one to give you a shock in an emergency and the other to detect abnormalities in your sinus rhythm. The latter can be
tested using an ECG machine but of course sometimes a person may only experience these disturbances from time to
time and the ICD is monitoring 24 hours a day every day.
Monitoring can now take place remotely where the patient has a device at home that will send the readings from their
ICD to their hospital using secure encrypted technology. This is now being offered to a percentage of those recently
fitted with an ICD.
Common arrhythmia symptoms.
Palpitations, irregularity in the pulse rate, dizziness, blackouts, shortness of
breath, general lethargy or chest pain might indicate that a patient is suffering from an arrhythmia. It is important
however to state that these symptoms might well indicate something else.
Various types of arrhythmia might be:
Atrial fibrillation.
This is the most common arrhythmia found in practice. Those who have it have an increased
risk of a stroke. It has been found that its prevalence roughly doubles with each 10 years of life.
There are three types of AF:
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o
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Paroxysmal.
Persistent.
Permanent.
A patient suffers occasional irregular AF.
A patient often experiences AF.
The AF cannot be cured by treatment.
In these first two cases the AF can be eliminated by suitable treatment but in the third case any treatment will not
eliminate it: only reduce it.
Atrial Flutter. This is usually paroxysmal, where the P wave in the ECG has a saw tooth appearance. The rhythm is
fast but regular.
Supraventricular tachycardia (SVT). This is present in some between 20 and 40 years of age and is rarely
evidence of heart disease. It is not sometimes shown by the ECG and further testing may be required. Some cases
are due to an inherited condition called the Wolff-Parkinson-White syndrome (see below). It may degenerate into
ventricular arrhythmias.
Ventricular Tachycardia (VT). This is almost always accompanied by palpitations and can be thought of as a
sequence of consecutive ventricular premature beats. Sometimes it only occurs a few times or it can be more
sustained for longer: in this case it usually occurs with people with structural heart disorder which has damaged the
ventricles for instance after a heart attack. Sustained VT can be dangerous, because it may develop into ventricular
fibrillation (VF) leading to cardiac arrest. Your ICD will protect you if this happens.
Bradycardia. An adult heart normally beats between 60-80 beats per minute. Infants’ hearts beat faster at about
110-130 beats per minute. If the beat is significantly less than this, the patient is said to be experiencing bradycardia.
Slower than average heart beats are common in people who are physically fit or those asleep. Some illnesses and
certain drugs used to treat high blood pressure may also slow the beat. There may be no symptoms or a patient may
experience dizziness or fainting. Only severe bradycardia (down to <30 beats per minute) becomes dangerous. Any
treatment will involve methods to speed up the heart rate, possibly by using drugs or a pacemaker.
Inherited arrhythmias. These may be inherited genetically through the family. They tend to be diagnosed through
an ECG machine. In all cases there is a danger that these syndromes might lead into VT and hence cardiac arrest.
However treatment may not always involve the use of the implantation of a device.
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Wolff Parkinson-White Syndrome (WPW).
This results from some “extra wiring” connecting the atria
and ventricles. The additional circuit occasionally allows fast and unstable rhythms to develop which might
lead to cardiac arrest. WPW tends to show itself in younger people but many patients have few or no
problems throughout their lives.
Long QT syndrome. The cause of this arrhythmia lies in the heart muscle cells which take slightly longer to
recover from a heart beat (about 0.1 second). It may be precipitated by certain types of exercise, loud noises
or other sudden stimuli. Events again usually occur in younger people.
Brugada syndrome.
This is a rare inherited syndrome which relates to the functioning of the heart
muscle cells and most commonly presents itself in people in their thirties. Affected people may experience a
sudden collapse and require immediate defibrillation.
Genetic cardiomyopathy.
This literally means disease of the myocardium or heart muscle. In this
disease the heart loses its ability to pump blood and beat at a normal rhythm. The condition tends to start
with mild symptoms but worsens over time. Cardiomyopathy might result as a complication of a blocked
coronary artery. The patient might need a heart bypass or heart transplantation.
Treatment of arrhythmias.
This can be broken down into different options:
 Anticoagulation in the blood. This will be done with drugs such as warfarin, aspirin or clopidogrel.
 Rate control through drugs.
These are chosen to slow down conduction through the AV node or reduce
the general heart beat or blood pressure. Drugs such as digoxin, beta blockers or calcium channel blockers
might be used.
 Catheter ablation.
This aims to cure the abnormal heart rhythm by destroying the pathway or area of
extra cells which are causing the palpitations using an inserted fine wire to produce a certain type of heat
source. Ablation may be done in the AV node. If the patient is experiencing atrial flutter, the ablation will be
done in the right atria.
 Rhythm control.
Drugs such as flecainide, propafenone, solalol and amiodarone will help.
Cardioversion or catheter ablation may be used in severe cases.
 Cardioversion. This may involve an electrical shock particularly to help with persistent AF. The procedure
is usually preceded by a sustained period of anti-coagulation using drugs and the use of heparin at the time of
the cardioversion. Warfarin is often recommended after cardioversion.
 Implantable Cardioverter Defibrillator (ICD). Most modern ICDs have three main functions: l) if your heart
rhythm is too slow, the device can act as a pacemaker. 2) If your heart beats too fast, the ICD can give you a
burst of extra beats at a slightly faster rate to bring your heart back to a normal rhythm. 3) If the latter
treatment is unsuccessful and you develop VF, the ICD will give you defibrillation by giving you an
electrical shock. This will usually cure the problem and save your life. Your ICD may have an extra lead on
the left ventricle which increases the pacemaker function of the device (a CRT/ICD).
 Coronary revascularisation.
In this case surgery is used to bypass obstructions in the arteries to restore
the flow of oxygen and nutrients to the heart. Once the blockage is removed, blood circulates to the heart
again.
References.
AA booklets:
CRT/ICD patient information, Cardioversion, Catheter ablation, Drug treatment for
heart rhythm disorders, What can I do about sudden cardiac arrest, Genetic testing for inherited heart conditions,
Long QT syndrome, Atrial fibrillation patient information, Atrial flutter patient information.
BHF booklets: Heart rhythms (No 14), The heart – technical terms explained (no 18)
Other sources: Genetic Health, Health Scout, Merck Manual home edition, Univ of Rochester.
GCS/12.01.10
Geoff Shaw