Ablation – a treatment to cure or improve symptoms related to fast heart rhythms. This involves passage of wires into the heart through the blood vessels at the top of the leg to enable treatment to be given to an area of electrical abnormality. Ablation usually involves the delivery of radio frequency (RF) energy to heat the tissues of the heart. It can also be achieved with cryotherapy where the tissues are cooled rather than heated.

Ambulatory Monitoring – recording of the heart rhythm for 24 hours or longer by a portable ECG recording machine.

Anticoagulation – use of drugs that decrease the risk of blood clotting. These are used during some cardiac procedures or taken as tablets to prevent stroke in atrial fibrillation. The commonest used drug for this purpose is Warfarin.

Arrhythmia – abnormal heart rhythm, slow or fast, sometimes irregular, often giving rise to symptom of palpitations. It can also result in symptoms of fatigue, dizzy spells or breathlessness.

Atria – top chambers of the heart that receive blood from the body and lungs. In normal rhythm these chambers contract in a coordinated fashion pumping blood into the lower heart chambers called the ventricles. In atrial fibrillation, this normal pumping function is lost.

Atrial Fibrillation – very fast chaotic beating of the atria giving rise to a fast and irregular rate of ventricular beating. It is commonly associated with palpitations, breathessness and lethargy. It can lead to stroke if not treated.

AV node – atrio ventricular node. A critical part of the heart’s electrical conduction system connecting the electrical system in the atria to that in the ventricles. If this is damaged or gets worn out with age, bradycardia can result and a pacemaker may be needed.

Bradycardia – slow heart rate, often less than 60 beats per minute. If sustained or frequent, can cause symptoms of dizziness and fainting. These patients may need implantation of a pacemaker to increase the heart rate.

Cardiac Resynchronisation therapy (CRT) – a special pacemaker used to improve heart function. This involves placement of a pacing wire to the back of the heart to stimulate the left ventricle and to one at the front of the heart for the right ventricle. The two ventricles thus contract simultaneously and more efficiently. CRT can used in combination with an implantable defibrillator.

Cardioversion – the use of a small energy shock to stop a fast or irregular heart rhythm. This is often used electively to interrupt AF and restore normal sinus rhythm. It may be performed externally using chest patches or internally by means of a catheter passed into the heart via a leg vein.

Defibrillation – delivery of an internal or external shock to restore the heart to normal rhythm from ventricular fibrillation.

ECG – electrocardiogram. The recording of the electrical activity of the heart using 10 electrodes placed on the skin of the arms, legs and chest wall.

Echocardiogram– an ultrasound scan of the heart that is able to study in detail the muscle and valvular function.

Electrophysiological study – a test involving recording of electrical signals from inside the heart. This is often combined with curative ablation in the same sitting if the cause of patient’s symptoms are identified.

Exercise Tolerance Test (ETT) – recording simultaneously the ECG and blood pressure during exercise. This is normally performed on a treadmill.

Event monitor/ Cardiomemo– an external recording device capable of recording the  heart rhythm when activated. The patient keeps this device at home and uses it at the time of his/ her symptoms.

Holter – see ‘Ambulatory monitoring’

ICD – implantable cardiac defibrillator. An implanted device connected to the heart via leads which are capable of delivering shock treatment internally should the heart go into ventricular tachycardia or ventricular fibrillation. These devices prevent sudden cardiac death.

Implantable Loop Recorder – Sometimes known as a Reveal device, this is a small implanted monitor which records heart rhythm continuously for up to 3 years. It is used  to throw light on the underlying cause for infrequent symptoms like syncope.

Myocardial Infarction– Also known as a heart attack in lay terms. It is due to blockage of a heart artery resulting in damage to some or most of the heart muscle. If this damage is sizeable, it can predispose to abnormal heart rhythms and sometimes to death.

Pacemaker – an implanted device connected to the heart via pacing leads. Modern pacemakers can be as small as a 50p coin and the battery can last up to 10 years .

Palpitations – a term used to describe a wide range of symptoms, all of which have in common a sensation of abnormality of heart beats (usually a rapid or irregular rhythm)

Pulmonary Veins - These are tubes attached to the back wall of the left atrium which carry blood from the lungs to the heart. Most cases of Atrial Fibrillation arise due to rapid electrical firing from one or more of these pulmonary veins.

RF -  Radiofrequency energy is the most commonly used modality to apply treatment during catheter ablation. It involves heating of the local heart tissue to cause permanent changes in its electrical conduction properties.

Sinus Rhythm – This is the normal electrical impulse of the heart which results in a healthy coordinated working of the heart chambers at a rate of between 60 and 100 beats per minute. 

Syncope – loss of consciousness due to fast or slow rhythms or blood pressure drop.

Sudden Cardiac Death – death within 1 hour of the onset of symptoms, frequently caused by abnormal heart rhythm and often associated with heart attacks.

Supraventricular Tachycardia (SVT) – fast heart rhythms involving the atria, often causing palpitations but rarely dangerous.

Tilt Table Test – a test to investigate reflex control of heart rate and blood pressure.

Vasovagal Reaction– an abnormal reflex causing a drop in heart rate, pressure or both leading to collapse.

Ventricles – the two lower chambers of the heart. These are the main pumping chambers. It is the right ventricle which pumps blood into the lungs and the left ventricle which pumps blood around the body.

Ventricular Tachycardia – a fast and usually regular rhythm of the ventricles. Can cause severe symptoms such as syncope or even death. In some situations this can be a benign rhythm.

Ventricular Fibrillation – an extremely fast and irregular rhythm of the ventricles. Without prompt treatment this will lead to sudden cardiac death.

Warfarin - The most commonly used drug for thinning the blood and decreasing the risk of clot formation/ stroke. Patients on Warfarin treatment need regular blood tests every few weeks or months for monitoring of their INR levels.

Wolff Parkinson White (WPW) Syndrome – a particular form of supraventricular tachycardia, often associated with palpitation but rarely can cause sudden cardiac death.