- Antiarrhythmic drugs
- A group of medicines used to regulate and control the heart’s rhythm. They may be of use in specific situations in people with LQTS (e.g. mexiletine). Ajmaline and flecainide are used in tests used to diagnose Brugada syndrome.
- Aorta
- The major blood vessel that leaves the left side of the heart. It supplies blood to the body.
- Aortic valve
- The valve through which blood passes from the heart into the aorta. The aortic valve is composed of three cusps. A bicuspid valve (a valve that has only two cusps or flaps) fails to open properly due to the absence of the third cusp and can narrow up due to repetitive damage.
- Arrhythmia
- A disturbance of the heart’s rhythm. A ventricular arrhythmia can be life threatening.
- Asystole
- When the heart’s rhythm stops completely because there is no electrical activity
- Atrial
- Of or belonging to the atria.
- Atrial Fibrillation (AF)
- An arrhythmia involving the atria (the two upper chambers of the heart).
- Atrium
- One of the two top chambers of the heart. (The plural of atrium is atria).
- AV block
- See heart block.
- AV node
- Atrioventricular node. The part of the heart that lies between the top chambers (atria) and bottom chambers (ventricles). It regulates the transmission of electrical impulses from the natural pacemaker in the atrium to the ventricle. It helps to prevent the heart from pumping too fast if the impulses from the atrium become too rapid.
- Bradycardia
- Slowing of the heart rate.
- Cardiac
- Of the heart or belonging to the heart.
- Cardiac Arrest
- The state of the heart when it is pumping so erratically or ineffectively that there is no significant blood pressure to supply the heart and brain.
- Cardiologist
- A doctor who specialises in the heart.
- Cardiopulmonary exercise test
- An exercise test that monitors the consumption of oxygen, using a set of breathing tubes.
- Cervical Sympathectomy
- A form of surgery that is useful for some people with LQTS. It reduces the amount of adrenaline and its by-products produced and delivered to the heart by certain nerves (the left cervical ganglia). It involves operating on the left neck and removing or blocking these nerves, which are not essential to normal function. The procedure can be relatively short but it does need a general anaesthetic.
- Channelopathy
- Conditions characterised by defective ion channels in the cells of the heart.
- Computed tomography (CT)
- An imaging technique where three-dimensional images are produced using a series of two-dimensional X-ray images.
- Congenital heart disease
- Disease of the heart, present from birth.
- Coronary Artery Disease (CAD)
- Narrowings and blockages of the arteries supplying the heart muscle, due to furring of the arteries. Also known as arteriosclerosis.
- Defibrillator
- A device used if a person has a cardiac arrest. It may be able to return the heart to a normal rhythm by delivering an electrical shock through the chest wall.
- Delta wave
- The ECG feature characteristic of Wolff-Parkinson-White (WPW) syndrome.
- DNA
- The genetic code from which proteins - the building blocks of life - are made. We all receive a copy of half of each of our parents' DNA when the egg and sperm meet to conceive a new human being.
- Ectopic beat
- An extra beat which occurs when the heart activates prematurely, disrupting its normal rhythm. The heart's natural pacemaker resumes its normal control after a brief pause. Most of the time the person does not notice these extra beats but, if they do become aware of them, the sensation depends on how close the ectopic beat occurs to the preceding normal beat. If it is close, only the pause might be noticed. If it occurs further away, it might be felt as an extra beat from the heart, making the rhythm feel irregular or erratic.
- Electrical cardioversion
- A Cardioversion is a procedure that can help your heart rhythm get back to its normal rhythm (called sinus rhythm) if you have persistently abnormal rhythm such as atrial fibrillation or atrial flutter.
- Fibrillation
- The fast irregular contraction of muscle fibres in the heart.
- Gene
- The segment of DNA responsible for the production of a specific substance such as a protein that in turn forms the basis for the body to exist and function.
- Genetic Mutation
- Any event that changes genetic structure; any alteration in the inherited nucleic acid sequence of the genotype of an organism.
- Heart block
- A failure of the heart's electrical impulses to conduct properly from the top chambers (atria) to the bottom chambers (ventricles) via the atrioventricular (AV) node. The severity of the condition and its associated risk can vary.
- Ion
- A chemical substance (such as sodium or potassium) that carries an electrical charge and forms the basis of the movement of electricity through the heart muscle.
- Ion channel
- The route that ions take in and out of the heart muscle cells to allow movement of electricity.
- Mitral valve
- This is the valve on the left side of the heart, between the atrium and ventricle.
- Mitral valve prolapse (MVP)
- When the heart is seen on an echocardiogram, the mitral valve can appear floppy. This is very common, and affects around 1 or 2 in every 20 people. It can become more severe and the valve can become thickened and leaky. Only in rare cases it can be inherited in a family and may be associated with arrhythmias and cardiac arrest.
- MRI
- An MRI uses a magnetic field and radio waves to create pictures of tissues, organs and other structures inside the body.
- Murmur
- The sound of the turbulent flow of blood in the heart, sometimes due to leakage through or narrowing of valves. It can be heard through a stethoscope.
- Mutation
- An abnormality or mis-spelling of the DNA code that causes its eventual product (usually a protein) to function abnormally, which in turn is responsible for a disease. A sporadic mutation is not inherited from a parent's DNA but occurs due to damage to the DNA after the egg or sperm that forms a human embryo is made.
- Palpitation
- A fast irregular heart beat that may be felt as the heart pounding.
- Prolonged repolarisation
- When repolarisation is slower than normal, the time taken for it to occur is described as prolonged. This can be represented on the ECG by abnormalities of T waves and an increase in the QT interval.
- Pulmonary embolus (PE)
- In certain circumstances a large clot can form in the deep veins of the legs - for example after long periods of immobility. The clot can dislodge and travel though the veins to the heart where it can block the arteries supplying the lungs and stop the flow of blood to the body. (Also called thromboembolism.)
- QT interval
- An ECG measure of repolarisation from the beginning of the QRS to the end of the T wave.
- Repolarisation
- The electrical resetting of the heart muscle ready for its next activation. The time taken is measured by the QT interval.
- RF ablation
- The use of high frequency radio waves to burn away small areas of heart tissue such as the extra or accessory pathways seen in Wolff-Parkinson-White syndrome.
- SA Node
- The sinoatrial node generates the normal or sinus rhythm of the heart. It is impulse generating tissue that acts as a pacemaker. It is located in the right atrium of the heart.
- Stethoscope
- A piece of equipment which a doctor uses to listen to the heart and chest.
- Syndrome
- A collection of medical features of an illness that make it a distinctive condition.
- Tachycardia
- A rapid heart rate.
- Thromboembolism
- See pulmonary embolus above.
- Vasovagal Syndrome
- A disorder of the nerves supplying the blood vessels and heart that can result in dizzy episodes or blackouts. This is due to sudden drops in blood pressure because of rapid opening up (dilation) of the arteries with or without sudden slowing of the heart rate. It is usually harmless although blackouts may place the person in dangerous situations. Treatment can involve tablets and/or a pacemaker.
- Ventricles
- The two bottom chambers of the heart.
- Ventricular
- From, or belonging to, the ventricle.
- Ventricular fibrillation
- In ventricular fibrillation (VF) the muscle fibres in the ventricles contract completely randomly so the ventricles cannot perform their pumping action.
- Ventricular tachycardia
- An abnormally rapid heart rhythm that originates from a ventricle, one of the lower chambers of the heart. Although the beat is regular, ventricular tachycardia is life-threatening because it can lead to a dreaded condition, ventricular fibrillation.
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