Glossary

abnormal morphology

Electrical emissions of the heart have been recognised as abnormal and are unsuitable for analysis. This may be due to the position or "tilt" of the heart and can be quite normal in some people.

arrest

A significant delay (greater than 3 seconds) in between heartbeats.

arrhythmia

Any variation from the normal rhythm of the heart.

artefact

Insufficient available ECG data to analyse. Possibly due to inadequate skin preparation, poor contact of electrodes and/or inaccurate positioning of electrodes on the chest.

asystole

Absence of heart beats, e.g. pause, arrest.

atria

The two upper chambers of the heart

atrial ectopic (AE)

A premature heartbeat impulse originating from within the atria, but outside the sinoatrial node. Atrial Ectopics are common in healthy people.

atrial fibrillation (AF)

Atrial fibrillation or atrial flutter

atrial fibrillation (controlled)

Atrial fibrillation is controlled when the heart rate response lies within normal limits (i.e. 50 to 120 beats per minute);

atrial fibrillation (uncontrolled)

Atrial fibrillation is uncontrolled when the heart rate response lies outside normal limits (i.e. 50 to 120 beats per minute);. If AF is uncontrolled, cardiac output may be compromised by periods of inappropriate tachycardia and bradycardia. Pauses and arrests may also be evident with an uncontrolled ventricular response.

atrial flutter (AF)

An abnormally rapid, well organised contraction of the atria at a rate of 250 to 350 per minute.

atrioventricular block

The failure to conduct the heart beat impulse from the atria to the ventricles.

atrioventricular node

Electrical relay station between the atria and the ventricles - electrical signals from the atria must pass through this node to reach the ventricles.

atrium

one of the upper chambers of the heart

autonomic nervous system

Part of the nervous system that controls the involuntary activity of many organs and muscles, including the heart.

autonomic tone

The effect of the autonomic nervous system on the heart rate.

bigeminy

Two ectopic beats separated by a normal beat.

bpm (BPM)

Beats per minute.

bradycardia

A slow heart rate. Appropriate bradycardia is a slow heart rate of more than 30 seconds duration between 40 and 50 beats per minute. Appropriate bradycardia is normally associated with periods of resting and sleeping. Inappropriate bradycardia is an abnormally slow heart rate.

bundle branch block

A form of heart block in which one ventricle contracts later than the other because of a delay in its electrical conduction.

couplet

Two ectopic beats occurring one after the other.

diaphoresis

Profuse perspiration.

ectopic

A heart beat originating from outside the sinoatrial node. Ectopic beats may be either atrial or ventricular in source.

electrocardiogram (ECG)

A recording, from the external wall of the chest, of electrical activity generated by the heart.

episode

A sequence of eight or more consecutive ectopic beats, or 30 or more seconds of a rhythm.

escape rhythm

A slow, protective rhythm that is seen after an ectopic beat.

false negative

An abnormal event which has not been detected by the ECG test.

false positive

A normal event which has been incorrectly classified as abnormal by the ECG test.

heart attack

See myocardial infarction.

heart block

Delay, or obstruction, of electrical conduction during contraction of the heart.

impulse

A general term for a heart beat observed on the ECG.

intraventricular conduction delay

Slower than normal conduction through the ventricles. These beats normally have a widened QRS complex.

intraventricular Conduction Delay (ICD)

This stands for Intraventricular Conduction Delay and is a generic acronym for wide morphologies. Among other conditions, IVCD include bundle branch blocks and Wolff-Parkinson-White syndrome. A previous heart attack may also show IVCD in the ECG test report.

ischaemia

Decreased flow of oxygenated blood to an organ due to obstruction of an artery

isolated

An ectopic beat that occurs in isolation.

missed beat

A delay between heart beats of twice the normal duration.

morphology

The form or structure of a waveform.

multifocal (MF)

Ectopic heart beats that originate from more than one location within the heart.

myocardial infarction (MI)

Deterioration of the myocardium, as a result of interruption of the blood supply to the area. A heart attack. An MI is specifically a deterioration beyond repair.

myocardial ischaemia

Inadequate blood flow in the coronary arteries, resulting in insufficient oxygen reaching the muscles of the heart. Myocardial ischaemia differs from a heart attack in that it is a recoverable deterioration.

neural networks

A method of computation, simulated on the way that the brain processes information.

no ECG

The MHM 100 could not detect a heart rhythm which may be due to a technical fault such as a broken lead.

normal sinus rhythm

A normal heart rhythm.

paroxysmal

Occurring with a sudden onset.

pauses

Delays (of up to 3 seconds) between heartbeats

presyncope

The sensation of lightheadedness and loss of strength that precedes syncope.

PR interval

The section of the heart beat impulse which indicates electrical conduction from the sinoatrial node to the ventricles. The PR interval starts at the beginning of the P wave and ends at the beginning of the QRS complex.

P wave

The section of the heart beat which indicates atrial contraction. The P wave is generally small and upright, and precedes the QRS complex on the ECG. P waves are absent in atrial fibrillation.

QRS complex

The section of the heart beat impulse which indicates ventricular contraction. The QRS complex is generally tall, narrow, and upright, and is normally the easiest waveform to identify on the ECG.

RR interval

The time between two consecutive heart beats, measured from one QRS complex to the next.

RR variability

Variation of rhythm, normally due to autonomic tone.

salvo

A sequence of four to seven ectopic beats one after the other.

second degree heart block

Some, but not all, heartbeats are conducted from the upper chambers to the lower. This may result in decreasing levels of blood being pumped around the body.

second degree heart block (type 1)

is where the pauses between each heartbeat become gradually longer until a beat is skipped entirely. This therefore becomes regularly occurring skipped beats

second degree heart block (type 2)

is where the electrical impulses starting in the aria (upper chambers) are unable to reach the ventricles (lower chambers) because of interference from somewhere below the AV node. This therefore results in decreasing levels of blood being pumped around the body.

sick sinus syndrome

Abnormal heart beat impulse generated by the sinoatrial node, which produces a wide variety of intermittent rapid and slow heart rates.

signal small

The ECG signal is too small to be analysed by the MHM 100.

sinoatrial exit block

The failure to conduct the heart beat from the sinoatrial node to the atria.

sinoatrial node

The hearts natural pacemaker. Contraction impulses normally start in this node, conduct through the atria and are then transmitted to the ventricles.

sinus arrhythmia

A marked change in the heart rate over only a few beats which occurs under normal conditions, usually linked to breathing patterns. Especially prevalent in fit young people.

stroke

A stroke is a brain attack, as opposed to a heart attack. A stroke is what happens when the blood supply to part of the brain is cut off. Without a blood supply, brain cells can be damaged or destroyed and won’t be able to do their job. Damage to the brain will therefore affect body functions. For example, if a stroke damages the part of the brain that controls how limbs move, limb movement will be affected.

ST segment

The section of the heart beat which indicates contracted ventricles. The ST segment immediately follows the QRS complex.

ST segment depression

Movement in the ST segment, which is lower than normal. Abnormal deviations may be seen with intraventricular conduction delays and myocardinal ischaemia.

ST segment depression (non-specific)

Non-specific ST segment depression is depression of the ST segment that is not associated with any or all of the following conditions: ischaemia, injury, myocardial infarction (heart attack), IVCD)

ST segment deviation

Movement in the ST segment, which is lower than normal. Abnormal deviations may be seen with intraventricular conduction delays and myocardial ischaemia.

supraventricular

Situated or occurring above the ventricles, especially in an atrium or atrioventricular node.

syncope

A transient loss of consciousness due to an inadequate blood supply to the brain. This is a possible symptom of arrhythmia.

tachycardia

A fast heart rate. Appropriate tachycardia is a fast heart rate of more than 30 seconds duration between 120 and 180 beats per minute. Appropriate tachycardia is normally associated with periods of exercise. Inappropriate tachycardia is an abnormally fast heart rate.

third degree heart block

otherwise known as complete heart block. Heartbeats are not conducted from the upper chambers to the lower. Because of this block in conduction, the lower chambers are contracting at a much slower rate than normal

transient ischaemic attack

Neurological symptoms caused by a temporary reduction in the supply of oxygen to the brain. These include numbness, paralysis, a difficulty in speaking or swallowing, and loss of vision. All of these can be symptoms of stroke, if sustained.

trigeminy

Two ectopic beats separated by two normal beats.

triplet

Three ectopic beats occurring one after the other.

T wave

The final section of the heart beat, indicating ventricular relaxation. The T wave is generally smaller and wider than the QRS complex.

unifocal

Originating from a single location in the heart.

ventricles

The two lower chambers of the heart.

ventricular ectopics (complex)

Heartbeats originating from within the ventricles in particular patterns. These include trigeminy, bigeminy, couplets, triplets, salvos and episodes

ventricular ectopics (frequent);

A rate of more than one heartbeat originating from the ventricles every two minutes.

ventricular ectopics (infrequent)

A rate of less than one heartbeat originating from the ventricles every two minutes. Infrequent Ventricular Ectopics are common in healthy people and are usually associated with intake of caffeine and alcohol etc.

ventricular ectopics (multifocal)

Heartbeats originating from more than one location within the ventricles

ventricular tachycardia (VT)

A fast, abnormal, and life-threatening rhythm, which is more common in people who have had a myocardial infarction

wide complex tachycardia (WCT)

A sequence of three or more consecutive, ventricular contractions, at a fast rate. In the absence of artefact, this should be considered as ventricular tachycardia.

Wolff-Parkinson-White syndrome

An extra electrical connection inside the heart that acts as a short circuit.