Electrocardiography

electrocardiogramECGelectrocardiographEKGelectrocardiogramselectrocardiographicECG monitorECGsheart monitorprecordial lead
Electrocardiography (ECG or EKG) is the process of recording the electrical activity of the heart over a period of time using electrodes placed over the skin.wikipedia
934 Related Articles

T wave

T-waveTT' wave
There are three main components to an ECG: the P wave, which represents the depolarization of the atria; the QRS complex, which represents the depolarization of the ventricles; and the T wave, which represents the repolarization of the ventricles.
In electrocardiography, the T wave represents the repolarization of the ventricles.

P wave (electrocardiography)

P waveP wavesP-wave
There are three main components to an ECG: the P wave, which represents the depolarization of the atria; the QRS complex, which represents the depolarization of the ventricles; and the T wave, which represents the repolarization of the ventricles.
The P wave in the ECG represents atrial depolarization, which results in atrial contraction, or atrial systole.

Electrophysiology

electrophysiologicalelectrophysiologistelectrophysiologic
These electrodes detect the tiny electrical changes on the skin that arise from the heart muscle's electrophysiologic pattern of depolarizing and repolarizing during each heartbeat.

Cardiology

cardiologistcardiologistscardiovascular medicine
ECG interpretation is a component of many healthcare fields (nurses and physicians and cardiac surgeons being the most obvious), but anyone trained to interpret an ECG is free to do so.However, "official" interpretation is performed by a cardiologist.
These studies are performed to assess complex arrhythmias, elucidate symptoms, evaluate abnormal electrocardiograms, assess risk of developing arrhythmias in the future, and design treatment.

Drug-induced QT prolongation

QT interval prolongationQT prolongationdrugs that prolong the QT interval
Monitoring the effects of a medication on the heart (e.g. drug-induced QT prolongation)
Drug-induced QT prolongation is seen with a QT interval above 450 ms on the ECG and is usually a result of treatment by anti-arrhythmic drugs, such as amiodarone and sotalol, or a number of other drugs that have been reported to cause this problem (e.g., cisapride).

Coronary artery disease

coronary heart diseaseischemic heart diseaseischaemic heart disease
The United States Preventive Services Task Force does not recommend an ECG for routine screening in patients without symptoms and those at low risk for coronary artery disease.
A number of tests may help with diagnoses including: electrocardiogram, cardiac stress testing, coronary computed tomographic angiography, and coronary angiogram, among others.

Hyperkalemia

high blood potassiumhyperkalaemiahigh blood potassium levels
Assessing severity of electrolyte abnormalities, such as hyperkalemia
High levels can also be detected on an electrocardiogram (ECG).

Shortness of breath

dyspnearespiratory distressdyspnoea
Suspected pulmonary embolism or shortness of breath
An electrocardiogram and cardiac enzymes are important both for diagnosis and directing treatment.

PR interval

PRPR-
Included in this analysis is computation of common parameters that include PR interval, QT interval, corrected QT (QTc) interval, PR axis, QRS axis, and more.
In electrocardiography, the PR interval is the period, measured in milliseconds, that extends from the beginning of the P wave (the onset of atrial depolarization) until the beginning of the QRS complex (the onset of ventricular depolarization); it is normally between 120 and 200ms in duration.

Hypertrophic cardiomyopathy

hypertrophic obstructive cardiomyopathyAsymmetric septal hypertrophyHCM
Hypertrophic cardiomyopathy screening in adolescents as part of a sports physical out of concern for sudden cardiac death (varies by country)
Diagnosis often involves an electrocardiogram, echocardiogram, and stress testing.

Cardiac stress test

stress testexercise stress testcardiac stress tests
Cardiac stress testing
To measure the heart's response to the stress the patient may be connected to an electrocardiogram (ECG); in this case the test is most commonly called a cardiac stress test but is known by other names, such as exercise testing, stress testing treadmills, exercise tolerance test, stress test or stress test ECG.

Artificial cardiac pacemaker

pacemakerpacemakersartificial pacemaker
Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the heart chambers, the presence of any damage to the heart's muscle cells or conduction system, the effects of heart drugs, and the function of implanted pacemakers. Biotelemetry of patients for any of the above reasons and such monitoring can include internal and external defibrillators and pacemakers
The rescuer selects the pacing rate, and gradually increases the pacing current (measured in mA) until electrical capture (characterized by a wide QRS complex with a tall, broad T wave on the ECG) is achieved, with a corresponding pulse.

Cardiac cycle

heartbeatheart beatventricular systole
These electrodes detect the tiny electrical changes on the skin that arise from the heart muscle's electrophysiologic pattern of depolarizing and repolarizing during each heartbeat.
In an electrocardiogram, electrical systole initiates the atrial systole at the P wave deflection of a steady signal; and it starts contractions (systole) of the ventricles at the Q deflection of the QRS complex.

Syncope (medicine)

syncopefaintingfaint
Fainting or collapse
A medical history, physical examination, and electrocardiogram (ECG) are the most effective ways to figure out the underlying cause.

Electrode

electrodescathodemicroelectrode
Electrocardiography (ECG or EKG) is the process of recording the electrical activity of the heart over a period of time using electrodes placed over the skin.
Electrodes for medical purposes, such as EEG (for recording brain activity), ECG (recording heart beats), ECT (electrical brain stimulation), defibrillator (recording and delivering cardiac stimulation)

Clinical cardiac electrophysiology

Electrophysiological interventionselectrophysiology
One additional form of ECG is used in clinical cardiac electrophysiology in which a catheter is used to measure the electrical activity.
These studies are performed to assess arrhythmias, elucidate symptoms, evaluate abnormal electrocardiograms, assess risk of developing arrhythmias in the future, and design treatment.

Driven right leg circuit

right leg driver
Additionally circuitry called the right leg driver can be used to reduce common-mode interference (typically the 50 or 60 Hz mains power).
Biological signal amplifiers such as ECG (Electrocardiogram) EEG (Electroencephalogram) or EMG circuits measure very small electrical signals emitted by the body, often as small as several micro-volts (millionths of a volt).

Defibrillation

defibrillatordefibrillatorsdefibrillate
Biotelemetry of patients for any of the above reasons and such monitoring can include internal and external defibrillators and pacemakers
They are used in conjunction with an electrocardiogram, which can be separate or built-in.

Einthoven's triangle

The limb leads form the points of what is known as Einthoven's triangle.
Einthoven's triangle is an imaginary formation of three limb leads in a triangle used in electrocardiography, formed by the two shoulders and the pubis.

Non-invasive procedure

non-invasivenoninvasivenon-invasive diagnosing
The graph of voltage versus time produced by this noninvasive medical procedure is an electrocardiogram.
Electrocardiography (EKG)

Atrial flutter

flutteratrial flutter (AFl)
An esophageal lead avails for a more accurate differentiation between certain cardiac arrhythmias, particularly atrial flutter, AV nodal reentrant tachycardia and orthodromic atrioventricular reentrant tachycardia.
Atrial flutter is characterized by a sudden-onset (usually) regular abnormal heart rhythm on an electrocardiogram (ECG) in which the heart rate is fast.

Pulseless electrical activity

electromechanical dissociationPEApulseless electrical activity (PEA)
An ECG does not equate with mechanical pumping activity of the heart, for example, pulseless electrical activity produces an ECG that should pump blood but no pulses are felt (and constitutes a medical emergency and CPR should be performed).
Pulseless electrical activity (PEA), also known as electromechanical dissociation, refers to cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not.

Heart

cardiachuman heartapex of the heart
Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the heart chambers, the presence of any damage to the heart's muscle cells or conduction system, the effects of heart drugs, and the function of implanted pacemakers. Electrocardiography (ECG or EKG) is the process of recording the electrical activity of the heart over a period of time using electrodes placed over the skin.
Diagnosis of heart disease is often done by the taking of a medical history, listening to the heart-sounds with a stethoscope, ECG, and ultrasound.

Echocardiography

echocardiogramechocardiographicultrasound of the heart
Ultimately, an echocardiogram or other anatomical imaging modality is useful in assessing the mechanical function of the heart.
(It is not abbreviated as ECG, because that is an abbreviation for an electrocardiogram.) Echocardiography uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart.

Lewis lead

A Lewis lead (requiring an electrode at the right sternal border in the second intercostal space) can be used to study pathological rhythms arising in the right atrium.
A Lewis Lead (also called the S5 lead) is a modified ECG lead used to detect atrial flutter waves when atrial flutter is suspected clinically, based on signs and symptoms, but is not definitely demonstrated on the standard 12 lead ECG.