P wave (electrocardiography)

P waveP wavesP-waveelectrical activation of the atria
The P wave on the ECG represents atrial depolarization, which results in atrial contraction, or atrial systole.wikipedia
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Electrocardiography

electrocardiogramECGEKG
The P wave on the ECG represents atrial depolarization, which results in atrial contraction, or atrial systole.
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.

Systole

systolicsystolic pressureventricular systole
The P wave on the ECG represents atrial depolarization, which results in atrial contraction, or atrial systole.
Contraction of the atria follows depolarization, represented by the P wave of the ECG.

Atrial fibrillation

atrial fibrilationparoxysmal atrial fibrillationAtrial fibrillation with rapid ventricular response
If the baseline has a totally irregular form, this suggests fibrillatory waves of atrial fibrillation or possibly artefact; a saw tooth shaped baseline suggests the flutter waves of atrial flutter.
A typical ECG in AF shows no P waves and an irregular ventricular rate.

Multifocal atrial tachycardia

This is taken as evidence of multiple (i.e. at least two) ectopic foci, and is called multifocal (or more correctly, multiform) atrial rhythm if the rate is ≤100) or multifocal atrial tachycardia if the rate is over 100.
'Multiform' simply describes the variable P wave shapes and is an observation, 'multifocal' is an inference about the underlying cause.

Pulmonary heart disease

cor pulmonalecardiopulmonary diseasechronic pulmonary heart disease
Peaked P waves (> 0.25 mV) suggest right atrial enlargement, cor pulmonale, (P pulmonale rhythm), but have a low predictive value (~20%).

PR interval

PRPR-short PR
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.

QRS complex

QRSJ-pointR wave
A Q wave is any downward deflection immediately following the P wave.

Right atrial enlargement

hypertrophied right atriumRightRight atrial hypertrophy
It can also indicate right atrial enlargement.
It is characterized by a P wave height greater than 2.5 mm.

Sinoatrial arrest

Sinus arrest
* Junctional escape (rate 40–60): originates near the AV node; a normal P wave is not seen, may occasionally see a retrograde P wave.

Sinoatrial node

sinus nodeSA nodesinoatrial
Normally the right atrium depolarizes slightly earlier than left atrium since the depolarization wave originates in the sinoatrial node, in the high right atrium and then travels to and through the left atrium.

Bachmann's bundle

The depolarization front is carried through the atria along semi-specialized conduction pathways including Bachmann's bundle resulting in uniform shaped waves.

Hypokalemia

hypokalaemialow blood potassiumhypokalemic
A P wave with increased amplitude can indicate hypokalemia.

Hyperkalemia

high blood potassiumhyperkalaemiahigh blood potassium levels
A P wave with decreased amplitude can indicate hyperkalemia.

Chronic obstructive pulmonary disease

emphysemaCOPDpulmonary emphysema
This appears particularly commonly in exacerbations of chronic obstructive lung disease.

Atrial flutter

flutteratrial flutter (AFl)
If the baseline has a totally irregular form, this suggests fibrillatory waves of atrial fibrillation or possibly artefact; a saw tooth shaped baseline suggests the flutter waves of atrial flutter.

Atrioventricular block

AV blockA-V blockatrio-ventricular blocks
This simultaneous contraction results in the P wave seen in an ECG tracing.

Agonal heart rhythm

Occasional P waves and QRS complexes can be seen on the electrocardiogram.

Sinus rhythm

normal sinus rhythmnormal rhythm(sinus) rhythm
It is characterised by the presence of correctly oriented P waves on the electrocardiogram (ECG).