P wave

Speeds_of_seismic_waves.svg

P wave

The P wave is a type of electrical wave that is observed in the electrocardiogram (ECG or EKG) of the heart. It represents the depolarization of the atria, which are the two upper chambers of the heart. The P wave is an essential component in the analysis of cardiac rhythm and heart function.

Characteristics

The P wave is typically a small, positive deflection in the ECG tracing. It precedes the QRS complex, which represents the depolarization of the ventricles. The normal duration of the P wave is less than 120 milliseconds, and its amplitude is usually less than 2.5 millimeters.

Physiological Significance

The P wave is generated by the electrical activity that originates in the sinoatrial node (SA node), which is located in the right atrium. This electrical impulse spreads through the atria, causing them to contract and push blood into the ventricles. The proper functioning of the P wave is crucial for the coordinated contraction of the heart and efficient blood flow.

Clinical Importance

Abnormalities in the P wave can indicate various cardiac conditions. For example:

• A prolonged P wave may suggest atrial enlargement.
• A notched P wave can be a sign of left atrial enlargement.
• An absent P wave may indicate atrial fibrillation or sinoatrial block.

Related Terms

• QRS complex
• T wave
• Electrocardiogram
• Atrial depolarization
• Sinoatrial node
• Atrial fibrillation
• Cardiac rhythm

See Also

• Heart
• Cardiology
• Electrophysiology
• Cardiac cycle