What is a PR interval on ECG?
What is a PR interval on ECG?
The PR interval incorporates the time from the depolarization of the sinus node to the onset of ventricular depolarization. The measurement starts from the beginning of the P wave to the first part of the QRS complex, with a normal duration between 0.12 to 0.20 seconds.
What does the PR interval represent?
The PR interval is the time from the beginning of the P wave (atrial depolarization) to the beginning of the QRS complex (ventricular depolarization). The normal PR interval measures 0.12-0.20 seconds (120-200 milliseconds). A prolonged or shortened PR interval can indicate certain disease.
What is the PR segment on ECG?
The PR segment is the portion of the ECG from the end of the P wave to the beginning of the QRS complex. The PR segment is different from the PR interval, which is measured in units of time. Remember that segments are different than intervals.
What does short PR interval on ECG mean?
A short PR interval (of less than 120ms) may be associated with a Pre-excitation syndromes such as Wolff–Parkinson–White syndrome or Lown–Ganong–Levine syndrome, and also junctional arrhythmia like atrioventricular reentrant tachycardia or junctional rhythm.
Why is the PR interval important?
The PR interval stretches from the onset of the P-wave to the onset of the QRS complex. It reflects the time interval from start of atrial activation (depolarization) to start of ventricular activation (depolarization). The PR interval reflects whether impulse conduction from the atria to the ventricles is normal.
What happens during PR interval?
The PR Interval is the time, in seconds, from the beginning of the P wave to the beginning of the QRS complex. The electrical signal passes from the atria to the ventricles through the atrioventricular (AV) node (2). The signal slows down as it passes through this node, allowing the ventricles to fill with blood.
What causes PR interval change?
Note that the PR interval can be altered by changing sympathetic and parasympathetic tone. Because of this, medications such as beta-blockers can lengthen the PR interval and result in a first-degree AV block. Also, a longer PR interval can cause the first heart sound (S1) to sound soft on examination, and vice versa.
What occurs in the PR segment?
The PR segment represents the electrical conduction through the atria and the delay of the electrical impulse in the atrioventricular node. After the signal leaves the AV node it travels along a pathway called the bundle of His (3) and into the right and left bundle branches (4, 5).