PR, ST, QT

The PR interval measures the time from the start of atrial depolarizationto the start of ventricular depolarization.  The PR interval includes the P wave and the straight line connecting it to the QRS complex. 
The ST segment measures the time from the end of ventricular depolarization to the start of ventricular repolarization.  The ST segment is the straight line connecting the end of the QRS complex with the beginning of the T wave.
The QT interval measures the time from the beginning of ventricular depolarization to the end of ventricular repolarization.  The QT interval includes the QRS complex, the ST segment, and the Twave.
Why are these intervals and segments important?  Please take time to review some of the videos provided in the blog header to understand these important elements of an EKG.  Please review the following site for more info. 
http://www.nottingham.ac.uk/nursing/practice/resources/cardiology/function/normal_duration.php

PQRST an electrical event

An EKG is an electrical waveform recording that records each cardiac cycle of contraction (systole) and relaxation (diastole).  These electrical events are what produce the basic waves and lines of the standard EKG.  Please see below.  The P wave is produced by atrial contraction or depolarization represented by the upward curve of the image below.  The QRS is produced by ventricular contraction or depolarization which is represented by the next wave which may have several variations.  This electrical waveform begins with a downward deflection or the Q wave, the next and first upward deflection or the R wave, and the next downward deflection after the upward deflection is called the S wave.  The T wave is the electrical representation of the ventricles end of depolarization and the start of ventricular repolarization or relaxation. 

 



Notice in the EKG strip on the right the locations of the PQRST.  For more information on the background of the PQRST and their meaning on the EKG please read http://www.edinformatics.com/inventions_inventors/electrocardiogram.htm

EKG: A tool with remarkable clinical power

- An EKG reading can diagnose an evolving heart attack, identify life threatening arrhythmias, effects of a pulmonary embolus or blood clot in the lungs, or just a normal heart that functions and beat properly.

- Come learn with me how to read EKGs.  They are easy to read, fun to interpret and can carry BIG meaning behind their readings. 

- Do you know the heart gives off electricity and what that electricity helps with?
- Do you know what the letters PQRST mean?