ECG Flashcards
P-R Interval
.12-.20 seconds, 3-5 small boxes
The time from the beginning of atrial activation to the beginning of ventricular activation Measured from the point where the P wave leaves the baseline to the beginning of the QRS complex.
P Wave
Atrial depolarization and the spread of electrical impulses throughout the L and R atria
This precedes each QRS complex
P wave
Why is a waveform representing atrial repolatization not seen on the ECG
It is buried in the QRS complex
QRS Complex
Spread of the electrical impulse through the ventricles= ventricular depolarization, triggering contraction of the ventricles
Why is the QRS complex bigger then the P wave?
QRS is significantly larger than the P wave b/c depolarization of the vents involves a considerably greater muscle mass
T wave
Ventricular Repolarization, the absolute refractory period is still present during the beginning of the T wave, the normal T wave is slightly asymmetric, return of K inward and Na outward (change in polarization of the cell)
What is an interval
It includes the waveform and the segment
Time in between small squares (1mm) on the ECG paper
.04 sec
Time in between each large square (5mm) on the ECG paper
.2 sec
15 boxes = how many seconds
3 seconds
Normal time and box count for PR interval
.12-.2 seconds or 3-5 little boxes
Normal time and box count for QRS Complex
.06-.10 seconds or 1.5-2.5 little boxes
ST segment
Slight pause after QRS complex, between QRS and T wave, normally flat segment of isoelectic line
QT interval
Measure from the beginning of the Q wave to the end of the T wave. Normally about .32-.40 seconds or 8-10 little boxes
What is abnormal deviation of the ST segment
.5mm from baseline
Longer the QT interval the increased risk for what?
arrhythmia