NSG 303 ATI EXAM REVIEW
P wave
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - indicates firing of SA node
- atrial depolarization
- the atria contract a split second after the P wave begins
- Should be upright (positive deflection) with rounded top in lead II
- No longer than 0.10 sec in length; no higher than 2.5 mm
PR interval
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - measure of time that it takes an electrical impulse
to depolarize the atria and travel to the ventricles
- To measure this interval, start from the beginning of the P wave (where it starts to
leave the baseline) and count the number of small boxes to the beginning of the QRS
complex
- Normal: 0.12 sec (three small boxes) to 0.20 sec (five small boxes) in length
QRS interval
what does it mean?
What is happening during it?
,Normal intervals/size - Answers - - ventricular depolarization
-depolarize from endocardial layer (inside of heart) to epicardial layer (outermost layer)
- QRS complex starts just before ventricular contraction
- the Q wave is always negative
- the R wave is the first positive wave of the complex
- the S wave is the first negative deflection after an R wave
- normal: 0.06-0.10 sec in length
QT interval
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - measure of time that it takes the ventricle to
depolarize and then repolarize
- Start where the QRS leaves baseline and measure to where the T wave returns to
baseline.
- This interval is heart-rate dependent and should never be more than half the distance
from one QRS to the next
- Normal: </= 0.52 sec in length
T wave
what does it mean?
What is happening during it?
, Normal intervals/size - Answers - - ventricular repolarization
- a normal T wave is slightly asymmetric; the peak of the wave is a little closer to its end
than to its beginning
- follows the same direction as QRS interval (+ or -)
U wave
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - Purkinje fiber repolarization
- may or may not occur (rare)
sinus bradycardia (SB) - Answers
- Sinus rhythm (NSR) with rate < 60
sinus tachycardia (ST) - Answers -
P wave
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - indicates firing of SA node
- atrial depolarization
- the atria contract a split second after the P wave begins
- Should be upright (positive deflection) with rounded top in lead II
- No longer than 0.10 sec in length; no higher than 2.5 mm
PR interval
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - measure of time that it takes an electrical impulse
to depolarize the atria and travel to the ventricles
- To measure this interval, start from the beginning of the P wave (where it starts to
leave the baseline) and count the number of small boxes to the beginning of the QRS
complex
- Normal: 0.12 sec (three small boxes) to 0.20 sec (five small boxes) in length
QRS interval
what does it mean?
What is happening during it?
,Normal intervals/size - Answers - - ventricular depolarization
-depolarize from endocardial layer (inside of heart) to epicardial layer (outermost layer)
- QRS complex starts just before ventricular contraction
- the Q wave is always negative
- the R wave is the first positive wave of the complex
- the S wave is the first negative deflection after an R wave
- normal: 0.06-0.10 sec in length
QT interval
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - measure of time that it takes the ventricle to
depolarize and then repolarize
- Start where the QRS leaves baseline and measure to where the T wave returns to
baseline.
- This interval is heart-rate dependent and should never be more than half the distance
from one QRS to the next
- Normal: </= 0.52 sec in length
T wave
what does it mean?
What is happening during it?
, Normal intervals/size - Answers - - ventricular repolarization
- a normal T wave is slightly asymmetric; the peak of the wave is a little closer to its end
than to its beginning
- follows the same direction as QRS interval (+ or -)
U wave
what does it mean?
What is happening during it?
Normal intervals/size - Answers - - Purkinje fiber repolarization
- may or may not occur (rare)
sinus bradycardia (SB) - Answers
- Sinus rhythm (NSR) with rate < 60
sinus tachycardia (ST) - Answers -
