ECG Flashcards
an ECG waveform that
moves toward the top of the paper
Positive Deflection
ECG waveform that
moves toward the bottom of the paper
Negative Deflection
Flat Wave
Isoelectric
Represents atrial depolarization
P Wave
Characteristics:
• Round
• Smooth positive deflection
• 0.11 seconds or less in
duration
P Wave
Results from the firing of the SA
node
P Wave
Represents atrial depolarization
AND impulse delay through the
AV junction
• Normal:
• 0.12 to 0.20 seconds (3-5
small boxes)
PR Interval
Measures the beginning of the P
wave to the beginning of the
QRS complex
PR Interval
Represents ventricular depolarization
• Q wave- first negative deflection
after P wave
• R wave- first positive deflection
after P wave
• S wave- first negative deflection
after R wave
• Normal: < 12 seconds (< 3 small
boxes)
QRS Complex
Represents early repolarization
of the ventricles
ST segment
Begins at the end of the QRS
complex and ends at the
beginning of the T wave
• Normal:
• Isoelectric
ST Segment
Represents ventricular
repolarization
• Normal:
• Rounded
• Deflected in the same way as
the preceding QRS complex
T Wave
Steps in Analyzing the
ECG Strip
Determine the heart rhythm
• Measure the heart rate
• Examine the P waves
• Examine the P:QRS ratio
• Measure the PR interval
• Examine the QRS complex
• Interpret the rhythm
originates from SA Node)
• Positively deflected and round
• Similar in shape and size
• Occurs regularly
Sinus
(originates from an irritable atrial foci)
• Differently shaped P waves
Atrial