6: EKG Waveforms Flashcards
Vertical axis of an EKG is _____.
Vertical axis of an EKG is voltage in millivolts (mV).
Horizontal axis of an EKG is _____.
Horizontal axis of an EKG is time in milliseconds (msec).
Each small box of an EKG represents _____.
Each small box of an EKG represents 0.04 seconds.
Each large box of an EKG represents _____.
Each large box of an EKG represents 0.20 seconds.
5 large boxes of an EKG represents _____.
5 large boxes of an EKG represents 1 second.
We measure an impulse traveling between a _____ and a _____ electrode.
We measure an impulse traveling between a positive and a negative electrode.
Impulse moving towards positive electrode = _____ deflection on graph.
Impulse moving towards positive electrode = positive deflection on graph.
Impulse moving towards negative electrode = _____ deflection on graph.
Impulse moving towards negative electrode = negative deflection on graph.
The more directly an impulse heads toward a positive lead, the _____ it will be on the graph.
The more directly an impulse heads toward a positive lead, the higher it will be on the graph.
The more directly an impulse heads away from a positive lead, the _____ it will be on the graph.
The more directly an impulse heads away from a positive lead, the lower (more negative) it will be on the graph.
T/F EKGs can diagnose arrhythmias and other cardiac abnormalities.
False. An EGK can only diagnose arrhythmias, though it can suggest other abnormalities.
What is the sequence of how the standard measurements of an EKG are written?
PR/QRS/QT
.12/.08/.40 for example
Represents time it takes for an impulse to spread through the atria, AV node, and bundle of His.
PR Interval
From beginning of P wave to beginning of QRS complex.
PR Interval
Normal PR Interval.
0.12-0.20 seconds (3-5 small squares)
Starts with deflection away from PR interval, continues to end of QRS complex (J point).
QRS Interval
Represents the time taken for an impulse to spread down the bundle branches and Purkinje fibers through the ventricles
QRS Interval
Normal QRS Interval.
0.04-0.12 (1-3 small squares)
T/F Every QRS complex must have a Q, R, and S wave.
False
The initial negative deflection in the QRS Interval.
Q Wave
The first positive deflection in a QRS Interval.
R Wave
Any subsequent negative deflection in a QRS Interval.
S Wave
Represents the entire time taken for electrical depolarization and repolarization of the ventricles.
QT Interval
Starts at the beginning of the QRS complex (same as the end point for PR) and continues to the end of the T wave.
QT Interval
The QTc (or QT corrected) corrects QT interval for _____.
The QTc (or QT corrected) corrects QT interval for heart rate.
T/F Fluctuation of heart rate makes comparison of one QT to another useless; QTc corrects for these changes.
True
The _____ the heart rate, the shorter the QT Interval.
The faster the heart rate, the shorter the QT Interval.
Normal QT Interval.
Less than 0.44 seconds (less than approximately 2.5 large boxes).
Represents depolarization of the atria (which hopefully leads to contraction of the atria).
P Wave
Represents depolarization of the ventricles (which hopefully leads to ventricular contraction).
QRS Complex
Represents repolarization of the ventricles.
T Wave
T/F Repolarization of the atria is not seen on an EKG.
True. It either happens during the QRS Complex or the voltage is so little it does not show up.
Represents absolute refractory period.
End of QRS Complex to the beginning of T Wave
Represents relative refractory period.
Part of T Wave to beginning of new P Wave
The period immediately following the firing of a nerve fiber where it cannot be stimulated no matter how great a stimulus is applied.
Absolute Refractory Period
A stronger than normal stimulus is needed to elicit nueronal excitation.
Relative Refractory Period
Cardiac pathway of electrical impulse.
Sinus Node - Internodal Pathways - AV Node - Bundle of His - Left and Right Bundle Branches - Purkinje Fibers
Falls between the QRS Complex and T Wave.
ST Segment
These, if present, are often confused with P Waves.
U Wave
Thought to represent repolarization of the Purkinje fibers.
U Wave
A slurred upstroke in the QRS complex often associated with a short PR Interval.
Delta Wave
