EKGs Flashcards
Is depolarization a process or a state?
Process
What is an EKG electrode detecting?
The flow of current
True or false: an EKG electrode will not show anything, unless there is a change in the membrane potential/ a flow of current
True
Positive charges moving toward an electrode produces what change on the EKG (rise above isoelectric line or drop below)?
Rises above
What is the P wave a result of?
Atrial myocyte depolarization
Where does depolarization begin for each heart beat?
In the SA node
Which wave on an EKG recording represents the SA node depolarizing?
There is none–too small to detect
What does the Q wave represent (if present)?
Septal depolarization
What is the first downward deflection of an EKG recording after the P wave? Is it alway present?
Q wave, not always there
What is the first upward deflection of an EKG recording after the P wave? Is it alway present?
R wave, should always be there
What is the first downward deflection of an EKG recording after the R wave? Is it alway present?
S wave, may be present
What does the R wave represent?
Ventricular muscle depolarization
What does the T wave represent?
Repolarization of the Ventricles
Which part of the EKG recording represents atrial repolarization?
There is none–hidden in the R wave
What is occurring in the atrial muscles between the P wave and the Q wave?
Ca influx into the atrial myocytes, maintaining the depolarization
What is happening to the AP between the P wave and the Q wave?
Going through the Purkinje fibers
What does the S wave represent?
Ventricular muscle depolarization away from the electrode
What does the ST segment represent relative to the ventricular myocytes?
Plateau of the AP d/t Ca influx
What is the chart speed of EKG paper?
25 mm/min
10 mm on the EKG paper corresponds to what mV?
1 mV
5 small boxes on EKG paper represent how many seconds?
0.2 seconds
5 large boxes (25 small boxes) on EKG paper represents what amount of time?
1 second
What is the interval between the beginning of the P wave, and the Q/R wave (whichever is present)?
PR interval
What is the interval between the end of the S (or R) wave, and the beginning of the T wave?
ST segment
What is the QRS interval?
Time between onset of the Q wave, to the end of the S wave
What is the QT interval?
Time between the onset of the Q wave, and the end of the T wave
What is the normal duration for the P wave?
1-2 small boxes
What is the normal duration of the PR interval?
3-5 small boxes
What is the normal duration of the QRS complex?
<1 to 3 small boxes
What is the normal duration of the ST segment?
Roughly half of R-R interval
What is the normal duration of the QT interval?
Variable (with HR)
What are the precordial leads?
V1, V2, V3, V4, V5, V6
What are the limb leads?
I, II, & III
What are the three augmented lead?
aVR, aVL, aVF