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68 Cards in this Set

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A wave of depolarization traveling towards a positive EKG electrode causes a _ deflection on paper
UPWARD
A wave of depolarization traveling away from positive electrode causes a _ deflection on paper
DOWNWARD
A wave of repolarization traveling towards a positive EKG electrode causes _ deflection on paper
DOWNWARD
A wave of repolarization traveling away from a positive EKG electrode causes a _ deflection on paper
UPWARD
What is the difference between segment and interval?
In electrocardiography, an interval includes at least one of the waves that it is named after, whereas a segment does not. In other words, a segment is simply a section of baseline which is between the waves that it is named after
Which segment on EKG represents plateau phase of repolarizaton
ST
In normal heart rate what is longer systole or diastole
Diastole
Where is ventricular systole on EKG
Begins at QRS complex and ends at the end of T wave
Where on EKG is early ventricular diastole
Between the end of T wave to beginning of P wave
Where on EG is late ventricular diastole
From beginning of P wave to the beginning of QRS complex
Is atrial repolarization seen on EKG
No
What is the physiological event behind U wave
Repolarization of Purkinje fibers, Purkinje fibers depolarize very fast but repolarize very slowly which causes U wave
The vertical axis of the tracing represents ?
Voltage
The horizontal axis of the tracing represents?
Time
At standard calibration, 1 mm = voltage?
0.1 mV
Standard paper speed of EKG
25 mm/sec
1 mm = how many seconds?
0.04 sec = 40 msec
horizontal distance between consecutive bold lines on an EKG represents how many seconds
0.2 sec = 1/5 sec = 1/300 min
the heart rate (the number of beats per minute) equals ?
300 divided by the number of “big blocks” between consecutive beats on a standard EKG tracing

ONLY FOR REGULAR RHYTHMS
For exceptionally slow heart rates or irregular rhythms, how do you determine heart rate
the 3 second interval marks may be used to determine heart rate.

Simply count the number of cardiac cycles (R-to-R intervals) over 2 consecutive 3 second intervals, and then multiply this number by 10 in order to determine the heart rate in beats per minute
Name 6 limb leads
I, II, III, avf, avl, avr
6 limb leads allow determination of axis in _ plane
FRONTAL
6 precordial chest leads (V1-V6) allow determination of axis in _ plane
HORIZONTAL
Bipolar limb lead means?
Each has 1 positive and 1 negative electrode
Augmented unipolar limb lead means?
Each has 1 positive electrode and 1 compound reference electrode (sum of the other 2)
Right arm - Left arm - which lead? Which electrode positive?
Lead I

Left arm
Right arm - left leg - which lead?

Which electrode positive
Lead II

Left leg
Left arm - left leg - which lead?

WHich electrode positive?
Lead III

Left leg
Which leads are lateral
I and avL
Which leads are inferior
II, III, avf
Where is normal QRS vector located on axis
Between 0 and 90, down and to the left
-30 --> + 150 axis - which lead
AVL
0--> + 180 axis - which lead
I
+ 30--> -150 axis - which lead

Is it positive or negative
Avr

negative
+ 60 --> - 120 axis --> which lead
LEAD ii
+ 90 --> - 90 AXIS --> WHICH LEAD
avF
+ 120--> -60 which lead
Lead III
Negative lead I

Negative aVf

Deviation?
Extreme right axis deviation
Positive in I

Negative in avF

Deviation
Left axis deviation
Positive lead I

Positive lead avF

Deviation
Normal
Negative lead I

Positive lead avF

Deviation?
Right axis deviation
What is the difference between devitation and rotation for axis in EKG
Deviation = frontal plane

Rotation = horizontal plane
If the change from negative to positive in precordial leads happens after V 4 (V5, V6, or never) - what type of rotation
Leftward axis rotation
If the change from neg to pos in precordial leads happens at V1 or V2 - what type of rotation
Rightward axis rotation
If the change from - to + in precordial chest leads happens after V 2 and at or before V4 - what type of rotation?
NO rotation, normal
If axis in precordial leads starts positive and stays positive - what type of rotation
Rightward axis
If axis in precordial leads start positive and ends positive - what type of rotation
Leftward axis
If axis in precordial leads starts positive and becomes negative by V6 = what type of rotation
Leftward axis
-QRS axis between –45 and –90 degrees
-QRS duration < 120 msec (unless associated with RBBB)
-Small Q waves in I and aVL
-rS patterns in II, III, and aVF
Left anterior fascicular block
QRS axis +120 degrees or greater
QRS duration < 120 msec (unless associated with RBBB)
Small Q waves in II, III, and aVF
RS patterns in I and aVL
Exclusion of other causes of RAD
Lateral wall MI
RVH
Left positerior fascicular block
Ability of specialized cells to spontaneously generate electrical impulses which may then spread throughout surrounding tissue
Automaticity
Potential pacemakers within the heart are also called
Automaticity foci
Rate for atrial automaticity foci
60-80
Rate for junctional (AV nodal) foci
40-60
Rate for ventricular foci
20-40
The pacemaker with the fastest rate is the dominant pacemaker - this is called _
Overdrive suppression
A protective mechanism whereby an automaticity focus with the next highest inherent rate begins pacing in the event of a pause or cessation of pacing activity of the previously dominant pacemaker
Escape
Transient escape of an automaticity focus (from overdrive suppression) to generate one beat.
This occurs when there is a pause in pacing activity in the previously dominant pacemaker.
Escape beat
Escape of an automaticity focus (from overdrive suppression) with subsequent pacing by that automaticity focus, at its inherent rate.
This occurs when there is a cessation (or arrest) of pacing activity in the previously dominant pacemaker
Escape rhythm
Escape beat occurs when _ while escape rhythm occurs when _
Escape beat = pause in present pacemaer

Escape rhythm = cessation of present pacemaker
Give EKG criteria for sinus rhythm
Each QRS complex is preceded by a P wave.

The P waves must be positive in lead II, and negative in lead aVR
EKG criteria for normal sinus rhythm
Sinus rhythm with a heart rate between 60 and 100 beats per minute
EKG criteria for sinus bradycardia
Sinus rhythm with a heart rate less than 60 beats per minute
EKG criteria for sinus tachycardia
Sinus rhythm with a heart rate greater than 100 beats per minute
EKG criteria for sinus arrhythmia
Same criteria as sinus rhythm and there is greater than 0.16 sec. difference between the shortest and the longest PP intervals within the same EKG tracing
Heart rate increases with inspiration or expiration
Inspiration
Most common cause of sinus arrhythmia
Most common cause is respiration
Heart rate increases with inspiration and decreases with expiration (due to changes in vagal tone during respiration)
The key to determining the origin of a completely inverted P wave in lead II is the
Length of PR interval (provided there is no AV nodal dysfunction)