ECG Part I Flashcards
The P Wave indicates ____ depolarization before atrial contraction
atria
The QRS complex indicates when the ____ depolarize before contraction
ventricles
The T Wave indicates when the ____ recover from the state of depolarization
ventricles
Flow of Electrical Currents moves from the ___ node to the __ node to the ____
SA –> AV –> Septum
Where is Lead I placed?
on the left arm
Where is Lead II placed?
on the right arm
Where is Lead III placed?
on the left foot
What do the 3 leads create?
Einthoven’s Triangle
Lead __ Potential + Lead __ Potential = Lead __ Potential
1 + 3 = 2
Where do you place V1?
4th intercostal space on the RIGHT side
Where do you place V2?
4th intercostal space on the LEFT side
Where do you place V6?
Mid-axillary line/armpit space in the 5th intercostal space on the LEFT side
AVL creates a ____ deflection, AVF creates a ___ deflection (down & left) and AVR creates a large ___ deflection due to a ___ vector vantage point
positive
positive
negative
positive
When examining an ECG, what are the main components to identify? (4)
- Rhythm
- PR interval
- QRS Axis & Morphology
- ST Segment depression & elevation
Each tiny square on an ECG indicates how many seconds?
0.4s
If the R-R interval is 1 second, what is the HR?
60bpm
The normal R-R interval is 0.83s which is a HR of 60/0.83s or ___bpm
72bpm
What are the 3 methods of determining HR?
- 1500 boxes = 60s; count the number of small boxes and divide from 1500 (ex: 23 boxes: 1500/23 = 65bpm)
- Countdown Method (1 large box = 300bpm, 2” = 150bpm, 3” = 75bpm, 4” = 60bpm, 5” = 50bpm and 6” = 43bpm)
- 10s Intervals = count number of R complexes and multiply by 6 –> this method accounts for the irregularity in the heart beat (more accurate)
Describe the normal pathway for cardiac conduction
- __ –> 2. __ –> 3. __ –> 4. ___ (split A or B)
A split: 5.__ –> 6.__
B split: 5. __ –> C, D, E splits
C split: 6.___
D split: 6. ___ –> 7. ____
E split: 6. ___ –> 7. ____
- SA node
- Atria
- AV node
- BUNDLE OF HIS
A split: Bundle of His –> Right Bundle Branch –> RIGHT VENTRICLE!
B split: Bundle of His –> Left Bundle Branch –> C, D, E
C split: Left Bundle Branch –> Septum
D split: Left Bundle Branch –> Left Posterior Fascicle –> LEFT VENTRICLE!
E split: Left Bundle Branch –> Left Anterior Fascicle –> LEFT VENTRICLE!
If electricity goes TOWARD a lead, it creates a ____ deflection whereas if it goes AWAY from a lead it creates a _____ deflection
positive; negative
Only what kind of leads will tell you cardiac axis?
limb leads
Bipolar Leads are __, ___, ___
Augmented Unipolar Leads are ___, ___, ___
I, II, III
aVR, aVL and aVF
What are the 3 methods for determining the cardiac axis?
- Determining Quadrant
- Getting approx. number on hexaxial reference system
- Getting exact number on hexaxial reference system
What is the Hexaxial reference system? What plane is it in?
diagram that is used to determine the heart’s electrical axis in the frontal plane.
Diagram showing how the polarity of the QRS complex in leads I, II, and III can be used to estimate the heart’s electrical axis in the frontal plane.
5 steps for the Hexaxial method:
- Determine the ____ lead
- Find the lead on the ____
- Find the _____ lead
- Determine if it is ___ or ___
- Find your ___
equiphasic diagram perpendicular positive/negative axis
Axis Deviations:
- -90 to 180: ____
- 90 to 180: ____
- -30 to -90: ____
ERAD
Right Axis Deviation
Pathological Left Axis Deviation
Transition of R wave:
- Early Transition: ____ rotation
- Late Transition: ____ rotation
counterclockwise
clockwise
Bundle Branch Blocks (BBB) include a QRS complex that is generally ____ (>120ms), P waves with a ____ rhythm or no P waves at all with a ____ rhythm and ___ elevation being normal with a LBBB
wide
supraventricular
ventricular
ST
RBBB is a conduction delay thru the right ventricle:
- ___ septal depolarization
- ___ left ventricular depolarization
- ____ right ventricular depolarization
- ____ R waves OR __ QRS phenomen
normal
normal
delayed
double; 2
In RBBB, the QRS morphology is altered:
- V1 and V2 show an ___ R wave progression, “_____” or RSR, and a ___ QRS complex
- Slurred __ wave in the ___ leads (I, aVL, V5 & V6)
Early
Rabbit Ears
Wide
S
Lateral
LBBB is a conduction delay thru the left ventricle:
- Septum will depolarize ____ from right to left
- ____ right ventricular depolarization
- ____ left ventricular depolarization
- ____ R waves or ___ QRS phenomenon that is not always as easily seen
abnormally
normally
delayed
double; wide
In LBBB, the QRS morphology is altered:
- V1 and V2 show an ___ and ___ RS pattern, a wide and upright __ pattern or RSR prime pattern in lateral leads (__________)
- NO _ wave in lateral leads (___)
deep; wide
RS
1, aVL, V5, V6
q
1, aVL, V5, V6
Take-aways from ECG I (6)
- Depolarization and Repolarization of ECG signal
- Identifying normal wave intervals (P-R, QRS complex, Q-T, etc)
- Determine HR from ECG
- Vectors of the conduction signal determine if ECG lead is positive or negative
- Bipolar leads and unipolar leads determine the cardiac axis
- Understanding R-wave progression can provide insite on left/right ventricular pathologies
