EKG Flashcards
Describe the conduction state of cardiac cells during Resting Membrane Potential, Depolarization and Repolarization?
RMP: Polarized
- *Depolarization:**
- Stimulus - Action Potential - Cell to Cell
- Polarity Reverses due to ionic fluxes (Ca++, Na+, K+)
- *Repolarization**:
- Cells return to resting state
What are the five phases of the Cardiac Action Potential?
4 - 0 - 1 - 2 - 3
Phase 4: Resting State
Phase 0: Rapid Depolarization
Phase 1: Initial Repolarization
Phase 2: Plateau phase of Repolarization
Phase 3: Final Repolarization
What is the resting membrane potential of the cardiac muscle?
-90 mV
Action Potential is due to fluxes in which ions?
Sodium, Potassium and Calcium
What is the normal electrical pathway of the heart ?
- Sinoatrial Node (SA)
- Atrioventricular Node (AV)
- Common Bundle (His)
- Bundle Branches:
- Left Anterior Fasicle
- Left Posterior Fasicle
- Right Bundle Branch - Purkinje Fibers
What is the polarization rate of the Sinoatrial Node?
60-100/min
What is the polarization rate of the AV Node?
40-60/min
What is the polarization rate of the Ventricle?
20-40/min
What are the seven steps of the cardiac depolarization sequence?
- Sinoatrial Node (SA)
- R & L Atrium
- Atrioventricular Node (AV)
- Common Bundle (His)
- Bundle Branches:
- Left Anterior Fasicle
- Left Posterior Fasicle
- Right Bundle Branch - Purkinje Fibers
- Myocardium
How does the septum depolarize?
From Left to Right
What is a Monophasic Waveform?
A complex all positive or all negative waveform
What is a Biphasic Waveform?
A complex waveform with both positive and negative deflections
What is a Triphasic Waveform?
Three deflections. e.g. rsR’
What is an Isoelectric or “equiphasic” Waveform?
A waveform where positive and negative (or vice versa) follow one another and are of equal deflection.
What makes a waveform a positive complex?
If the electrical current is traveling towards an EKG lead
What makes a waveform a negative complex?
If the electrical current is traveling away from an EKG lead
What makes a waveform a Biphasic complex?
If the electrical current is traveling perpendicular to an EKG lead
What is R’ called?
R Prime
What does the QRS Complex represent with respect to what is happening in the heart?
Ventricular Depolarization
What does the P wave represent?
1st deflection of a complex; atrial depolarization and contraction.
What is the intrventricular septum?
The wall that separates the right and left ventricles
What is a segment?
A segment is a straight line connecting two waves.
- PR Segment
- ST Segment
What is an interval?
An interval encompasses at least one wave plus, in most cases, the connecting straight line.
- PR Interval
- QRS Interval
- ST Interval
- QT Interval
What does the T Wave on an EKG represent?
Deflection after QRS wave showing Ventricular Repolarization
What is the Q Wave?
1st negative deflection after the P wave
What is the R Wave?
1st Positive Deflection after the P Wave
What is the S Wave?
1st Negative Deflection after the R wave.
What is the U Wave?
Deflection after the T wave, but it is rarely present
What is the “J” or Junction Point?
Where the QRS complex ends and the ST segment begins. Used to measure ST-segment deviation in relation to baseline.
What is the R-R Interval?
Interval from one R deflection to the next R deflection, which represents one complete cycle.
What is the TP Segment?
The TP Segment represents electrical baseline and is the segment from the end of ventricular repolarization to the beginning of atrial depolarization.
What are the three inferior leads and their angles?
Limb Leads:
Lead II +60
Lead III +120
Lead aVF +90
aVF - Augmented Vector Foot