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Questions and Answers
An ECG is a composite of all the ______ potentials generated by nodal and contractile cells at a given time.
An ECG is a composite of all the ______ potentials generated by nodal and contractile cells at a given time.
action
In an ECG, electrical events ______ the mechanical events of contraction or relaxation.
In an ECG, electrical events ______ the mechanical events of contraction or relaxation.
precede
The ______ is the part of the ECG that represents atrial depolarization.
The ______ is the part of the ECG that represents atrial depolarization.
P wave
The ______ complex on an ECG represents ventricular depolarization.
The ______ complex on an ECG represents ventricular depolarization.
The ______ on an ECG represents ventricular repolarization.
The ______ on an ECG represents ventricular repolarization.
The P-R interval on an ECG measures the time from the beginning of atrial excitation to the beginning of ______ excitation.
The P-R interval on an ECG measures the time from the beginning of atrial excitation to the beginning of ______ excitation.
The S-T segment represents the time between ventricular depolarization and the start of ventricular ______.
The S-T segment represents the time between ventricular depolarization and the start of ventricular ______.
The Q-T interval measures the period from the beginning of ventricular depolarization through ventricular ______.
The Q-T interval measures the period from the beginning of ventricular depolarization through ventricular ______.
In a normal sinus rhythm, the ______ node usually paces the heart at 75 BPM.
In a normal sinus rhythm, the ______ node usually paces the heart at 75 BPM.
In junctional rhythm, the ______ node paces the heart at 40-60 BPM.
In junctional rhythm, the ______ node paces the heart at 40-60 BPM.
[Blank] rhythm results from damage to the SA node, where the AV node takes over the role of pacing the heart.
[Blank] rhythm results from damage to the SA node, where the AV node takes over the role of pacing the heart.
A heart block is characterized by a ______ of the conductive pathway, affecting the heart's electrical signals.
A heart block is characterized by a ______ of the conductive pathway, affecting the heart's electrical signals.
In a heart block, the AV node may fail to conduct some ______ node impulses, leading to irregularities in the heart rhythm.
In a heart block, the AV node may fail to conduct some ______ node impulses, leading to irregularities in the heart rhythm.
[Blank] is characterized by a continuous disorganized AP pattern in the ventricles.
[Blank] is characterized by a continuous disorganized AP pattern in the ventricles.
Ventricular fibrillation can be treated by defibrillating with high ______ to cause a simultaneous refractory period.
Ventricular fibrillation can be treated by defibrillating with high ______ to cause a simultaneous refractory period.
What kind of rhythm?
What kind of rhythm?
What kind of rhythm?
What kind of rhythm?
What kind of rhythm?
What kind of rhythm?
What kind of rhythm?
What kind of rhythm?
What kind of rythym
What kind of rythym
Flashcards
Electrocardiogram (ECG)
Electrocardiogram (ECG)
Composite of all the action potentials generated by nodal (pacemaker) and contractile cells at a given time. Not a tracing of a single action potential.
P wave
P wave
Represents atrial depolarization. This is when the atria contract.
QRS complex
QRS complex
Represents ventricular depolarization. This leads to ventricular contraction.
T wave
T wave
Represents ventricular repolarization. This prepares the ventricles for the next contraction.
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P-R interval
P-R interval
Time from the beginning of atrial excitation to the beginning of ventricular excitation.
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S-T segment
S-T segment
Time between ventricular depolarization and the start of ventricular repolarization.
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Q-T interval
Q-T interval
Period from the beginning of ventricular depolarization through ventricular repolarization.
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Sinus Rhythm
Sinus Rhythm
A normal ECG trace, indicating proper heart rhythm.
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Junctional Rhythm
Junctional Rhythm
Arrhythmia where the AV node takes over pacing the heart due to a damaged SA node, resulting in a slower heartbeat and absent P wave.
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Heart Block
Heart Block
Arrhythmia characterized by a blockage in the heart's conductive pathway, leading to the AV node failing to conduct some SA node impulses, resulting in a slower heartbeat and more P waves than QRS complexes.
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Ventricular Fibrillation
Ventricular Fibrillation
A continuous, disorganized electrical pattern in the ventricles, leading to chaotic, abnormal ECG deflections.
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Extrasystole
Extrasystole
Arrhythmia where the SA node fires early, resulting in an extra heartbeat followed by a compensatory pause.
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Electrocardiogram (ECG)
- ECGs are a composite of all action potentials generated by nodal (pacemaker) and contractile cells at a given time
- ECGs do not trace single action potential
- Electrical events precede mechanical events of contraction or relaxation
ECG Waves, Complexes and Intervals:
- P wave signifies atrial depolarization
- The QRS complex signifies ventricular depolarization
- The T wave signifies ventricular repolarization
- The P-R interval indicates the time from the beginning of atrial excitation to the beginning of ventricular excitation
- The S-T segment represents the time between ventricular depolarization and the start of ventricular repolarization
- The Q-T interval represents the period from the start of ventricular depolarization through ventricular repolarization
Steps of ECG reading
- Atrial depolarization, initiated by the SA node, causes the P wave
- With atrial depolarization complete, the impulse is delayed at the AV node
- Ventricular depolarization begins at the apex, causing the QRS complex.
- Atrial repolarization occurs
- Ventricular depolarization is complete
- Ventricular repolarization begins at the apex, causing the T wave
- Ventricular repolarization is complete
Sinus Rhythm
- This represents a normal ECG trace
Arrhythmia: Junctional Rhythm
- This occurs when the SA node is damaged, and the AV node takes over pacing the heart.
- Junctional rhythm is characterized by a slower heartbeat
- The SA node typically paces the heart at 75 BPM, while the AV node paces it at 40-60 BPM
- There is no visible P wave
- Ventricles contract with relatively greater force
Arrhythmia: Heart Block
- Heart block is the blockage of conductive pathways
- This is where the AV node fails to conduct some SA node impulses
- This can cause a slower heartbeat
- There will be more P waves than QRS waves
Arrhythmia: Ventricular Fibrillation
- Ventricular fibrillation involves a continuous disorganized action potential (AP) pattern in the ventricles
- This leads to chaotic, abnormal ECG deflections
- It requires a cure by defibrillation with high voltage to cause a simultaneous refractory period
Arrhythmia: Extrasystole
- In extrasystole, the SA node fires early
- This creates an extra heartbeat followed by a pause, which may be felt as a "thud"
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