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Where is impulse generated?
Sinoatrial (SA) node - right atrium near Sup. VC
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Where is the AV node?
Posterior septal wall of right atrium near tricuspid valve
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What is the order of conduction?
- SA node
- AV node
- AV (His) bundle
- Right/Left bundle branches
- Purkinje fiber network
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What are the Bipolar limb leads?
- I - right arm to left arm
- II - right arm to left leg
- III - left arm to left leg
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What are the Augmented unipolar limb leads?
- aVR - V to right arm
- aVL - V to left arm
- aVF - V to left leg
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What is the triangle made up by the bipolar limb leads?
Einthoven's Triangle
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What is responsible for the P wave?
Atrial muscle depolarization
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What is responsible for the QRS complex?
- Ventricular depolarization
- also, atrial repolarization
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PR interval
Measure of conduction through the AV node
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ST segment
Measure of time where all myocardium in Phase 2 plateau state
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What is responsible for the T wave?
Repolarization of the ventricles
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What is responsible for the U wave?
Repolarization of myocardial "M" cells
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What are the leads of a 12 lead ECG?
- Bipolar (I, II, III)
- Augmented unipolar (aVR, aVL, aVF)
- Precordial leads (V1-V6)
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Define:
1. Tachycardia
2. Bradycardia
3. Sinus rhythm
- 1. >100 bpm
- 2. <60 bpm
- 3. impulse originates at SA node
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Define Mean QRS Vector
How to determine?
- Sum of all vectors in ventricles during depolarization
- Closest to most positive lead
- If both I and aVF have positive QRS, then probably normal
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