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15 Cards in this Set
- Front
- Back
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What are the diagnostic uses of ECG?
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To detect:
- heart rhythm disturbances - conduction system disease - chamber sixe - coronary artery disease - myocardial ischemia/infarction - drug and electrolyte effects - congenital heart disease |
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At what depolarization of the muscle will the potential difference between 2 leads be MAXIMAL?
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when the muscle is depolarized by 50%
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When is the deflection on an ECG positive? Negative? Flat?
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Postive/UP: when moving from - pole to + pole
Negative/down: when moving from + to - Wavefront moving parallel to recording dipole = large deflection Wavefront moving perpendicular to dipole: NO deflection (flat) |
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What factors affect the amplitude and quality of the ECG recording?
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- closer to anterior chest wall (region of heart generating the signal), te greater the recording
- speed of wavefront propagation - mass of myocardial tissue activated - state of health/disease of myocardium (e.g., scar tissue slows propagation) - direction of wavefront in relation to dipole (e.g., perpendicular = flat; parallel = larger deflection) |
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Anatomic position of Lead I
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R arm (+) to L arm (-)
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Anatomic position of Lead II
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R arm (+) to L leg (-)
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Anatomic position of Lead III
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L arm (+) to L leg (-)
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What are the names of Leads I, II, III?
What do they "form"? |
Limb Leads
Form "Einthoven's Triangle" |
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What are unipolar leads?
What leads are unipolar? |
Only one pole, the positive one, is attached to each extremity -- signals are filtered and augmented...
- Augmented Limb Leads - Precordial Leads |
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What are Augmented Leads?
What are their names and positions? Where is the negative pole? |
unipolar leads from which the signal is filtered and augmented
Postive Poles: aVR - right arm aVL - left arm aVF - left foot Negative Pole: central ground - "WIlson Central Terminal" |
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What are the Precordial Leads?
What are their names and positions? |
unipolar leads placed across the precordium
V1 - 4th RICS, next to sternum V2 - 4th LICS, next to sternum V3 - between V2 and V4 V4 - 5th LICS, midclavicular line V5 - 5th LICS, preaxillary line V6 - 5th LICS, midaxillary line |
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Which leads correspond to information about particular regions of the heart?
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II, III, aVF - inferior wall
V1 to V4 - anterior L ventricle V5, V6, I, aVL - lateral/apical L vent V1, V2 - interventricular septum V1 - right ventricle |
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ECG paper:
- Speed? - Distance within little box? - Distance wihtin big box? - Time within each little box? - 1 second? - measurement along Y axis? |
- speed: 25 mm/s
- little box: 1 mm - big box: 5 mm (5 little boxes) - little box: 0.04 seconds (40 ms) - 1 s = 5 big boxes - Y axis: 10 mm/mVolt |
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What is a cycle length?
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Time between 2 heart beats
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How do you convert cycle length to BPM?
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1. Use formula
2. Memorize: x # big boxes = 300/x bpm 3. If heart rate is irregular, count # QRS complexes in 6 seconds (30 big boxes) and multiply by 10 = 60 s. |
