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In the resting state, each cardiac muscle fiber is polarized with a net...
A. Negative outside/Positive inside
B. Positive outside/Negative inside
B. Positive outside/Negative inside
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What is an Electrocardiograph?
An instrument which measures the difference between voltage levels at any specific point across the heart
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Placement of all 9 electrodes for an EKG...
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Name the leads of a 12 lead EKG...
I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, V6
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What is the Hexaxial Reference System?
How is it determined?
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Conventions: (Normal, Left axis deviation, Right axis deviation, and degrees of axis deviation)
- 0 to +90 = Normal
- 0 to -90 = Left axis deviation
- +90 to +180 = Right axis deviation
- -90 to -180 = Degrees of axis deviation
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Standard speed and amplification of an EKG?
- Speed= 25 mm/sec
- Amplification= 1mV/cm
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The P wave represents...
Atria excitation, originates in SA node
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The T wave represents...
The deflection following the QRS complex
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The Q wave represents...
- "Crossing of excitation" over the inter-ventricular septum.
- Enlarged Q could indicate an old MI
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The R wave represents...
Depolarization of the ventricles
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The S wave represents...
- Late phase depolarization of the ventricles.
- Has little/no interpretive significance.
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Excitation of Heart Muscle...
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Which is the pace maker for the heart:
SA node or AV node?
SA (sino atrial) node
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Einthoven's Law...
A complex (EKG) in lead 2 equals the sum of the corresponding complexes in leads 1 and 3 (2=1+3)
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Unipolar "Augmented limb leads"...
- aVR = Right Arm
- aVL = Left Arm
- aVF = Left Leg (foot)
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Placement V1...
Just to the right of the sternum in 4th interspace
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Placement V2...
Just to the left of the sternum in the 4th interspace
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Placement of V4...
Placed in the mid clavicular line (MLL) in 5th interspace
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Placement V3...
Halfway between leads 2 and 4
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Placement V5...
Placed at the same level of V4 in the anterior axillary line (AAL)
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Placement V6...
Placed at the same level of V4 in the middle axillary line (MAL)
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Placement V7...
Placed at the same level as V4 in posterior axillary line (PAL)
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Bipolar leads are...
- Lead I = RA vs LA
- Lead II = RA vs LL
- Lead III = LA vs LL
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What id ischemia?
Reduced blood flow relative to needs and results in too little oxygen (02)
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Best look at the Heart are seen with which 3 leads?
Lead II, aVF, V5
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Arrhythmia's are...
Premature ventricular beats or ectopic beats
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QRS complex is viewed as...
- Q= first down strike after P wave before R wave
- R= first upward deflection
- S= last downstroke
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The P-R interval...
Nodal delay of AV junction
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The S-T segment...
The delay between completion of depolarization and the beginning of re-polarization of ventricles
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The Exercise EKG is mainly used for...
Indicating coronary insufficiency
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