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23 Cards in this Set
- Front
- Back
atrial T wave
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occurs about 0.15-0.2 seconds after P wave termination (usually obscured by ventricular depolarization (QRS complex))
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time range of repolarization in ventricular fibers
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0.20 to 0.35 seconds
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Voltage of QRS vs T
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T is much less due to prolonged length
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10 small divisions up and down in EKG
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1 millivolt
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25 mm horizontal direction in EKG
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1 seond (divided into five 0.2 seond intervals which is broken into five 0.04 second intervals)
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Voltge of EKG
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varies on electrode placement (can be up to 3-4 mV)
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between arms and legs mV range
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1-1.5 mV from top of R to bottom of S
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PQ or PR interval Beginning of P and Q)
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time between atria excitation and ventricular excitation (0.16 s)
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QT interval (beginning of Q, end of T)
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contration of ventricles (0.35 s)
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Determining Heart rate from EKG
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60/(time interval between heartbeats)
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averge current flow in heart
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negativity toward base and positivity toward apex
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Why does current flow reverse for 0.1 s immediately before depolarization ends
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last part of heart to depolarize is the outer walls near base of heart
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electrode with positive reading
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lead connected to positive terminal is more positive
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EKG lead
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combination of two wires and their electrodes making a complete circuit between body and EKG
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Lead I
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neg terminal R arm, positive terminal L arm
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Lead II
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neg terminal R arm, positive terminal L leg
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Lead III
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neg terminal L arm, positive terminal L leg
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Eithoven's Law
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If two leads are known, can find 3rd by adding the two known leads
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Diagnosing arrhythmias
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Doesn't matter which lead you use, diagnosed by distance between peaks
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Diagnosing abnormalities of muscle contration or impulse conduction
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change patterns of some leads and doesn't affect others
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chest leads (V1-V6)
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records relatively minute abnormalities in ventricles (V1-V6 are positive; indifferent electrode (arms, L leg) are negative)
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V1 and V2
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record negative because they are nearer the base of heart
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Augmented unipolar limb leads
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Two limb leads connected to negative and one to positive (names after limb connected to positive)
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