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25 Cards in this Set
- Front
- Back
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Localizing infarcts: which ECG leads for posterior wall infarcts?
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Might find larger, abnormal R waves in V1-V3
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Localizing infarcts: which ECG leads for anterior wall infarcts?
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V1-V4
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Localizing infarcts: which ECG leads for lateral wall infarcts?
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aVL, I, V5, V6
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Localizing infarcts: which ECG leads for inferior (apical) infarcts?
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II, III, aVF
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When the QRS shape/duration indicates abnormal ventricular activation, four general possibilities
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1.Abberancy (2’ to L/R block, AV block, hyperkalemia, pharmacological block)
2.Ventricular foci 3.Alternative conduction pathway (pre-excitation, bypass of AV node) 4.Pacing |
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Two leads used to determine electrical axis (rule of thumb)
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aVF (+ means below the x-axis, - means above the x axis) and I (+ means to the right of the y-axis, - means to the left of the x-axis)
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Give the estimates for QRS duration under normal, conduction delayed, and conduction blocked (pacing, preexcitation, focal) circumstances
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Normal = 100 ms or less
Delayed = 100 ms – 120 ms Focal = +120 ms |
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Normal duration of PR interval
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120 ms – 200 ms
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Rule of thumb for normal length of QT interval
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QT should be less than half the RR interval
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Leads to assess atrial function
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V1 and V2
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When looking at V1 and V2 for atrial function, if sinus rhythm is not found, look for these kinds of atrial problems (4)
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1.Atrial flutter
2.Atrial fibrillation 3.Atrial tachycardia (SVT) 4.Retrograde (p wave proceeding QRS) |
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Hyperkalemic ECG changes (4)
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1.peaked t waves
2.merging of QRS/T 3.loss of p wave 4.”sine wave” pattern |
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Hypokalemic ECG changes (2)
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1.flattened T waves
2.positive U wave proceeding T wave |
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ECG hallmarks of RBBB (3)
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1.V5/V6: greater negative deflections in QRS
2.V1/V2:extra,large R’ wave 3.Widened QRS |
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ECG hallmarks of LBBB (3)
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1.V5/V6:wide, deep Q waves in QRS
2.wide QRS 3.biphasic waves in V5/V6 |
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Intracardiac electrode ECG allows for more precise measurement of two intervals - what are they?
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AH: atrial to bundle of His conduction time (AV conduction time)
HV:bundle of His to ventricular conduction system, typically 40 ms (bundle conduction time) |
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2’ block (occasional skipped QRS complexes) is due to a conduction problem in the _______ or the ______. The former is more common. These are known as Mobitz Type I and Type II, respectively.
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Problem in AV conduction (type I)
Problem in bundle conduction (type II) |
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Things that cause AV block/delay
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Hyperkalemia, RV/Inferior ischemia, digitalis, Beta Blockers, Parasympathetics
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In 3’ heart block (dissociated p and QRS waves), how can one tell how far downstream the rescue focus is?
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Width of the QRS complex (wider, further downstream)
junctional, fasicular, ventricular |
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L Bundle
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L bundle gives off posterior fascicle, then anterior fascicle
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“Tri-fascicular” block
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2 fascicle block + prolonged PR interval
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Wandering pacemaker
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Various atrial foci (p’ waves), less than 100/min, irregular QRS complexes
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Junctional Escape
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Lone QRS complexes due to failure of upstream foci or proximal AV node block; slower rate (40-60 bpm); retrograde P waves may be seen, with possible inversion in leads with positive QRS’s
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Atrial/Junctional Irritability VS Ventricular Irritability
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AJ = sympathetics, less parasympathetics, stimulants
Ventricular = hypoxia, hypokalemia |
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Atrial flutter
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Atrial Flutter: atrial foci origin; saw-tooth appearance; 250-350 atrial beats per minute; usually one P wave conducts down to the ventricles for every 2, 3, or 4 P waves fired
-can't have too fast of a heart rate with flutter (ventricular contraction requires AV conduction) |
