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32 Cards in this Set
- Front
- Back
Cardiac arrhythmias cause(s)
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1) abnormal rhythmicity of pacemaker 2) shift of pacemaker 3) blocks of impulse 4) abnormal pathways of impulse 5) spontaneous generation of spurious impulses
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trachycardia
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over 100 for adult; causes by increased T, sympathetic stimulation, or toxic conditions
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bradycardia
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less than 60 bpm; vagal/parasympatheic stimulation
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carotid sinus syndrome
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baroreceptors excessively sensitive, mild external P on neck elicits strong parasympathetic response
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respiratory sinus arrythmia
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change in CO by as much as 30% during inspiration/exspiration; 'spillover' of signals from medullary respiratory center
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sinoatrial block
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blocked before entering atrial muscle; sudeen cesation of P wave; ventricles pick up their own rhythm
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atrioventricular block
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1) ischemia of AV node/bundle fibers delays 2) compression of AV bundle by scar/calcification 3) inflammation of AV node/bundle 4) extreme stimulation by vagus nerves
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first degree atrioventricular heart block
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prolonged PR (or PQ) interval; greater than 0.2 s; can be used to measure severity of disease
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second degree atrioventricular heart block
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PR interval 0.25-0.45 s; sometimes strong enough to pass to ventricle, sometimes not; See P wave without QRS-T = dropped beats
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complete (3rd degree) AV block
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ventricles spontaneously establish own signal; P waves dissociated from QRS-T
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Stokes-Adams Syndrome
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total AV block comes and goes; borderline ischemia of conductive system; periodic fainting episodes
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electrical alternans
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partial intraventricular block every other heartbeat; often occurs in tachycardia since some parts of the purkinje system are not recovered from previous depolarization
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extrasystole/premature beat/ectopic beat
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contration before time when a normal contraction would be expected
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possible causes of ectopic beats
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1) local areas of ischemia 2) small calcified plaques 3) toxic irritation of AV node, purkinje system, myocardium 4) mechanical initiation during cardiac catheterization
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premature atrial contractions
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often followed by compensatory pause, often seen in healthy individuals
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deficit in # of radial pulses compared to heart contractions
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can occur with premature contractions
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AV nodal/bundle premature contraction
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missing P wave
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Premature ventricular contractions in ECG
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1) QRS complex prolonged 2) QRS high voltaage 3) T wave has opposite potential
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what can cause PVC
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cigarettes, coffee, lack of sleep, various mild toxic states, emotional irritability
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vulnerable period of causing ventricular fibrillation
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just at end of T wave when ventricles are coming out of refractoriness
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vector analysis of ectopic area
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average vector tail is in direction of ectopic spot in heart (where depolarization occurs first)
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paroxysmal tachycardia, drugs used for
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vagal stimulation, quinidine, lidocaine (depress normal Na+ permeability of cardiac muscle membrane during generation of AP)
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atrial paroxysmal tachycardia concerns
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generally frightens a person, but rarely any harm
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ventricular paroxysmal tachycardia concerns
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serious condition, can cause vernticular fibrillation; is generally present due to considerable ischemia
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long pathway of cirsus movement occurs in
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dilated hearts
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decreased rate of conducation in circus movements occur in
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blockage of purkinje system, ischemia of muscle, high K+ levels, or other factors
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shortened refractory period in circus movements occur in
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response to various drugs like epinephrine, or after repeated electrical stimulation
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voltage in V-fib
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start at 0.5 mV, but drop quickly to .2-.3 mV
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when does heart become too weak to be revived by defibrillation
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within 1 minute
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common cause of atrial firbillation
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atrial enlargement from heart valve lesions or ventricular failure
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atrial flutter
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strong P waves; QRS only follows every 2 or 3 P waves
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cardiac arrest
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no spontaneous rhythm remains; pacemaker can help
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