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excitability
bility of cell to respond to stimulus
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Automaticity
ability of cell to reach threshold potential and generate impulses without an outside stimulus
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SA node is:
- pacemaker of the heart
- sets pace and transmits impulses throughout the myocardium
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conductivity
ability of the muscle to move an impulse from cell to cell
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what neurotransmitters work within the sympathetic (adrenergic) nervous system?
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what do epi and norepi do in the body?
- raise BP
- increase HR
- enhance force of myocardial contraction
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which NT works with cholinergic parasympathetic nervous system?
- acetylcholine
- --decrease HR
- --lower BP
- --reduce force of myocardial contraction
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rate of Bundle of His?
40-60
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rate of bundle branches?
- 20-40
- purkinjie fibers? 15-40
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during resting state what levels are these electrolytes at INSIDE cell?
- Na+ lower
- K+ higher
- Ca+ lower
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what happens to K+, Na+, and Ca++ during depolarization in reference to cells?
- heart contracts due to Na+ and Ca+ moving into cell
- and K+ moves out
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what is action potential?
depolarization
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repolarization?
return to resting state
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what is EKG?
graphic display of conduction
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monophasic action potential?
depolarization and repolarization of cardiac muscle cells
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what are dysrythmias?
- disorders of the hearts conduction
- disturbance in rate, rhythm or both
- ID by analyzing EKG
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QRS Complex:
- ventricular depolarization
- contraction of the ventricles
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P wave?
- atrial depolarization
- contraction of the atrium
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duration of P wave should be:
less than 3 small squares OR <.11
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T wave:
ventricular REpolarization
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normal PR interval?
- .12-.20
- indicates AV conduction time
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steps for interpretation of EKG?
- 1. look for P-QRS-T
- 2. determine rate..atrial= count P waves, ventricular= count R waves
- 3. determine A-V rhythms, R-R for regularity
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sinus arrhythmias?
minor regular variations in HR and pulse pressure assoc with resp
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sinus brady?
- <60 BPM, left untreated if asymptomatic
- Symptomatic: Atropine IV, Dopamine, Epi
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sinus tachy?
- >100 BPM
- caused by fever, etc
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Tx for atrial flutter?
- anticoagulation, Cardizem, Digoxin
- if unstable: cardioversion
- caused by: aging, hypoxia, electrolyte disturbances, increased atrial pressures, tricuspid vavle disease
- saw-tooth shaped waves, 200-350 threat of clotting
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Tx for A fib?
- Goal: to decrease atrial irritation, decrease rate of ventricular response
- CHRONIC: anticoagulation, Warfarin (coumadin), Digoxin, Cardizem, cardioversion if meds not effective synchronized
- threat of clotting
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why cardiovert?
so pt doesnt go into vfib and need defibrillation
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First degree heart block?
- PR = >.20 (prolonged)
- delayed conduction through the AV junction
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multifocal:
look different
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PVC Tx:
- Amiodarone bolus 150 mg over 10 mins
- IV flow of 1 mg/minute
- may need oral antiarrythmic
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Cardioversion and defib are synchronized or not?
- cardioversion- synchronized
- defibrillation- unsynchronized
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Asystole occurs:
- most commonly following termination of atrial, AV junctional or ventricular tachycardias. this pause is usually insignificant
- in AMI, CAD asystole may continue: cardiac arrest
- Tx: CPR, artificial pacing, Epi, atropine
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complications of pacemakers use?
- infection
- bleeding, hematoma
- dislocation of lead
- cardiac tampponade
- pacemaker malfunction
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sympathetic system: fight or flight:
increase HR, and BP, enhance force of contractions
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during resting state, K+ is where?
inside cell
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V Tach Tx?
- 1. epi
- 2. amiodarone
- 3. lidocaine
- 4. procainamide
- AICD
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V fib tx?
- defib
- CPR
- epi 1 mg
- vasopressin 40 U
- AICD
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AV node pacemaker, what type of rhythm is there?
- Junctional- absent or inverted P wave
- 40-60 bpm
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