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35 Cards in this Set
- Front
- Back
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electrical properties of the heart
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-SA node: pacemaker for the heart
-AV node: impulses originating in atria must travel through AV node to reach ventricles -His-Purkinje fibers: conduct electrical excitation very rapidly to all parts of ventricles |
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cardiac action potentials
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-cardiac cells initiate and conduct conduct action potentials consisting of self-propagating waves of depolarization followed by repolarization
-generated by movement of ions into and out of cells -ion fluxes happen through specific channels in the cell membrane |
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fast potential locations
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occur in His-Purkinje fibers and in atrial and ventricular muscles
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fast potential phases
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0) depolarization
1) (partial) repolarization 2) plateau 3) repolarization 4) stable potential |
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slow potential locations
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occur in cells of SA and AV nodes
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slow potential phases
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0) slow depolarization mediated by calcium influx
1) absent 2 and 3) not significant 4) depolarization |
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atrial fibrillation
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-supraventricular
-most common sustained dysrhythmia -treated with beta blockers (e.g. atenolol or metoprolol) -treated with warfarin for stroke patients |
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atrial flutter
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-supraventricular
-250-300 bpm -treatment: cardioversion |
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sustained supraventricular tachycardia
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-supraventricular
-150-200 bpm -first line of treatment is carotid sinus massage or Valsalva's maneuver -second line of treatment is IV beta blocker or calcium channel blocker |
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sustained ventricular tachycardia
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-dangerous
-150-200 bpm -treatment: cardioversion or IV amiodarone |
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ventricular fibrillation
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-life-threatening emergency
-treatment: defibrillation |
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ventricular premature contractions/beats
(VPCs or VPBs) |
-beats occur prematurely in cardiac cycle
-treated with beta blocker |
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digoxin-induced ventricular dysrhythmias
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-treatment: lidocaine or phenytoin
-can almost always be controlled |
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torsades de pointes
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-ventricular dysrhythmia
-atypical, undulating, rapid, ventricular tachydysrhythmia that can evolve into vfib -treatment: IV magnesium plus cardioversion |
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classes of antidysrhythmics
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I: sodium channel blockers
II: beta blockers III: potassium channel blockers IV: calcium channel blockers |
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indications and therapeutic effects of QUINIDINE (class IA)
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indications: supraventricular and ventricular dysrhythmias
effects on heart: -blocks sodium channels -slows impulse conduction -delays repolarization -blocks vagal input to the heart -widens QRS complex -prolongs QT interval |
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side effects of QUINIDINE
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(class IA)
-diarrhea -cinchonism -cardiotoxicity -arterial embolism -alpha-adrenergic blockade resulting in hypotension -hypersensitivity reactions |
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drug interactions of QUINIDINE
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(class IA)
-digoxin |
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therapeutic effects of LIDOCAINE (class IB)
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-blocks sodium channel
-slows conduction in all areas of the heart -reduces automaticity of ventricles and His-Purkinje system -accelerates repolarization other class IB agents: phenytoin and mexiletine |
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side effects of LIDOCAINE
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(class IB)
-CNS effects -paresthesias -drowsiness -confusion |
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flecainide and propafenone (class IC)
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-block cardiac sodium channels
-delay ventricular repolarization -can exacerbate existing dysrhythmias and create new ones |
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major components of an ECG
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-P wave: atrial depolarization
-QRS complex: ventricular depolarization -T wave: ventricular repolarization |
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PROPANOLOL (Inderal)
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-non-selective beta-adrenergic antagonist
-class II -decreased automaticity of SA node -decreased conduction velocity through AV node -decreased myocardial contractility |
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PROPANOLOL (Inderal) indications and therapeutic effects
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(class II)
-dysrhythmias caused by excessive sympathetic stimulation -supraventricular tachydysrhythmias -suppression of excessive discharge -slowing of ventricular rate |
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adverse effects of PROPANOLOL (Inderal)
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-heart block
-heart failure -AV block -sinus arrest -hypotension -bronchospasm in asthma patients |
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BRETYLIUM (class III) indications and therapeutic effects
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indications:
-vfib -vtach therapeutic effects: -delay repolarization of fast potentials -prolonged QT interval |
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BRETYLIUM side effects
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(class III)
-profound persistent hypertension |
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AMIODARONE (Cordarone, Pacerone) (class III) indications
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-for life-threatening ventricular dysrhythmias only
-recurrent vfib -recurrent hemodynamically unstable vtach |
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AMIODARONE (Cordarone, Pacerone)
therapeutic effects |
(class III)
-reduces automaticity in SA node -negative inotropic -reduces conduction velocity -QRS widening -prolonged PR and QT intervals |
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AMIODARONE (Cordarone, Pacerone) side effects
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(class III)
-pulmonary toxicity -cardiotoxicity -toxicity in pregnancy and breastfeeding -corneal microdeposits -optic neuropathy |
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AMIODARONE (Cordarone, Pacerone) drug interactions
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-quinidine
-digoxin -procainamide -diltiazem -phenytoin -warfarin |
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VERAPAMIL and DILTIAZEM (class IV) indications and therapeutic effects
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indications: slow ventricular rate due to afib or atrial flutter, termination of SVT
therapeutic effects: -reduces SA node automaticity -slows AV node conduction -negative inotropic |
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VERAPAMIL and DILTIAZEM adverse effects
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(class IV)
-bradycardia -hypotension -AV block -heart failure -peripheral edema -constipation |
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ADENOSINE indications and therapeutic effects
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indication: paroxysmal SVT (supraventricular tachycardia)
therapeutic effects: -decreases SA node automaticity -slows conduction through AV node -prolonged PR interval |
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ADENOSINE side effects and drug interactions
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side effects:
-sinus bradycardia -dyspnea -hypotension -FACIAL FLUSHING drug interactions: -methylxanthines -dipyridamole |
