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44 Cards in this Set
- Front
- Back
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Classes of Antidysrhythmic Drugs |
Class I: sodium channel blockers- slow it down Class II: beta blocker (block epinephirne and norepinephrine. Class III: potassium channel blocker Class IV: Calcium channel blockers- hear contracting too rapidly |
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Antidysrhthmic Drugs |
An abnormality in the rhythm of the heartbeat. Two basic types of dysrhythmias: 1. Tachydysrhythmias: heart rate is increased 2. Bradydysrhythmias: heart rate is slowed - Dysrhythmias are also known as arrhythmias |
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Electrical properties of the heart |
Impulse conduction: pathways and timing SA node, AV node, His |
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SA node |
pacemaker of heart fires 60-100 times/minute |
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AV node |
fires 40-60 times/minute |
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His-Purkinje system |
Fires more than 40 times/minute |
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Cardiac action potentials |
Occur in fibers of the His-Purkinje system and in atrial and ventricular muscle. There are 5 distinct phases: Phases 0, 1, 2, 3, and 4. |
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Phase 0 |
depolarization (resting) |
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Phase 1 |
(partial) repolarization |
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Phase 2 |
plateau |
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Phase 3 |
Repolarization (low cardiac output)
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Phase 4 |
Stable potential |
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The electrocardiogram |
P wave QRS complex T wave PR interval QT interval ST segment |
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P wave |
Depolarization in the atria. The current has traveled form AV node to atria |
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QRS complex |
Depolarization of the ventricles. Current going down bundle branches. |
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T wave |
Repolarization of the ventricles. Ventricular filling. |
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Gneration of Dysrhythmias |
2 fundamental causes: 1. Disturbances of automaticity 2. Disturbances of conduction -Atrioventricular block
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Classification of Antidysrhythmic Drugs |
Vaughan Williams Classification Class 1: sodium channel blockers Class 2: beta blockers Class 3: potassium channel blockers Class 4: Calcium channel blockers Other: adenosine, digoxin, and ibutilide |
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Supraventricular dysrhythmias |
Impuse arises above the ventricle Atrial flutter Atrial fibrillation Sustained supraventricular tachycardia (SVT) |
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Multiple Varied P waves |
Atrail fibrillation. Wavy baseline and irregular rhythm. The atria is quivering. It pools and clots in the atria. |
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Ventricular dysrhthmias |
Sustained ventricular tachycardia Ventricular fibrilation Ventricular premature beats Digoxin-induced ventricular dysrhythmias Torsades de Pointes |
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No P wave |
Ventricular fibrillation |
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Class I: Sodium channel Blockers |
Treat atrial and ventricular dysrhythmias Class IA agents: Quinidine Class IB agents: Lidocaine |
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Quinidine: Effects on the heart |
Blocks sodium channels Slows impulse conduction Delays repolarization |
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Quinidine: Effects on the ECG |
Widens the QRS complex Prolongs the QT interval Slows the rhythm |
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Quinidine: Therapeutic uses |
Used against supraventricular and ventricular dysrhthmias |
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Quinidine: Adverse Effects |
Diarrhea Cinchonsim Cardiotoxicity Atrerial embolism (due to atrial fibrilation) Alpha-adrenergic blockade, resulting in hypotension Hypersensitivity reactions Drug interaction: Digoxin |
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Cinchonism |
Tinnitus, H/A, nausea, vertigo, disturbed vision |
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Lidocaine (Xylocaine): Effects on the heart and ECG |
Blocks cardiac sodium channels Slows conduction in the atria, ventricles, and His-purkinje system Reduces automaticity in the ventricles and His-Purkinje system |
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Lidocaine: Adverse effects |
CNS effects Drowsiness Confusion Paresthesias |
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Paresthesias |
tingling and numbness in extremities |
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Class II Beta blockers |
Propranolol (Inderal) Carvedilol (Coreg) |
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Class II Beta Blockers: Propranolol (Inderal) and Carvedilol (Coreg): Effects on the heart and ECG |
Decreased automaticity of the SA node Decreased velocity of conduction through the AV node. Decreased myocardial contractility: negative inotropic effect |
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Cass II Beta Blockers: Popranolo (inderal) and Carvedilol (Coreg) Therapeutic use |
Dysrhythmias caused by excessive sympathetic stimulation Supraventricular tachydysrhythmias: suppression of excessive discharge and slowing of heart rate |
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Class II Beta Blockers: Propranolol (Inderal) and Carvedilol (Coreg): Adverse Effects |
Heart block Heart failure AV block Sinus arrest Hypotension Bronchospasm (in asthma patients) |
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Class III: Potassium channel blockers- Amiodarone (Cordarone, Pacerone) Therapeutic uses |
Long term therapy for life-threatening ventricular dysrhythmias and converting atrial fibrilation to normal sinus rhythm. Recurrent ventricular fibrilation Recurrent hemodynamically unstable ventricular tachycardia |
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Class III: Potassium channel blockers: Amiodarone (Cordarone, Pacerone) Effects on the heart and ECG |
Reduces automaticity in the SA node Reduced contractility Reduced conduction velocity QRS widening Prolongation of the PR and QT intervals |
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Class III: Potassium Channel blockers: Amiodarone (Cordarone, Pacerone) Adverse Effects |
Pulmonary toxicity Cardiotoxicity Toxicity in pregnancy and breastfeeding Corneal microdeposists Optic neuropathy |
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Class III Potassium Channel Blockers: Amiodarone (Cordarone, Pcerone): Drug Interactions |
Quinidine Diogoxin Procainamide Diltiazem Phenytoin Warfarin |
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Class IV: Calcium Channel Blockers: Verapamil and Diltiazem |
Reduces SA nodal automaticity Delays AV nodal conduction Reduces myocardial contractility Therapeutic uses: 1. Slows heart rate (atrial fibrilation or atrial flutter) 2. Terminate SVT caused by an AV nodal reentrant circuit |
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Class IV: Calcium Channel Blockers: Berapamil and Diltiazem Adverse Effects |
Bradycardia Hypotension AV block Heart failure Peripheral edema Constipation |
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Adenosine: Effects on the heart and ECG |
Decreases automaticity in the SA node Slows conduction through the AV node Prolongation of PR interval |
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Adenosin: Therapeutic use |
Termination of paroxysmal SVT |
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Adenosine: Adverse effects |
Sinus bardycardia, possible asystole Dyspnea Hypotension Facial flushing. |
