Term
| Class 1A drugs - quinidine, procainamide (Procanbid) |
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Definition
| agents that slow rate of rise of phase 0 of AP (slowing conduction velocity) and increase AP duration & effective refractory period (ERP); have INTERMEDIATE speed of interaction with phase 0 Na channels |
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Term
| Class 1B drugs - lidocaine (Xylocaine) |
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Definition
| agents that have less slowing effect on rate of rise of phase 0 (less slowing of conduction velocity) & decrease AP duration & ERP; they RAPIDLY interact with phase 0 Na channels |
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Term
| Class 1C drugs - flecainide (Tambocor) |
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Definition
| agents that markedly depress rate of rise of phase 0 (marked slowing of conduction velocity); have LITTLE net effect on AP duration or ERP; interacts SLOWLY with phase 0 Na channels |
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Term
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Definition
| class 1A antiarrhythmic, inhibits Na channels but also K channels with changes in AP; Uses: tx of various supreventricular & ventricular arrhythmias, inhibits ectopic atrial & ventricular arrhythmias, prevents reentry arrhythmias by transforming unidirectional block into bidirectional block, used to maintain NORMAL RHYTHM after CARDIOVERSION of atrial flutter or fibrillation; IV & oral |
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Term
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Definition
| causes other arrhythmias (prolonged QT --> torsades de pointes [TdP]); nausea, vomiting, DIARRHEA; CINCHONISM (ringing of ears, headache); decreased BP, increased regular sinuse rate; Increases digoxin levels |
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Term
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Definition
| class 1A antiarrhythmic that inhibits Na channels but inhibits K channels due to a metabolite of drug; Pk: oral & IV, metabolite NAPA (N-acetylprocainamide) that prolongs AP duration but also has class 3 properties that inhibit K channels |
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Term
| SEs of procainamide (Procanbid) |
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Definition
| reversible lupus syndrome; CNS side effects; GI intolerance; less decrease in BP & increase in regular sinus rate than other 1A drug; ventricular arrhythmias but less of TdP |
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Term
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Definition
| Class 1B antiarrhythmic that rapidly interacts with Na channels, shortens phase 3 repolarization, decreasing AP duration & ERP, with only slight decrease in phase 0 slope; Uses: emergency tx of ventricular arrhythmias during myocaridal ischemia (MI), suppresses ventricular arrhythmias caused by automaticity b/c it can decrease slope of phase 4, abolishes ventricular reentry despite decrease in AP duration & decrease in ERP & little decrease in conduction; STOPS TdP; Pk: ONLY IV |
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Term
| SEs of lidocaine (Xylocaine) |
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Definition
| wide toxic-therapeutic ratio; little impairment of left ventricular fcn (no neg. inotropic fcn); CNS: drowsiness, slurred speech, confusion, convulsions; cardiach arrhythmias may occur, aggravated by hyperkalemia |
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Term
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Definition
| Class 1C antiarrhythmics interact more slowly but more notably by blocking Na channels, markedly suppresses phase 0 slope --> marked slowing of conduction, also inhibits some K channels in ventricles but blocks some late-opening Na channels but NO NET EFFECT on duraiton of AP & ERP, increase in threshold of phase 0; Uses: refractory (resistant) arrhythmias; Pk: oral |
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Term
| SEs of flecainide (Tambocor) |
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Definition
| neg. inotropic effects that aggravates CHF; dizziness, blurred vision, HA, nausea; aggravates preexisting arrhythmias, induces life-threatening ventricular tachycardia |
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Term
| Class II Antiarrhythmics - propanolol [Inderal-LA], acebutalol [Sectral], esmolol [Brevibloc] |
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Definition
| beta-adrenergic antagonists that block cardiac beta receptor actions on Ca channel, decreasing inward Ca currents; diminish phase 4 depolarization, depressing automaticity, decrease phase 0 slope which slows conduction, increases AP duration & ERP; uses: treat arrhythmias caused by increases SNA or excess catecholamine release, atrial flutter, fibrillation, AV nodal reentrant tachycardia, prevents supraventricular arrhythmias, suppresses DADs |
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Term
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Definition
| Class II antiarrhythmic; reduces incidence of sudden adrenergically-driven arrhythmic deaths after MIs; has membrane stabilizing properties |
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Term
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Definition
| class II antiarrhythmic; its beta-1-specificity reduces risk of bronchospasm; partial agonist activity may decrease risk of too much suppression of normal cardiac function |
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Term
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Definition
| class II antiarrhythmic; very short acting beta blocker used IV in acute arrhythmias that occur during surgeries or emergencies |
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Term
| SEs of Beta-blockers - propanolol, acebutalol, esmolol |
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Definition
| sinus bradycardia, AV blockade, Rebound angina, asthmatic attacks,masks severe hypoglycemic rxns, CNS: sedation, fatigue, sleep alterations; AVOID combining with Ca Channel blockers |
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Term
| Class III Antiarrhythmics - amiodarone (Cordarone), dofetilide (Tikosyn) |
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Definition
| agents that inhibit K channels during AP --> diminish outward K current --> prolongs repolarization (Phase 3), prolonging AP duration & ERT |
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Term
| amiodarone (Cordarone), dronadarone (newly FDA approved) |
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Definition
| Class III antiarrhythmic; decreases conduction velocity by decreasing cell-to-cell coupling --> prolongs AP duration & ERP; Uses: severe, refractory (resistant) supraventricular & ventricular tachyarrhythmias, pts that wear ICDs (implantable cardioverter defibrillators) --> reduces how often ICD must deliver shocks; Limited by toxicity; PK: oral, concentrates in tissues w/ prolonged half-life of several wks; contains iodine |
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Term
| SEs of amiodarone (Cordarone) |
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Definition
| interstitial pulmonary fibrosis, dizziness, hyper- or hypothyroidism, blue skin discoloration (iodine accumulation in skin), TdP can occur due to increase AP duration in ventricular tissues (rare) |
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Term
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Definition
| PURE class III agent; inhibits only K channels, prolonging APD & ERP; Uses: supraventricular arrhythmias, atrial fibrillation, suppression of "Reentry" phenomena; Pk: oral & IV; SEs: ventricular TdP (high dosed IV) |
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Term
| Class IV Antiarrhythmics - verapamil (Calan), diltiazem (Cardizem) |
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Definition
| agents that block voltage-sensitive L-type Ca channels --> decrease inward current carried by Ca in phase 0, 2 & 4 --> suppresses phase 0 & 4 slopes, slightly prolonging APD & ERP late in phase 3 |
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Term
| verapamil (Calan), diltiazem (Cardizem) |
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Definition
| class IV drugs that bind mostly to Ca channels --> decrease inward Ca current --> decrease slopes of phase 0 & phase 4 --> slowing conudction, suppressing automaticity --> increases APD & ERP, Uses: arrhythmias that traverse highly Ca-dependent cardiac tissues, supraventricular arrhythmias, stops DADs, reentrant supraventricular tachycarida, protects normal ventricular rate during atrial flutter & fibrillation; MAKES WPW WORSE when accompanied by atrial fibrillation |
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Term
| SEs of diltiazem (Cardizem), verapamil (Calan) |
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Definition
| decreases normal sinus rate & normal AV conduction; negative inotropic action; avoid combo with Beta-blockers |
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Term
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Definition
| miscellaneous antiarrhythmic; decreases conduction velocity & decreasese abnormal impulse formation in AV node by inhibiting Ca influx & by activating ACh-sensitive phase 4 K current (hyperpolarization of resting membrane potential); IV is drug of choice for abolishing acute paroxysmal supraventricular tachycardia; |
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Term
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Definition
| low toxicity; flushing, shortness of breath, chest pain due to bronchospasm |
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Term
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Definition
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