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10 Cards in this Set
- Front
- Back
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Quinidine
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Direct action on AV node to increase Effective Refractory Period [but the anticholinergic effect decreases AV node refractoriness]
Toxicities include depressed myocardial contractility; prolonged Q-T interval can lead to arrhythmias, such as torsades des pointes; slowed conduction Significant antimuscarinic activity G.I. Effects (e.g. Nausea or Diarrhea) limit use in up to 30% of Patients Local anesthetic actions |
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PROCAINAMIDE
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Reversible Lupus-like syndrome without renal or neurological problems
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DISOPYRAMIDE
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Depresses myocardial contractility (may precipitate heart failure)
Anticholinergic effects even greater than quinidine |
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LIDOCAINE
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Must be given i.v. due to high "first pass" hepatic metabolism
Clearance is directly related to hepatic blood flow (i.e., hepatic intrinsic clearance is exceptionally high) Adverse effects primarily on the CNS (convulsions, tremors, nystagmus) Primary uses: Acute management of ventricular arrhythmias [Drug of choice for acute management of ventricular arrhythmias] |
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FLECAINIDE
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PROARRHYTHMIC EFFECTS. Effective suppression of ventricular premature beats, but exacerbates ventricular arrhythmias, increasing mortality
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PROPRANOLOL, METOPROLOL
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Primary uses: management/prevention of supraventricular and ventricular arrhythmias, particularly in patients with M.I.
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AMIODARONE
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Prolongs Q-T interval; prolongs period of refractoriness
Actions associated with K+ channel inhibition, but multiple mechanisms and sites for amiodarone and other “Class III” drugs Complex pharmacokinetics, Very long elimination half-life after chronic use. Accumulates in tissues – many adverse effects Pulmonary fibrosis (~10%) – can be fatal |
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ADENOSINE
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Mechanism: agonist at adenosine receptors.
Increases ACh-sensitive K+ conductance in SA and AV nodes and atria. Thus, shortened AP, reduced automaticity and slowed conduction. Decreases cAMP-induced calcium influx. Denervated hearts are supersensitive Effects inhibited by adenosine receptor antagonists [caffeine and theophylline], potentiated by adenosine uptake inhibitor [Persantine] Very short elimination half-life (< 10 sec); only used i.v. Virtually ALL patients experience chest pain and dyspnea Primary Use: Rapid management of Paroxysmal Supraventricular Tachycardia |
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VERAPAMIL
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Blocks inward calcium current and prolongs desensitized form of the channel.
Thus, main effects in slow fibers (nodal tissue), and also in damaged fibers [e.g. hypoxic cells] in which sodium channels are refractory and calcium currents are more prominent. Contraindicated in Wolff-Parkinson-White syndrome Primary uses: Management of supraventricular arrhythmias and atrial fibrillation |
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Nifedipine
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Is NOT Effective for Treating Arrhythmias
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