Pharmacology II: Antiarrhythmic Agents
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Questions and Answers

Which ion channels are primarily responsible for the inward depolarizing current during phase 2?

  • Chloride channels
  • Potassium channels
  • L-type Calcium channels (correct)
  • Sodium channels

    • The repolarization phase of cardiac cells involves an influx of potassium ions.

    False (B)

    What is the primary function of pacemaker cells?

    To spontaneously initiate action potentials (automaticity)

    The cardiac conduction pathway begins with the __________ node.

    <p>Sinoatrial</p> Signup and view all the answers

    Which of the following has the fastest intrinsic rate of spontaneous depolarization?

    <p>Sinoatrial node (D)</p> Signup and view all the answers

    Match the following components of the cardiac conduction system with their descriptions:

    <p>Sinoatrial node = Primary pacemaker of the heart Atrioventricular node = Delays impulse transmission Bundle of His = Conducts impulses to ventricles His-Purkinje conduction system = Rapidly conducts impulses within ventricles</p> Signup and view all the answers

    What happens to Ca++ currents during phase 3?

    <p>They inactivate.</p> Signup and view all the answers

    The __________ wave represents ventricular repolarization on an ECG.

    <p>T</p> Signup and view all the answers

    What heart rate corresponds to atrial flutter with 1:1 conduction?

    <p>220 bpm (B)</p> Signup and view all the answers

    Bradycardia can be a result of decreased conduction velocity.

    <p>True (A)</p> Signup and view all the answers

    Who introduced the Vaughan Williams classification?

    <p>Miles Vaughan Williams</p> Signup and view all the answers

    Class __________ antiarrhythmic agents usually block Na+ channels with an intermediate action.

    <p>Ia</p> Signup and view all the answers

    Which drug is classified under Class Ib antiarrhythmic agents?

    <p>Lidocaine (C)</p> Signup and view all the answers

    Match the following antiarrhythmic classes with their major actions:

    <p>Class Ia = Na+ channel block (intermediate) Class Ib = Na+ channel block (fast on-off) Class Ic = Na+ channel block (slow on-off) Class II = Beta blockade (indirect Ca++ block)</p> Signup and view all the answers

    Class Ic agents have an action that includes decreasing automaticity.

    <p>True (A)</p> Signup and view all the answers

    What effect do Class II antiarrhythmic agents have on conduction velocity?

    <p>Decreases</p> Signup and view all the answers

    What effect does norepinephrine have when it stimulates beta-1 adrenergic receptors?

    <p>Increased sinus rate (C)</p> Signup and view all the answers

    Beta blockers have a positive chronotropic action that increases heart rate.

    <p>False (B)</p> Signup and view all the answers

    What is one potential adverse effect caused by beta blockers?

    <p>Bradycardia</p> Signup and view all the answers

    Beta blockers reduce heart rate by decreasing SA node ______.

    <p>automaticity</p> Signup and view all the answers

    Match the following beta blocker drugs with their specific properties:

    <p>Metoprolol = IV and PO Esmolol = Short-acting (t½ ~ 9 min); IV only Propranolol = IV and PO Carvedilol = Blocks alpha-1 receptors</p> Signup and view all the answers

    Which of the following drugs is NOT considered a beta-blocker?

    <p>Sotalol (B)</p> Signup and view all the answers

    Intrinsic sympathomimetic activity (ISA) is a desirable property in beta blockers.

    <p>False (B)</p> Signup and view all the answers

    What is the role of beta-blockers in myocardial infarction or ischemic tissue?

    <p>They increase the energy required to cause fibrillation.</p> Signup and view all the answers

    Normal sinus rhythm (NSR) is the regular rhythm of __________ bpm that originates with depolarization of the ___________ node.

    <p>60-100; sinoatrial</p> Signup and view all the answers

    Which of the following is NOT one of the basic mechanisms of arrhythmias?

    <p>Increased rhythmicity (D)</p> Signup and view all the answers

    All antiarrhythmics are proarrhythmic.

    <p>True (A)</p> Signup and view all the answers

    What are the two goals of antiarrhythmic therapy?

    <p>Terminate ongoing arrhythmia; Prevent future/recurrent arrhythmia</p> Signup and view all the answers

    Which of the following factors can precipitate or exacerbate arrhythmias?

    <p>Electrolyte abnormalities (C)</p> Signup and view all the answers

    Match the following definitions with their terms:

    <p>Altered automaticity = Change in the rate of impulse generation Triggered activity = Abnormal impulses triggered by previous depolarization Heart block = Impaired conduction through the heart Reentry = A circuit of impulses that can cause arrhythmias</p> Signup and view all the answers

    Antiarrhythmics suppress arrhythmias by __________ flow through specific ion channels.

    <p>blocking</p> Signup and view all the answers

    Name one type of arrhythmia that results from disturbances in impulse transmission.

    <p>Heart block or Reentry arrhythmias</p> Signup and view all the answers

    Which of the following drugs primarily block K+ channels?

    <p>Sotalol (B), Dronedarone (D)</p> Signup and view all the answers

    Amiodarone exhibits rapid dissociation rates from Na+ channels.

    <p>False (B)</p> Signup and view all the answers

    What is the therapeutic range for the drug mentioned to accumulate in the body?

    <p>1.5-5 mcg/mL</p> Signup and view all the answers

    Flecainide is used for supraventricular arrhythmias in patients with structurally __________ hearts.

    <p>normal</p> Signup and view all the answers

    Match the class of antiarrhythmics with their characteristics:

    <p>Class Ia = Prolong AP duration, dissociation rate of recovery 1-10 sec Class Ib = Longer dissociation kinetics with recovery time in hours Class Ic = Weak QT prolongation, primarily prolongs QRS complex Class III = K+ channel block, used for various arrhythmias</p> Signup and view all the answers

    Which of the following statements about Class I antiarrhythmics is true?

    <p>They can have use-dependent block characteristics. (C)</p> Signup and view all the answers

    Diltiazem is classified as a Class IV antiarrhythmic.

    <p>True (A)</p> Signup and view all the answers

    Name one adverse effect related to dose and accumulation of antiarrhythmic drugs.

    <p>Tremor</p> Signup and view all the answers

    Which of the following drugs is a derivative of amiodarone?

    <p>Dronedarone (B)</p> Signup and view all the answers

    Dronedarone is more effective than amiodarone in treating atrial fibrillation.

    <p>False (B)</p> Signup and view all the answers

    What is the primary concern when using Sotalol?

    <p>QT prolongation</p> Signup and view all the answers

    Dronedarone blocks ______+ and Ca++ channels.

    <p>K</p> Signup and view all the answers

    Match each drug with its specific monitoring requirement:

    <p>Amiodarone = LFTs and pulmonary function tests Dronedarone = LFTs first 6 months Sotalol = CrCL for dose adjustment All drugs = Bradycardia monitoring</p> Signup and view all the answers

    Which drug should be avoided in patients at high risk for vascular events?

    <p>Dronedarone (C)</p> Signup and view all the answers

    Sotalol has multiple drug interactions.

    <p>False (B)</p> Signup and view all the answers

    What is the elimination route for Sotalol?

    <p>Renally</p> Signup and view all the answers

    Most of the drugs discussed are water ________.

    <p>insoluble</p> Signup and view all the answers

    The half-life (t½) of many of these drugs is typically:

    <p>Weeks to months (B)</p> Signup and view all the answers

    Study Notes

    Pharmacology II: Antiarrhythmic Agents

    • Learning Objectives:
      • Compare and contrast action potentials of SA/AV nodal and non-nodal myocytes.
      • Identify the pathway for normal impulse propagation through the heart and its relation to ECG waveforms in normal sinus rhythm.
      • Classify antiarrhythmic drugs using the Vaughan Williams classification.
      • Describe the mechanism of action and effect on the cardiac action potential of individual antiarrhythmic drugs.
      • Discuss drug properties, patient factors, and considerations for their use in patients.
      • Explain expected adverse effects and contraindications for individual antiarrhythmic drugs.
      • Recommend appropriate monitoring parameters for antiarrhythmic drugs.

    Definitions and Terminology

    • Arrhythmia: Any disturbance in the cardiac electrical impulse.
    • Transmembrane/Membrane Potential: Electrical charge across the plasma membrane of a cardiac cell.
    • Action Potential: Change in electrical potential associated with the propagation of an impulse along the cell membrane.
    • Refractory Period: Period during which a cell is incapable of generating another action potential, preventing overlapping impulses.
    • Electrocardiogram (ECG): Measures the overall electrical activity of the heart.
    • Torsades de Pointes (TDP): Polymorphic ventricular tachycardia.

    Cardiac Action Potentials

    • SA/AV Nodal Pacemaker Cells: Depolarization is Ca++-dependent, exhibiting spontaneous firing.
    • Atrial and Ventricular Cells (Non-nodal): Depolarization is primarily Na+-dependent.

    Normal Impulse Propagation

    • Normal Sinus Rhythm (NSR): Regular heart rhythm originating from the SA node, at a rate of approximately 60-100 bpm.

    Mechanisms of Arrhythmias

    • Arrhythmias can range from asymptomatic to life-threatening.
    • Causes include disturbances in impulse formation or conduction.

    Antiarrhythmic Drug Therapy

    • Goals: Terminate ongoing arrhythmias and prevent recurrences.
    • Mechanisms: Blocking ion channels, altering autonomic function, and modifying automaticity, threshold potential, maximum diastolic potential, and AP duration.

    Classification of Antiarrhythmic Drugs

    • Vaughan Williams Classification: Categorizes drugs based on their electrophysiological effects.
      • Class Ia: Prolong repolarization, moderate effect on conduction velocity; example: quinidine.
      • Class Ib: Shorten repolarization; less effect on conduction; example: lidocaine.
      • Class Ic: Prolong repolarization, strong effect on conduction velocity; example: flecainide.

    Other Antiarrhythmic Agents

    • Digoxin: Positive inotrope, slows AV node conduction, and reduces ventricular response in atrial flutter and fibrillation.
    • Adenosine: Short-acting antiarrhythmic drug that can terminate supraventricular tachycardias.

    Specific Drug Properties

    • Each drug has unique properties, adverse effects, uses, and patient care considerations.

    Class IV Antiarrhythmics: Calcium Channel Blockers

    • Mechanism of action: Block calcium channels and slower conduction velocities.

    Other Antiarrhythmic Agents (Outside Vaughan Williams Classification)

    • Adenosine: Naturally occurring nucleoside that slows AV nodal conduction.

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    Antiarrhythmic Agents PDF Lecture Notes 2025

    Description

    This quiz covers the essential concepts of antiarrhythmic agents in pharmacology. You'll explore the classification of these drugs, their mechanisms of action, and important patient considerations. Additionally, the quiz examines the effects of these drugs on cardiac action potentials and potential adverse effects.

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