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Questions and Answers
What are the four classes of anti-arrhythmic drugs according to Vaughan-Williams classification?
What are the four classes of anti-arrhythmic drugs according to Vaughan-Williams classification?
What is the term for the rapid influx of calcium ions during the action potential in calcium-dependent cells?
What is the term for the rapid influx of calcium ions during the action potential in calcium-dependent cells?
Depolarization
What does the term 'automaticity' refer to in the context of cardiac cells?
What does the term 'automaticity' refer to in the context of cardiac cells?
The ability of cardiac cells to generate electrical impulses on their own
Class Ia antiarrhythmic drugs have a minimal effect on conduction.
Class Ia antiarrhythmic drugs have a minimal effect on conduction.
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Which of the following is NOT a class Ia antiarrhythmic drug?
Which of the following is NOT a class Ia antiarrhythmic drug?
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What is the primary adverse effect associated with Procainamide?
What is the primary adverse effect associated with Procainamide?
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Which class of antiarrhythmic drugs is known for blocking beta-adrenergic receptors?
Which class of antiarrhythmic drugs is known for blocking beta-adrenergic receptors?
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What ECG findings are characteristic of Class Ia agents?
What ECG findings are characteristic of Class Ia agents?
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What is the primary clinical use of Lidocaine?
What is the primary clinical use of Lidocaine?
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Lidocaine is the most cardiotoxic antiarrhythmic drug.
Lidocaine is the most cardiotoxic antiarrhythmic drug.
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Class Ic antiarrhythmic drugs have a marked effect on conduction.
Class Ic antiarrhythmic drugs have a marked effect on conduction.
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What is the primary adverse effect associated with Propafenone?
What is the primary adverse effect associated with Propafenone?
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What effect do Class IV antiarrhythmic drugs have on the heart?
What effect do Class IV antiarrhythmic drugs have on the heart?
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What is the most common class of antiarrhythmic drugs used for maintenance in patients with atrial fibrillation?
What is the most common class of antiarrhythmic drugs used for maintenance in patients with atrial fibrillation?
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Amiodarone is a cumulative drug with a short half-life.
Amiodarone is a cumulative drug with a short half-life.
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What is one of the most notable adverse effects associated with Amiodarone?
What is one of the most notable adverse effects associated with Amiodarone?
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Adenosine is a short-acting antiarrhythmic drug with a half-life of approximately 15 seconds.
Adenosine is a short-acting antiarrhythmic drug with a half-life of approximately 15 seconds.
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What is the primary mechanism by which Adenosine exerts its antiarrhythmic effects?
What is the primary mechanism by which Adenosine exerts its antiarrhythmic effects?
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Adenosine is contraindicated in patients with asthma.
Adenosine is contraindicated in patients with asthma.
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Digoxin is an effective antiarrhythmic for both atrial and ventricular arrhythmias.
Digoxin is an effective antiarrhythmic for both atrial and ventricular arrhythmias.
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In the setting of atrial fibrillation, which class of antiarrhythmics are commonly used for rate control?
In the setting of atrial fibrillation, which class of antiarrhythmics are commonly used for rate control?
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Beta-blockers are contraindicated in patients with heart failure.
Beta-blockers are contraindicated in patients with heart failure.
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Class Ib antiarrhythmic drugs are effective for both atrial and ventricular arrhythmias.
Class Ib antiarrhythmic drugs are effective for both atrial and ventricular arrhythmias.
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Prolonged QT interval is associated with an increased risk of Torsades de Pointes.
Prolonged QT interval is associated with an increased risk of Torsades de Pointes.
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Which of the following antiarrhythmic drugs has the highest risk of Torsades de Pointes?
Which of the following antiarrhythmic drugs has the highest risk of Torsades de Pointes?
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What is the term for the delay between the initiation of an action potential and the time when the cell can be re-excited?
What is the term for the delay between the initiation of an action potential and the time when the cell can be re-excited?
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What is the term for the time it takes for a cell to return to its resting membrane potential after an action potential?
What is the term for the time it takes for a cell to return to its resting membrane potential after an action potential?
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Study Notes
Vaughan-Williams Classification of Antiarrhythmic Drugs
- Class Ia: Sodium channel blockers with intermediate effects on conduction and repolarization
- Class Ib: Sodium channel blockers with short-acting, minimal effects on conduction and repolarization
- Class Ic: Sodium channel blockers with marked effects on conduction, prolonging repolarization
- Class II: Beta-adrenergic receptor blockers
- Class III: Potassium channel blockers that prolong repolarization
- Class IV: Calcium channel blockers
Calcium Influx
- The term “calcium influx” refers to the rapid influx of calcium ions (Ca++) during the action potential in calcium-dependent cells. This calcium influx plays a crucial role in the contraction of heart muscle cells.
Automaticity
- Automaticity refers to the inherent ability of cardiac cells to generate their own electrical impulses. This property allows the heart to beat spontaneously and rhythmically.
- In the context of cardiac cells, automaticity relates to their ability to self-depolarize and fire action potentials without external stimulation.
Class Ia Antiarrhythmics
- Have minimal effect on conduction
- Examples: Quinidine, Procainamide, Disopyramide
Procainamide
- Primary adverse effect: Lupus-like syndrome
Beta-Blockers
- Class II antiarrhythmics are known for blocking beta-adrenergic receptors.
- Examples: Propranolol, metoprolol, atenolol
ECG Findings of Class Ia Agents
- Prolonged QT interval
- Widened QRS complex
- Reduced heart rate
Lidocaine
- It's used primarily for the treatment of ventricular arrhythmias.
- It's the most cardiotoxic antiarrhythmic drug.
Class Ic Antiarrhythmics
- Marked effect on conduction
- Examples: Flecainide, Propafenone
Propafenone
- Primary adverse effect: Bradycardia, heart block
Class IV Antiarrhythmics
- Examples: Verapamil, Diltiazem
- They have a negative inotropic effect, meaning they reduce the force of contraction of the heart muscle.
- They also slow the heart rate.
Atrial Fibrillation
- Most common class of antiarrhythmics used for maintenance: Class III (potassium channel blockers)
- Examples: Amiodarone, Sotalol, Dronedarone
Amiodarone
- Notable adverse effects: Pulmonary toxicity, thyroid dysfunction
Adenosine
- Primary mechanism of action: It stimulates adenosine receptors in the heart, slowing down the rate of depolarization and reducing conduction velocity.
- Contraindicated in patients with asthma: Because it can trigger bronchospasm.
Digoxin
- Not effective for all arrhythmias: It's only effective for atrial arrhythmias, not ventricular arrhythmias
Rate Control in Atrial Fibrillation
- Commonly used: Beta-blockers and Calcium Channel Blockers (Class IV antiarrhythmics)
- Note: Beta-blockers are contraindicated in patients with heart failure.
Class Ib Antiarrhythmics
- Effective for both atrial and ventricular arrhythmias
- Examples: Lidocaine, Mexiletine, Tocainide
Torsades De Pointes
- Most common antiarrhythmic drug associated with Torsades de Pointes: Dofetilide
Repolarization
- Refractory period: The delay between the initiation of an action potential and the time when the cell can be re-excited.
- Repolarization: The time it takes for a cell to return to its resting membrane potential after an action potential.
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Description
This quiz focuses on the drug therapy for dyrrhythmias covered in BMS 204 Pharmacology. Students will explore classifications of antiarrhythmic drugs, their applications in treating various arrhythmias, and the specific uses of digoxin and lidocaine. Understanding the adverse effects of these agents is also integral to this study.
