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Questions and Answers
Which of the following scenarios would necessitate careful consideration or potential avoidance due to the antiarrhythmic properties of the prescribed medication?
Which of the following scenarios would necessitate careful consideration or potential avoidance due to the antiarrhythmic properties of the prescribed medication?
- A patient with paroxysmal supraventricular tachycardia (PSVT) being prescribed a Class Ib antiarrhythmic.
- A patient with a history of controlled hypertension requiring a Class II antiarrhythmic.
- A patient with rate-controlled atrial fibrillation being initiated on a Class III antiarrhythmic.
- A patient with known structural heart disease being considered for a Class Ic antiarrhythmic. (correct)
A patient is prescribed an antiarrhythmic drug that prolongs the repolarization phase of the cardiac action potential. Which class of antiarrhythmics does this medication belong to, and what is a potential ECG finding associated with this effect?
A patient is prescribed an antiarrhythmic drug that prolongs the repolarization phase of the cardiac action potential. Which class of antiarrhythmics does this medication belong to, and what is a potential ECG finding associated with this effect?
- Class II; prolonged PR interval
- Class III; prolonged QT interval (correct)
- Class IV; widened QRS complex
- Class Ib; shortened QT interval
A patient with a history of asthma and supraventricular tachycardia (SVT) requires an antiarrhythmic medication. Considering their respiratory condition, which of the following would be the MOST appropriate choice?
A patient with a history of asthma and supraventricular tachycardia (SVT) requires an antiarrhythmic medication. Considering their respiratory condition, which of the following would be the MOST appropriate choice?
- Lidocaine (Class Ib) (correct)
- Propranolol (Class II)
- Amiodarone (Class III)
- Verapamil (Class IV)
A patient is started on an antiarrhythmic medication and subsequently develops new onset constipation, thyroid abnormalities, and visual disturbances. Which antiarrhythmic drug is MOST likely responsible for these side effects?
A patient is started on an antiarrhythmic medication and subsequently develops new onset constipation, thyroid abnormalities, and visual disturbances. Which antiarrhythmic drug is MOST likely responsible for these side effects?
Which of the following antiarrhythmic drug pairs includes one that primarily affects the AV node and another that primarily affects the ventricles?
Which of the following antiarrhythmic drug pairs includes one that primarily affects the AV node and another that primarily affects the ventricles?
Flashcards
Class Ia Antiarrhythmics action
Class Ia Antiarrhythmics action
Slows conduction velocity, prolongs the effective refractory period, and increases the action potential duration.
Class Ib Antiarrhythmics action
Class Ib Antiarrhythmics action
Shortens the action potential duration, decreases the effective refractory period in ventricular tissue.
Class Ic Antiarrhythmics action
Class Ic Antiarrhythmics action
Significantly slows conduction velocity in the atria and ventricles. Has little effect on the duration of the action potential or refractory period.
Class II Antiarrhythmics Action
Class II Antiarrhythmics Action
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Class III Antiarrhythmics Action
Class III Antiarrhythmics Action
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Study Notes
- Antiarrhythmic agents are categorized into four main classes based on their mechanisms of action
Class I Antiarrhythmics
- Affect sodium channels, altering the action potential of cardiac cells
Class Ia
- Includes disopyramide, procainamide, and quinidine
- Action: Moderate sodium channel blockade, prolonging repolarization
- Uses: Treat a variety of atrial and ventricular arrhythmias
- Side Effects: May cause QT prolongation, increasing the risk of torsades de pointes
Class Ib
- Includes lidocaine and mexiletine
- Action: Weak sodium channel blockade, shortening repolarization
- Uses: Primarily for ventricular arrhythmias, especially post-myocardial infarction
- Side Effects: Generally fewer than Class Ia, but can cause neurological symptoms
Class Ic
- Includes flecainide and propafenone
- Action: Strong sodium channel blockade, with minimal effect on repolarization
- Uses: Supraventricular arrhythmias in patients without structural heart disease
- Contraindications: Not recommended for patients with structural heart disease due to proarrhythmic potential
Class II Antiarrhythmics
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Beta-blockers, including acebutolol, esmolol, and propranolol
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Action: Decrease heart rate and contractility by blocking beta-adrenergic receptors
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Uses: Supraventricular tachycardias, rate control in atrial fibrillation
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Side Effects: Bradycardia, hypotension, fatigue
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Other medications in this class: adenosine and digoxin
Class III Antiarrhythmics
- Includes amiodarone, dofetilide, dronedarone, ibutilide, and sotalol
- Action: Primarily potassium channel blockers, prolonging repolarization
- Uses: Used for a variety of atrial and ventricular arrhythmias
- Side Effects: Variable, can include QT prolongation (torsades de pointes), thyroid abnormalities (amiodarone)
Class IV Antiarrhythmics
- Calcium channel blockers, including diltiazem and verapamil
- Action: Block calcium channels, slowing AV node conduction
- Uses: Supraventricular tachycardias, rate control in atrial fibrillation
- Side Effects: Bradycardia, hypotension, AV block
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Description
Antiarrhythmic agents are classified based on how they affect cardiac cells. Class I drugs, including types Ia, Ib, and Ic, primarily act on sodium channels. These drugs treat different arrhythmias, each with specific uses and side effects.
