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Questions and Answers
Which of the following are examples of Class IV antiarrhythmics?
Which of the following are examples of Class IV antiarrhythmics?
- Diltiazem (correct)
- Lisinopril
- Amlodipine
- Verapamil (correct)
What is the mechanism of action (MOA) for Class IV antiarrhythmics?
What is the mechanism of action (MOA) for Class IV antiarrhythmics?
Decrease conduction velocity, increase effective refractory period, increase PR interval
How do Class IV antiarrhythmics treat arrhythmias?
How do Class IV antiarrhythmics treat arrhythmias?
Block L-type Ca2+ channels in the SA and AV nodes
Which phase of the SA and AV node action potential does Ca2+ dictate?
Which phase of the SA and AV node action potential does Ca2+ dictate?
What phase of the SA and AV node action potential do Class IV antiarrhythmics prolong?
What phase of the SA and AV node action potential do Class IV antiarrhythmics prolong?
What is the effect of Class IV antiarrhythmics on the AV node?
What is the effect of Class IV antiarrhythmics on the AV node?
What is the clinical use of Class IV antiarrhythmics?
What is the clinical use of Class IV antiarrhythmics?
Which antiarrhythmic classes control Afib via rhythm control (restoring NSR)?
Which antiarrhythmic classes control Afib via rhythm control (restoring NSR)?
Which antiarrhythmic classes control Afib via rate control (AV nodal conduction delay)?
Which antiarrhythmic classes control Afib via rate control (AV nodal conduction delay)?
What are some common side effects of Class IV antiarrhythmics?
What are some common side effects of Class IV antiarrhythmics?
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Study Notes
Class IV Antiarrhythmics Overview
- Examples include Verapamil and Diltiazem.
- Primarily recommended for managing nodal (supraventricular) arrhythmias.
Mechanism of Action
- Decrease conduction velocity through cardiac tissue.
- Increase the effective refractory period, prolonging PR interval on ECG.
Treatment of Arrhythmias
- Target and block L-type calcium channels located in the SA and AV nodes.
- Control cardiac action potential phases, specifically prolonging phase 4, leading to a reduced sinus rate.
Action Potential Phases
- Calcium ions are crucial in determining phase 0 upstroke of SA and AV node action potentials.
- Prolonging phase 4 results in a decreased frequency of action potentials in the sinus node.
Effects on AV Node
- Class IV antiarrhythmics significantly prolong AV nodal conduction, which results in altered heart rate dynamics.
Clinical Applications
- Utilized for preventing nodal arrhythmias.
- Effective in rate control for atrial fibrillation (Afib) with rapid ventricular response.
Comparison of Antiarrhythmic Classes
- Class I and III antiarrhythmics are focused on rhythm control, aiming to restore normal sinus rhythm (NSR).
- Class II and IV antiarrhythmics are used for rate control, managing AV nodal conduction delays.
Side Effects
- Potentially lead to AV heart block and heart failure.
- May cause sinus node depression, constipation, and flushing as common side effects.
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