Root of the neck
Optional reading Moore, Clinically Oriented Anatomy, 9th ed., Deep structures of neck section through Nerves in root of neck. The root of the neck (base of the neck, cervicothoracic region) is important because it is the region of continuity between the neck and thorax, and the neck and upper limbs. It can be somewhat confusing […]
Additional resources and references
Additional resources Tulane. https://tmedweb.tulane.edu/pharmwiki/doku.php/intro_to_antiarrhythmics Kim, C.J. et al. Antiarrhythmic drugs and anaesthesia: part 1. mechanisms of cardiac arrhythmias. BJA Education, Volume 23, Issue 1, 8–16. https://www.bjaed.org/article/S2058-5349(22)00141-X/fulltext Kim, C.J. et al. Antiarrhythmic drugs and anaesthesia. Part 2: pharmacotherapy. BJA Education, Volume 23, Issue 2, 52–60. https://www.bjaed.org/article/S2058-5349(22)00147-0/fulltext TikTok with helpful memory aids: https://www.tiktok.com/@medschoolbro/video/7235035002306579718?lang=en References Antiarrhythmic Drugs. In: Stringer JL. eds. Basic […]
Self-assessment questions
Source The following self-assessment questions were adapted from: Antiarrhythmic Drugs. In: Kruidering-Hall M, Katzung BG, Tuan R, Vanderah TW. eds. Katzung’s Pharmacology Examination & Board Review, 14th Edition. McGraw Hill; 2024. Accessed January 10, 2026. Question 1 of 5 A 54-year-old airline pilot is admitted to the emergency department with chest pain and a rapid heart rhythm. The ECG […]
Comparing antiarrhythmic drugs
Antiarrhythmic impact on action potentials Image credit: Amboss. Class I–IV antiarrhythmics (Singh Vaughan–Williams classification) Class Subclass / Drugs Primary Mechanism AP Phase Target ECG Effects Class I (Na⁺ channel blockers) IA: Quinidine, Procainamide, Disopyramide Moderate Na⁺ block + K⁺ block → ↓ conduction, ↑ refractory period Phase 0 (↓ slope), Phase 3(prolong via K⁺ block) ↑ QRS, ↑ QT IB: Lidocaine, Mexiletine […]
Additional antiarrhythmics
So far, this module has covered high-yield antiarrhythmic medications by historical Singh Vaughan-Williams classification. There are other antiarrhythmics of note that will be covered now. Adenosine Adenosine binds to A1 adenosine receptors in the AV node (Gi‑coupled). Gi inhibits adenylyl cyclase → ↓ cAMP → reduced L‑type Ca²⁺ channel activity. This leads to: Slowed AV nodal conduction Increased […]
Class IV antiarrhythmic drugs
Class IV antiarrhythmics: Calcium channel blockers Drugs Verapamil Diltiazem Question Class IV antiarrhythmics are calcium channel blockers. Drugs from which other antiarrhythmics classes also reduce or blunt calcium’s effects? Select all that apply. Rationale Class II (beta‑blockers) antiarrhythmics do notblock Ca²⁺ channels directly, but reduce calcium influx by decreasing cAMP‑mediated activation of L‑type Ca²⁺ Amiodarone, a Class III […]
Class III antiarrhythmic drugs
Class III antiarrhythmics: Potassium channel blockers Class III drugs primarily target rapid (IKr) and slow (IKs) delayed rectifier K+ The main effects are increased action potential duration and refractoriness, which helps suppress atrial and ventricular arrhythmias caused by re-entry. Class III drugs can cause life-threatening proarrhythmia. Drugs Sotalol Amiodarone Ibutilide Dofetilide Dronedarone Memory aid A […]
Class II antiarrhythmic drugs
Class II antiarrhythmics: Beta-adrenergic receptor blockers Drugs Carvedilol Propranolol Atenolol Bisoprolol Metoprolol Esmolol Typically considered Class III, but also Class II is sotalol (sotalol will be discussed with Class III agents in this module) Memory aid Beta-blockers have the common drug stem -lol. Background required to understand mechanism We will cover more information regarding the […]
Class I antiarrhythmic drugs
Class I antiarrhythmics: Voltage-gated sodium channel blockers Class I drugs block Na+ channels, reduce excitability, and increase the threshold potential. The Class I antiarrhythmics are further broken down into 3 categories: Class IA, IB, and IC. Class Generic names Mnemonic device Image IA Disopyramide Quinidine Procainamide Double Quarter Pounder IB Lidocaine Mexiletine Lettuce Mayo IC […]
Antiarrhythmic drugs
There are several strategies to categorize antiarrhythmic drugs, each with their advantages and disadvantages. For the purposes of this learning module, we will use the Singh Vaughan-Williams classification system, which originally contained four classes, but was updated to include drugs that do not fit into those classes. The Singh Vaughan-Williams classification system now includes Class […]