Medications Affecting Cardiac Rhythm

A set of flashcards covering vocabulary and key clinical details of antiarrhythmic and rhythm-affecting medications including Classes IA, IB, IC, III, and miscellaneous agents.

Quinidine

A Class IA sodium-channel blocker with potassium-channel effects that slows conduction and prolongs repolarization/QT.

Cinchonism

A toxic symptom set caused by quinidine therapy that includes tinnitus, hearing changes, blurred vision, headache, and confusion.

Lidocaine (Xylocaine)

A Class IB sodium-channel blocker used IV for acute life-threatening ventricular dysrhythmias, especially in ischemic cardiac tissue.

Early CNS Toxicity (Lidocaine)

A progression of symptoms starting with mouth numbness, metallic taste, and tinnitus, which can advance to seizures, coma, and respiratory arrest.

Propafenone (Rythmol)

A Class IC sodium-channel blocker with mild beta-blocking activity used to maintain sinus rhythm in selected atrial fibrillation cases.

Flecainide (Tambocor)

A Class IC sodium-channel blocker for strong conduction slowing; it is avoided after Myocardial Infarction ($MI$) due to increased mortality risk.

Negative Inotropy

A characteristic of Class IC drugs like propafenone and flecainide that can worsen heart failure.

Amiodarone (Cordarone / Pacerone)

A Class III antiarrhythmic that primarily blocks potassium channels and prolongs repolarization, but also has sodium, calcium, and beta-blocking effects.

Pulmonary Pneumonitis/Fibrosis

A life-threatening serious adverse reaction associated with amiodarone that requires lung monitoring via imaging or $PFTs$.

Blue-gray Discoloration

A specific skin side effect that can occur with long-term exposure to amiodarone.

Adenosine (Adenocard)

An adenosine-receptor agonist/transient AV-nodal blocker with an ultra-short half-life of $< 10\,s$ used to terminate narrow-complex SVT.

Adenosine Administration Protocol

Must be given as a very rapid IV bolus through the closest port, immediately followed by a rapid saline flush.

Atropine (Atropen)

A muscarinic anticholinergic and vagolytic medication used to increase heart rate in symptomatic bradycardia.

Anticholinergic Side Effects (Atropine)

Includes dry mouth, blurred vision, photophobia, constipation, and urinary retention.

Phase-0 Depolarization

The stage of the cardiac action potential where fast sodium channels are blocked by Class IA medications like quinidine.

Torsades de pointes

A serious ventricular dysrhythmia associated with QT prolongation, specifically monitored during quinidine therapy.