Antiarrhythmics

See Mechanism of Action of Select Antiarrhythmics table.

Pharmacologic Profile

General Use

General Action and Information

MECHANISM OF ACTION OF SELECT ANTIARRHYTHMICS

DRUG	MECHANISM
Lidocaine	Class Ib (Na channel blocker)
Esmolol, metoprolol, and propranolol	Class II (beta blockers: ↓ AV nodal conduction and ↓ automaticity)
Amiodarone	Class III (K channel blocker; also has Na channel, beta receptor, and Ca channel blocking properties)
Diltiazem and verapamil	Class IV (nondihydropyridine calcium channel blockers: ↓ AV nodal conduction)
Adenosine	Restores sinus rhythm by slowing conduction and interrupting re-entrant pathways in the AV node
Atropine	Inhibits the action of acetylcholine at postganglionic sites located in the heart →↑ HR
Digoxin	↓SA and AV nodal conduction

¹ AV = atrioventricular; Ca = calcium; K = potassium; Na = sodium; SA = sinoatrial.

Contraindications

Differ greatly among various agents. See individual drugs.

Precautions

Differ greatly among agents used. Appropriate dosage adjustments should be made in older adults and those with renal or hepatic impairment, depending on agent chosen. Correctable causes of arrhythmias (electrolyte abnormalities, drug toxicity) should be evaluated. See individual drugs.

Interactions

Differ greatly among agents used. See individual drugs.

Nursing Implications

Assessment

Monitor ECG, HR, and BP continuously throughout IV administration and periodically throughout oral administration.

Implementation

Take HR before administration of oral doses. Withhold dose and notify physician or other health care provider if HR <50 bpm.

Patient/Family Teaching

Instruct patient to take oral doses around the clock, as directed, even if feeling better.
Instruct patient or family member on how to take pulse. Advise patient to report changes in pulse rate or rhythm to health care provider.
Caution patient to avoid taking OTC medications without consulting health care provider.
Advise patient to carry identification describing disease process and medication regimen at all times.
Emphasize the importance of follow-up exams to monitor progress.

Evaluation/Desired Outcomes