Antidysrhythmic Drugs

Quinidine

MOA: Anticholinergic and blocks parasympathetic activation -> increase SA node automaticity and AV conduction (Pretreated with digoxin, verapamil, or a beta blocker) Used for supraventricular and ventricular: long term use typical, may increase mortality, antimalarial Adverse effects: - SEVERE DIARRHEA (take with meals) - Cinchonism (running in the ears, headache, nausea, vertigo, and disturbed vision, notify provider if develops) - Embolism with atrial fibrilation - Hypotension - Hypersensitivity reaction

The nurse is caring for a patient receiving amiodarone. Which body system should the nurse assess for serious adverse effects of this medication?

Respiratory Reason: amiodarone can cause pulmonary toxicity and precipitates HF

Ventricular Dysrhythmias

- Ventricular Tachycardia - Ventricular fibrillation (Life-threatening emergency) - Torsades de Pointes (Prolongation of QT interval)

causes of dysrhythmias

- Changes in normal rate of discharge of SA or AV nodes - Phase 4 depolarization in cells that do not normally depolarize - Excessive discharge of sympathetic nervous system (tachycardia) - Excessive parasympathetic nervous system (bradycardia) - AV block if impulse conduction delayed or stopped through AV node - Hypoxia - Electrolyte imbalance - Cardiac surgery - Reduced coronary blood flow - Myocardial infarction - Antidysrhythmic drugs (digoxin)

Adenosine

- Drug of choice for terminating paroxysmal supraventricular tachycardia(SVT) - Decreases automaticity In the SA node (working at original signaling of atria) and slow conduction through the AV node - Very short half-life - Administered IV

Cardiac Action Potentials

A. Fast potentials through atria and ventricles B. Slow potential through SA and AV node

In which part of the conduction pathway in a healthy heart is the electrical impulse delayed to provide a time for the blood to fill the ventricles?

AV node

A patient develops supraventricular tachycardia (SVT) is hypotensive. Which medication should the nurse anticipate will be administered?

Adenosine Reason: Adenosine is the drug of choice for terminating paroxysmal supraventricular tachycardia(SVT)

Procainamide

Administer evenly spaced around the clock Adverse effects: - Systemic lupus erythmateous (SLE) like syndrome - Blood dyscrasias (signs of infection, bruising, or bleeding)

Class III: Potassium Channel Blockers MOA and meds

Amiodarone (primary) Dronedarone Solatol (and beta blocker) Dofetilide Ibutilide MOA: delay repolarization of fast potentials

Antidysrhythmics meds

Class I: Sodium Channel blockers (Class A, B, C) Class II: Beta blockers Class III: Potassium Channel blockers CLass IV: Calcium Channel blockers Other: Adenosine and Digoxin

The nurse is caring for a patient prescribed quinidine for a supraventricular dysrhythmia. What is a common adverse effect of this drug?

Diarrhea

Which medication is not associated with prolongation of the QT interval?

Diltiazem (K+ channel blocker) Reason: this med is associated with the prolongation of PR interval and bradycardia

Lidocaine

IV agent used only for ventricular dysrhythmias Adverse effects: CNS (drowsiness, confusion, paresthesias), seizures (avoid giving to pts with seizure hx), RARE respiratory arrest Lidocaine monitoring: - BP (can cause hypotension) - EKG toxicity (can further lead to dysrhythmias)

Dronaderone

Less toxic than amiodarone, but less effective (sister drugs) - shorter half-life Adverse effects: diarrhea, weakness, nausea, skin reactions Contraindications: severe HF, previous liver or lung toxicity from amio, permanent afib, AV block, abnormal EKG, bradycardia, pregnancy, cyp3A4 inhibitors

Amiodarone

MOA: promotes vasodilation in coronary and peripheral blood vessels Used for: atrial and ventricular dysrhythmias Drug interaction: CYP3A4 **long half-life causes significant adverse effects, levels can stack up Adverse effects: - Pulmonary toxicity(chest x-ray and pulmonary function tests) - Precipitates HF - Thyroid toxicity (baseline and during treatment) - Liver toxicity(liver function tests before and after tx) - Ophthalmic effects (eyes) - Toxicity in pregnancy and breast feeding - Photosensitivity reactions(Avoid sunlamps and wear sunscreen) - CNS reactions - GI reactions

The nurse is administering IV lidocaine to a patient with a ventricular dysrhythmia. What is the priority nursing intervention to prevent a potential complication with this drug?

Monitor the electrocardiogram (ECG)

Amiodarone is prescribed for a patient with atrial fibrillation. What is the most important nursing intervention before administering the medication?

Obtain baseline serum thyroid and liver function studies Reason: amiodarone can cause liver and thyroid toxicity

The nurse is interpreting an electrocardiogram(ECG). Which component represents the depolarization of ventricles?

QRS complex

Supraventricular Dysrhythmias

Tachycardia Types: - Atrial fibrillation - Atrial flutter - Supraventricular tachycardia (SVT)

Class IV: Calcium Channel Blockers

Verapamil and diltiazem only - Not active against ventricular dysrhythmias - Increases digoxin levels - Interacts with beta blockers and leads to AV block (compound effect, total block of signaling through AV node)

Dysrhythmias

abnormality in the speed or rhythm of the heartbeat (arrhythmia used interchangeably) Pathophysio: Impulses originate SA node (the pacemaker) -> rapidly through atria -> slowly through AV node (provide time for filling) -> rapidly through ventricles via His-Purkinje system ** meds are used less frequently as some increase risk of death ** nonpharmacologic therapies including defibrillators and ablation (shut down certain nerves) used more frequently

Class IC: Sodium Channel blockers

flecainide propafenone MOA: Na channel blockade, pronounced prodysrhythmic action

Class IB: Sodium Channel Blockers MOA and meds

lidocaine phenytoin mexiletine MOA: increase conduction velocity in the atria, ventricles, and His-Purkinje system ** accelerates repolarization (sets up for next pump better)

Class II: Beta Blockers

propanolol acebutolol esmotolol sotalol (grouped under K+ blockers) **functionally couples to calcium channel therefore effects are very similar

Class IA: Sodium Channel blockers MOA and meds

quinidine procainamide dispyramide MOA: Decrease conduction velocity in the atria, ventricles, and His-Purkinje system. **Delay repolarization (delays reset structering, can prolong refilling, bad!)