Antiarrhythmics & AF (NAPLEX)

Cardiac conduction of the heart

• Impulse begins at SA node

• Travels to R/L atria causing atrial contraction

• Continues through Bundle of His

• Divides R bundle branch for RV and L bundle branch for LV

• Signal spreads through ventricles through Purkinje fibers causing ventricles to contract

Hearts natural pacemaker

AV node

4 phases of cardiac action potential

• Phase 0: sodium influx causes rapid ventricular depolarization/contraction

• Phase 1: sodium channels close

• Phase 2: influx of calcium; efflux of potassium

• Phase 3: potassium efflux causes rapid ventricular repolarization/relaxation

• Phase 4: resting membrane potential

What is PVC's?

• Premature ventricular contractions

• "skipped heart eats"

• Common & can be related to stress, caffeine, nicotine, exercise

• Can cause VTACH

What is a series of PVC's that result in HR>100?

VTACH

What is considered a prolonged QTC?

>440-460 ms

Drugs the increase QTC

LOTS HAHA

Risk factors for QTC prolongation (7)

• Higher doses

• Concurrent drugs

• Renal or liver disease

• DDI

• Electrolytes: hypoK, HypoMg, HypoCa

• Heart failure

• Females

Vaughan williams classes **

CLASS I: sodium channel blockers

• IA: Disopyramide, Quindine, Procainamide

• IB: Lidocaine, Mexiletine

• IC: Flecainide, Propafenone

CLASS II: beta blockers

CLASS III: potassium channel blockers

• Dronedarone, Dofetilide, Sotalol, Ibutilide, Amiodarone

CLASS IV: non-DHP CC

• Verapamil, Diltiazem

Double Quart Pounder, Lettuce, Mayo, Fries Please!

Because Dieting During Stress Is Always Very Difficult

Amiodarone BW (3)

• Pulmonary toxicity

• Hepatotoxicity

• Proarrhythmic

Amiodarone warnings (4)

• Hypo & hyperthyroidism (hypo more common) - amio inhibits peripheral conversion of T4 to T3

• Visual impairments (optic neuropathy, corneal microdeposits)

• Photosensitivity (blue-gray skin discoloration)

• Peripheral neuropathy

Amiodarone infusions >2 hours require a _____ container

non-PVC (example: polyolefin, glass)

What filter should you use with amiodarone?

0.22 micron

Amiodarone PK

CYP3A4, 2C9, 2D6 inhibitor

Amiodarone DDI (4)

• Digoxin

• Warfarin

• Simvastatin, lovastatin

• Sofosbuvir (can enhance bradycardia)

Disopyramide main adverse effect

anticholinergic (dry mouth, constipation, urinary retention)

Quindine adverse effects (4)

• Drug induced lupus

• Diarrhea

• Stomach cramping

• Cinchonism - tinnitus, hearing loss, blurred vision, headache, delirium

What medication can cause toxicity called cinchonism?

Quinidine

Procainamides active metabolite

NAPA (N-acetyl procainamide) which is renally cleared

Procainamide therapeutic level: ___-___ mcg/mL

4-10 mcg/mL

Procainamide BW

Potentally fatal blood dyscrasias (agranulocytosis)

Long term use of this medication can cause positive antinuclear antibody (ANA) which can result in drug induced lupus?

Procainamide

What Class is only useful for ventricular arrhythmias (no use in AF)?

• Class IB: Lidocaine; Mexiletine

What medication can cause taste disturbance (metallic)?

Propafenone

Dofetilide BW

• Must be started in a setting with continuous EKG monitoring

• Assess CrCl for a minimum of 3 days

Dronedarone BW

Contraindicated in patients with decompensated HF or permanent AF due to increased risk of death, stroke, and HF

Does dronedarone affect thyroid?

NO - it does not contain iodine like amio does

Sotalol renal adjustments with CrCl < _____

<60 mL/min

What is used for supraventricular re-entrant tachycardias?

Adenosine

Intermittent AF that terminates within 7 days of onset

A. Paroxysmal AF

B. Persistent AF

C. Long-standing AF

D. Permanent AF

A. Paroxysmal AF

Continuous AF sustained for >7 days

A. Paroxysmal AF

B. Persistent AF

C. Long-standing AF

D. Permanent AF

B. Persistent AF

Goal resting HR for AF is < ___ bpm in pts with symptomatic AF

<80

RATE CONTROL

Remains in AF and takes meds to control ventricular rate or HR

• Beta blockers

• non-DHP CCB

• +/- digoxin

RHYTHMN CONTROL

Goal is to restore & maintain NSR

• Class Ia, Ic, or III antiarrhythmics (amio)

What medication enhances vagal tone?

Digoxin

IV to PO digoxin dose conversions

When converting PO to IV, reduce dose by 20-25%

Electrolytes increasing risk of digoxin toxicity (3)

• HypoK

• HypoMg

• HyperCa

Amiodarone half-life approx ___ days

60

Dofetilide, dronedarone, and sotalol exert their predominant electrophysiologic effect in Phase _____.

Phase 3

Which meds are used only IV for treating arrhythmias?

A. quindine & sotalol

B. digoxin & disopyramide

C. propafenone & procainamide

D. dofetilide & flecainide

E. ibutilide & lidocaine

E. ibutilide & lidocaine

Therapeutic range for digoxin for AF: ___-___ ng/mL

0.8-2 ng/mL

Heart failure is 0.5-0.9

How long should a pt remain on anticoagulation for PPX after cardioversion?

4 weeks

what anitarrhythmics are known for causing drug induced lupus? (3)

• Quindine

• Procainamide

• Amiodarone

When amiodarone & warfarin are used together: decrease the warfarin dose by ____-____%

30-50%