ARRHYTHMIAS

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ARRHYTHMIAS

- When the frequency of the atrial and ventricular beats are different it’s call an arrhythmia

- When cardiac cells lack oxygen, they become depolarized which leads to altered impulse formation and/or altered impulse conduction.

200

frequent cause of arrhythmia is

coronary artery disease

300

CARDIAC ACTION POTENTIAL - non-pacemaker cardiac myocytes

Summit, Plummet, Continue, Plummet

400

Summit

Sodium = Phase 0 (influx of sodium)

500

Plummet

1. Potassium = Phase 1 (slight potassium efflux)

600

Continue

1. Calcium = Phase 2 (calcium influx in exchange for potassium efflux)

700

Plummet

Potassium = Phase 3 (major potassium efflux)

800

Resting Phase

Phase 4

Sodium channel blockers

100

Class Ia

procainamide, disopyramide, quinidine

200

Class Ib

lidocaine, mexiletine

300

Class IC

flecainide, propafenone

Beta blockers

100

Name 2 meds 

Esmolol (Brevibloc) 

Propranolol (Inderal)

Potassium channel blockers

100

Name 5 

• Amiodarone (Cordarone)

Afib: 600 to 800 mg daily in divided doses for a total load of up to 10 g, then a maintenance dose of 200 mg once daily 

VT: 400 mg every 8 to 12 hours for 1 to 2 weeks, followed by 200 to 400 mg once daily

• Dofetilide (Tikosyn) initiate inpatient

      500mg twice daily if QTc is >500 msec reduce to 240mg twice daily

• Sotalol (Betapace)

      80 mg twice daily if after 3 days QTc is <500mcg increase to 160mg twice daily

• Ibutilide (Covert) 

     <60 kg: 0.01 mg/kg over 10 minutes or ≥60 kg: 1 mg over 10 minutes

• Dronaderone (Multaq)

     400mg twice daily with meals

Calcium channel blockers

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Names top 2

• Diltiazem (Cardizem, Cartia, Tiazac)

   Acute ventricular rate control:

         IV: Bolus dose: 0.25 mg/kg (actual body weight) over 2 min; if rate control is insufficient after 15 min, a repeat   bolus dose of 0.35 mg/kg over 2 minutes may be given (average dose: 25 mg). Start continuous infusion if patient responds after 1 or 2 bolus doses

         Continuous infusion): Initial: 5 to 10 mg/hour; infusion rate may be increased in 5 mg/hour increments according to ventricular response, up to a           maximum of 15 mg/hour. 

Chronic ventricular rate control (off-label use):

      Oral:

IR: 30 mg 4 times daily; ↑to achieve rate control; max: 480 mg/day 

ER: 120 mg once daily or in 2 divided doses depending on formulation;  max: 480mg/day

• Verapamil (Veralan, Calan)

      Acute ventricular rate control:

      IV: 

      Bolus: Initial: 5 to 10 mg over ≥2 minutes; if there is inadequate  response, dose may be repeated after 15 to 30 min;    if there is adequate response after 1 to 2 bolus doses, then may begin a continuous infusion 

      Continuous infusion: Initial: 5 mg/hour; titrate to goal heart rate up to a maximum of 20 mg/hour  

      Chronic ventricular rate control:

      Oral:

      IR: 40 mg 3-4 times daily; ↑to achieve rate control; max: 480 mg/day 

      ER: 120 or 180 mg once daily; ↑to achieve rate control; max: 480 mg/day 

Miscellaneous Agents

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Name the top 3 mentioned

• Adenosin (Adenocard) slows conduction time through the AV node, interrupting the re-entry pathways through the AV node, restoring normal sinus rhythm

• Digoxin (Lanoxin) When changing from oral (tablets or liquid) to IV therapy, dosage may need to be reduced by 20% to 25%

Magnesium sulfate off label IV for torsades de pointes