Week 7: Antiarrhythmics

Question 1

5 Classes of Antiarrhythmics

Answer 1

Class I - Sodium Channel Blockers
Class 2 - Beta Blockers
Class 3 - Potassium Channel Blockers
Class 4 - Calcium Channel Blockers

Question 2

Pharmacodynamics of Class I Antiarrhythmics

Answer 2

Sodium Channel Blockers
A- lengthen the duration of action potential
B- shorten the duration of action potential
C- minimally increase action potential

Question 3

Pharmacodynamics of Class II Antiarrhythmics

Answer 3

Beta Blocker - reduce adrenergic activity of the heart

Question 4

Pharmacodynamics of Class III Antiarrhythmics

Answer 4

Potassium Channel Blockers (Amiodarone) - prolong effective refractory period and reduce speed of conduction

Question 5

Pharmacodynamics of Class IV Antiarrhythmics

Answer 5

Calcium Channel Blockers - Non-dihydropyridines (Verapamil & Diltiazem)
- block the influx of calcium in myocardial smooth muscle cells reducing contractility (negative inotropism) - decrease SA and AV node conduction - significantly reduce afterload

Question 6

Amiodarone / potassium channel blockers cautions/ contraindications

Answer 6

• avoid in SSS and higher degrees of AV blocks
• avoid in iodine sensitivity
• may cause thyroid abnormalities (hypothyroidism is most common)

Question 7

Amiodarone ADRs

Answer 7

• blue-gray skin tone (iodine under the skin)
• corneal deposits
• thyroid issues
• lung damage not evident until advanced

Question 8

Monitoring necessary when a patient is taking amiodarone

Answer 8

At least every 6 months:

• Chest xray - PFTs
• TSH, free T4
• Ophthalmic exam
• Liver function tests