Antiarrhythmics

Question 1

Class I - Mechanism and general effects (all subclasses)

Answer 1

Sodium Channel blockade
Myocyte/Purkinje: slow/block conduction (eg. retrograde currents)
Pacemaker: ↓ Phase 4 slope AND ↑ Threshold

Question 2

Class Ia - Drugs

Answer 2

Quinidine
Procainamide
Disopyramide

Question 3

Class Ia - Use(s)

Answer 3

re-entrant or ectopic SVT and VT

Special: disopyramide for hypertrophic cardiomyopathy

Question 4

Class Ia - Effect

Answer 4

↑ AP duration => ↑ QT and ↑ ERP

“A”verage ↓ Phase 0 slope

Question 5

Quinidine Adverse Effects

Answer 5

Cinchonism = headache + tinnitus

Question 6

Procainamide Adverse Effects

Answer 6

Drug-induced SLE

Question 7

Disopyramide Adverse Effects

Answer 7

Heart failure

Question 8

Class Ia Adverse Effects (all)

Answer 8

↑ QT (torsades risk)

Thrombocytopenia

Question 9

Class Ib - Drugs

Answer 9

Lidocaine
Mexiletine
(Phenytoin = primarily an anticonvulsant)

Question 10

Class Ib - Use(s)

Answer 10

Ventricular arrhythmias (esp post-MI, "B"ad cells)
Digoxin-induced arrhythmias

Question 11

Class Ib - Effect

Answer 11

↓AP duration, especially in ischemic tissue

minimal Phase 0 slope ↓

Question 12

Class Ib - Adverse Effects

Answer 12

CNS stimulation/depression

Question 13

Class Ic - Drugs

Answer 13

Flecainide

Propafenone

Question 14

Class Ic - Use(s)

Answer 14

SVT’s (incl. A. fib)

Question 15

Class Ic - Effect

Answer 15

Markedly ↓ Phase 0 slope (“C”razy blockade)

Large ERP ↑ in AV node and bypass tracts only

Question 16

Class Ic - Adverse Effects

Answer 16

Arrhythmia! (esp post. MI) “C”ontraindicated

Question 17

Class II - Mechanism + Effect

Answer 17

Beta receptor blockade
Decrease nodal activity via ↓ cAMP => ↓ Ca2+ currents
↓ Phase 4 Slope in pacemakers and
AV Node especially sensitive => ↑ PR intervale

Question 18

Class II - Drugs

Answer 18

“ol”s
Nonselective: propranolol, timolol, carvedilol, nadolol
“Pro Tim Carnival Nads”

Question 19

Class II - Use

Answer 19

SVT (incl. V rate control for A. fib and flutter)

Question 20

Class II - Adverse Effects (all)

Answer 20

Cardiac: ↓HR, AV block, HF
CNS: sedation, sleep alteration
Other: Impotence, COPD/asthma exacerbation, unopposed α1-agonism (vasoconstriction) with cocaine or pheochromocytoma

Question 21

Class II - Adverse Effects (specific drugs)

Answer 21

Metoprolol: dyslipidemia
Propranolol: vasospasm in Prinzmetal angina

Question 22

Class II Overdose Tx

Answer 22

Atropine + Glucagon

Question 23

Class III - Mechanism + Effect

Answer 23

Potassium channel blockade

↑ AP duration => ↑ ERP + ↑ QT

Question 24

Class III - Drugs

Answer 24

Amiodarone
Ibutilide
Dofetilide
Sotalol (also non-specific β-Blocker)
"AIDS"

Question 25

Class III - Use

Answer 25

A. Fib + A. flutter

V.tach (A+S)

Question 26

Class III - Adverse Effects (all)

Answer 26

↑ QT and torsades de pointes risk

Question 27

Class III - Adverse Effects (specific drugs)

Answer 27

Amiodarone: Pulmonary fibrosis, hepatotoxic, thyroid (b/c high iodine content), corneal deposits, blue/grey skin deposits, neuro, constipation, heart block, HF, bradycardia
Remember: Amiodarone is Class I, II, III, AND IV. Check LFT’s, PFT’s, and TFT’s before use

Question 28

Class IV - Mechanism + Effect

Answer 28

Calcium channel blockade
Pacemaker: ↓ conduction velocity, ↑ ERP, ↑ threshold
Ultimate EFfect: ↑ PR and ↓ HR

Question 29

Class IV - Drugs

Answer 29

Verapamil, diltiazem

but other non-cardiac Calcium blockers, remembers

Question 30

Class IV - Use

Answer 30

SVT

rate control in A. fib

Question 31

Class IV - Adverse Effects (all)

Answer 31

Cardiac: HF, AV block
Other: constipation, flushing, edema,

Question 32

Adenosine - Mechanism, Use, Adverse Effects

Answer 32

K efflux => hyperpolarization
short-acting to abolish SVT’s (like re-entrant rhythms)
Adverse Effects: flushing, hypotension, bronchospasm, “sense of impending doom”

Question 33

Magnesium (use?)

Answer 33

torsades and digoxin toxicity

Question 34

Which classes cause QT prolongation?

Answer 34

Ib and III

Question 35

Which classes cause ↑PR => potential AV block?

Answer 35

II and IV

and amiodarone…