class II and class III antiarrhythmics

Question 1

What are the class II antiarrhythmics?

Answer 1

beta blockers- end in -olol. (one exception: carvedilol)

Question 2

What is the mechanism for the class II anti-arrhythmics?

Answer 2

they will decrease SA and AV nodal activity by decreasing cAMP and decreasing calcium currents. they suppress abnormal pacemeakes by decreasing the slope of phase 4 (funny channels- make the depolarize more slowly). AV node is especially sensitive (it has prolonged repolarization)
esmolol is very short acting.

Question 3

What is the clinical use of the class II antiarrhythmics?

Answer 3

as an anti-arrhythmic, beta blockers are used for SVT and to slow ventricular rate during A-fib and A-flutter.

Question 4

toxicities of all of the class II antiarrhythmics?

Answer 4

impotence, exacerbation of COPD/asthma, CV effects (like bradycardia, AV block, CHF), CNS effects (sedation, sleep changes). may mask signs of hypoglycemia.

Question 5

toxicities of specific class II antiarrhythmics? contraindications? tx for OD?

Answer 5

metoprolol: dyslipidemia
propranolol: exacerbate vasospasm in prinzmetal angina.
all contraindicated in cocain usesrs.
treat overdose with glucagon.

Question 6

What are the class III antiarrhythmics?

Answer 6

potassium channel blockers: amiodarone, ibutilid, dofetilide, sotalol

Question 7

mechanism of class III antiarrhythmics

Answer 7

these are K channel blockers that prolong the repolarization phase. they incr. AP duration and the effective refractory period. incr. QT interval.

Question 8

use of class III antiarrhythmics

Answer 8

used when other antiarrhythmics fail. they treat A fib, A flutter, and VT (amiodarone, sotalol)

Question 9

toxicity of amiodarone

Answer 9

MULTIPLE. must check LFTs, pulmonary function tests, and thyroid function tests regularly.
can cause: pulmonary fibrosis, hepatotoxicity, hypo or hyperthyroidism (it is 40% iodine by weight), corneal deposits, blue/grey skin deposits, neuro effects, CV bradycardia, heart block, and CHF, and constipation.

Question 10

toxicity of ibutilide

Answer 10

torsades de pointes

Question 11

toxicity of sotalol

Answer 11

torsades de pointes; excessive beta blockade

Question 12

Class IV antiarrhythmics

Answer 12

calcium channel blockers: verapamil and diltiazem

Question 13

Class IV antiarrhythmics mechanism

Answer 13

decrease conduction velocity, incr. PR, incr. effective refractory period

Question 14

class IV anitarrhythmics use

Answer 14

prevention of nodal arrythmia (SVT), rate control in AFib

Question 15

Class IV antiarrhythmics toxicity

Answer 15

constipation, flushing, edema, CV effects