Flashcards in class II and class III antiarrhythmics Deck (15):
What are the class II antiarrhythmics?
beta blockers- end in -olol. (one exception: carvedilol)
What is the mechanism for the class II anti-arrhythmics?
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.
What is the clinical use of the class II antiarrhythmics?
as an anti-arrhythmic, beta blockers are used for SVT and to slow ventricular rate during A-fib and A-flutter.
toxicities of all of the class II antiarrhythmics?
impotence, exacerbation of COPD/asthma, CV effects (like bradycardia, AV block, CHF), CNS effects (sedation, sleep changes). may mask signs of hypoglycemia.
toxicities of specific class II antiarrhythmics? contraindications? tx for OD?
propranolol: exacerbate vasospasm in prinzmetal angina.
all contraindicated in cocain usesrs.
treat overdose with glucagon.
What are the class III antiarrhythmics?
potassium channel blockers: amiodarone, ibutilid, dofetilide, sotalol
mechanism of class III antiarrhythmics
these are K channel blockers that prolong the repolarization phase. they incr. AP duration and the effective refractory period. incr. QT interval.
use of class III antiarrhythmics
used when other antiarrhythmics fail. they treat A fib, A flutter, and VT (amiodarone, sotalol)
toxicity of amiodarone
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.
toxicity of ibutilide
torsades de pointes
toxicity of sotalol
torsades de pointes; excessive beta blockade
Class IV antiarrhythmics
calcium channel blockers: verapamil and diltiazem
Class IV antiarrhythmics mechanism
decrease conduction velocity, incr. PR, incr. effective refractory period
class IV anitarrhythmics use
prevention of nodal arrythmia (SVT), rate control in AFib