What class of antiarrhythmic drugs blocks potassium channels prolonging phase 3 of the action potential and slowing the rate and conduction of the heart?
I.
IV.
III.
II.
The Correct Answer is C
Choice A rationale
Class I antiarrhythmic drugs block sodium channels, affecting phase 0 of the action potential, not phase 3.
Choice B rationale
Class IV antiarrhythmic drugs block calcium channels, which affects phase 2 of the action potential and slows heart rate and conduction.
Choice C rationale
Class III antiarrhythmic drugs block potassium channels, prolonging phase 3 of the action potential. This results in a prolonged repolarization period, reducing the risk of arrhythmia.
Choice D rationale
Class II antiarrhythmic drugs are beta-blockers that primarily affect phase 4 of the action potential, reducing heart rate and conduction, but they do not block potassium channels.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale
Checking vitamin K levels doesn't directly monitor warfarin's effect.
Choice B rationale
PTT and aPTT assess heparin, not warfarin.
Choice C rationale
INR specifically measures warfarin's effectiveness and safety.
Choice D rationale
Platelet levels don't monitor the anticoagulant effect of warfarin.
Correct Answer is B
Explanation
Choice A rationale
Discontinuing carbidopa-levodopa abruptly can lead to withdrawal symptoms and a worsening of Parkinson's symptoms. Insomnia is a possible side effect but should be managed under medical supervision.
Choice B rationale
Carbidopa-levodopa can cause orthostatic hypotension, leading to dizziness and an increased risk of falls. Patients should be advised to rise slowly from a sitting or lying position to prevent these effects.
Choice C rationale
Dark urine can be a harmless side effect of carbidopa-levodopa due to the excretion of metabolites. It is not usually a cause for concern unless accompanied by other symptoms.
Choice D rationale
High-protein foods can interfere with the absorption of carbidopa-levodopa, reducing its effectiveness. It is recommended to take the medication on an empty stomach or with low-protein foods.
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