Class IV antidysrhythmics or calcium channel blockers have what action on the cardiovascular system?
Increase blood vessel spasm.
Decrease flow of calcium ions thus decreasing heart rate and contractions.
Decrease refractory period.
Increase heart rate.
The Correct Answer is B
Class IV antidysrhythmics or calcium channel blockers decrease the flow of calcium ions into cardiac and vascular smooth muscle cells, thus decreasing heart rate and contractions. By reducing the calcium influx, they also decrease the slope of phase 0 and 4 and prolong phase 2 of the cardiac action potential. This results in vasodilation, reduced myocardial oxygen demand, and decreased conduction through the AV node.
Choice A is wrong because calcium channel blockers do not increase blood vessel spasm, but rather cause vasodilation.
Choice C is wrong because calcium channel blockers do not decrease refractory period, but rather prolong it by extending phase 2 of the cardiac action potential.
Choice D is wrong because calcium channel blockers do not increase heart rate, but rather decrease it by slowing down the pacemaker activity and AV nodal conduction.
Normal ranges for heart rate are 60 to 100 beats per minute, and for blood pressure are 120/80 mmHg or lower.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Taking niacin with an NSAID such as ibuprofen can reduce flushing, the most common adverse effect of niacin therapy. Flushing is a side effect of taking large doses of niacin (vitamin B3) supplements.It happens when the niacin causes the small blood vessels in your skin to dilate so more blood can rush through.Flushing can cause skin redness, warmth, itching, tingling, or burning sensations.
Choice A is wrong because taking niacin before starting daily activities can increase the risk of flushing and interfere with your routine.Flushing usually occurs within 15 to 30 minutes of taking niacin and lasts for about an hour.
Choice B is wrong because taking niacin with a sedative can increase the risk of liver damage, especially if the sedative is acetaminophen (Tylenol).Niacin can also cause liver problems at high doses, so combining it with another liver-toxic drug is not advisable.
Choice C is wrong because taking niacin with grapefruit juice can increase the risk of side effects, such as low blood pressure, dizziness, or fainting.Grapefruit juice can interfere with the metabolism of some drugs, including niacin, and make them more potent or toxic.
Normal ranges for niacin intake vary depending on age and gender.The recommended dietary allowance (RDA) for adult males is 16 mg per day and for adult females is 14 mg per day.Higher doses of niacin may be prescribed by a doctor to treat high cholesterol or other conditions, but they should be taken under medical supervision and with caution.
Correct Answer is ["B","C"]
Explanation
The nurse should contact the provider and ask the patient if they are feeling light headed or dizzy.
Choice A is wrong because administering the medication could worsen the patient’s condition.Furosemide is a diuretic that can cause dehydration, electrolyte imbalance, and hypotension.The patient already has a low serum potassium level of 2.8 mEq/L, which is below the normal range of 3.5 to 5.0 mEq/L.Giving furosemide could lower the potassium level further and increase the risk of cardiac arrhythmias.The patient also has a significant drop in blood pressure from lying to sitting position, which indicates orthostatic hypotension.Giving furosemide could lower the blood pressure more and cause dizziness, fainting, or falls.
Choice D is wrong because encouraging the patient to get up quickly and walk around could also cause dizziness, fainting, or falls due to orthostatic hypotension.The patient should be advised to change positions slowly and carefully, and to avoid activities that require alertness until their blood pressure stabilizes.
Choice E is wrong because holding the medication without contacting the provider could delay the appropriate treatment for the patient’s fluid retention.The nurse should notify the provider of the patient’s vital signs, laboratory results, and symptoms, and follow their orders regarding the medication dosage or alternative therapy.
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