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 B
Explanation
The nurse should contact the provider before administering furosemide because the patient 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.Furosemide is a diuretic that can cause potassium loss and worsen hypokalemia, which can lead to cardiac arrhythmias, muscle weakness, and fatigue. The nurse should also monitor the patient’s blood pressure, weight, and urine output, as furosemide can lower blood pressure and cause dehydration.
Choice A. Administer medication is wrong because the nurse should not give furosemide without checking with the provider first, as it could be harmful to the patient with low potassium.
Choice C. Hold medication is wrong because the nurse should not withhold furosemide without a valid reason or an order from the provider, as it could cause fluid overload and worsen the patient’s condition.
Choice D. Give potassium supplement is wrong because the nurse should not give potassium supplement without an order from the provider, as it could cause hyperkalemia or interact with other medications.
Correct Answer is A
Explanation
Intermittent claudication is a condition in which leg pain is produced upon increased activity and ischemia to tissues, but then the pain is reduced with rest. This is because the blood flow to the leg muscles is insufficient to meet the increased demand during exercise, but adequate at rest.Intermittent claudication is a common symptom of peripheral artery disease (PAD), which is a narrowing of the arteries that supply blood to the legs.
Choice B, sporadic ischemia, is wrong because it is not a specific medical term for a condition that causes leg pain.
Ischemia means reduced blood flow to a part of the body, which can cause pain, but it can be caused by various factors and affect different organs.
Choice C, angina, is wrong because it is a term for chest pain caused by reduced blood flow to the heart, not the legs.
Angina can also be triggered by physical activity and relieved by rest, but it is not related to PAD or leg ischemia.
Choice D, restless leg syndrome, is wrong because it is a condition that causes an uncomfortable urge to move the legs, usually at night or when lying down.
Restless leg syndrome does not cause pain or ischemia in the legs, and it is not improved by rest.It is thought to be related to a problem with the nervous system or iron deficiency.
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