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","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.
Correct Answer is D
Explanation
HDL stands for high-density lipoprotein, which is a type of cholesterol that carries excess cholesterol from other parts of the body to the liver, where it can be removed.
HDL is sometimes called “good” cholesterol because it helps protect against heart disease.Having high HDL levels is not a characteristic of metabolic syndrome, but rather a protective factor.
Metabolic syndrome is a group of conditions that increase the risk of heart disease, stroke, and type 2 diabetes.These conditions include:
• Low HDLs (choice A): Having low levels of HDL cholesterol is a risk factor for metabolic syndrome, as it means there is less “good” cholesterol to remove excess cholesterol from the blood vessels.
• Type II diabetes mellitus (choice B): This is a condition where the body does not use insulin properly, leading to high blood sugar levels.
Insulin is a hormone that helps the cells take up glucose from the blood.
Insulin resistance is a key feature of metabolic syndrome.
• Hypertension (choice C): This means having high blood pressure, which can damage the heart and blood vessels over time.
High blood pressure is often associated with obesity and insulin resistance, which are common in metabolic syndrome.
• Abdominal obesity (choice E): This means having excess fat around the waist and trunk, also known as central or visceral obesity.
This type of fat is more harmful than fat in other parts of the body, as it can release inflammatory substances that affect the metabolism and increase the risk of cardiovascular disease.
• Hyperglycemia (choice F): This means having high blood sugar levels, which can damage the blood vessels and organs over time.
Hyperglycemia can result from insulin resistance or type 2 diabetes, which are both components of metabolic syndrome.
The normal ranges for some of these conditions are:
• HDL cholesterol: more than 40 mg/dL for men and more than 50 mg/dL for women
• Blood pressure: less than 120/80 mmHg
• Blood sugar: less than 100 mg/dL after fasting or less than 140 mg/dL two hours after eating
• Waist circumference: less than 40 inches for men and less than 35 inches for women
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