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 C
Explanation
ACE inhibitors are a type of medication used to treat high blood pressure and heart failure. They work by blocking the production of a hormone called angiotensin II, which narrows the blood vessels and increases blood pressure.By preventing this hormone from acting, ACE inhibitors lower blood pressure and reduce the workload on the heart. One of the most common side effects of ACE inhibitors is a dry cough, which occurs in 12–19% of people who take them. The cough is caused by the accumulation of a substance called bradykinin, which is normally broken down by angiotensin-converting enzyme (ACE).When ACE is inhibited, bradykinin levels increase and cause irritation and inflammation in the airways.
Choice A is wrong because decreased white blood cells are not a common side effect of ACE inhibitors.
However, some people may develop a condition called neutropenia, which is a low level of a type of white blood cell called neutrophils.This can increase the risk of infections and may require stopping the medication.
Choice B is wrong because swelling of the face and lips is not a common side effect of ACE inhibitors.
However, some people may develop a rare but serious allergic reaction called angioedema, which is a swelling of the deeper layers of the skin and mucous membranes.
This can affect the face, lips, tongue, throat, or other parts of the body and can cause difficulty breathing or swallowing.Angioedema can be life-threatening and requires immediate medical attention.
Choice D is wrong because renal failure is not a common side effect of ACE inhibitors.
However, some people may experience a decrease in kidney function or an increase in blood levels of creatinine, which is a waste product filtered by the kidneys.
Correct Answer is A
Explanation
Terazosin is a medication that belongs to the class of alpha-adrenergic blockers, which relax the muscles in the prostate and bladder neck, making it easier to urinate.It also lowers blood pressure by relaxing the veins and arteries, allowing blood to flow more easily.Therefore, terazosin can cause dizziness or fainting, especially when getting up from a sitting or lying position.To prevent this, the patient should rise slowly and avoid standing for long periods or becoming overheated.
Choice B is wrong because terazosin is not a cure for benign prostatic hyperplasia (BPH), but a symptom reliever.Stopping the medication may cause the urinary problems to return or worsen.
The patient should continue taking terazosin as prescribed by the doctor, unless advised otherwise.
Choice C is wrong because decreasing fluid intake may increase the risk of dehydration, urinary tract infections, bladder stones, and kidney problems.
The patient should drink enough fluids to stay hydrated and flush out the urinary system.
Choice D is wrong because grapefruit juice may interact with terazosin and increase its blood levels, leading to more side effects such as low blood pressure, drowsiness, or headache.
The patient should avoid drinking grapefruit juice while taking terazosin, or consult the doctor before doing so.
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