Why are Verapamil and Diltiazem considered to be antidysrhythmic medications but Nifedipine is not, if all three medications are calcium channel blockers?
Nifedipine is a dihydropyridine and therefore only affects the movement of calcium into the cells of vascular smooth muscle.
Verapamil and Diltiazem affect the movement of calcium into the cells of both the heart and blood vessels.
All three medications have antidysrhythmic properties.
Nifedipine affects the movement of calcium into the cells of both the heart and blood vessels.
The Correct Answer is B
Choice A reason:
Nifedipine is a dihydropyridine calcium channel blocker that primarily affects vascular smooth muscle, leading to vasodilation. While it can lower blood pressure, it does not significantly affect cardiac conduction or rhythm, which is why it is not used as an antidysrhythmic.
Choice B reason:
Verapamil and Diltiazem are calcium channel blockers that affect the movement of calcium into the cells of both the heart and blood vessels. They have a significant impact on cardiac conduction and can be used to treat arrhythmias by slowing down the heart rate and reducing the conduction through the atrioventricular node.
Choice C reason:
Not all three medications have antidysrhythmic properties. Only Verapamil and Diltiazem are effective as antidysrhythmic agents due to their effects on cardiac conduction. Nifedipine does not share these properties and is therefore not used to manage arrhythmias.
Choice D reason:
Nifedipine primarily affects the movement of calcium into the cells of vascular smooth muscle, not the heart. Its main use is in the treatment of hypertension and angina, where its vasodilatory effects are beneficial. It does not significantly impact cardiac rhythm or conduction like Verapamil and Diltiazem do.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A reason:
Hepatocellular jaundice occurs due to damage or dysfunction of the liver cells (hepatocytes). This type of jaundice is associated with liver diseases such as hepatitis or cirrhosis, where the liver cannot effectively process bilirubin. It is not directly related to increased red blood cell breakdown but rather to the liver’s inability to handle bilirubin.
Choice B reason:
Hemolytic jaundice results from an increased breakdown of red blood cells, leading to a higher production of bilirubin, which the liver cannot clear fast enough. This condition causes an overload of bilirubin in the blood, resulting in jaundice. Hemolytic jaundice is typically seen in conditions such as hemolytic anemia, where red blood cell destruction exceeds the liver's ability to process and excrete bilirubin.
Choice C reason:
Obstructive jaundice is caused by a blockage in the bile ducts, preventing bilirubin from being excreted into the digestive system. This blockage can result from gallstones, tumors, or strictures. It is not related to the increased breakdown of red blood cells but rather to the obstruction of bile flow, leading to bilirubin buildup in the liver and subsequently in the blood.
Choice D reason:
Metabolic jaundice results from metabolic disorders that affect bilirubin processing or liver function. These disorders can lead to abnormalities in bilirubin metabolism, but they are not directly caused by increased red blood cell breakdown. Metabolic jaundice is less common than other forms and typically involves inherited conditions affecting bilirubin conjugation and excretion.
Correct Answer is A
Explanation
Choice A reason:
The onset of warfarin is delayed, meaning it takes longer to achieve a therapeutic effect. Warfarin requires several days to adjust to effective anticoagulation levels because it works by inhibiting the synthesis of clotting factors that are already present and active in the bloodstream. In contrast, heparin has an immediate anticoagulant effect when administered, which is crucial for patients with acute conditions like deep vein thrombosis.
Choice B reason:
Warfarin does not prevent platelet aggregation. Instead, it works by inhibiting vitamin K-dependent clotting factors, which are essential for blood coagulation. Platelet aggregation is primarily inhibited by antiplatelet drugs like aspirin or clopidogrel, not anticoagulants like warfarin.
Choice C reason:
Heparin does not necessarily have fewer adverse effects compared to warfarin. Both anticoagulants have their specific risks and side effects. Heparin is preferred in acute settings due to its rapid onset of action, but it can cause complications like heparin-induced thrombocytopenia (HIT), which requires careful monitoring.
Choice D reason:
Heparin does not have a longer half-life than warfarin. In fact, heparin's half-life is relatively short, which is why it is often administered via continuous infusion or frequent subcutaneous injections. Warfarin has a longer half-life, but its delayed onset of action makes it less suitable for immediate anticoagulation needs.
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