The client is being given a calcium channel blocker. Calcium channel blockers have what effect on the heart?

Correct Answer: B

Rationale: The correct answer is B: Calcium channel blockers decrease the velocity of electrical activity on the AV node. This is because calcium channel blockers specifically target calcium channels in the heart, which are responsible for the influx of calcium ions during the cardiac action potential. By blocking these channels, calcium channel blockers slow down the rate of electrical conduction through the AV node, leading to a decrease in heart rate and potentially a decrease in blood pressure. Explanation of why the other choices are incorrect: A: Calcium channel blockers do not increase the preload on the heart. Preload is the amount of blood that fills the heart before it contracts, and calcium channel blockers do not directly affect this. C: Calcium channel blockers do not block sodium channels in the heart muscle. They primarily target calcium channels. D: Calcium channel blockers do not cause vasoconstriction of coronary arteries. They may actually cause vasodilation in coronary arteries, leading to increased blood flow to the heart muscle.

Correct Answer: C

Rationale: The correct answer is C because nitroprusside works by relaxing vascular smooth muscle, leading to vasodilation and subsequently lowering blood pressure. Nitroprusside does not affect the renin-angiotensin-aldosterone system (choice A), calcium channels in blood vessels (choice B), or sodium channels in the heart (choice D). Vasodilation is the primary mechanism of action for nitroprusside in reducing blood pressure.

Correct Answer: A

Rationale: The correct answer is A: Thrombocytosis. Warfarin is an anticoagulant that works by inhibiting blood clotting. Thrombocytosis is a condition where there is an excessive number of platelets in the blood, increasing the risk of blood clots. Giving warfarin to a patient with thrombocytosis can further increase the risk of bleeding complications. Summary of incorrect choices: B: Mild thrombocytopenia - This condition involves a low platelet count, which would actually make the patient more susceptible to blood clots, not a contraindication for warfarin. C: Lumbar puncture - This procedure involves obtaining cerebrospinal fluid and is not directly related to the use of warfarin. D: History of eye surgery in the distant past - This is not a contraindication for warfarin unless there were specific complications related to the surgery that would increase the risk of bleeding

Correct Answer: D

Rationale: The correct answer is D: Abciximab. Glycoprotein IIb/IIIa inhibitors like abciximab are used for preventing stroke in high-risk patients. These drugs block platelet aggregation by binding to the glycoprotein IIb/IIIa receptor. Plavix (A) and Ticlid (B) are antiplatelet drugs that work through different mechanisms and are not glycoprotein IIb/IIIa inhibitors. Aspirin (C) is also an antiplatelet drug but does not specifically target the glycoprotein IIb/IIIa receptor.

Correct Answer: B

Rationale: The correct answer is B because gemfibrozil can potentiate the hypoglycemic effects of sulfonylurea drugs by displacing them from protein binding sites, leading to increased free drug levels. This interaction can result in dangerously low blood sugar levels. A: Gemfibrozil does not affect digoxin levels. C: Gemfibrozil does not lower theophylline levels. D: Gemfibrozil can be taken with cimetidine without significant drug-drug interactions.