Correct Answer: A

Rationale: The correct answer is A, Holter monitor. A Holter monitor is a portable device that continuously records the heart's electrical activity over 24 to 48 hours, aiding in the diagnosis of arrhythmias and other heart conditions. Choice B, an Electrocardiogram, provides a snapshot of the heart's electrical activity at a specific point in time, not over an extended period like a Holter monitor. Choice C, a Stress test, measures how the heart responds to physical activity and is not used for continuous monitoring of electrical activity. Choice D, a Chest X-ray, is used to visualize the structures of the chest, not to measure the heart's electrical activity.

Correct Answer: A

Rationale: The correct answer is A: Administer potassium supplements. A potassium level of 2.9 mEq/L indicates hypokalemia (low potassium levels). Furosemide (Lasix) is a loop diuretic that can cause potassium loss. Therefore, the priority action is to administer potassium supplements to correct the imbalance. Option B is incorrect because holding the furosemide without addressing the low potassium level could further worsen the imbalance. Option C is incorrect as continuing the current dose of furosemide without addressing the low potassium level could lead to complications. Option D is incorrect because decreasing the dose of furosemide does not directly address the low potassium level that needs immediate correction.

Correct Answer: A

Rationale: The correct answer is Aortic valve. The aortic valve is positioned between the left ventricle and the aorta. It prevents blood from flowing back into the left ventricle after it has been pumped into the aorta. The mitral valve (Choice B) is located between the left atrium and the left ventricle, the tricuspid valve (Choice C) is between the right atrium and right ventricle, and the pulmonary valve (Choice D) is situated between the right ventricle and the pulmonary artery. Therefore, they are not responsible for preventing backflow from the aorta into the left ventricle.

Correct Answer: A

Rationale: Stent placement is a procedure where a small mesh tube (stent) is inserted into an artery to keep it open and improve blood flow, often following angioplasty.

Correct Answer: A

Rationale: A stroke occurs when the blood supply to part of the brain is interrupted or reduced, leading to brain cell death and potential disability. Choice B, a heart attack, involves a blockage in the blood vessels that supply the heart muscle. Choice C, a pulmonary embolism, is a blockage in one of the pulmonary arteries in the lungs. Choice D, pneumonia, is an infection that inflames the air sacs in one or both lungs.