ATI RN
Cardiovascular System Practice Exam
1. What term refers to the degree of myocardial fiber stretch before contraction, related to the volume of blood distending the ventricles at the end of diastole, and determined by the amount of venous return?
- A. Preload
- B. Afterload
- C. Contractility
- D. Ejection fraction
Correct answer: A
Rationale: The correct answer is A: Preload. Preload is the degree of myocardial fiber stretch before contraction, influenced by the volume of blood returning to the heart. This parameter is related to the amount of blood in the ventricles at the end of diastole. Choice B, Afterload, refers to the pressure or resistance that the ventricles must overcome to eject blood. Choice C, Contractility, is the intrinsic ability of the heart muscle to contract. Choice D, Ejection fraction, is the percentage of blood pumped out of the ventricles with each contraction.
2. The nurse is administering enoxaparin (Lovenox) to a client. What is the most important lab value to monitor?
- A. Platelet count
- B. Hemoglobin
- C. White blood cell count
- D. aPTT
Correct answer: A
Rationale: The correct answer is A: Platelet count. When administering enoxaparin, it is crucial to monitor the platelet count because enoxaparin can lead to a rare but serious side effect known as thrombocytopenia, which is a decrease in platelet levels. Monitoring the platelet count helps in detecting this adverse effect early. Choices B, C, and D are incorrect because hemoglobin, white blood cell count, and aPTT are not the most important lab values to monitor specifically for enoxaparin administration.
3. Which surgical procedure involves grafting a blood vessel to bypass a blocked artery in the heart?
- A. Coronary artery bypass graft (CABG)
- B. Valve replacement
- C. Stent placement
- D. Angioplasty
Correct answer: A
Rationale: The correct answer is A, Coronary artery bypass graft (CABG). This surgical procedure involves grafting a blood vessel to bypass a blocked coronary artery, improving blood flow to the heart muscle. Choice B, Valve replacement, is a procedure to replace a damaged heart valve and is not directly related to bypassing blocked arteries. Choice C, Stent placement, involves inserting a mesh tube to keep blocked arteries open and is different from grafting a blood vessel. Choice D, Angioplasty, is a procedure to widen narrowed or blocked arteries, typically using a balloon catheter, and does not involve grafting a blood vessel.
4. What is the amount of blood the heart pumps through the circulatory system in a minute?
- A. Cardiac output
- B. Stroke volume
- C. End-diastolic volume
- D. Ejection fraction
Correct answer: A
Rationale: The correct answer is A: Cardiac output. Cardiac output is the volume of blood pumped by the heart per minute. It is calculated by multiplying the stroke volume (the amount of blood pumped out of the heart in each beat) by the heart rate (number of heartbeats per minute). This question specifically asks for the total amount of blood pumped through the circulatory system in a minute, which is represented by cardiac output. Choices B, C, and D are incorrect because stroke volume refers to the amount of blood pumped out of the heart in each beat, end-diastolic volume is the volume of blood in the heart at the end of diastole, and ejection fraction is the percentage of blood pumped out of the heart with each contraction, not the total amount pumped per minute.
5. What structure separates the left and right sides of the heart?
- A. Interventricular septum
- B. Endocardium
- C. Epicardium
- D. Pericardium
Correct answer: A
Rationale: The interventricular septum is the correct answer as it is the wall that separates the left and right sides of the heart, ensuring the oxygenated and deoxygenated blood do not mix. The endocardium is the inner lining of the heart chambers, the epicardium is the outermost layer of the heart wall, and the pericardium is the sac that surrounds the heart, providing protection and anchoring the heart in place. Therefore, choices B, C, and D are incorrect in the context of separating the left and right sides of the heart.
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