In what ways can a myocardial infarction develop? (Select all that apply)
A coronary artery vasospasm occurs causing reduced blood flow.
A thrombus builds up and obstructs the blood flow to the heart.
A traumatic injury to the chest results in bruising of the chest wall.
An embolus travels and blocks perfusion through the coronary arteries.
A systemic infection occurs which causes significant hyperthermia.
Correct Answer : A,B,D
Choice A reason: Coronary artery vasospasm causes transient vessel constriction, reducing blood flow to the myocardium, leading to ischemia and potentially infarction. This is a recognized cause, particularly in variant angina, making this a correct mechanism for myocardial infarction.
Choice B reason: A thrombus forming in a coronary artery, often due to plaque rupture, obstructs blood flow, causing myocardial ischemia and infarction. This is the most common cause of myocardial infarction, making this a correct mechanism.
Choice C reason: Chest wall bruising from trauma does not directly cause myocardial infarction, which requires coronary artery occlusion. Trauma may cause cardiac contusion but not infarction, making this choice incorrect for myocardial infarction development.
Choice D reason: An embolus, such as from a clot elsewhere, can block a coronary artery, stopping blood flow to the myocardium, causing infarction. Though less common than thrombosis, it is a valid mechanism, making this a correct choice.
Choice E reason: Systemic infection with hyperthermia does not directly cause myocardial infarction. It may increase cardiac demand, potentially exacerbating ischemia, but infarction requires coronary occlusion, not just fever, making this choice incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A reason: Poison ivy causes a type IV (cell-mediated) hypersensitivity reaction, where T-cells react to urushiol, triggering a delayed inflammatory response. This leads to dermatitis with itching and rash, making this the correct choice.
Choice B reason: Allergic hypersensitivity is a broad term, often referring to type I (IgE-mediated) reactions, like anaphylaxis. Poison ivy involves T-cell-mediated delayed hypersensitivity, not immediate allergic responses, making this choice incorrect.
Choice C reason: Immune complex hypersensitivity (type III) involves antigen-antibody complexes causing tissue damage, as in lupus. Poison ivy reactions are T-cell-driven, not immune complex-mediated, making this choice incorrect for the reaction.
Choice D reason: Cytotoxic hypersensitivity (type II) involves antibodies attacking cell surface antigens, as in hemolytic anemia. Poison ivy causes a T-cell-mediated skin reaction, not antibody-driven cytotoxicity, making this choice incorrect.
Correct Answer is D
Explanation
Choice A reason: Chronic renal failure typically causes hypocalcemia due to reduced vitamin D activation and phosphate retention, not increased serum calcium. Kidneys fail to regulate calcium homeostasis, leading to bone and mineral disorders, making this choice incorrect.
Choice B reason: Increased glomerular filtration rate (GFR) indicates healthy kidney function. Chronic renal failure is defined by decreased GFR, as nephrons are progressively damaged, reducing filtration capacity, making this choice incorrect for the condition.
Choice C reason: Chronic renal failure causes anemia due to decreased erythropoietin production, leading to low hemoglobin levels. Increased hemoglobin is not expected, as kidney dysfunction impairs red blood cell production, making this choice incorrect.
Choice D reason: Chronic renal failure impairs potassium excretion, leading to hyperkalemia (increased serum potassium). Damaged kidneys cannot filter potassium effectively, causing accumulation, which can lead to cardiac arrhythmias, making this the correct laboratory finding.
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