A nurse is obtaining a preoperative medical and surgical history from a client scheduled for a cataract extraction procedure. Which of the following client statements require further investigation by the nurse?

A. Creatine kinase (CK) test: While creatine kinase isoenzymes, including CK-MB, can be elevated following myocardial infarction (MI), they are not specific to cardiac muscle injury. CK is found in various tissues throughout the body, so elevated levels can also indicate damage to skeletal muscle or brain tissue, among other sources.

B. Creatine kinase-myocardial band (CK-MB) test: CK-MB is a cardiac-specific isoform of creatine kinase, and elevated levels can indicate myocardial injury, particularly in the context of an acute MI. However, troponin T is a more sensitive and specific marker for myocardial injury.

C. Brain natriuretic peptide (BNP) test: Brain natriuretic peptide is primarily used in the diagnosis and management of heart failure. While elevated BNP levels can indicate heart muscle strain or stress, they are not specific markers for acute myocardial infarction or early injury to the cardiac muscle.

D. Troponin T test: This is the correct answer. Troponin T is a highly specific marker for cardiac muscle injury. Elevated troponin levels can be detected within hours of myocardial infarction and persist for several days, making it an essential tool in the diagnosis of acute coronary syndromes, including myocardial infarction. Troponin T is considered one of the gold standard biomarkers for detecting early injury to the cardiac muscle.

A. "Blood flow is altered and causes blood to pool in the legs." This statement inaccurately describes venous insufficiency rather than peripheral arterial disease (PAD). In PAD, blood flow is reduced or obstructed due to atherosclerosis, leading to inadequate oxygen supply to tissues rather than pooling of blood in the legs.

B. "Blood flow is altered due to atherosclerosis affecting the tissues' ability to receive oxygen-rich blood." This statement correctly explains the underlying pathology of peripheral arterial disease (PAD). Atherosclerosis, characterized by the buildup of plaque in the arteries, narrows or blocks blood flow, impairing the delivery of oxygen-rich blood to the tissues. This can result in symptoms such as pain, cramping, and tissue damage, especially during activity when oxygen demand increases.

C. "Blood flow is altered due to incompetent valves causing increased venous pressure." This statement describes venous insufficiency rather than PAD. In venous insufficiency, faulty valves in the veins result in increased venous pressure, leading to symptoms such as swelling, heaviness, and varicose veins, but it does not involve arterial obstruction as seen in PAD.

D. "Blood flow is altered due to excessive stretching of the ventricles impairing the heart to contract." This statement describes a condition related to the heart's function rather than peripheral arterial disease. Excessive stretching of the ventricles may occur in conditions such as heart failure, but it does not directly affect blood flow in the peripheral arteries as seen in PAD.