1. Right Answer: D
Explanation: (A) Decreased stroke volume and blood pressure will occur secondary to decreased diastolic filling. (B) Tachycardia primarily decreases diastole; systolic time changes very little. (C) Contractility decreases owing to the decreased filling time and decreased time for fiber lengthening. (D) Decreased O2 supply due to decreased time for filling of the coronary arteriesincreases ischemia and infarct size. Tachycardia primarily robs the heart of diastolic time, which is the primary time for coronary artery filling.
2. Right Answer: A
Explanation: (A) Inotropic therapy will increase contractility, which will increase myocardial O2 demand. (B) Decreased heart rate to the point of bradycardia will increase coronary artery filling time. This should be used cautiously because tachycardia may be a compensatory mechanism to increase cardiac output. (C) The goal in the care of the MI client with angina is to maintain a balance between myocardial O2 supply and demand. (D) Decrease in systemic vascular resistance by drug therapy, such as IV nitroglycerin or nitroprusside, or intra-aortic balloon pump therapy, would decrease myocardial work and O2 demand.
3. Right Answer: D
Explanation: (A) Norepinephrines side effects are primarily related to safe, effective care environment and include decreased peripheral perfusion and bradycardia. (B)Dobutamines side effects include increased heart rate and blood pressure, ventricular ectopy, nausea, and headache. (C) Propranolols side effects include elevated blood urea nitrogen, serum transaminase, alkaline phosphatase, and lactic dehydrogenase. (D) Epinephrine increases serum glucose levels by increasing glycogenolysis and inhibiting insulin release. Prolonged use can elevate serum lactate levels, leading to metabolic acidosis, increased urinary catecholamines, false elevation of blood urea nitrogen, and decreased coagulation time.
4. Right Answer: C
Explanation: (A) Hypokalemia can cause digoxin toxicity. Administration of KCl would prevent this. (B) Thyroid agents decrease digoxin levels. (C) Quinidine increases digoxin levels dramatically. (D) Theophylline is not noted to have an effect on digoxin levels.
5. Right Answer: A
Explanation: (A) Sinus bradycardia and atrioventricular (AV) heart block are usually a result of right coronary artery occlusion. The right coronary artery perfuses the sinoatrial and AV nodes in mostindividuals. (B) Occlusion of the left main coronary artery causes bundle branch blocks and premature ventricular contractions. (C)Occlusion of the circumflex artery does not cause bradycardia. (D) Sinus tachycardia occurs primarily with left anterior descending coronary artery occlusion because this form of occlusion impairs left ventricular function.
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