Correct Answer: A

Rationale: The correct answer is A: Electrocardiogram (ECG or EKG). An electrocardiogram is a test that measures the electrical activity of the heart and can detect arrhythmias and other heart conditions by recording the heart's electrical impulses. Choices B, C, and D are incorrect because a chest X-ray is used to visualize the structures in the chest, an MRI (Magnetic Resonance Imaging) is used to provide detailed images of organs and tissues, and a CT scan (Computed Tomography) is a type of imaging that uses X-rays to create detailed cross-sectional images of the body.

Correct Answer: A

Rationale: The correct answer is A, systole. Systole is the phase of the cardiac cycle when the heart contracts and pumps blood out of the chambers. During diastole (choice B), the heart relaxes and fills with blood, contrasting with systole. Contractility (choice C) refers to the ability of the heart to contract effectively. Afterload (choice D) is the pressure the heart must work against to eject blood during systole.

Correct Answer: B

Rationale: The correct answer is B: Positive inotropic, negative chronotropic effect. Digoxin strengthens the heart muscle, providing a positive inotropic effect, which increases the force of contraction. It also decreases the heart rate, having a negative chronotropic effect. Choice A is incorrect because digoxin has a positive inotropic effect, not a negative inotropic effect. Choice C is incorrect as digoxin does not have a positive chronotropic effect but a negative one. Choice D is incorrect because while digoxin has a positive inotropic effect, it does not have a positive chronotropic effect.

Correct Answer: A

Rationale: The correct answer is A: Hold the spironolactone and notify the healthcare provider. A potassium level of 5.9 mEq/L is high, indicating hyperkalemia. Spironolactone is a potassium-sparing diuretic that can further increase potassium levels. Therefore, the priority action is to hold the medication to prevent exacerbating hyperkalemia and notify the healthcare provider for further guidance. Choice B is incorrect because administering potassium supplements would worsen hyperkalemia. Choice C is incorrect because continuing spironolactone could lead to a further increase in potassium levels. Choice D is incorrect because increasing the dose of spironolactone would exacerbate the hyperkalemia.

Correct Answer: A

Rationale: The correct answer is A: Coronary perfusion pressure. Coronary perfusion pressure refers to the process of coronary artery blood flow to the myocardium during diastole when coronary vascular resistance is reduced. This process ensures that the myocardium receives sufficient oxygen and nutrients for proper functioning. Choice B, Coronary vascular resistance, is the opposite of what is described in the question. During coronary perfusion, resistance is reduced to enhance blood flow. Choices C and D, Diastolic filling and Ventricular ejection, do not directly relate to the process of coronary artery blood flow during diastole.