A patient newly diagnosed with left-sided heart failure is admitted to the hospital. The nurse will observe this patient closely for:

Choice A reason: The cells of the myocardium become hypertrophic in response to increased workload or pressure, not as a result of myocardial infarction. Hypertrophy is an adaptive mechanism that can lead to impaired ventricular function over time.

Choice B reason: The resulting hypoxia leads to ischemic injury and myocardial cell death. This is the main cause of impaired ventricular function after a myocardial infarction. The loss of viable myocardial tissue reduces the contractility and pumping ability of the heart.

Choice C reason: There is a temporary alteration in electrolyte balance that can be corrected. This is not the primary cause of impaired ventricular function after a myocardial infarction. Electrolyte imbalance can occur due to fluid loss, renal impairment, or medication side effects, but it can be managed with appropriate interventions.

Choice D reason: There is too much pressure on the heart and the ventricles begin to dysfunction. This is not the direct cause of impaired ventricular function after a myocardial infarction. Increased pressure on the heart can result from hypertension, valvular disease, or pulmonary embolism, but it is not related to myocardial ischemia or necrosis.

Choice A reason: This is the correct mechanism of action of propranolol. Propranolol is a beta blocker medication, which means that it blocks the beta receptors in the heart and blood vessels. This reduces the sympathetic stimulation in cardiac muscle, which lowers the heart rate, contractility, and oxygen demand. This also reduces the renin release from the kidneys, which lowers the blood pressure.

Choice B reason: This is not the mechanism of action of propranolol. Propranolol does not increase the diuretic response in the renal tubules. This is the effect of diuretic medications, such as furosemide or hydrochlorothiazide, which increase the urine output and decrease the blood volume and pressure.

Choice C reason: This is not the mechanism of action of propranolol. Propranolol does not inhibit the conversion of angiotensin I to angiotensin II. This is the effect of angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril or enalapril, which block the formation of angiotensin II, a potent vasoconstrictor that raises the blood pressure.

Choice D reason: This is not the mechanism of action of propranolol. Propranolol does not block alpha receptors throughout the body. This is the effect of alpha blockers, such as doxazosin or prazosin, which block the alpha receptors in the blood vessels and cause vasodilation, which lowers the blood pressure.