Restriction of which electrolyte is recommended in the management of high blood pressure?

Choice A reason: Cardiac output has not fallen below normal levels. Cardiac output is the amount of blood pumped by the heart per minute. It is affected by the heart rate and the stroke volume. Angina pectoris does not directly affect the cardiac output, but it can reduce the stroke volume due to impaired ventricular filling.

Choice B reason: The vagus nerve is not stimulated. The vagus nerve is a cranial nerve that innervates the heart and other organs. It is part of the parasympathetic nervous system, which slows down the heart rate and lowers the blood pressure. Angina pectoris does not activate the vagus nerve, but it can trigger the sympathetic nervous system, which increases the heart rate and blood pressure.

Choice C reason: Myocardial stretch has not exceeded the upper limits. Myocardial stretch is the degree of tension or load on the cardiac muscle fibers. It is determined by the end-diastolic volume, which is the amount of blood in the ventricle at the end of relaxation. Angina pectoris does not cause excessive myocardial stretch, but it can impair the myocardial contractility due to ischemia.

Choice D reason: The myocardial oxygen supply has fallen below demand. This is the main cause of angina pectoris. It occurs when the coronary arteries, which supply blood and oxygen to the heart muscle, are narrowed or blocked by atherosclerosis or spasm. This creates an imbalance between the oxygen demand of the heart, which increases during exertion, and the oxygen supply, which is reduced by the obstruction.

Choice A reason: This is not the definition of ejection fraction. The percentage of blood that leaves the heart in a minute is related to the cardiac output, which is the product of the heart rate and the stroke volume.

Choice B reason: This is the correct definition of ejection fraction. It is the ratio of the stroke volume (the amount of blood pumped by the left ventricle) to the end-diastolic volume (the amount of blood in the left ventricle at the end of diastole). It is a measure of the efficiency of the heart and reflects the contractility of the cardiac muscle.

Choice C reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart with each beat is the stroke volume, which is one of the factors that determine the ejection fraction.

Choice D reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart in a minute is the cardiac output, which is influenced by the ejection fraction, but not equivalent to it.