A nurse is teaching the partner of a client who had an acute myocardial infarction (MI) about the reason blood was drawn from the client. Which of the following statements should the nurse make regarding cardiac enzyme studies?

The P wave is the first wave on the ECG strip and represents the electrical activity of the atria. It reflects the depolarization of the atrial myocardium, which is the process of changing the electrical charge of the cardiac cells from negative to positive, triggering a contraction. The P wave precedes the QRS complex, which represents ventricular depolarization, and the T wave, which represents ventricular repolarization.

The other options are not correct because:

a. Slow repolarization of ventricular Purkinje fibers. This statement is incorrect because it describes the U wave, which is a small and sometimes invisible wave that follows the T wave on the ECG strip. It reflects the repolarization of the ventricular Purkinje fibers, which are specialized cardiac cells that conduct electrical impulses to the ventricles. The U wave is more prominent in conditions that cause hypokalemia, such as diuretic use or vomiting.

c. Early ventricular repolarization. This statement is incorrect because it describes the ST segment, which is the flat line between the QRS complex and the T wave on the ECG strip. It reflects the early phase of ventricular repolarization, which is the process of restoring the electrical charge of the cardiac cells to negative after a contraction. The ST segment can be elevated or depressed in conditions that cause myocardial ischemia or injury, such as angina or myocardial infarction.

d. Ventricular depolarization. This statement is incorrect because it describes the QRS complex, which is the largest and most visible wave on the ECG strip. It reflects the depolarization of the ventricular myocardium, which triggers a ventricular contraction. The QRS complex follows the P wave and precedes the T wave on the ECG strip.

A: Vertigo is a common finding in clients with essential hypertension due to changes in blood flow and possible impacts on the inner ear, which can affect balance.
B: Blurred vision, while it can be associated with hypertension, is not as directly related to essential hypertension as vertigo is. It is more commonly a sign of complications from prolonged uncontrolled hypertension.
C: Dyspnea or difficulty breathing is not typically a direct symptom of essential hypertension, though it can be a symptom of complications such as heart failure, which can be a result of long-standing, uncontrolled hypertension.
D: Uremia, which is an elevated level of waste products in the blood, is not a symptom of essential hypertension but rather a sign of kidney failure, which can be a secondary complication of chronic hypertension. Essential hypertension itself does not directly cause uremia.