A nurse is providing instructions to a client who has a new prescription for sublingual nitroglycerin (Nitrostat) to treat angina pectoris. Which of the following instructions should the nurse include?

The nurse should place a towel under the client's head to protect it from injury during the seizure. The nurse should also loosen any tight clothing, remove any objects that could harm the client, and maintain a patent airway.

Place the client in a prone position is wrong because it can compromise the client's breathing and increase the risk of aspiration. The nurse should place the client in a side-lying position after the seizure to facilitate drainage of oral secretions and prevent aspiration.

Holding the client's arms and legs still is wrong because it can cause injury to the client or the nurse. The nurse should not restrain or interfere with the client's movements during the seizure but rather ensure a safe environment and observe the seizure activity.

Leaving the client to get help is wrong because it can endanger the client's safety and well-being. The nurse should stay with the client during the seizure and call for assistance if needed, but not leave the client alone or unattended.

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.