A staff nurse is teaching a client who has secondary hypothyroidism about the disease process. The client asks the nurse what causes secondary hypothyroidism. Which of the following responses should the nurse make?

A. Cool, clammy skin can be a sign of a myocardial infarction. It occurs due to the body's stress response during an MI, leading to decreased perfusion and sweating. This symptom is consistent with the autonomic response to a heart attack.
B. Chest pain radiating into the back, jaw, or arms is a classic symptom of myocardial infarction. This radiation of pain is due to the way pain signals are transmitted and referred from the heart to other parts of the body. It is a common and significant symptom of MI.

C. Nausea and vomiting can occur during a myocardial infarction, particularly in older adults. These symptoms are related to the autonomic nervous system's response to the stress of an MI and can sometimes be the presenting symptoms, especially in women and older adults.
D. Peripheral edema is generally not a direct symptom of myocardial infarction. It is more commonly associated with chronic heart failure or other conditions leading to fluid overload. While MI can lead to heart failure over time, peripheral edema itself is not a typical acute symptom of an MI.

A. Atrial fibrillation is characterized by irregularly irregular rhythms with no distinct P-waves. Instead, it has a chaotic baseline with fibrillatory waves. The ventricular response can be irregular and variable. The description provided (regular P-waves in a sawtooth formation) does not match the typical appearance of atrial fibrillation, which lacks regular P-waves and has an irregular rhythm.
B. Atrial flutter is characterized by regular, sawtooth-shaped P-waves known as "F-waves" or "flutter waves." The classic pattern is referred to as "F-waves" with a "sawtooth" appearance, often seen in the inferior leads (II, III, aVF). The atrial rate is typically between 240 to 340 beats per minute, which fits the rate of 260 beats per minute in the description. The ventricular rate can be regular or irregular, depending on the degree of AV node conduction. A

C. Unstable angina is a clinical diagnosis of chest pain due to myocardial ischemia. It is not associated with specific ECG findings related to the P-wave morphology or rate. The ECG findings described do not correspond to unstable angina, which would typically present with ST-segment changes or other signs of myocardial ischemia rather than a specific P-wave pattern.
D. Premature atrial contractions (PACs) are early beats originating from the atria that interrupt the normal rhythm. They usually present as a single early beat with a different morphology of the P-wave compared to the sinus P-waves, but do not result in a regular sawtooth pattern or a sustained rhythm at high rates like the one described.