A Holter monitor is NOT used for which of the following purposes?

The use of a Holter monitor is primarily focused on monitoring the heart's electrical activity over an extended period, usually 24 to 48 hours, while the patient engages in their normal daily activities. It is particularly effective for identifying intermittent cardiac dysrhythmias, which may not be captured during a standard electrocardiogram (ECG) that only provides a snapshot of the heart's rhythm.

When considering the purposes for which a Holter monitor is used, option A, which states that it is not used for assessing cardiac risk prior to surgery, is correct. This is because a Holter monitor does not provide comprehensive cardiac risk assessment. Instead, preoperative cardiac risk is typically evaluated through a combination of the patient's medical history, physical examination, and other tests, such as a resting ECG, echocardiography, or exercise stress testing.

The other options reflect scenarios where Holter monitoring is indeed beneficial. It is often employed to evaluate patients experiencing unexplained syncope (B), as it can capture arrhythmias that may correlate with syncopal episodes. Additionally, the monitor is effective for discovering intermittent cardiac dysrhythmia (C), as it records the heart's activity over time, allowing for intermittent issues to be detected. Lastly,