What is the purpose of a 12-lead ECG in diagnosing bradycardia?

The purpose of a 12-lead ECG in diagnosing bradycardia is primarily to rule out underlying myocardial infarction. When a patient presents with bradycardia—a slower than normal heart rate—it is crucial to identify whether this condition is a result of ischemia or infarction in the heart muscle. A 12-lead ECG provides a comprehensive view of the heart's electrical activity, capturing different angles that can reveal ST segment changes or other abnormalities indicative of a myocardial infarction. These findings are critical for guiding further management and treatment decisions.

In contrast to assessing heart rate alone, which does not provide the necessary context regarding the heart's condition, or evaluating lung function and determining blood pressure, the use of a 12-lead ECG focuses on uncovering potentially life-threatening cardiac issues that could be the root cause of bradycardia, thus ensuring appropriate and timely interventions.