Cardiac Diagnostic Procedures and Testing
Know the purpose, preparation, and limitations of the major cardiac tests: 12-lead ECG, Holter and event monitors, exercise stress testing, echocardiography (transthoracic and transesophageal), cardiac catheterization and angiography, and cardiac biomarkers such as troponin. Understand what each test answers - rhythm over time, ischemia under stress, structure and ejection fraction, coronary anatomy, or myocardial injury.
Expect questions on patient preparation and safety: fasting before sedation or stress testing, holding caffeine and certain medications before a stress test per protocol, explaining that Holter patients keep a symptom diary and avoid bathing, and that transesophageal echo requires sedation and a fasting state. Know that troponin rises with myocardial injury and that timing of draws matters.
Traps: assuming a resting ECG rules out coronary disease; confusing echocardiography (structure/function) with angiography (anatomy of vessels); forgetting that stress testing has contraindications such as unstable angina; and mixing up which monitor is worn continuously (Holter) versus only when symptoms occur (event monitor). Another trap is expecting a single normal troponin to exclude infarction.
Rule of thumb: match the question's clinical goal to the test - "Is it rhythm?" → monitor or ECG; "Is it ischemia with exertion?" → stress test; "What is the ejection fraction and valve function?" → echo; "Where is the blockage?" → catheterization.
Worked example: a patient reports palpitations that occur a few times a month and last seconds. A 24-hour Holter is unlikely to capture them; a symptom-triggered event monitor is the better choice.