Which ECG finding may be seen in pericardial tamponade, and which bedside imaging helps confirm the diagnosis?

Which ECG finding may be seen in pericardial tamponade, and which bedside imaging helps confirm the diagnosis?

• A. Electrical alternans; FAST exam
• B. ST elevations; chest X-ray
• C. Peaked T waves; CT chest
• D. Prolonged QT; MRI

Answer: (A)

Electrical alternans is the classic ECG clue for pericardial tamponade. When a large amount of fluid surrounds the heart, the heart swings within the pericardial sac, causing beat-to-beat variation in the amplitude (and sometimes axis) of the QRS complexes. This phenomenon points toward tamponade rather than other common ECG patterns. To confirm the diagnosis at the bedside, ultrasound is used—usually a focused cardiac ultrasound or FAST exam with cardiac views. It rapidly reveals a pericardial effusion and can show signs of tamponade physiology, such as right ventricular diastolic collapse, indicating that the fluid is actually impairing filling. This bedside imaging is preferred in acute settings because it is fast, noninvasive, and can directly demonstrate the underlying issue. Other ECG patterns listed don’t fit tamponade: ST elevations occur with pericarditis, peaked T waves with hyperkalemia, and prolonged QT with various electrolyte or drug issues. While CT or MRI can visualize effusions, they’re not first-line or bedside investigations for acute tamponade.

Electrical alternans is the classic ECG clue for pericardial tamponade. When a large amount of fluid surrounds the heart, the heart swings within the pericardial sac, causing beat-to-beat variation in the amplitude (and sometimes axis) of the QRS complexes. This phenomenon points toward tamponade rather than other common ECG patterns.

To confirm the diagnosis at the bedside, ultrasound is used—usually a focused cardiac ultrasound or FAST exam with cardiac views. It rapidly reveals a pericardial effusion and can show signs of tamponade physiology, such as right ventricular diastolic collapse, indicating that the fluid is actually impairing filling. This bedside imaging is preferred in acute settings because it is fast, noninvasive, and can directly demonstrate the underlying issue.

Other ECG patterns listed don’t fit tamponade: ST elevations occur with pericarditis, peaked T waves with hyperkalemia, and prolonged QT with various electrolyte or drug issues. While CT or MRI can visualize effusions, they’re not first-line or bedside investigations for acute tamponade.