What echocardiographic findings suggest a pericardial effusion is causing tamponade?

Background: Pericardial tamponade is neither a clinical nor an echocardiographic diagnosis alone. The echocardiogram carries diagnostic value and should be performed when there is suspicion for tamponade based on the history and physical exam. A pericardial effusion uncovered on point-of-care ultrasound (POCUS) may be mistaken for tamponade and thereby lead to inappropriate and invasive management with pericardiocentesis. Objective: This narrative review will summarize the echocardiographic findings and associated pathophysiology that support the diagnosis of pericardial tamponade. It will provide a succinct description of the core findings for which emergency physicians should evaluate at the bedside, along with potential pearls and pitfalls in this evaluation. Labeled images and video clips are included. Discussion: The core echocardiographic findings of pericardial tamponade consist of: a pericardial effusion, diastolic right ventricular collapse (high specificity), systolic right atrial collapse (earliest sign), a plethoric inferior vena cava with minimal respiratory variation (high sensitivity), and exaggerated respiratory cycle changes in mitral and tricuspid valve in-flow velocities as a surrogate for pulsus paradoxus. Conclusion: The emergency physician must recognize and understand the core echocardiographic findings and associated pathophysiology that suggest pericardial tamponade. Together with the history and clinical exam, these findings can help make the overall diagnosis and determine management.