From the Guidelines
Pulmonary embolism (PE) cannot be directly visualized on an echocardiogram, but an echo can show indirect signs that suggest its presence, such as right ventricular dysfunction or dilation, as noted in the 2019 ESC guidelines 1. Echocardiography may reveal other signs, including septal flattening, tricuspid regurgitation, or pulmonary hypertension, when a significant PE is present. In some cases, a large clot may be visible in the right heart chambers or main pulmonary artery, though this is uncommon, as mentioned in the 2008 guidelines 1. The test can help risk-stratify patients by evaluating right heart strain, which may influence treatment decisions, and is particularly useful in assessing the hemodynamic impact of suspected PE in unstable patients. For definitive diagnosis of PE, CT pulmonary angiography, ventilation-perfusion scanning, or pulmonary angiography are the preferred imaging modalities as they can directly visualize the clot within the pulmonary vasculature. Some key points to consider when using echocardiography in PE diagnosis include:
- The presence of right ventricular overload and dysfunction can suggest PE, especially in patients with suspected high-risk PE 1
- Echocardiography can be used to evaluate the size and function of the right ventricle, which can help guide treatment decisions 1
- The test can help identify alternative diagnoses, such as cardiogenic shock or tamponade, which can present similarly to PE 1
- Echocardiography serves as a complementary tool in PE management rather than a primary diagnostic test, as noted in the 2000 guidelines 1.
From the Research
Echocardiogram Findings for Pulmonary Embolism (PE)
- Pulmonary embolism (PE) can be suggested by certain echocardiographic findings, including increased right ventricle: left ventricle size ratio, abnormal septal motion, McConnell's sign, tricuspid regurgitation, elevated pulmonary artery systolic pressure, and decreased tricuspid annular plane systolic excursion 2.
- Echocardiography can visualize the embolic material in the right heart cavities in some cases, and can be used to monitor the response to therapy and the dissolution of thrombi 3.
- Right ventricular dilatation on bedside echocardiography performed by emergency physicians has been found to be highly specific for pulmonary embolism, but has poor sensitivity 4.
Diagnostic Accuracy of Transthoracic Echocardiography for PE
- The diagnostic accuracy of transthoracic echocardiography for PE has been found to have a consistently high specificity and low sensitivity, making it potentially adequate as a rule-in test at the bedside in critical care settings 5.
- Echocardiography is not recommended as a routine imaging test to diagnose suspected pulmonary embolism, but it is useful for identifying patients with pulmonary embolism who may have a poor prognosis 6.
- Echocardiographic markers such as moderate or severe right ventricular hypokinesis, persistent pulmonary hypertension, a patent foramen ovale, and free-floating right-heart thrombus can identify patients at risk for death or recurrent thromboembolism 6.