Imaging Modalities in Pulmonary Embolism: Echocardiography

The utility of echocardiography in pulmonary embolism varies widely based on specific clinical settings. Pulmonary embolism presents with a complex spectrum of disease severity ranging from cardiac arrest or frank obstructive shock, to a low risk condition with no measurable hemodynamic effect. The diagnostic yield of echocardiography follows this spectrum: in patients with hemodynamic instability, when other imaging studies are not feasible, bedside echocardiography can effectively rule out pulmonary embolism by demonstrating a normal sized and contractile right ventricle as well as potentially identify other etiologies of shock. Similarly, a dilated and hypokinetic right ventricle in these settings strongly suggests the diagnosis. On the other hand, in low-risk patients with low clot burden, echocardiography is unlikely to be of significant diagnostic and prognostic value. In this chapter, we outline the echocardiographic findings in pulmonary embolism. These findings can be broadly divided into the following categories: anatomic findings (thrombi in transit), measures of chamber size, measures of function and global/regional contractility, and Doppler derived estimates of regurgitation, pressure and resistance. We also describe the utility of transesophageal echocardiography and point of care ultrasound in the management of patients with pulmonary embolism.