Pulmonary embolism echocardiography or ultrasound


 * Associate Editors-in-Chief: Ujjwal Rastogi, MBBS [mailto:urastogi@perfuse.org]

Overview
Approximately 40% of patients with PE have evidence of right heart strain on echocardiography. RV dysfunction and RV thrombus on echocardiography help in assessing prognosis. Not every patient with a (suspected) pulmonary embolism requires an echocardiogram, but elevations in cardiac troponins or brain natriuretic peptide may indicate heart strain and warrant an echocardiogram.

Echocardiography
In massive and submassive PE, dysfunction of the right side of the heart can be seen on echocardiography, an indication that the pulmonary artery is severely obstructed and the heart is unable to match the pressure. Some studies suggest that this finding may be an indication for thrombolysis.

The specific appearance of the right ventricle on echocardiography is referred to as the McConnell sign, which refers to akinesia of the mid-free wall but normal apical motion. This phenomenon has a 77% sensitivity and a 94% specificity for the diagnosis of acute pulmonary embolism.

Echocardiography should be used to confirm the presence of right ventricular dysfunction if multidetector CT is not available.

The diagnosis of right ventricular dysfunction requires the presence of at least two out of these, though in absence of right ventricular hypertrophy:
 * 1) Right-to-Left ventricular end diastolic diameter ratio>0.9 in the apical four-chamber view.
 * 2) Right-to-Left ventricular end diastolic diameter ratio>0.7 in the parasternal long-axis or subcoastel four-chamber view.
 * 3) Paradoxical interventricular septal motion
 * 4) Systolic pulmonary artery pressure over 30 mmHg.

In another study, a value of less than 1.0 for Right-to-Left ventricular diameter was shown to have a 100% negative predictive value for an uneventful outcome (95% CI: 94.3%, 100%).

In addition to above, Echo can also be useful in patients with right heart thromboemboli or patent foramen ovale patients, which have shown to have higher rate of complication and mortality.

The following video explains the McConnell sign.