Right ventricular outflow tract doppler flow abnormalities suggestive of pulmonary embolism - case series and review

Abstract

Background: Pulmonary embolism (PE) is one of the most challenging diagnoses in emergency medicine, mainly because symptoms range from asymptomatic disease to sudden death. The role of echocardiography in the workup of suspected PE has been supportive and used primarily to assess the right ventricular (RV) size and function, which is important for risk stratification. Several echocardiographic parameters described in the literature lack the desired accuracy. Recently, a potential value of less well-recognized RV outflow tract (RVOT) Doppler variables has been reported. The early systolic notching (ESN) pattern was observed in 92% of patients with high and intermediate risk PE, making it a promising sign in selected PE patients.

Case presentation: In this case series, we demonstrate a typical ESN pattern on RVOT Doppler evaluation in three patients with intermediate-risk PE presenting to our emergency department (ED). None of the patients had been previously diagnosed with pulmonary hypertension or other chronic pulmonary and cardiac disease. The pre-test probability was low. Massive proximal emboli were found on CT angiograms, involving pulmonary truncus or main pulmonary arteries. Previously, the ESN pattern was identified on a focused echocardiogram, which was the only echocardiographic indicator of increased pulmonary vascular resistance.

Conclusions: RVOT Doppler flow pattern of ESN has potential clinical utility for the detection of PE in ED patients. ESN could identify patients at higher risk, which are otherwise stratified as low risk according to the latest guidelines. Moreover, this case series illustrates that even in the absence of other echocardiographic findings of RV strain, the presence of ESN should alert to the possibility of acute PE. Further prospective studies are needed to assess its diagnostic value in a selected subgroup of patients, similar to the cases presented, that would have no other obvious reason for the altered RVOT Doppler curve.

Keywords: Early systolic notching; Emergency medicine; Focused echocardiography; Pulmonary embolism; Pulsed wave doppler; Right ventricular outflow tract.

Fig. 1

Normal RV: LV ratio, TAPSE 23 mm

Fig. 2

RVOT VTI early systolic notch (ESN) pattern, AT 45 ms

Fig. 3

Massive embolus in the right main pulmonary artery and its branches

Fig. 4

Massive embolus in the left main pulmonary artery and its branches

Fig. 5

RVOT VTI early systolic notch (ESN) pattern, AT 55 ms

Fig. 6

Massive filling defects in right main pulmonary artery

Fig. 7

Normal RV size and RV: LV ratio

Figs. 8

8a, b, c, ESN pattern of RVOT VTI and reduced AT

Fig. 9

Saddle pulmonary embolus at pulmonary truncus bifurcation and main pulmonary arteries