What is the role of echocardiography in the workup of persistent pulmonary hypertension of the newborn (PPHN)?

Updated: Sep 03, 2019
  • Author: Kate A Tauber, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
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Answer

Answer

The diagnosis of persistent pulmonary hypertension of the newborn (PPHN) should be suspected whenever the level of hypoxemia is out of proportion to the level of pulmonary disease. Echocardiography plays a major role in screening and assisting in making the diagnosis of PPHN. It is considered the most reliable, convenient, and noninvasive test to establish the diagnosis of PPHN, assess cardiac function, and rule out associated structural heart disease.

Echocardiography with Doppler and color-flow mapping allows the physician to assess the presence and direction of the shunt at the ductus arteriosus and foramen ovale. It can estimate the pulmonary arterial systolic and diastolic pressures especially when the ductus arteriosus is restrictive. The right ventricle systolic pressure (RVSP) is estimated from the maximal tricuspid regurgitation flow velocity (v) in milliseconds and the estimated right atrial pressure (RAP) in the modified Bernoulli equation: RVSP = 4v2 + RAP. In newborns, a reasonable estimate of RAP is 5 mm Hg. Pulmonary diastolic pressure (PDP) can be estimated when pulmonary insufficiency is present as: PDP = 4V2 + RAP, where V is the insufficiency peak velocity.

Abnormal-appearing right ventricular dilatation, leftward bowing of the interventricular septum into the left ventricle, tricuspid regurgitation (TR), and right-to-left or bidirectional shunting at the patent foramen ovale and patent ductus arteriosus are the cardinal findings seen on echocardiography in infants with PPHN.

Echocardiographic factors that appear to be predictive of poor outcomes (progression to death/ECMO) in infants with PPHN include diminished tricuspid annular plane systolic excursion (TAPSE), right ventricular global longitudinal peak strain (GLPS), and a predominant right-to-left shunt across the patent ductus arteriosus. [31]

Echocardiography is also used to define the anatomy of the pulmonary veins and to rule out obstructed total anomalous pulmonary venous return, which presents in a similar clinical scenario, prior to initiating extracorporeal membrane oxygenation (ECMO).

Although rarely utilized, additional morphologic and functional information can be acquired by magnetic resonance imaging (MRI) and computed tomography (CT) of the chest tomography, if lung pathology is suspected.


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