Persistent Pulmonary Hypertension

Larissa V. Furtado, MD

Key Facts

Terminology

Persistent pulmonary hypertension of newborn (PPHN)

Etiology/Pathogenesis

Failure of pulmonary circulation to transition from a high- to low-pressure system at birth
High pulmonary vasculature resistance prevents adequate pulmonary blood flow and perfusion leading to hypoxemia, acidemia, and lactic acidosis
Not completely understood
Multifactorial

Clinical Issues

Most frequently occurs in term or near-term neonates

Microscopic Pathology

Peripheral extension of smooth muscle and circumferential muscularization of pulmonary arterioles

Gas exchange is primarily performed by the placenta in utero. Lungs are bypassed due to high pulmonary vascular resistance. Oxygenated blood from the placenta

reaches the heart via the ductus venosus & inferior vena cava

& enters the left atrium through the foramen ovale

. Blood flows to the aorta from the left ventricle or via ductus arteriosus

, & only 5-10% of cardiac output reaches the lungs. At birth, systemic vascular resistance increases, lung vascular tone decreases, & pulmonary perfusion starts. Failure of the pulmonary circulation to make this transition at birth results in persistent pulmonary hypertension.

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