Neonatal Thyrotoxicosis and Persistent Pulmonary Hypertension Necessitating Extracorporeal Life Support

Abstract

ABSTRACT. We report a case of neonatal Graves' disease involving an infant with severe persistent pulmonary hypertension (PPHN) associated with neonatal thyrotoxicosis that necessitated extracorporeal membrane oxygenation. Hyperthyroidism, although uncommon in the newborn period, has been associated with pulmonary hypertension among adults. The exact mechanisms responsible for this effect on pulmonary vascular pressure are not well understood. Recent studies have provided evidence that thyrotoxicosis has direct and indirect effects on pulmonary vascular maturation, metabolism of endogenous pulmonary vasodilators, oxygen economy, vascular smooth muscle reactivity, and surfactant production, all of which may contribute to the pathophysiologic development of PPHN. Therefore, because PPHN is a significant clinical entity among term newborns and the symptoms of hyperthyroidism may be confused initially with those of other underlying disorders associated with PPHN (eg, sepsis), it would be prudent to perform screening for hyperthyroidism among affected newborns. ABBREVIATIONS. PPHN, persistent pulmonary hypertension; PVR, pulmonary vascular resistance; ECMO, extracorporeal membrane oxygenation; NO, nitric oxide; NOS, nitric oxide synthase; TTF-1, thyroid transcription factor-1; ADMA, asymmetricH yperthyroidism, although uncommon in the newborn period, has been associated with pulmonary hypertension among adults. 1,2 The exact mechanisms responsible for this effect on pulmonary vascular pressure are not well understood. Persistent pulmonary hypertension (PPHN), a major cause of morbidity and death among term newborns, 3 is associated with perinatal asphyxia and perhaps chronic intrauterine hypoxia. Acute hypoxemia induces pulmonary vasoconstriction, whereas prolonged hypoxia causes hypertrophy of the smooth muscle layer of the small pulmonary arterioles, resulting in persistently elevated pulmonary vascular tone. 3 In either situation, increased pulmonary vascular resistance (PVR) causes a subsequent increase in right ventricular pressure, a patent foramen ovale, and a patent ductus arteriosis in the postnatal period. The resultant, potentially severe, right-to-left shunting is the hallmark of PPHN. Infants with severe PPHN may require extracorporeal membrane oxygenation (ECMO) for adequate oxygen delivery until the elevated PVR resolves.Although the pathophysiologic development of PPHN is multifactorial, certain conditions, such as congenital diaphragmatic hernia, cyanotic congenital heart disease, and sepsis, predispose infants to elevated PVR. These conditions are associated with hypoxia, acidosis, and elevated levels of proinflammatory cytokines. This environment promotes altered vasodilator synthesis and increased vasoconstriction through several poorly defined pathways. Interestingly, thyrotoxicosis is associated with similar clinical and biochemical findings.The association between hyperthyroidism and pulmonary hypertension is unclear. Thyroid hormone has dramatic and contrasting effects on the cardiovascular sy...

Congenital hepatic arteriovenous malformation: an unusual cause of neonatal persistent pulmonary hypertension

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