Fatal persistent pulmonary hypertension presenting late in the neonatal period.

Abstract

Two cases of fatal idiopathic persistent pulmonary hypertension presented late in the neonatal period. Lungs were examined histologically by light and electron microscopy, and immunocytochemical studies were used to identify nerves. There was extension of medial smooth muscle distally along the arterial pathway so that most precapillary arteries had completely muscular walls, which in some cases completely obliterated the vessel lumen. Enlarged endothelial cells also contributed to the reduction in the size of the lumen. Nerve fibres accompanying muscular arteries were found in the alveolar region, more distal than is normal. The predominant neuropeptide was the vasoconstrictor tyrosine. Possible infection. At 2 months of age it was noted that he became cyanosed when crying and feeding. He also had tachypnoea and sweatiness at rest. Arterial blood gas analysis while breathing air showed: pH 7-42, carbon dioxide tension 4-9 kPa, oxygen tension 4-7 kPa, and base excess 0-7. He was referred to the Brompton Hospital for investigation of suspected cyanotic heart disease.On examination his weight had fallen to below the third centile for age. He was cyanosed and there was a prominent right ventricular impulse. The pulmonary component of the second sound was loud but there were no murmurs. His respiratory rate was 46 breaths/ minute. The chest radiograph showed mild cardiomegaly and normal pulmonary vascular markings. The electrocardiogram showed a mean frontal QRS axis of + 150°and right ventricular hypertrophy. The cross sectional echocardiogram showed normal anatomy of the heart with normal atrioventricular and ventriculoarterial connections. The right atrium was enlarged and the interatrial septum bowed from right to left. The right ventricle was grossly dilated with poor systolic function. The parasternal short axis view showed that the left ventricle was 'squashed', suggesting a high right ventricular pressure.Cardiac catheterisation was carried out under general anaesthesia. The oxygen saturation in the aorta was 53%. The right ventricular pressure was 90/0-4 mm Hg with a simultaneous left ventricular pressure of 68/0-5 mm Hg. Using an estimated oxygen consumption of 150 ml/min/ m2 pulmonary vascular resistance was 24 units/ m m air and 10 5 units/i2 in 100% oxygen.Angiography showed poor right ventricular function but no intracardiac abnormalities. A diagnosis of persistent pulmonary hypertension of the newborn was made, and a pulmonary arterial line was left in.The patient was extubated into headbox oxygen. The pulmonary artery pressure at this stage was 156/80 mm Hg with a systemic pressure of 80/30 mm Hg. Prostacyclin and adenosine were infused through the pulmonary arterial line. The patient was placed in a continuous subatmospheric (negative) extrathoracic pressure chamber and given 100% oxygen. None of these manoeuvres succeeded in lowering the pulmonary artery pressure appreciably, and it remained higher than the systemic pressure. On the day after cardiac catheterisation the patient had a card...

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Chronic in ovo hypoxia decreases pulmonary arterial contractile reactivity and induces biventricular cardiac enlargement in the chicken embryo

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Pulmonary hypertension’s variegated landscape: a snapshot

“…12 Developmental origin: D2 (possible), D3, PD. 182,183 There are a few reports of infants with signs/symptoms of PH in the early neonatal period in whom unremitting and ultimately fatal PH is diagnosed weeks or months later, 184,185 and patients with apparently idiopathic PH as young as one month of age are included in one study. 182 Since these and a few other reports suggest that incomplete fall of fetal PVR may account for a few cases of idiopathic PH, possible D2 origin is indicated.…”