[Primary pulmonary hypertension in childhood--clinical course and morphologic correlations with particular reference...

This is a case report of a 13-year-old girl who developed clinical symptoms of primary pulmonary hypertension (PPH). The prognosis is determined by progressive overloading of the right heart. Tissue from both the right and the left atria was examined using immunohistochemical methods. Cardiodilatin/alpha-ANP (atrial natriuretic peptide)-producing myoendocrine cells were analysed. As recent investigations have shown, the atrium and especially the atrial appendages of the heart function as an endocrine organ which is stimulated by pressure and volume overload, and which produces a natriuretic and vasodilatory peptide hormone from myoendocrine cells. In our case we found a general hyperplasia of the myoendocrine cells of the right atrium which is interpreted as a secondary reaction towards an increasing overload. This also means a temporary compensation of the progressive obstruction of the small pulmonary arteries, initiated by vasodilatory heart peptides. These investigations are in agreement with those of other groups who found an increased production of cardiac hormones in atrial overload. In the perinuclear area, electron microscopy shows zones of autophagolysis and the typical specific atrial granules which account for a dysfunction of atrial myoendocrine cells, as seen in other cardiac diseases. Our results may contribute to a better understanding of the pathogenesis of PPH and may help in diagnosis and therapy.