T. Tanaka et al., HISTOLOGIC-STUDY OF THE SMALL PULMONARY-ARTERIES IN 38 PATIENTS WITH PULMONARY ATRESIA AND INTACT VENTRICULAR SEPTUM, Japanese Circulation Journal, 60(5), 1996, pp. 293-299
The structure of the small pulmonary arteries was studied during autop
sies performed on 38 patients with pulmonary atresia with intact ventr
icular septum. The thicknesses of the media of these small pulmonary a
rteries measured using a quantitative morphometric method varied widel
y. However, there was a notable tendency toward thinning of the media,
especially in neonates. In cases in which the patient had undergone p
rostaglandin El treatment, the media was thinner, which suggests that
the longer the treatment, the thinner the media. Intimal lesions were
observed in 18 of the 38 patients (47%), including 12 of the 22 neonat
es (55%). Intimal lesions were also found in the patients with thinner
media. Based on these results, we propose that organized thrombus for
mation and intimal proliferation are more likely to develop in patient
s with reduced pulmonary blood flow, such as in those with pulmonary a
tresia and intact ventricular septum. In prostaglandin-treated patient
s, an imbalance between the markedly thinner median muscle and the rel
atively higher pulmonary blood flow and pressure may contribute to fib
rous intimal proliferation. Small pulmonary arteries with a strikingly
thinner media may be vulnerable to higher pressure, predisposing the
patient to the development of intimal lesions.