Abstract
SUMMARY The morphology of the central pulmonary artery was studied by selective angiography in 21 previously unoperated patients (aged 11 days-21 years, median 4 years) with pulmonary atresia associated with various types of congenital heart disease. Angiographic findings were confirmed at operation in 10 patients. There was juxtaductal obstruction of the left pulmonary artery in two thirds of the patients with complete atresia in a quarter. Six of seven patients without juxtaductal obstruction had pulmonary valve atresia, but all nine patients with juxtaductal stenosis had truncal atresia. No patient had stenosis of the right pulmonary artery.
Abstract
Congenital pulmonary atresia often occurs in association with tetralogy of Fallot, atrioventricular discordance, ventriculoarterial discordance, univentricular heart, or with intact ventricular sep- (Table) . All were investigated by cross sectional echocardiography and angiocardiography. The morphology of the central pulmonary artery (pulmonary trunk and main branches) was studied by biplane cut-film or cine angiography. After ventriculography or aortography, selective pulmonary angiography was performed by catheterisation of the persistent ductus arteriosus, except in one patient (case 6) in whom the ductus arteriosus was not patent and in five patients under the age of 1 year (cases 1, 2, 7, 8, and 16 

of normal, or nearly normal, pulmonary arteries is important for successful operation, and peripheral pulmonary stenosis or atresia often make intracardiac repair difficult.9 10 Preoperative diagnosis of peripheral pulmonary stenosis or atresia by conventional diagnostic methods is not easy. Since 1981 we have used preformed catheters to enable us to visualise the ductus arteriosus and adjacent central pulmonary arteries in patients with pulmonary atresia. " We now report the angiographic appearance of the central pulmonary arteries in pulmonary atresia and discuss the develo'ment of juxtaductal obstruction of the left pulmonary artery.
Patients and methods
Since the beginning of November 1981, we have used selective angiography to investigate 77 patients
Patients and methods
Requests for reprints to Dr Kazuo Momma, Department of Paediatric Cardiology, Heart Institute ofJapan, Tokyo Women's Medical College, Kawada-cho 10, Shinjuku-ku, Tokyo 162, Japan.
Patients and methods
Accepted for publication 12 August 1985 with pulmonary atresia associated with various other congenital anomalies in whom the central pulmonary artery originally gave rise to right and left pulmonary arteries. Twenty one patients who had not been treated surgically form the present study group. They range in age from 11 of Valsalva were seen at its interior end. In truncal atresia the pulmonary trunk was short and cone shaped. These features were most clearly shown on lateral angiograms. In six patients (cases 16-21) with additional juxtaductal pulmonary atresia, the pulmonary trunk could not be visualised. The ductus arteriosus was left sided in 20 patients, including two with the asplenia syndrome (cases 7 and 10). The remaining patient (case 6) had a closed ductus arteriosus. We use the term juxtaductal obstruction to describe stenosis or atresia of the left pulmonary artery at its junction with the ductus. The diagnosis of postnatal development of juxtaductal atresia was based on the angiographic demonstration, with the catheter in the ductus, of a left pulmonary artery continuous with the ductus, but at an angle to it, study; the angiographic diagnosis was confirmed in all.
Results

ANGIOGRAMS OF THE PULMONARY ARTERY
The pulmonary trunk was clearly visualised in 16 patients. There was pulmonary valve atresia in six patients (43%) and truncal atresia in the remaining 10 patients. The appearance of the central pulmonary artery corresponded to one of four patterns (Fig. 1) In seven patients the pulmonary trunk gave rise to right and left branches without stenosis. All these patients except one (case 15) had pulmonary valve atresia. In one (case 6) the ductus was closed, and pulmonary vein wedge angiography showed that the entire central pulmonary artery was hypoplastic (Fig. 2) .
ANGIOGRAMS OF THE PULMONARY ARTERY
In the other 14 patients, there was juxtaductal obstruction of the left pulmonary artery. In nine of these 14 patients the pulmonary trunk divided into right and left pulmonary arteries, but there was a cone shaped narrowing of the left pulmonary artery in each case (Figs. 3, 4 , and 5). These nine patients all had truncal atresia. In the remaining five patients, there was complete juxtaductal obstruction, and selective injection of contrast medium into the ductus demonstrated only the left pulmonary artery (Fig. 6 ). In three of these five patients, pulmonary vein wedge angiography demonstrated normal branching of the right pulmonary artery, though proximal right pulmonary artery and pulmonary trunk were not opacified so that the type of pulmonary atresia could not be determined.
CORRELATION BETWEEN TYPES OF PULMONARY
ATRESIA AND JUXTADUCTAL OBSTRUCTION Figure 7 shows the age of the patients, the type of pulmonary atresia, and the presence or absence of juxtaductal obstruction. None of the six patients with valvar atresia had juxtaductal obstruction of the left pulmonary artery. In contrast, all except one of those -with truncal atresia had juxtaductal obstruction in the left pulmonary artery. Juxtaductal obstruction was more severe proximal than distal to the ductus and five of eight patients aged > 3 years with juxtaductal, obstruction had atresia. inferior aspect of the aortic arch with an acute angle between ductus and descending aorta (Fig. 5 ).
ANGIOGRAMS OF THE DUCTUS ARTERIOSUS
In the other two patients, with pulmonary atresia and an intact ventricular septum, the ductus was shorter, originated more caudally at the isthmus, and made an obtuse angle with the descending aorta. The ductus originating from the inferior aspect of the aortic arch was widest at its aortic origin, was tubular or cone shaped, and had localised stenosis at its junction with the pulmonary artery (Figs. 4 and 5) . A large ductus could be catheterised with a balloon catheter (Figs. 4 and 6 ). A small ductus had to be catheterised using a preformed ductus catheter (Figs. 3 and 5 ).
Discussion
The development of juxtaductal obstruction of the left pulmonary artery in patients with pulmonary atresia has been described before but not as a definite entity.'2 14 Our angiographic observations provided not only a diagnosis but also information about the development of juxtaductal obstruction. Several possible mechanisms have been proposed to explain the development of juxtaductal obstruction. It has been suggested that, as in the case of coarctation of the aorta,'5 the shearing force of rapid flow leads to development of a jet lesion at the bifurcation of the artery. This mechanism may explain the progression of juxtaductal obstruction after infancy. We, however, have seen juxtaductal obstruction in a 3 month old infant, and the early appearance of this obstruction suggests that ductal constriction may be a factor. Presbitero etal reported evidence to support this hypothesis in one of their patients.'2 They suggested that as the ductus arteriosus closed, ductal tissue extended into and narrowed the left pulmonary artery.
Discussion
In the nineteenth century it was suggested that ductal tissue might be a cause of coarctation of the aorta (Skodaic theory). '6 17 More recently this Skodaic theory was invoked to account for angiographically diagnosed juxtaductal stenosis in the left pulmonary artery in tetralogy of Fallot in some patients. 18 19 An understanding of the development of juxtaductal obstruction in pulmonary atresia is relevant to the management of congenital cardiac diseases associated with pulmonary atresia. The present study showed the progressive nature of this lesion, especially proximal to the ductus, and its association with truncal atresia. In patients with truncal atresia, juxtaductal stenosis was already present in infancythe youngest such patient in this series was A few comments are needed on the technique of selective angiography of the pulmonary artery in patients with pulmonary atresia and a central pulmonary artery. The origin and shape of the ductus arteriosus in -pulmonary atresia -are characteriStiC. 14 20 1420 It arises from the inferior aspect of the aortic arch and makes an acute angle with the descending aorta. We have used three techniques for catheterisation of this type of ductus. In a large high flow ductus, a transvenous balloon catheter (Berman) can be advanced through the right ventricle and ascending aorta into the ductus. An angiographic catheter may also be inserted through the brachial artery. In 1981 we developed a third technique in which we used a preformed ductus catheter.1 This catheter is inserted percutaneously from the femoral artery and easily enters the ductus. We have used it extensively in children aged > 1 year, and even a narrow ductus with an internal diameter of 2 mm can be entered.

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