Teaching Case

Presented in our hospital, with a history of PDA ligation 15 years before, with a cough and 3 episodes of haematemesis in past 3days. Normal pulse, BP, both radial and femoral pulses. Basal crepitation noted in left lung field. Echocardiography shows normal left ventricular function and no pulmonary hypertension.

Chest X-ray PA view showing widening of mediastinum , curvilinear calcific density in the region of aortic knuckle. Inhomogeneous patch in left upper zone. On CT angiography the characteristic location of luminal out-pouching along the inferior surface of arch of aorta in aortopulmonary window suggested the diagnosis of a ductus arteriosus aneurysm. The partially thrombosed aneurysm originated from the ventral part of the aorta at the level of the ostium of the left subclavian artery.

Ductus arteriosus is a normal anatomic structure that provides communication between the left pulmonary artery and aorta during the foetal life. A remnant of the sixth aortic arch, closes soon after birth. Closure usually begins at the pulmonary end and progresses towards the aorta. Complete anatomical obliteration requires up to 12 weeks. An indentation of the aortic wall at the site of insertion of the obliterated ductus arteriosus is seen in approximately 9-26% of adults on angiography studies and refers to ductus diverticulum, the systemic pressure in the aorta leads to aneurysmal dilatation.
Aneurysm of the ductus arteriosus may occur either spontaneously or may follow surgical repair of PDA. 140 cases of aneurysm of the ductus arteriosus have been reported in the literature of which 106 occurred spontaneously and 38 followed surgical treatment of PDA [1].The most common complication in adult is rupture occurring in 28% of cases [1]. Other complications include erosion into the adjacent structures (pericardium, bronchi, oesophagus), endocarditis and thrombosis [1, 2]. Aneurysm greater than 3cm in diameter, those producing symptoms or progressive enlargement should be surgically resected [2].
Danza et al suggest two radiographic features indicative of a ductus arteriosus aneurysm. These signs are parietal calcification at the periphery of the lesion and/or the mottled calcification at the aortic side of the mass in addition to a small pedicle linking the lesion to the pulmonary artery. The pedicle may be obscured by large aneurysms [3].
The atherosclerotic aneurysms are usually large and more often affect the wide part of the aortic circumference, and they may be calcified. Post traumatic aneurysms of the thoracic aorta are typically located in the posterior part of the arch just distal to the origin of the left subclavian trunk. They tend to grow towards the left, projected not only towards the aortic window, but also into the posterior wall of the aorta.