Secondary collapse of a Palmaz stent implanted for native aortic coarctation
A 21 year old woman was referred for native aortic coarctation. At 6 months of age she had had a repair of an aorto-pulmonary window, at 12 months a surgical closure of an atrial septal defect, and at 7 years a left pneumonectomy. During the first years of life aortic coarctation was not discovered.
At presentation she had systemic hypertension and superior–inferior limb gradient of 30 mm Hg. Echocardiography and magnetic resonance imaging confirmed aortic coarctation. Direct stenting of the coarcted segment was performed utilising a Palmaz 308 stent mounted on an 18 mm balloon. After stenting there was no residual gradient and the profile of the aortic hysthmus was regular.
Six months later the patient still had systemic hypertension and a superior–inferior limb gradient of 40 mm Hg. Computed tomography showed deviation of the heart, deformation (panel A), and possible rupture (panel B) of the stent, and did not identify any cause of extrinsic compression.
The risk of surgical repair of coarctation was considered to be elevated, thus, redilation of the stent was attempted, utilising a 18 mm balloon. Peak to peak gradient diminished from 50 to 20 mm Hg and aortic profile appeared more regular.
Two months after the second catheterisation systemic hypertension persisted and there was a superior–inferior limb gradient of 50 mm Hg. Computed tomography showed an incompletely expanded stent, with a transversal diameter of 8.8 mm (panel C) and an axial diameter of 4.6 mm (panel D).
In June 2003, the patient had implantation of a right conduit between the ascending and descending aorta. At last follow up she was asymptomatic and had a normal aortic pressure.
We are unable to explain the reasons for the repeated stent collapse, apart from a possible compression between the spine and the beating heart.