Various reasons for repeat dilatation of stented pulmonary arteries in paediatric patients

Abstract

Objective: To evaluate the reasons for repeat intervention in patients treated with balloon expandable stents for pulmonary artery stenoses, with particular analysis of the time intervals between interventions.

Design: A retrospective observational study.

Setting: A single paediatric cardiology centre.

Patients: 38 patients, mean age 6.9 years, range 6 days to 34 years (one adult patient); mean weight 19.7 kg, range 2.5-75 kg.

Intervention: Implantation of balloon expandable stents in 46 cases of main pulmonary artery stenosis, right pulmonary artery stenosis, left pulmonary artery stenosis, or right ventricle to pulmonary artery conduits.

Main outcome measures: Adaptation of stent diameter to patient growth; development of pulmonary arteries; pressure gradient in the right ventricle.

Results: 56 stents were implanted in 46 lesions. During a mean follow up time of 2.2 years, 40 repeat dilatations were performed on 28 of 42 reinvestigated stents. A second repeat dilatation was performed on eight stents, and a third on four stents. The mean time period between implantation and repeat dilatations was 15.5 months.

Conclusions: Repeat dilatation of stented pulmonary arteries was done mainly to adapt the stent diameter to the patient's growth. However, repeat dilatations were also performed to relieve stent obstruction caused by intimal proliferation (17.5%), or to overcome progressive external compression (25%). While most repeat interventions in adult patients are for intimal hyperplasia, in paediatric patients they are needed for a variety of reasons.

Figure 1

Curved course of the catheter used for stenting a left pulmonary artery stenosis in an infant. A 12 mm Palmaz iliac stent is implanted to overcome a circumscribed stenosis.

Figure 2

Stenting of native main pulmonary artery stenosis in a child with tetralogy of Fallot, hypoplastic pulmonary arteries, and major aortopulmonary collateral arteries, before stent implantation (left panel) and after implantation (right panel).

Figure 3

Embolised stent in the right ventricle. The stent has remained in the same position for six years.

Figure 4

Aneurysm formation four months after stenting of a right ventricle to pulmonary artery conduit.

Figure 5

Intimal hyperplasia in a left pulmonary artery stent seven months after implantation in an 8 month old infant.

Figure 6

Hypoplastic left and right pulmonary artery in a 3 month old infant after surgical correction of truncus arteriosus (left panel). Middle panel: the same patient at the age of 7 months, four months after stent implantations in the left and right pulmonary artery and after the first redilatation; the stent to vessel ratio on the right side was chosen to be 1.5:1 to allow for expected growth. The right panel shows the result one year after the first redilatation.