Intravascular ultrasound identification of stent entrapment in vivo with in vitro confirmation

OBJECTIVES: One potential complication of stenting is "stent jail" due to placement of a stent across a side branch, which may impede additional interventions. Another form of stent entrapment may occur if the guidewire is accidentally withdrawn and then unknowingly passes through a stent loop during reentry with subsequent high pressure expansion. The purpose of this study was to evaluate this form of stent entrapment in vitro by intravascular ultrasound (IVUS). METHODS: A guidewire was passed through the end or middle diamonds of Palmaz-Schatz and Palmaz stents or the middle of Gianturco-Roubin stents. A 3.5 mm balloon was inflated over the guidewire through the various side holes of the stents. RESULTS: IVUS images presented three distinct patterns depending on the type of stent and position of balloon entry: 1) external compression and loss of wall continuity in the Palmaz-Schatz and Palmaz stents, 2) displacement of the side diamond across the lumen, and 3) external compression of the Gianturco-Roubin stent. The first and second patterns but not the third one were associated with impairment of lumen access. CONCLUSIONS: Based upon this in vitro verification, IVUS imaging can be used to identify the presence of stent entrapment in vivo.