The potential hazard of a non-slip element balloon causing distal longitudinal stent deformation: the first clinical experience and in vitro assessment

Figure 1. Case 1. A. The pre-procedural coronary angiogram revealed severe stenosis at the left anterior descending (LAD) artery and the first diagonal branch. B. After deployment of a 2.75/20 mm SYNERGY stent (Boston Scientific, Natick, MA, USA) at the diagonal branch without protrusion to the LAD artery, intravascular ultrasound (IVUS) showed distal stent malapposition. C. Post-dilatation using a 2.75/13 mm non-slip element (NSE) balloon was performed. When pulling back the NSE after deflation, slight resistance was encountered. Then longitudinal stent deformation was detected, with shortening of the distal end of the stent, using fluoroscopy after removal of the NSE (red arrow). D. Further dilatation, with a 2.75/15 mm non-compliant balloon, was then performed. Fluoroscopy and IVUS subsequently showed that the deformed stent had been successfully dilated.

Figure 2. Case 2. A. The coronary angiogram showed severe stenosis at the mid-left anterior descending (LAD) artery. B. After deployment of a 3.0/16 mm SYNERGY stent at the LAD artery, optical coherence tomography (OCT) images revealed malapposition of the distal end of the stent. C. After post-dilatation with a 3.0/13 mm non-slip element balloon, longitudinal stent deformation was identified at the distal end of the stent using magnified fluoroscopy (red arrow). D. OCT images revealed shortening of the distal edge of the stent. E, F. After further dilatation with a 3.25/8 mm non-compliant balloon, the stent was checked for successful reconstruction using magnified fluoroscopy (red arrow) and OCT images.

Figure 3. Image of non-slip element (NSE) balloon. After the procedure, the NSE balloon catheter was checked, revealing that the distal connection of the NSE was turned up (red arrow). The black arrowhead shows the structural feature of three elements that are attached only proximally and distally and not bonded to the balloon body.

Figure 4. Longitudinal stent deformation (LSD) in case 1 was reproduced in the bench test. A. Using a bifurcation model (inner diameter 4.0–3.5–3.5 mm), the Runthrough® NS guide wire (Terumo Corporation, Tokyo, Japan) was positioned and a 3.0/28 mm SYNERGY stent was deployed at nominal pressure. B. A 3.0/13 mm non-slip element (NSE) balloon was delivered, which had already been inflated and deflated out of the silicon tube, into the stent. C, D. When the NSE was pulled back, the distal connection was entrapped along the inner curve of the bend (white arrow) and the distal stent was gradually shortened (red arrow). E. The catheter was pushed into the distal stent once and pulled back carefully. Then, the entrapped NSE was successfully removed and distal LSD occurred (red arrow).

Figure 5. Longitudinal stent deformation (LSD) in case 2 reproduced in the bench test. A. Using a bifurcation silicon tube (inner diameter 3.5–3.5–2.5 mm), a 2.5/28 mm SYNERGY stent was deployed at nominal pressure. B. Delivery of a 2.5/13 mm non-slip element (NSE) balloon through the stent was performed without complications. C. While pulling back the NSE, the distal connection was entrapped in the distal edge of the stent along the outer curve of the bend (white arrow) and distal LSD occurred (red arrow). D. The device could not be removed because the deformation had progressed significantly. Therefore, reconstruction of the deformed stent by balloon dilatation at high pressure was performed. E. Accordingly, the NSE was successfully withdrawn through the stent.