Impact of the Balloon Inflation Time and Pattern on the Coronary Stent Expansion

Percutaneous coronary intervention for bifurcation coronary lesions using optimised angiographic guidance: the 18th consensus document from the European Bifurcation Club

The 2023 European Bifurcation Club (EBC) meeting took place in Warsaw in October, and the latest evidence for the use of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) to optimise percutaneous coronary interventions (PCI) on coronary bifurcation lesions (CBLs) was a major focus. The topic generated deep discussions and general appraisal on the potential benefits of IVUS and OCT in PCI procedures. Nevertheless, despite an increasing recognition of IVUS and OCT capabilities and their recognised central role for guidance in complex CBL and left main PCI, it is expected that angiography will continue to be the primary guidance modality for CBL PCI, principally due to educational and economic barriers. Mindful of the restricted access/adoption of intracoronary imaging for CBL PCI, the EBC board decided to review and describe a series of tips and tricks which can help to optimise angiography-guided PCI for CBLs. The identified key points for achieving an optimal angiography-guided PCI include a thorough analysis of pre-PCI images (computed tomography angiography, multiple angiographic views, quantitative coronary angiography vessel estimation), a systematic application of the technical steps suggested for a given selected technique, an intraprocedural or post-PCI use of stent enhancement and a low threshold for bailout use of intravascular imaging.

Efficacy of Post-Dilatation during Carotid Artery Stenting for Unstable Plaque Using a Double-Layer Stent Evaluated by OFDI

Objective

This study aimed to use optical frequency domain imaging (OFDI) to evaluate the efficacy of post-dilatation (PD) after stent placement for unstable plaques during carotid artery stenting (CAS) using a double-layer stent.

Methods

Twelve unstable carotid plaque lesions diagnosed by MRI were evaluated using OFDI during CAS. The pre-procedural minimum lumen diameter was 1.6 ± 0.7 mm. Each lesion was pre-dilated with balloon catheters (diameter, 5.3 ± 0.5 mm), and a double-layer stent was deployed. PD was performed with balloon catheters of the same size as those used for pre-dilatation. Cross-sectional OFDI images within the stented segment were evaluated at 1-mm intervals for a 20-mm segment, including the most stenotic lesion. Slice rates for the presence of in-stent plaque protrusion (PP) and plaque between the double-layer lumen were calculated.

Results

No procedural complications occurred with the use of an embolic protection device. Compared to after stent placement, slice rates for any PP (44 ± 19% to 62 ± 22%, P <0.05) and plaque between the double-layer lumen (79 ± 16% to 91 ± 34%, P <0.05) were significantly increased after PD; slice rates for >500 μm PP (7.5 ± 14% to 0%, P <0.05) were significantly decreased. Visible debris were captured in 50% of lesions.

Conclusion

PD after double-layer carotid stent placement decreases in-stent large PP. Double-layer construction contributed to the prevention of large PP, as the PP may have been crushed into debris by PD.

Degradation modeling of poly-l-lactide acid (PLLA) bioresorbable vascular scaffold within a coronary artery

In this work, a strain-based degradation model was implemented and validated to better understand the dynamic interactions between the bioresorbable vascular scaffold (BVS) and the artery during the degradation process. Integrating the strain-modulated degradation equation into commercial finite element codes allows a better control and visualization of local mechanical parameters. Both strut thinning and discontinuity of the stent struts within an artery were captured and visualized. The predicted results in terms of mass loss and fracture locations were validated by the documented experimental observations. In addition, results suggested that the heterogeneous degradation of the stent depends on its strain distribution following deployment. Degradation is faster at the locations with higher strains and resulted in the strut thinning and discontinuity, which contributes to the continuous mass loss, and the reduced contact force between the BVS and artery. A nonlinear relationship between the maximum principal strain of the stent and the fracture time was obtained, which could be transformed to predict the degradation process of the BVS in different mechanical environments. The developed computational model provided more insights into the degradation process, which could complement the discrete experimental data for improving the design and clinical management of the BVS.

Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents

Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.