Crimping-induced structural gradients explain the lasting strength of poly l-lactide bioresorbable vascular scaffolds during hydrolysis.

Biodegradable polymers open the way to treatment of heart disease using transient implants (bioresorbable vascular scaffolds, BVSs) that overcome the most serious complication associated with permanent metal stents-late stent thrombosis. Here, we address the long-standing paradox that the clinically approved BVS maintains its radial strength even after 9 mo of hydrolysis, which induces a ∼40% decrease in the poly l-lactide molecular weight (). X-ray microdiffraction evidence of nonuniform hydrolysis in the scaffold reveals that regions subjected to tensile stress during crimping develop a microstructure that provides strength and resists hydrolysis.

Design Principles of Bioresorbable Polymeric Scaffolds.

The concept for a bioresorbable vascular scaffold combines the best features of the first 3 generations of percutaneous coronary intervention (namely), balloon angioplasty, bare metallic stents, and drug-eluting stents, into a single device. The principles of operation of a BRS follow 3 phases of functionality that reflect the different physiologic requirements over time; revascularization, restoration, and resorption. Most BRS designs make use of the continuum of hydrolytic degradation in aliphatic polyesters, such as poly(l-lactide), in which molecular weight, strength, and mass decrease progressively in 3 distinct stages, consistent with the in vivo requirements of each performance phase.

Paving the way to a bioresorbable technology: Development of the absorb BRS program.

Bioresorbable scaffolds (BRS) combine attributes of the preceding generations of percutaneous coronary intervention (PCI) devices with new technologies to result in a novel therapy promoted as being the fourth generation of PCI. By providing mechanical support and drug elution to suppress restenosis, BRS initially function similarly to drug eluting stents. Thereafter, through their degradation, BRS undergo a decline in radial strength, allowing a gradual transition of mechanical function from the scaffold back to the artery in order to provide long term effectiveness similar to balloon angioplasty.

Multiplicity of morphologies in poly (l-lactide) bioresorbable vascular scaffolds.

Poly(l-lactide) (PLLA) is the structural material of the first clinically approved bioresorbable vascular scaffold (BVS), a promising alternative to permanent metal stents for treatment of coronary heart disease. BVSs are transient implants that support the occluded artery for 6 mo and are completely resorbed in 2 y. Clinical trials of BVSs report restoration of arterial vasomotion and elimination of serious complications such as late stent thrombosis.

In vivo characterisation of bioresorbable vascular scaffold strut interfaces using optical coherence tomography with Gaussian line spread function analysis.

Aims: Optical coherence tomography (OCT) of a bioresorbable vascular scaffold (BVS) produces a highly reflective signal outlining struts. This signal interferes with the measurement of strut thickness, as the boundaries cannot be accurately identified, and with the assessment of coverage, because the neointimal backscattering convolutes that of the polymer, frequently making them indistinguishable from one another. We hypothesise that Gaussian line spread functions (LSFs) can facilitate identification of strut boundaries, improving the accuracy of strut thickness measurements and coverage assessment.

Spatial distribution and temporal evolution of scattering centers by optical coherence tomography in the poly(L-lactide) backbone of a bioresorbable vascular scaffold.

Background: Scattering centers (SC) are often observed with optical coherence tomography (OCT) in some struts of bioresorbable vascular scaffolds (BVS). These SC might be caused by crazes in the polymer during crimp-deployment (more frequent at inflection points) or by other processes, such as physiological loading or hydrolysis (eventually increasing with time). The spatial distribution and temporal evolution of SC in BVS might help to understand their meaning.