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Part I – Bioabsorbable polymers in medicine

Design principles and performance of bioresorbable polymeric vascular scaffolds

Abbott Vascular, Santa Clara, CA, USA

Aims: Bioresorbable polymeric vascular scaffolds may spawn a fourth revolution in percutaneous coronary intervention (PCI) and a novel treatment termed vascular restoration therapy. The principal design considerations for bioresorbable scaffolds are discussed in the context of physiological behaviour using the Bioabsorbable Vascular Solutions (BVS) ABSORB Cohort B scaffold (Abbott Vascular) as an example.

Methods and results: The lifecycle of a bioresorbable scaffold is divided into three phases: (1) revascularisation; (2) restoration; and (3) resorption. In the revascularisation phase spanning the first three months after intervention, the bioresorbable scaffold should perform comparably to metallic drug-eluting stents (DES) in terms of deliverability, radial strength, recoil, and neointimal thickening. The ensuing restoration phase is characterised by gradual erosion of radial strength and a loss of structural continuity, where the time scale at which each occurs is related to the hydrolytic degradation rate of the polymer. Natural vasomotion in response to external stimuli is theoretically possible at the end of this phase. Finally, in the resorption phase, the passive implant is systematically resorbed and processed by the body.

Conclusions: Limited clinical data speak to the potential of bioresorbable scaffolds as a new therapy, and future studies will prove critical to inspiring a fourth revolution in PCI.

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