Arterioembolic Characteristics of Differentially Diluted CaHA-CMC Gels Within An Artificial Macrovascular Perfusion Model.

BACKGROUND: Despite the recently increased incidence and improved awareness of filler-induced ischemic injuries, the arterioembolic behavior of filler products has not been well described. OBJECTIVES: To evaluate the embolic behavior of varying dilutions of calcium hydroxylapatite-carboxymethylcellulose (CaHA-CMC) gel mixtures within an artificial macrovascular perfusion model of the proximal facial artery with correlation against published instances of ischemic injuries in the literature. METHODS: CaHA-CMC gel mixtures were assessed through the Pulsatile Unit for the Laboratory Simulation of Arterioembolic Restrictions (PULSAR) system at different flow rates. The occlusive behavior, embolic particle size distributions, and morphological attributes were evaluated through direct photographic and videographic captures followed by digital image processing. The PubMed database was systematically queried for all published instances of CaHA-CMC-associated ischemic injuries. RESULTS: Undiluted CaHA-CMC demonstrated highly cohesive behavior upon PULSAR inoculation, with a tendency toward proximal occlusion. Gel fragmentation resulted in a polydisperse embolic mixture averaging 0.151 ± 0.61†mm² (interquartile range: 0.006-0.022†mm²) in size. Product dilution had a profound effect on embolic behavior, with a significant reduction in average particle size (0.018 ± 0.03†mm²; interquartile range: 0.005-0.018†mm²; P < .0001) and complete elimination of proximally occlusive capacity for hyperdiluted mixtures compared with undiluted product (P = .002). Confirmed hyperdiluted CaHA-CMC-associated ischemic injuries represented only 3% of published reports, with a predominantly self-limited clinical course. CONCLUSIONS: Embolized CaHA-CMC gels produce polydisperse particle mixtures with a preponderance of microparticles. Hyperdilution profoundly reduced the proximally occlusive potential of the product.