Efficacy of hyaluronidase in treating calcium hydroxylapatite-induced arterial occlusion: an experimental study using the leporine auricular artery as a model.

INTRODUCTION: Hyaluronidase "melts" hyaluronic acid (HA); no such antidote exists for calcium hydroxylapatite (CaHA). Experimental evidence demonstrating efficacy of hyaluronidase in treating arterial compromise due to CaHA is lacking. Nevertheless, its use is mentioned in papers describing the management of vascular occlusion due to CaHA. Objectives & hypotheses. To investigate the efficacy of hyaluronidase as a treatment for CaHA-induced arterial occlusion using the leporine auricular artery as a model. STUDY DESIGN: A prospective case control series. METHODS: Six Oryctolagi cuniculi were divided into two groups of three, Groups 1 and 2. Right auricular blood flow was examined by Doppler in all six. In all six, the right auricular artery was then occluded by injection of CaHA. Occlusion was confirmed by Doppler. On Day 0, Group 1 received injection of hyaluronidase, Group 2 did not. In each group, one occluded ear was biopsied on Day 1 and another on Day 4. On Day 7, the third occluded ear in each group was examined by Doppler and then biopsied. RESULTS: Doppler demonstrated that, without hyaluronidase blood flow rate at Day 7 was only 10% of the pre-occlusion flow rate, whereas with hyaluronidase blood flow rate at Day 7 was considerably recovered at 58% of the pre-occlusion rate. Histology revealed a similar story: without hyaluronidase at Day 7 the arterial wall anatomy was largely destroyed, whereas with hyaluronidase the arterial wall anatomy was largely conserved. CONCLUSIONS: Hyaluronidase improves tissue viability after arterial occlusion by CaHA. This finding has important implications for patient care.