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Objective:
To assess effects of acute aortic lengthening on vessel integrity in a novel model of tissue expander stimulated lengthening of arteries (TESLA).
Design:
Animal Model
Setting:
Freestanding children’s hospital
Patients:
None
Interventions:
Adult Sprague-Dawley rats underwent retroaortic tissue expander placement and inflation. An equivalent strip of expander material was placed in sham controls. Marking sutures were placed at and approximately 2cm proximal to the aortic bifurcation; segment length was measured before and after placement of the retroaortic material. After 48 hours, the segment was measured in vivo and after specimen removal. Tension across all samples was standardized by hanging a 7g weight from each specimen. Histology was evaluated using hematoxylin and eosin and Elastin-van Gieson. Wall thickness was measured at four points along the sections using Adobe Photoshop Software. Data were compared using ANOVA with post-hoc comparisons (two-tailed p<0.05 considered significant).
Main Outcome Measures:
Aortic length
Results:
Six experimental rats were compared with three sham animals. Weight ratio (weight at sacrifice/weight at initial surgery) was not significantly different between groups (0.99±0.03vs1.01±0.01;p=0.28). The weighted aortic length in the experimental group was significantly different from that of sham animals (2.3cm ±0.11vs1.97cm ± 0.12;p=0.02) and the length ratio (weighted measurement/initial measurement) was significantly different between groups (1.17±0.06vs1.0±0.05;p=0.007). Analysis of variance indicated no significant differences in the amount of wall thickness (mm) between groups (p=0.123). There were no signs of vessel injury in either group.
Conclusions:
Using a novel animal model for aortic stretch, we have demonstrated a 17% increase in length in a 48-hour period without evidence of vessel injury. Future studies will include a chronic stretch model as well as assessment for vascular growth and function.