The Vortex shunt: Short-term feasibility studies in the fetal lamb model of lower urinary tract obstruction and pleural effusion.

Background: The suboptimal shunt design of the currently available vesico-amniotic and thoraco-amniotic shunts is likely at tributed to the risk of shunt failure, either by displacement, kinking, or obstruction, resulting in treatment failure and the need for additional fetal intervention.

Objective: To evaluate the feasibility of ultrasound-guided insertion, drainage, and short-term dislodgement risks of the novel Vortex shunt in fetal lambs with surgically induced lower urinary tract obstruction (LUTO) and pleural effusion.

Study Design: LUTO was surgically created in eight fetal lambs at a median of 71 days (range 69-72; term = 145) gestation. LUTO phenotype developed in 5, of which four survived to shunt insertion at a median of 98 days (range 97-99). The three lambs that did not develop the LUTO phenotype and the one intrauterine fetal demise underwent pleural effusion creation. In the shunted LUTO fetuses 24 h post-deployment, the location and patency of the shunt were evaluated on fetal ultrasound and autopsy. In pleural effusion fetuses, shunt deployment was followed by immediate euthanasia and obduction.

Results: The deployment of the Vortex shunt was successful in all animals. In the LUTO group, bladder drainage was observed immediately after shunt placement, and functionality was confirmed 24 h later. Immediate drainage of the pleural effusion after shunt insertion led to the resolution of the pleural effusion. Accurate shunt positioning was verified in all fetuses through post-procedural and pre-necropsy ultrasound and during autopsy. There were no complications related to the shunt deployment. The short duration between shunt placement and autopsy limits our ability to draw definitive conclusions about the long-term effects of our shunt.

Discussion: These preclinical experiments provide proof-of-concept data on the novel fetal Vortex shunt. We demonstrated short-term safety and functionality without dislodgement after 24 h of deployment. The findings are the basis for long-term preclinical efficacy and safety studies in the LUTO fetal lamb model.

Conclusion: The novel Vortex shunt was tested for short-term safety and functionality in a preclinical fetal lamb model of lower urinary tract obstruction and pleural effusion.