Search

Fallopian tube occlusions represent one of the most common causes of female sterility. As an innovative treatment approach for affected persons, we previously presented the concept of a novel polymeric, self-expanding, and bioresorbable microstent. As a basis for microstent development, knowledge of the mechanical properties of the anatomical target structure represents a crucial requirement. The current work describes a methodological approach for the experimental determination of radial Fallopian tube compliance using optical coherence tomography. It could be shown that a quantitative assessment of the mechanical properties of porcine Fallopian tube samples - as a whole anatomical structure including the Tunica mucosa, the Tunica muscularis, and the Tunica serosa - is possible, using the described test setup. Future investigations on human samples will allow for valuable information regarding the structural-mechanical properties of the Fallopian tube. Therefore, the current work offers perspectives for the development of a novel gynecological microstent for the treatment of Fallopian tube occlusions.

An unfulfilled pregnancy is often due to impaired patency of the female Fallopian tubes. To circumvent tubal obstruction, cost-intensive in vitro fertilisation (IVF) is currently indicated. The only therapeutic treatment concepts available are transvaginal tubal lavage/catheterization or laparoscopy with minimally invasive or complex surgical tubal reconstruction, which are associated with side effects. The development of new and cost-effective non- or minimally invasive therapeutic concepts that can restore the patency of the Fallopian tubes would be key in the treatment of female infertility and can fulfil the desire to have children. Therefore, in the present work, ex vivo anatomical studies are carried out on various laboratory mammals (pigs, rabbits, guinea pigs). Using these animal models, it was also evaluated whether a sensor-ureterorenoscope can be inserted through the whole female reproductive tract to the Fallopian tubes. This device will be used for endoscopically guided implantation of a novel tubal microstent prototype via its tailor-made delivery system into the isthmus region of the Fallopian tubes in upcoming studies. This work serves to identify an optimal species for a longitudinal animal study, in which the feasibility as well as the tissue reaction to the implant will be evaluated.

Female sterility is caused by Fallopian tube occlusions in one of three cases. Current treatment methods achieve unsatisfying pregnancy rates and are associated with high costs or significant psychological and physiological stress. Our previously described microstent technology opens up new therapeutic possibilities to restore the lumen of the Fallopian tube without surgery. In this work, a Finite Element Analysis model of a physiologically relevant loading of the device is presented. Therefore, microstent radial force was analysed as a function of the device diameter up to a minimum diameter of 1.4 mm, which was found after microstent implantation ex vivo. A bilinear constitutive material model considering isotropic hardening was used for modeling of the microstent. The Finite Element Analysis results were validated using corresponding results of experimental investigations. In this context, a maximum deviation of 15% between experimental radial force and the corresopnding simulation results (1.33 N vs. 1.13 N) was found. Maximum von Mises stresses of approximately 88 MPa were determined. A good agreement between simulation and experiments was found. Therefore, future simulations will be carried out as a basis for microstent design optimisation.

Involuntary female infertility represents a sensitive issue, which is frequently caused by an impaired patency of the Fallopian tube. Current treatment options, such as in vitro fertilisation (IVF) or tubal reconstruction, are related to high costs or surgical risks. Therefore, a need for an alternative highly safe and effective minimally invasive therapy option is assumed. The current work presents a proof-of-concept for a novel microstent in combination with a delivery system for treatment of proximal Fallopian tube occlusions. For this purpose, a microstent prototype was implanted into a porcine Fallopian tube ex vivo using the presented delivery system. The results of the procedure were analyzed using a micro-computed tomography (μ-CT). Based on the μ-CT imaging, critical parameters of the microstent, such as radial patency, were assessed. The microstent implantation leads to an increased opening area of the Fallopian tube. Additionally, the microstent does not impair the anatomical shape of the tube epithelium and adapts well to the anatomical path. In further studies, the functionality of the Fallopian tube will be examined after microstent implantation in vivo.

Obstructions of the Fallopian tube represent one of the most common reasons for an unfulfilled desire to have children. Microstent technology opens up new therapeutic possibilities to restore the natural lumen of the Fallopian tube within a single treatment. Within the current work we developed a self-expandable biodegradable microstent for gynecological applications. Based on a novel microstent design, prototypes were manufactured from poly-L-lactide tubing by means of fs-laser cutting. Microstent prototypes were characterized morphologically by means of scanning electron microscopy and biaxial laser scanning. As manufactured, a microstents outside diameter of about 2.3 mm and a strut thickness / width of about 114 μm / 103 μm was measured. Mechanical characterization of microstents included bending as well as crimping and release behavior. After crimping to a minimum diameter of 0.8 mm and consecutive release, a microstent recovery to a diameter of 1.8 mm was found. Therefore, proof-of-concept for the self-expandable microstent could be successfully provided.

The expansion capacity and accessibility of the side branch is essential for the stenting of complex bifurcations. Since previous measurement methods only provide limited information based on geometrical data of stent cells, a new measurement approach was developed which considers the mechanical deformation capacity of the stent design. This approach provides essential information on the stent with regard to the application of bifurcation stenting. Four different commercially available coronary stents (nominal diameter 3.0 mm) were dilated and a central strut cell was over-expanded by means balloon catheters of increasing nominal diameter (2.0 to 5.0 mm). After balloon inflation, the remaining cell size was investigated for maximum cell diameter and strut fractures. Large expansion capacity without cell damage is taken as a measure of the accessibility of the side branch. In none of the expansion experiments the desired target size could be achieved, which is due to the elastic recoil of the stent cells. Deviations from the target diameter between 14-38% were determined. However, larger diameters also showed a constriction of the balloon, so that in some cases the target diameter could not be achieved at all. No strut fractures occurred even at maximum balloon diameter and pressure (5.0 mm noncompliant balloons). As a result the side branch accessibility differs depending on the individual stent designs. No particular risk for the stent was found by extensive overdilatation.