We want to go deeper into the human body, using incisions that are smaller or even non existent. For this purpose we need small flexible tools that are able to deliver sufficient forces without buckling.
In an effort to facilitate high force delivery in a small flexible medical instrument, the pulze catheter prototype (2 mm) has been developed. Buckling is prevented by using a dynamic loading method, in which a high-speed indenter collides with the non-moving target. The flexible prototype consists of a distal spring-loaded indenter, which is manually actuated using a compliant (re)load mechanism, allowing for loading, locking, and (re)loading of the prototype while inserted in the body.
We are currently testing this catheter ex-vivo. Further development of this crossing prototype may in time allow for performing surgery deep inside the body.
In nature multiple animals have developed intriguing shooting mechanisms for food capture, defence, and reproductive reasons. Think for example on the amazing tongue shooting capability of the chameleon and the appendage strike of the mantis shrimp.
These shooting mechanisms can offer inspiration for new ideas on the technological development of fast acceleration mechanisms in medicine. High-speed shooting mechanisms can, for example, be used for the endovascular treatment of Chronic Total occlusions (CTOs). CTOs are heavily calcified and are thus difficult to puncture and cross with the small (0.36 mm) guidewire. The required force to puncture the CTO is often higher than the buckling force of the guidewire due to the low bending stiffness (EI) and long (unsupported) length (L). As a result, the guidewire often buckles. Buckling in turn causes procedural failure since the CTO cannot be crossed. Buckling of the crossing tool may be prevented by using a high-speed crossing tools as this increases the buckling resistance of the guidewire and potentially minimizes the puncture force of the CTO.
With this in mind an innovative high-speed crossing tool was developed using nature’s shooting mechanisms as inspiration. The crossing tool (OD 2 mm) incorporates an innovative spring-driven indenter and decoupling mechanism for high-speed puncturing of the proximal cap. First tests have been very promising. The prototype hit the CTO with an average speed of 3.4 m/s and was able to deliver a maximum force of 20 N (without buckling), which is well over the required 1.5 N to puncture the CTO. Additionally, the device was tested on CTO models made out of calcium and gelatine of different consistency. Puncture was achieved with on average 2.5 strikes for heavily calcified (77 wt% calcium) CTO models.
We feel that with continued development of this technique it will become possible to deliver high forces in ultra thin devices, such as guidewires, and as such increase the success rate of the the endovascular treatment of CTOs and other minimal invasive applications.
Cushing’s disease is a naturally occurring progressive pituitary disorder that can be found in multiple species, including dogs, donkeys, horses, and humans. In horses, treatment of Cushing’s disease is aimed at controlling and reducing the severity of the clinical signs using oral medication, rather than removing the tumor from the pituitary gland (which is often performed in humans), due to the fact that to date surgical removal has been technically impossible. Therefore, a new paradigm in pituitary surgery in horses was developed in close collaboration with expert veterinarian Johannes van der Kolk of the Faculty of Veterinary Medicine of the University Utrecht. In contrast to the human vascular system, multiple superficial veins in the horse, like the facial vein, can provide direct access to the pituitary gland. This superficial vein was used to guide an innovative flexible morcellator towards the pituitary gland. Once arrived at the pituitary gland, this morcellator uses a flexible drive cable to actuate a rotating cutting blade at the tip of the instrument to resect and subsequently remove the pituitary tumors. First cadaver experiments have proven successful in inserting this instrument and removing pieces of pituitary tumor. Further research needs to be done before clinical application of the instrument can take place. Nevertheless, continued development of this approach may in time improve the quality of life of horses suffering from Cushing’s disease.
Sakes A., Arkenbout E.A., Kolk J.H. van der, Breedveld P. (2014). Design of an endovascular morcellator for the surgical treatment of Cushing’s disease in horses. Proc. 26th International Conference of Society for Medical innovation and Technology (SMIT), Sept. 18-20, Shanghai, China, p 90.
Sakes A., Arkenbout E.A., Kolk J.H. van der, Breedveld P. (2013). A comprehensive overview of removal methods for the surgical treatment of Cushing’s disease for human and veterinary applications. Proc. 2013 ASME Design of Medical Devices Conference, April 8-11, Minneapolis, MN, USA, 2 p.
Current minimally invasive laparoscopic tissue harvesting techniques for pathological purposes involve taking multiple imprecise and inaccurate biopsies, usually using a laparoscopic forceps or other assistive devices. Potential hazards, e.g. cancer spread when dealing with tumorous tissue, call for a more reliable alternative in the form of a single laparoscopic instrument capable of repeatedly taking a precise biopsy at a desired location. Therefore, the aim of this project was to design a disposable laparoscopic instrument tip, incorporating a centrally positioned glass fibre for tissue diagnostics; a cutting device for fast, accurate and reliable biopsy of a precisely defined volume and a container suitable for sample storage.
Inspired by the sea urchin’s chewing organ, Aristotle’s lantern, and its capability of rapid and simultaneous tissue incision and enclosure by axial translation, we designed a crown-shaped collapsible cutter operating on a similar basis. Based on a series of in vitro experiments indicating that tissue deformation decreases with increasing penetration speed leading to a more precise biopsy, we decided on the cutter’s forward propulsion via a spring. Apart from the embedded spring-loaded cutter, the biopsy harvester comprises a smart mechanism for cutter preloading, locking and actuation, as well as a sample container.
A real-sized biopsy harvester prototype was developed and tested in a universal tensile testing machine at TU Delft. In terms of mechanical functionality, the preloading, locking and actuation mechanism as well as the cutter’s rapid incising and collapsing capabilities proved to work successfully in vitro. Further division of the tip into a permanent and a disposable segment will enable taking of multiple biopsies, mutually separated in individual containers. We believe the envisioned laparoscopic opto-mechanical biopsy device will be a solution ameliorating time demanding, inaccurate and potentially unsafe laparoscopic biopsy procedures.
Jelinek F., Breedveld P. (2013). Bio-inspired spring-loaded biopsy harvester. Proc. 2013 ASME Design of Medical Devices Conference, April 8-11, Minneapolis, MN, USA, 2 p.
Jelinek F., Goderie J., Rixel A. van, Stam D., Zenhorst J., Breedveld P. (2013). Crown cutter – the impact of tooth quantity and bevel type on tissue deformation and penetration forces. Proc. ASME Design of Medical Devices Conference – Europe Edition 2013, Oct. 7-9, TU Aula Conference Centre Delft, Delft, the Netherlands, 1 p.
Jelinek F., Goderie J., Rixel A. van, Stam D., Zenhorst J., Breedveld P. (2013). Crown cutter – the impact of tooth quantity and bevel type on tissue deformation and penetration forces. Proc. 25th International Conference of Society for Medical innovation and Technology (SMIT), Sept. 5-7, Baden-Baden, Germany, 1 p.
Jelinek F., Breedveld P. (2013). Bio-inspired spring-loaded biopsy harvester. Proc. 21th International Congress of the European Association for Endoscopic Surgery (EAES) – “Amazing Technologies” session, June 19-22, Vienna, Austria, 1 p.
Jelinek F., Breedveld P. (2013). Bio-inspired spring-loaded biopsy harvester. Abstr. 4rd Dutch Bio-Medical Engineering Conference, Jan. 24-25, Egmond aan Zee, the Netherlands, 1 p.