Q&A: LEAP valve - introducing a new category of stent design
Med-Tech Innovation News has invited Daniel F. King of Draper to provide exclusive executive comment on the debut of the LEAP Valve. King is a senior member of the technical staff at Draper where he leads development of the Low-force Expanding/ Adaptable Paediatric (LEAP) Valve—the first heart valve that can grow with the patient.
What is the LEAP valve made from?
Draper’s LEAP paediatric heart valve is the focus of pre-clinical studies at two U.S. research institutions—Boston Children’s Hospital and Seattle Children’s Hospital. The LEAP valve used in the studies is made of a Nitinol stent and a tissue valve. The design of the stent allows for a doubling in size, regardless of its starting diameter. We are selecting small diameter tissue valves to meet the needs of the smallest patients for our first studies. The stent design, however, can be scaled and an appropriate tissue valve selected for larger sizes.
How does it expand?
The growth adaptive expandable stent, when used as part of a prosthetic heart valve device, is designed to enlarge passively as the patient grows. The LEAP valve is optimised for the haemodynamics of the child and may be small enough for use in infants born with heart defects. The expandable design gives the LEAP valve enough stored energy to continuously expand from an initial diameter to a fully expanded diameter over time.
Stents can be classified into two broad classes: self-expanding stents and balloon expandable stents. Draper is introducing a third category of stent design: a growth adaptive stent that conforms to the biological structure, such as a heart valve annulus, and expands as the tissue structure grows or changes shape. This is accomplished through the design of flexures within the stent that are optimised to exert sufficient force to expand within a patient without damaging the patient’s tissue.
Where is the LEAP valve currently available?
The LEAP valve is currently undergoing pre-clinical studies at two U.S. research institutions—Boston Children’s Hospital and Seattle Children’s Hospital. Because the device is patented, medical device manufacturers can license the design through an agreement with Draper.
Give us some insight into the MANTIS technology and the effect that can have on device manufacturing?
A major manufacturing challenge for bioprosthetics is the need to integrate two disparate materials (soft tissue and metal) into a single functioning device. MANTIS (Mechanical AdhesioN to TISsue) is an alternative attachment solution that aims to solve this problem. MANTIS is being developed to adhere to compliant, wet surfaces while also possessing both sufficient adhesive strength and flexibility to withstand dynamic environments within the heart and device expansion. For use with the LEAP valve MANTIS will be manufactured from biocompatible but non-biodegradable materials. For other indications where degradation would be beneficial, the same MANTIS manufacturing techniques could be applied to biodegradable materials.
MANTIS can save the labour-intensive work of suturing by hand because it achieves valve-stent integration through a mechanical tissue adhesion method that can be more automated. MANTIS will adhere rapidly, be compliant yet strong enough to withstand dynamic conditions within the body and be deployable in wet environments such as internal organs and wounds.
What kind of devices can it be used for?
MANTIS could be used as an adhesive medical device coating for securing catheters, nasogastric tubes, endotracheal tubes, and chest tubes during en route care. Beyond medical intervention, MANTIS could enable new capabilities in wearable device deployment and human-technology interfaces.