Stylet-type stent device with a new multiple activation mechanism

Technical field

This invention refers to an innovative stent device with a mechanism for multiple activation by an inner stylet, which can be used for maintaining the patency of the rhinopharyngeal cavity, vessels, biliary duct as well as other hollow viscera (e.g. trachea, bronchi, gastroenteric system, urinary system, etc.)

Background

Stent devices are widely used for maintaining the patency of the rhinopharyngeal cavity, vessels, biliary duct and other hollow viscera.

One of the numerous applications of stent devices is maintaining the patency of the rhinopharyngeal cavity as symptomatic treatment of the Obstructive Sleep Apnea Syndrome (OSA).

The Obstructive Sleep Apnea Syndrome (OSA) affects males and females with an incidence of 3-7% and 2-5%, respectively (Punjabi 2008). The main causes of OSA is obesity, craniofacial injuries, decreased pharyngeal muscle tone, neurological syndromes, stress syndrome and aging. Clinical manifestations of OSA are snoring, hypertension, hypoxemia, myocardial ischemia and sleep deprivation, which in turn cause fatigue and stress. For these reasons OSA has been classified as a major causative factor of traffic accidents and its treatment is proposed as a crucial preventive measure (Tergearet. Al 2009).

OSA is caused by obstruction of the rhinopharyngeal airway during sleep, due to a set back of the tongue, anatomical abnormalities of the pharynx, obesity or local decreased muscle tone.

The current therapeutic approach of OSA restricts the consumption of sedatives, tranquillizers and alcohol, and encourages the use of oral devices for rectifying and retaining the tongue, as well as small respirators that cause continuous positive end-expiratory pressure. (Continuous Positive Airway Pressure, CPAP). However, neither the above approaches nor any related surgery have been proven sufficient for solving the problem so far, and the therapeutic challenge of OSA remains a hot spot of research. The stent device described by the current invention applied in the rhinopharyngeal cavity, is an alternative treatment for the Obstructive Sleep Apnea Syndrome (OSA). The main benefit compared to existing devices are:

• its simple repetitive application by the patient himself, • the "drawer slide release" mechanism, and

• the film-coating option by a biocompatible membrane.

Another wide medical field of stent device application is the treatment of stenosis or occlusions in vessels, ducts i.e. biliary or other hollow cavities . In such cases, the construction of a stent device according to the invention outweighs the known stent devices because of the possibility of repetitive activation through the drawer slide release mechanism of the inner stylet. It provides the huge benefit of reversible activation and inactivation of the stent device by the interventional physician, thus allowing for maximal safety and accuracy during the positioning process of stent devices.

One of the most challenging applications of stent devices is the multi-branched stenting of Y-shaped, T-shaped or tripod-shaped vessels. Existing devices for T- or Y-stenting require precise manipulation and complicated design of the interventional approach by highly specialized personnel: The interventionist needs to assemble in situ (at the point of intervention) linear stent pieces in a row in order to build-up the necessary branch. By using the proposed drawer-slide release mechanism, according to the invention, the construction of a ready-to-use stent device with the appropriate branches and shape is possible for each case. Moreover, this design allows for coating the ready-to- use branched stent devices with a biocompatible film . And, last but not least, the drawer slide release mechanism according to the invention can be combined with the existing pusher-mechanism, which significantly facilitates the positioning of a branched stent device

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described hereinafter by the attached drawings wherein:

Figure 1 shows a longitudinal sectional view of the stent device, where the following can be seen:

a stent device with a mesh structure (1)

an atraumatic film coating (2)

an inner activation stylet (3)

an outer stylet handle for easy activation (4)

an outer end of constant diameter (5),

Figure 2.1 shows a cross sectional view of a stent device before activation. The stylet (3) occupies the center of the figure, the mesh structure of the stent device (1) surrounds the stylet and there is the atraumatic film coating (2) on the outside, Figure 2.2 shows a cross sectional view of the stent device after activation and after removing the activation stylet, where the following can be seen:

a stent device with a mesh structure (1) and

an atraumatic film coating (2),

Figure 3.1 shows a cross sectional view of the stent device with the drawer slide release mechanism before activation. The three trails of the double-sided female configuration are engaged to the corresponding male protrusions on the inner surface of the mesh structure, and the stent device remains closed. There can be seen:

a stent device with a mesh structure (1)

an inner activation stylet (3)

a double sided trail with a longitudinal groove on each side (7) fixed protrusions on the inner surface of the stent device lumen (8),

Figure 3.2 shows a cross sectional view of the stent device with the drawer slide release mechanism after activation. The inner stylet has been removed and the three double sided trails with a female configuration are disengaged from the male configuration of the stylet, which results in the unfolding of the stent device. There can be seen:

a stent device with a mesh structure (1)

an inner activation stylet (3)

a double sided trail with a longitudinal groove on each side (7) fixed protrusions on the inner surface of the stent device lumen (8),

Figure 4 shows a longitudinal sectional view of the stent device at the time of the progressive removal of the inner stylet (along the direction of the arrow). The stylet gradually releases the respective trails and the stent device begins to unfold to the maximum of the predetermined diameter. There can be seen: a stent device with a mesh structure (1)

an atraumatic film coating (2)

an inner activation stylet (3)

a double sided trail with a longitudinal groove on each side (7), Figure 5.1 shows the bow shape of the stent device. There can be seen:

outer end of constant diameter (about 15 mm) (5),

Figure 5.2 shows the mesh structure of the stent device (1), Figure 6.1 shows the longitudinal sectional view of a stent-type endotracheal tube with inner activation stylet. (3)

Figure 6.2 shows a longitudinal sectional view of a stent-type endotracheal tube positioned in the trachea, fully unfolded at its end, after the removal of the inner activation stylet. The sealing of the trachea is achieved by the unfolding the stent-type end of the tube. There can be seen:

1. A mesh structure (1)

Description of the invention

The stent device according to the invention is characterized by a drawer slide release activation mechanism.

The drawer slide release mechanism consists of two or more longitudinal trails (see Figure 3.1). Each trail has on both sides a longitudinal groove-guide of a semi-circular or triangular cross section (double sided female trail) and is engaged to

a) the mesh structure of the stent device along the longitudinal axis thereof through appropriate, equidistanced protrusions (8) along a straight line which is parallel to the central axis of the stent device; these protrusions are placed on the inner surface of the lumen of the mesh structure, and are matching in shape the groove-guide of the trail (7). (Figure 3.1)

b) the inner stylet of the stent device through the appropriate longitudinal protrusion on the outer surface thereof, which matches in shape the groove-guide of the trail.

Each longitudinal trail is fixed by welding or by other suitable means to the mesh structure of the stent device at only one point at the front end of the stent device.

Thus, an engagement of the stylet (which has a male configuration on its outer surface) to the mesh structure of the stent device (which also has a male configuration on its inner surface), through the trail with double sided female configuration, is provided.

The one-spot fixed attachment of each trail to the mesh structure of the stent device ensures the possibility of the repetitive unfolding and folding of the stent device. This precludes a stent device blockage because of the increasing of its length during folding, or decreasing of its length during unfolding. The possibility of gliding of the mesh structure relatively to the double sided trail and consequently relatively to the stylet is always provided. If the stent device is ready-to-use, the outer surface (male configuration) of the inner stylet of the device engages to the corresponding groove-guides of the trail (See Figure 3.1). The stent remains folded. Removing the stylet releases progressively the female grooves from the corresponding male surfaces and the stent device is activated and unfolds (See Figure 3.2 and 4).

This mechanism enables the refolding of the device by moving the stylet to the opposite direction. This is a very important feature for vessel, biliary duct or other hollow viscera stent devices for it enables replacing. This is novel because all existing stent devices can be activated One-way' and none of them supports a reversible activation, therein flexibility, safety and cost reduction during positioning.

Another application of the aforementioned mechanism is an endotracheal tube or a tracheostomy tube without an air chamber (cuff) for sealing the trachea. In this case, the necessary sealing of the trachea is achieved by adjusting the stent device to the end of the endotracheal tube. This stent device must be covered by an atraumatic material (e.g. silicone) and must be equipped with a drawer slide release mechanism. (Figure 6.1 and 6.2)

Another application of the aforementioned mechanism is a Y-shaped, T- shaped stent or a multi-branch stent (e.g. a tripod). The new drawer slide release mechanism combined with the existing pusher-type catheter provides critical advantages, i.e. easy insertion of the stent device and the possibility of assembling ready-to-use stent devices with the appropriate branching.

In this case, the main body of the stent device unfolds according to the existing pusher-type mechanism, while the other branches unfold through the new drawer slide release mechanism (the drawer slide release mechanisms of the branches pass through the main body and end up each in a separate branch).

Conclusion: the new drawer slide release mechanism:

• enables the refolding or re-unfolding of the device to provide a multi-use device (e.g. a rhinopharyngeal stent device)

· can be applied to the stent devices for the vessels, the biliary duct and vessels or other hollow viscera, optimizing the accuracy of the stent placement

• can be applied to the endotracheal tube or the tracheostomy tube, sealing the trachea without an air sealing chamber ( cuff )

· in combination with the existing pusher-type catheter provides critical advantages in the construction of Y-shaped, T-shaped or multi- branched stent devices. The main advantage is that the activation is achieved by an inner stylet and a drawer slide release mechanism, which allows an easy, safe and repetitive refolding (reloading). The activation of the currently existing stent devices is achieved by a pusher with an equal diameter or by an expanding air chamber. In both these cases, the user doesn't have the opportunity to correct the placement as is the case with the new drawer slide release mechanism

Description of a preferred embodiment according to the invention

An innovative OSA therapeutic approach implementing the stent device according to the invention proposes a rhinopharyngeal airway stent (RAS) with an inner activation stylet. More specifically, this device comprises:

• a stent-type tube with the mesh structure, which is bow-shaped and has a varying diameter after activation

• an inner activation stylet of the stent device, which operates with a drawer slide release mechanism

• an outer coating made of a material with a special molecular structure with the following characteristics: mucosa adherency, water permeability, atraumatic consistency, impregnability with drugs or fragrances and flexibility enough to follow the perimeter changes during RAS-unfolding. The outer film coating is replaceable in order to have a multi-use RAS

• a sufficiently thin tip (2-3 mm), which allows for user self-insertion through the nostril into the rhinopharyngeal cavity . After insertion and activation, the RAS unfolds to a predetermined diameter (e.g. 7, 8 or 9 mm), ensuring the patency of the upper airway.

• The other end of the RAS, which remains outside the nostril, has a stable structure with a larger diameter (15mm), so that it cannot pass through the nostril into the rhinopharyngeal or be ingested. It is also possible to connect the outer end of the RAS with appliances for monitoring of parameters (e.g., temperature, pressure, partial gas pressure, etc.), or with appliances for additional wetting. (Fig. 1 no. 5)

It is obvious to one skilled in the art that the drawer slide release mechanism can be formed in a way that: the stylet presents a male or female (protrusion or groove) configuration on the its outer surface, respectively the trail presents a female or male configuration on its inner surface and a female or male configuration on its outer surface and respectively the mesh presents a male or female configuration on its inner surface.

The scope of the invention is defined by the following claims only and is not limited by the aforementioned exemplary embodiments.