The present invention relates to a scaffold. In particular, the present invention relates to a scaffold for a tube.
Scaffolds are implanted into tubular biological structures (an artery, a vein, the hepatic duct, the cystic duct, the bile duct, the pancreatic duct, the urethra, the ureter, the oesophagus, the gastric outlet, the duodenum, the colon, the trachea, a bronchus, etc.) to keep the narrowed (“stenosed”) central channel (“lumen”) open and/or prevent leakage through the breached (perforated, ruptured, “dissected”) wall. When used for such purposes, the scaffolds are generally referred to as stents or stent-grafts.
Known stents comprise a scaffold consisting of “struts” which may be coated by polymers or other molecules. The scaffold is generally made of metals or alloys, but may also be made of polymers or composites. The polymer coating (which may comprise several layers) can be passive (i.e. only separating the struts from the biological tissues) or active (i.e. releasing or “eluting” drugs), and durable or biodegradable. Apart from imperfections or defects from the manufacturing processes, microscopic pits may also be intentionally created on the strut surface (usually on the side away from the lumen and towards the wall of the tubular biological structure - “abluminal”) to form reservoirs for drugs. The openings in the scaffold/ between the struts can be spanned by a membrane or fabric to prevent leakage from the lumen (if the tubular structure’s wall has been breached) or encroachment of the lumen from the surrounding environment.
Stents are either self-expanding or expanded with an actuation mechanism (most commonly an inflatable balloon in current clinical practice). A self-expanding stent has a preferred shape due to the intrinsic elasticity of its members and will be able to continue to withstand the constricting influences from elastic recoil of the surrounding biological tissues after deployment. A balloon-expandable stent requires the permanent deformation of some members (dedicated stress concentration points) to achieve the final deployed shape. For a balloon-expandable stent, once the balloon has been deflated, the deployed stent must withstand the constricting influences of the surrounding environment and may be “crushed” or recoil under its intrinsic elasticity to a smaller diameter. To counteract this, balloon expandable stents often need to be expanded to a larger than target diameter during deployment, but over-expansion can cause dissection/ tear in the wall of the tubular biological structure.
Unless a stent is biodegradable, its persistence in a tubular biological structure creates problems: risk of migration, risk of fracture, difficulty/ impossibility of stent retrieval post implantation, and physical bulk (which may cause obstruction to the lumen of the tubular biological structure in which it is implanted). These shortcomings spurred the development of bioabsorbable stents, but their clinical performance has not matched that of the proven metal drug-eluting stents.
Elution (sustained localised gradual release) of anti-proliferative drugs was incorporated into stent design to reduce new overgrowth of the inner lining (“neo-intimal hyperplasia”), which was the main mechanism of in-stent re-stenosis in bare metal stents used in arteries (mainly coronary arteries in clinical practice). However, drug elution creates its own problems, some of which are related to the polymer coatings applied to stent struts in order to hold the drugs.
Anti-proliferative drugs delay arterial wall healing (“endothelialisation” i.e. covering of the stent struts by the normal biological lining of the artery), which in turn can lead to late stent thrombosis (and potentially another heart attack or even death). Incomplete stent endothelialisation is more likely when stent struts are not in direct physical contact with the arterial wall (i.e. stent mal-apposition).
Anti-proliferative drugs (mainly sirolimus) can also lead to “evaginations” (i.e. outward budding of blind sacs from the artenal lumen), especially when the vessel wall is tom (“dissected”) or protrudes between the stent struts into the lumen (“prolapse”) at implantation. These blind sacs are associated with a higher risk of stent mal-apposition, incomplete endothelialisation and stent thrombosis. (Biodegradable stents will inevitably develop strut fracture as the scaffold base material gradually degrades as intended over time, and that can cause stent mal-apposition and evaginations).
Polymer coatings were incorporated into stent design primarily to enable elution. However, these polymer coatings create their own problems. The polymer coatings on stent struts can crack/ fracture, delaminate and form webs and ridges during either manufacture or stent deployment (especially likely if the blood vessel wall is highly calcified). These surface defects cause uneven drug distribution on the stent surface: excessive drug elution may delay endothelialisation: inadequate drug elution may result in neo-intimal hyperplasia. Furthermore, fragments of the polymer coatings can break off as “micro-plastics” and shed into the lumen of the tubular biological structure. If the tubular biological structure is a blood vessel, the polymer fragments are “micro-emboli” that will be washed downstream by blood flow until they are wedged into capillaries too small to allow their passage, effectively blocking them off from the circulation. Micro-embolism of these polymer fragments, together with biological debris released from disruption of atherosclerotic plaques during stretching of the artery, may cause (wholly or partly) the “no-reflow” phenomenon (i.e. no distal blood flow into a previously patent distal artery segment after the patency of the previously narrowed/ occluded proximal segment has been restored by stenting).
The polymers in the coatings, whether they are durable or biodegradable, can induce inflammatory cell and platelet aggregation, which in tum can cause stent thrombosis (blood clotting) and re-stenosis, especially if the surface of the polymer coating has defects.
Stent thrombosis may occur early (0 hours to 30 days post implantation), late (> 30 days to 1-year post implantation) and very late (> 1 year post implantation). Stent thrombosis can acutely occlude a blood vessel, depriving the organ supplied by it of oxygen and other vital nutrients (“ischaemia”). Ischaemia, if prolonged, may lead to irrevocable damage or even death of the entire organ. Thrombosis of a stent in the coronary arteries supplying the heart is associated with a 50 - 70% chance of a heart attack and a 20 - 40 % of sudden death. Stent thrombosis can occur with both bare metal and drug-eluting stents.
The ends of a tubular biological object (the “ostia”) may be slanted with respect to its longitudinal axis if it branches off another tubular biological object or cavity. If an ostium of the tubular object is narrowed and a cylindrical stent is placed inside it, the end of the stent cannot be flush with the ostium: either part of the wall of the tubular object is not covered/ protected by the stent, or a short length of the stent protrudes beyond the ostium (potentially causing obstruction, trapping of luminal contents or inducing thrombosis).
For the coronary arteries, “bifurcation” stenosis involving both the main vessel and a side branch are frequently encountered in clinical practice. Many technologies and techniques have been specifically developed to tackle bifurcation lesions, but they still leave either incomplete vessel wall coverage (“provisional T stenting”) or redundant stent materials protruding beyond the side branch ostium into the lumen of the main vessel (“T stenting and small protrusion” or TAP. “culotte”, mini-crush).
Infection is yet a further problem in known stents. Stents, covered stents and stent-grafts are foreign bodies inside the human or animal body and can be become colonised by bacteria. Once infection has taken hold, biofilms form and bacterial infection becomes very difficult if not impossible to eradicate, Infection of stents, covered stents and stent-grafts can be a persistent and recurrent source of bacteria or related toxins in the blood stream (“septicaemia”), resulting in failure of the scaffold and necessitating its removal from the human or animal body. Infected stents or other biological scaffolds can be very difficult or even impossible to remove through minimally invasive surgery.
Covered stents can stop the ingress of materials or ingrowth from the wall of the tubular biological structure into the stent lumen, and also the egress of materials from the lumen of a breached tubular biological structure into its surroundings. In theory, these functionalities would give covered stents many advantages over uncovered stents, but covered stents also have some disadvantages which stop them from being more widely adopted in practice. The membrane or fabric covering a stent inevitably add rigidity and physical bulk (which can be quite substantial); the covering membrane/ fabric can also impede the deformation or relative movements of the stent struts, and; the mechanical factors make a covered stent less deformable, deliverable and capable of conforming to a tortuous anatomical course
Covered stents can stop the ingrowth from the wall of the tubular biological structure into its lumen, but this also make them more prone to migration post implantation. Flared uncovered ends may mitigate against the migration of covered stents, but the ends may be obstructed by tumour overgrowth and injure the object’s wall because they have to be oversized compared to the tubular biological object in order to achieve fixation The fabric or membrane covering a stent may be resistant to attachment by biological molecules and cells, impeding endothelialisation of the stent if it is implanted in a blood vessel and the covered stent may remain capable of inducing blood clot formation (“thrombogenic”) indefinitely as a result.
Covered stent-grafts and stents are used to treat aortic aneurysms or perforated coronary arteries, but the entrance into any side branch will also be covered. This blockage issue is generally resolved by making windows (“fenestration”) in the covering membrane/ fabric. either before implantation outside the patient’s body or during implantation inside the patient’s body. In the case of intra-procedure fenestration, an angioplasty guide wire with a relatively sharp stiff end, a needle or a powered catheter is needed to perforate the covering membrane/ fabric. The window in the covenng membrane/ fabric and the ostium of the “liberated” side branch need to be reinforced with another stent in order to prevent them from collapsing.
The use of tube scaffolds is not limited to stents in clinical medicine. Another specific area that could benefit from the use of tube scaffolds is in the implantation of electric cables (“leads”) for cardiac implantable electronic devices (pacemakers, implantable cardioverter-defibrillators; referred to as CIEDs) or neuro-stimulators. During CIED implantation, leads are typically inserted from the shoulder (“pectoral”) region of the human body. However, for anatomical reasons, deploying the lead tip at certain specific positions in the heart (e.g. the His bundle, across the inter-atrial septum, into the inter-ventricular septum) is more effectively performed from the groin (“femoral”) region, which means the connector pin of the lead needs to be transferred from the groin region outside the body, through the blood vessels and the heart in the body, and then into the shoulder region outside the body. There are currently no dedicated tools for such a lead transfer process. Doctors performing such manoeuvres (e.g., the Jurdham technique) have had to improvise and modify available medical products to fashion their own tools.
It is an object of the present invention to mitigate or obviate the above-mentioned problems regarding scaffolds for tubes. In particular, it is an object of the present invention to mitigate or obviate the problems associated with: stent deployment; stent retrieval; drug eluting stents; stent thrombosis; ostial coverage even if the ostium is slanted; stent migration; infection of stents; covered stents (rigidity and physical bulk, stent migration, stent non-endothelialisation, and side branch access); the femoral pull through technique for CIED implantation, and; the manufacture and deployment of a flexible tubular-shaped electric battery.
According to an aspect of the invention there is provided a scaffold for a tube, the scaffold comprising a membrane and a pair of splines integrally formed with or embedded in the membrane, the splines being spaced apart from one another with the membrane spanning therebetween, the membrane further comprising a pair of grooves disposed between the splines adapted to receive the splines when the membrane is folded over on itself, wherein one groove is engaged with one spline and the other groove engages with the other spline.
It should be noted that “scaffold” and “stent” may be used interchangeably.
Preferably, the scaffold has a flattened configuration and a rolled configuration.
Preferably, the scaffold is transformable between the flattened and rolled configurations.
Ideally, the scaffold can be reversibly, repeatedly and freely transformed between the flattened and rolled configurations.
Ideally, in the rolled configuration the splines are engaged with the grooves. Advantageously, when the splines are engaged with the grooves the scaffold forms a closed tube with open ends or a truncated cone with open ends, and is capable of providing support to another tube, including tubular biological structures.
Preferably, in the rolled configuration the splines and grooves are helical in shape.
Ideally, the grooves are parallel with one another or diverging/converging from one another, and they are straight or curved.
Preferably, the grooves do not overlap one another and are discrete from one another.
In one embodiment, the scaffold is substantially cylindrical in the rolled configuration.
In another embodiment, the scaffold is substantially conical in the rolled configuration.
Ideally, in the rolled configuration, the grooves and splines are overlapping spiral helices.
Ideally, the cone has a narrow diameter end near the apex and a wide diameter end at the base.
Preferably, the grooves and splines diverge from one another in a direction from the narrow diameter end towards the wide diameter end.
Ideally, the amount of membrane between the splines and grooves increases in a direction from the narrow diameter end towards the wide diameter end.
Ideally, in the rolled configuration, the cone is truncated.
Preferably, the cone has a circular base
Ideally, in the rolled configuration, the splines and grooves form intertwining spiral helices with a transverse diameter that decreases in a direction from the base of the cone to the apex.
Ideally, the scaffold forms a right circular cone when in the rolled configuration.
Preferably, the scaffold is configurable as a helix formation.
By “helix formation”, we mean the splines and grooves are substantially helical in shape.
Ideally, the scaffold is telescopic in the rolled configuration such that it can longitudinally expand or retract.
Preferably, the diameter of the scaffold in the rolled configuration is operably adjustable.
Ideally, longitudinally extending the scaffold in the rolled configuration reduces its diameter.
Preferably, the scaffold is configurable as a telescopic cylindrical or conical helix formation.
Ideally, the scaffold is configurable as a telescopic cylindrical or conical helix formation by rolling up a flat scaffold membrane patch.
Ideally, the scaffold self assembles into the rolled configuration.
Preferably, the splines and/or the receiving grooves are formed of shape memory materials that will assume a pre-set spiral shape at predetermined temperature such that the scaffold self assembles into the rolled configuration at a predetermined temperature.
Preferably, the splines and/or the receiving grooves are formed of either shape memory materials that will assume a pre-set helical or conical spiral shape (spontaneously or in response to actuation), or malleable materials that will retain the shape after non-elastic deformation.
Ideally, the receiving grooves match substantially half of the profile of the splines.
Ideally, the longitudinal orientation of the grooves are opposing so that one groove extends out of the membrane on one side of the membrane and the other groove extends out of the membrane on the other side of the membrane.
Preferably, the cross sections of the splines are circular, elliptical, rectangular, triangular or any other regular or irregular geometric shapes.
Preferably, the pair of splines are principal splines and the scaffold comprises one or more auxiliary splines.
Ideally, the auxiliary spline or splines are disposed proximal to one or both longitudinal ends of the scaffold.
Preferably, the auxiliary spline or splines are made of materials having shape memory.
Ideally, the auxiliary spline or splines extend fully or partially between the principal splines
Ideally, the scaffold comprises one or more handles to facilitate deployment and retrieval of the scaffold.
In one embodiment, the one or more handles are formed from auxiliary splines.
Ideally, the one or more handles are formed from a material having shape memory such as nitinol.
ideally. the one or more handles may be deformed and are configured to return to a pre-set shape upon being heated to a predetermined temperature.
Preferably, the one or more handles may be positioned such that entry into the central hollow of the scaffold in the rolled configuration by a retrieval tool. such as an inflatable balloon, is not prevented.
ideally, the one or more handles may be folded away from the longitudinal axis of the scaffold in the rolled configuration
Preferably, upon reaching a pre-set temperature, the one or more handles fold towards the longitudinal axis of the scaffold in the rolled configuration. Advantageously, this narrows a part of the scaffold lumen. In use, a balloon may be inserted into the scaffold and inflated with a liquid that warms the one or more handles to the pre-set temperature, causing the one or more handles to fold towards the central axis of the lumen. The balloon may then be partially deflated and pulled, the handle now creating a blockage to movement of the balloon through the scaffold and enabling retrieval of the scaffold.
In one embodiment, the scaffold has internal handles that do not protrude outside the scaffold membrane. splines and grooves.
In another embodiment, the scaffold has external handles that protrude outside the scaffold membrane, splines and grooves.
In yet another embodiment, the scaffold has both internal and external handles.
In some embodiments, the handles may be detachable.
In one embodiment, the handle is anchorable to a surface, e.g., via sutures or the like.
Ideally, the handle comprises an aperture to receive an anchoring means such as a suture. Advantageously, the scaffold can be applied to a structure such as a lead, and the handle used to anchor the lead to a surface, such as biological tissues.
Ideally, the scaffold membrane may be impregnated with a lubricant such as perfluorocarbons.
In one embodiment, the scaffold comprises an auxiliary spline and an auxiliary groove, the auxiliary groove being positioned to receive the auxiliary spline. Advantageously, a series of such scaffolds can form a continuous surface by the auxiliary spline of one scaffold slotting into the auxiliary spline of an adjacent scaffold.
In one embodiment, wherein the splines are parallel to the grooves, the width-wise distance from the first spline to the first groove is the same width-wise distance as that from the second spline to the second groove.
In another embodiment, wherein the membrane when flattened is trapezoidal in shape and bound by curved lines rather than straight parallel lines, the angular distance from the first spline to the first groove is equal to that of the angular distance from the second spline to the second groove.
Preferably, the splines and the grooves are constructed out of a single material (e.g. a metal, an alloy, a polymer, a copolymer) or a composite of several materials (e.g. a metal alloy, a mixture of polymers, a polymer doped with inorganic compounds, a polymer reinforced with microfibrils of other materials, etc.).
In one embodiment, the scaffold membrane comprises polytetrafluoroethylene, most preferably, expanded polytetrafluoroethylene (ePTFE).
Preferably, the membrane is formed from two or more membrane layers.
Ideally, the membrane comprises two or more layers of ePTFE.
Preferably, the membrane comprises a core layer sandwiched by outer layers.
Preferably, the core layer is more rigid than one or both outer layers.
Preferably, the membrane comprises fluorinated ethylene propylene (FEP).
Ideally, the core layer is formed from fluorinated ethylene propylene (FEP).
In another embodiment, the scaffold membrane comprises a bioabsorbable polymer such as polylactic acid (PLA), poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), poly-LD-lactic acid (PDLA), polyglycolic acid (PGA), poly(lactic-co-glycolic acid) co-polymer (PGLA), polycarprolactone (PCL). poly(glycolide-co-caprolactone) co-polymer (PGCL), polydioxanone (PDX), polyorthoesters (POE), or combinations thereof.
In one embodiment, the membrane is formed entirely from a single layer of bioabsorbable polymer.
The principal and/or auxiliary spline-groove joints may be left bare or sealed with an adhesive that may be rigid (e.g. a resin) or elastic (e.g. an elastomer) when set. In this embodiment, the adhesive may be pressure activated. Additionally, or alternatively, the adhesive may comprise two components that, when mixed, begin curing. Advantageously, one component may be disposed on the splines and another on the grooves so that when they are brought into contact the adhesive is activated.
The scaffold may be engineered to release molecules into the surrounding environment and may thereby be drug-eluting. In this embodiment, the membrane can be engineered to release molecules into the surrounding environment.
In one embodiment, the scaffold is a parallelogram with acute and obtuse internal angles (i.e < 90° or > 90°, but ≠ 90° in its flattened configuration, wherein the splines form the longer edges.
Ideally, when transformed from the flattened configuration into the rolled configuration, a spline engages with a groove that is further away and not immediately adjacent. Advantageously, this engagement retains the scaffold in the rolled configuration with overlap of layers of the scaffold membrane in certain sections.
Preferably, in the rolled configuration, the scaffold forms a continuous surface of alternating single-layered, double-layered or multi-layered wall thickness.
Ideally, in the rolled configuration, the splines and grooves form helices whose turns directly stack on one another in the neutral unbent state.
Preferably, when the scaffold in the rolled configuration is bent along its longitudinal axis, the overlap between turns of the scaffold ensures a continuous surface is maintained, even if part of the splines is no longer locked in the receiving grooves.
Ideally, the longitudinal span of the scaffold in the rolled configuration can be increased or decreased.
Ideally, the splines slidably engage with the grooves so that the spline can be slid along a groove when in the rolled configuration.
Preferably, the longitudinal span of the scaffold in the rolled configuration can be increased or decreased by winding up the turns of the splines and grooves into helices of larger or smaller pitches (with corresponding smaller or larger transverse diameters).
Ideally, the scaffold in the rolled configuration may have flush ends, wherein the scaffold terminates in ends defining planes that are orthogonal to the longitudinal axis of the scaffold, or staggered, wherein the ends stagger in the direction of the longitudinal axis of the scaffold.
Alternatively, one longitudinal end may be flush, and the other end staggered.
In one embodiment, the scaffold may have a plurality of rolled configurations, wherein different rolled configurations provide different diameters.
In one embodiment, the scaffold comprises a plurality of pairs of grooves.
Ideally, in one rolled configuration, the splines are locked with one pair of grooves, whereas in another rolled configuration the splines are locked with a different pair of grooves.
Preferably, the diameter of the rolled configuration doubles, halves or alters in any ratio when transforming between the different rolled configurations.
In one embodiment, the scaffold has a first rolled configuration and a second rolled configuration. The first rolled configuration may be half the diameter of the second rolled configuration.
In one embodiment, the splines have a teardrop shaped cross-section and the grooves are correspondingly shaped to receive the splines, with the cross-section of one groove corresponding to the pointed end of the teardrop shaped spline, and the other groove being shaped to correspond to the rounded end of the teardrop shaped spline.
In one embodiment, the scaffold has a spline-groove arrangement wherein the splines project from the surface of the membrane and have spaces to either lateral side of the spline to receive the groove, which envelopes the spline at either lateral side thereof.
In one embodiment, the thickness of the membrane is variable.
Ideally, the thickness of the membrane is greater in the space between the grooves than in the space between either spline and said spline’s nearest groove.
Preferably, the thickness of the membrane is substantially or exactly doubled in the space between the grooves than in the space between either spline and said spline’s nearest groove.
Ideally, in the flattened configuration, a first planar surface of the membrane extends from the first spline to the second groove, and a second planar surface extends from the second spline to the first groove, overlapping in the space between the grooves where the membrane is doubled in thickness.
In one embodiment, the scaffold is fixable to a pin plug for connecting the scaffold to the connector pin of a lead used with a CIED or a neuro-stimulator.
Ideally, the scaffold is joinable to the base of a pin plug.
Preferably, the pin plug comprises a female connecting means for connecting to the connector pin for a lead.
Ideally, the female connecting means comprises a central cylindrical core surrounded by a cylindrical shell, with the space between the core and shell being sized to receive the connector pin of a lead.
Preferably, the central cylindrical core and the cylindrical shell or mounted on a plate Ideally, the pin plug comprises a handle configured to receive a snare or other grasping device. Preferably, the handle has a neck and a wide portion.
In one embodiment, the scaffold is adapted for use in the manufacture of batteries.
Ideally, the scaffold has a pair of receiving groves located adjacent to the splines.
Preferably, the scaffold membrane has a plurality of layers.
Preferably, the scaffold membrane comprises a current conductor strip.
Ideally, the scaffold membrane comprises a cathode.
Preferably, the current conductor strip and the cathode are sandwiched between structural layers.
Ideally, one layer on one side of the cathode and conductor strip is permeable to ions (electrolytes) and solvents whereas one layer on the other side is impermeable to ions (electrolytes) and solvents.
Ideally. the scaffold membrane comprises, in order being arranged from the exterior to interior when in the rolled configuration: one or more layers of ePTFE, a laminating layer of FEP, a thin (cathode) current conductor strip (e.g. made out of aluminium foil), a cathode (e.g. carbon monofluoride, manganese dioxide, generally mixed with other binding materials into a paste), and one of more layers of ePTFE (semi-permeable).
Advantageously, the scaffold can be wrapped around a central anode core (e.g. lithium metal) containing a central (anode) current collector which is also malleable/ flexible (e.g. a copper wire, a silver wire, an aluminium wire, a graphene string, a carbon nanotube construct).
Ideally, the spline-groove joints are sealed with an elastic but impermeable adhesive.
Advantageously, lithium is highly malleable and can be easily be shaped with grooves or indentations to accommodate the bulges of the cathode paste. The semi-permeable luminal ePTFE layers allow the passage of ions (electrolytes) and solvents and can be made to be extremely thin to minimise the internal resistance of the battery. The luminal layers can also be made to be extremely strong against tear (e.g by orienting successive layers of ePTFE so that their fibrils lie orthogonally) to prevent the cathode and the anode coming into direct physical contact (which would generate an internal short circuit of the battery and a runaway electrochemical and thermal reaction). The FEP laminating layer seals up the entire battery (except for connections for the current collectors) and prevents the leakage of its contents (mainly the solvents).
Ideally, the external layer is impregnated with a perfluorocarbon. Advantageously, this renders the entire battery resistant against tissue ingrowth, thrombosis (blood clot formation) and bacterial colonisation. Such a flexible cylindrical high energy density will be very useful for powering CIEDS (e.g. a leadless pacemaker, an implantable “string” subcutaneous defibrillator). However, the same battery will also be useful for powering other non-medical consumer electronic products.
According to a further aspect of the invention there is provided a scaffold for a tube that can be deployed inside the tube to engage with and provide support to said tube, the diameter of the scaffold being operably adjustable and the scaffold further being retrievable by operably reducing the diameter of the scaffold such that it disengages from the tube and can be removed from the tube.
Ideally, the scaffold is configured such that the diameter of the scaffold can be adjusted remotely, using one or more tools to adjust the diameter of the scaffold from a location distal to that of the scaffold.
According to a further aspect of the invention there is provided a method for retrieving a scaffold from a tube, the method comprising the step of inserting an inflatable balloon into the lumen of the scaffold and inserting a heated substance into the balloon to inflate the balloon and heat the scaffold such that the shape of the scaffold is altered by the heat thereby trapping the balloon in the scaffold, then drawing the balloon and the scaffold out of the tube.
According to a further aspect of the invention there is provided a method of extracting a lead from a human or animal body, the lead being enveloped by a scaffold having two nitinol principal splines and a nitinol auxiliary spline, the method comprising the steps of applying an electric current to the splines resulting in the splines heating and assuming their predetermined shape resulting in radial expansion of the scaffold thereby urging the surrounding tissues away from the lead, the method then comprising removing the lead by drawing it out from the scaffold.
Ideally, the method comprising the step of inserting a locking stylet or lead locking device inside the lumen of the lead to provide tensile strength and distal lead tip control.
Preferably, the method composing the step of inserting a sheath around the lead through the channel newly created within the radially expanded scaffold.
Ideally, the method comprising removing the lead with the locking stylet or lead locking device.
Preferably, the method comprising inserting a guide wire through the sheath.
Ideally, the method comprising removing the scaffold by pulling on its proximal end around the guide wire.
According to a further aspect of the invention there is provided a method for inserting a transvenous lead, the method comprising initially applying a pin plug and scaffold arrangement to a lead pin, positioning said arrangement with a ramrod dilator, applying a snare to the handle of the pin plug, and drawing the lead through a sheath via the snare.
According to a further aspect of the invention there is provided a method of applying a conical scaffold at a slanted ostium, the method comprising urging the end of the scaffold flush or near flush with the slanted ostium using an inflatable balloon.
Ideally, the method comprising the step of initially inserting the scaffold applied to a deflated balloon in a non-expanded state into the slanted ostium, using a guide wire.
Preferably, the method comprising inflating the balloon to expand the scaffold.
Ideally, the method comprising removing the balloon and inserting a second shorter balloon via a guide wire into the scaffold at the portion where the scaffold is proximal in the slanted ostium and inflating said balloon.
Preferably, the method comprising pulling the second shorter balloon over the guide wire to draw the proximal scaffold out past the slanted ostium.
Ideally, if there is a wall opposing the slanted ostium, the method comprises inserting a deflated balloon via a guide wire along the opposing wall such that it opposes the scaffold, and inflating the balloon so that it abuts the opposing wall and urges the scaffold to make it flush or near with the slanted ostium.
Alternatively, the urging balloon can be inserted in a guide catheter and inflated so that the guide catheter prevents the balloon from being displaced away from the scaffold when it contacts the scaffold, the scaffold then being urged flush with the slanted ostium.
Ideally, the method comprising removing the balloon.
According to a further aspect of the invention there is provided a method for manufacturing a battery, the method comprising the steps of providing a central anode core (e.g. lithium metal) containing a central (anode) current collector which is also malleable/ flexible (e.g. a copper wire, a silver wire, an aluminium wire, a graphene string, a carbon nanotube construct), and wrapping the central anode core with a scaffold, the scaffold comprising a current conductor strip and a cathode.
According to a further aspect of the invention there is provided a battery, the battery comprising a scaffold for a tube.
Ideally, the scaffold forms an outer layer of the battery.
It will be appreciated that optional features applicable to one aspect of the invention can be used in any combination, and in any number. Moreover, they can also be used with any of the other aspects of the invention in any combination and in any number. This includes, but is not limited to, the dependent claims from any claim being used as dependent claims for any other claim in the claims of this application.
The invention will now be described with reference to the accompanying drawings in which:
In
The receiving grooves 4a, 4b match half of the profile of the splines 3a, 3b. whose cross section is circular, but may also be elliptical, rectangular, triangular or any other regular or irregular geometnc shapes in other embodiments. The scaffold 1 is made from a rectangular strip. In another embodiment as shown in
The principal splines 3a, 3b and/ or the receiving grooves 4a, 4b are made of either shape memory materials that will assume a pre-set helical (e.g.
In the rectangular scaffold 1, the pair of receiving grooves 4a. 4b indent the membrane 2 in opposing directions. In other words, when the scaffold 1 is flattened, one receiving groove 4a projects out of the plane of the membrane 2 in one direction, and the other receiving groove 4b projects out of the plane of the membrane 2 in the opposing direction. The width-wise distance from the first spline 3a to the first groove 4b is the same width-wise distance as that from the second spline 3b to the second groove 4a. The width of the membrane 2 can thereby be divided in the ratio k: (1 - k): k (0 < k < 1),
Regarding the trapezoidal scaffold membrane 102, the angular distance from the first spline 103a to the first groove 104b is equal to that of the angular distance from the second spline 103b to the second groove 104a. Therefore, the angular width of the membrane 102 is divided in the ratio k: (1 - k): k, (0 < k < 1),
The principal and auxiliary splines and/or the receiving grooves (principal or auxiliary) need to be rigid enough to provide adequate mechanical support for and confer the required shape on the scaffold, but flexible enough to deform without breaking when an external force is applied. The splines and the grooves may be constructed out of a single material (e.g. a metal, an alloy, a polymer, a copolymer) or a composite of several materials (e.g. a metal alloy, a mixture of polymers, a polymer doped with inorganic compounds, a polymer reinforced with microfibrils of other materials, etc.). In the embodiment shown in
In the embodiment shown in
The principal and/or auxiliary spline-groove joints may be left bare or sealed with an adhesive (not shown) that may be rigid (e.g. a resin) or elastic (e.g. an elastomer) when set. The adhesive may be formed from a single component activated by pressure or by two components that are separately attached to or coated on to the principal splines and the receiving grooves, so that the adhesive only forms when the splines and the grooves come into physical contact and the curing process (if the adhesive is a two-part polymer) is activated. The adhesive may impart additional rigidity or flexibility and leak resistance to the scaffold.
The handles can be made of materials and into shapes and forms that will enhance the scaffold’s utility. The handles need to be attachable to the scaffold securely and relatively easily during manufacturing.
The “pores” of an ePTFE membrane can be made small enough to stop cell migration, and be impregnated with perfluorocarbons such as perfluoropolyether (PFPE), perfluoroperhydrophenanthrone (PFPH) or per-fluorodecalin (PFD) to produce a slippery liquid-infused porous surface (SLIPS) to prevent or reduce thrombosis, inflammation and bacterial adhesion. (Non-bioabsorbable fluoropolymer coated metal stents have been shown to be less thrombogenic and inflammatory than other drug-eluting stents covered with absorbable polymers.) A “drug-eluting” SLIPS can also be engineered to release molecules into the surrounding environment.
Referring now to
Where w is the width and k the “overlap” ratio of the strip: α the pitch angle, λ the pitch (longitudinal separation between successive turns of the same element of the scaffold), d the transverse diameter and s the length of one complete tum of the principal splines 3a, 3b and receiving grooves 4a, 4b in the resulting helical formation respectively (
Referring now to
If a circular arc subtends an angle θ in the cone’s base circle and an angle Φ in the developing circular sector, then:
Any point (r, θ, z) (in three-dimensional cylindrical co-ordinates) on a right circular cone with the apex at the origin, axis along the z axis and apex angle β:
can be mapped (matched) continuously one-to-one to a point (ρ, Φ) (in two-dimensional polar co-ordinates) in the developing circular sector with the centre at the origin through equations (4) - (6), even if θ and Φ are allowed to take continuous values outside (0,2Π).
The scaffold 201 forms a telescopic conical helix formation when in the rolled configuration as shown in
If ƒ (ϕ) is a monotonic (strictly increasing or decreasing) differentiable function in ϕ, then
(A a scale factor) describes a spiral in the (ρ,ϕ) plane, which translates into another spiral:
in the (r,θ) plane and a conical spiral through equation (6). (The spiral in the (r,θ) plane is “shrunk” in size by a factor of sin β <1 and accelerated in rotational speed by a factor of cosec β > 1 compared to the spiral in the (ρ,ϕ) plane.)
The scaffold 201 relies on the splines 203a, 203b slotting into the receiving grooves 204a, 204b when the membrane 202 is rolled up into a telescopic conical helix formation. Suppose a principal spline 203a and its receiving groove 204a lying on the same radius (same angle Φ) in the developing circular sector, let their respective equations be:
A0 < A1 (i.e. the principal spline lies closer towards the origin than its receiving groove). In order that the principal spline 203a slots into its receiving groove 204a after a complete turn 2Π of the scaffold strip in θ (which corresponds to 2Π sin β in ø, equation (5)):
The ratio A1 /A0 is determined by 2π sin β and independent of ø and stays the same as ø varies. Replace 2Π sin β with φ and A1/A0 with g(φ) (φ and hence β are allowed to vary continuously):
Let ϕ = 0, then:
Substituting equation (12) into equation (11):
For
(natural numbers or positive integers), q> 0:
∴ In ƒ(ϕ) is linear if ϕ is a rational number.
As ƒ (ϕ) is assumed to be differentiable. In ƒ (ϕ) is also differentiable where it is well defined. Thus
A conical scaffold 201 as shown in
A geometrical argument for the same deduction result works as follows. A spiral function ƒ(ϕ) can be transformed to cover the entire (p,ϕ) plane by either radial scaling ƒ(ϕ) ↦ A ƒ (ϕ) or angular rotation around the origin ƒ(ϕ) ↦ ƒ (ϕ + ψ). For the conical scaffold 201, these 2 families of spiral functions have to coincide, and one member can be transformed to another member by either scaling or rotation. For this to happen. the direction of the local tangent vector pρ + pϕϕ (p(ϕ)= A ƒ(ϕ)) needs to be scaling and rotation invariant (i.e. stays the same regardless of A and ϕ) and has a non-zero component in both directions (otherwise, one member cannot be transformed to another by both scaling and rotation, of circle) (
Equation (16) is the same as equation (15).
If a̅ = tan-1 b is the “slanted” pitch angle of the telescopic conic helix formation (
If a̅ > 0, tan a̅ > 0, ƒ(ϕ) and ρ(ϕ) increase with ϕ (i.e. expanding spirals). If a̅ < 0, tan α̅ < 0, ƒ(ϕ) and p(ϕ) decrease with ϕ (i.e. contracting spirals).
Suppose the telescopic conical helix formation is to have a minimum transverse diameter d . Without loss of generality, let
indicates text missing or illegible when filed
for the principal spline closest to the origin. and correspond to the point on the telescopic conical helix formation with the smallest transverse radius.
indicates text missing or illegible when filed
If a receiving groove and the remaining principal spline is phase shifted from the lowest principal spline by ψ in θ, the slant height ρ1 (ϕ) is given by: For one complete turn in the telescopic conical helix formation (i.e. ψ = 2Π): the overlap ratio k : While the overlap ratio κ stays constant if the apex angle β and the slanted pitch angle α̅ stay constant, the width of membrane overlap ρ(ϕ+2Πsinβ)-ρ(ϕ) = ρ(ϕ)(κ-1) varies with ϕ. Regardless of whether α̅ > 0 or α̅ < 0 (and ρ is an expanding or contracting spiral), membrane overlap is wider at the wide end of the telescopic conical helix formation.
A transverse cut across the cone at slant height p0 corresponds to a circular arc of radius p0 in the (p,ϕ) plane. If and the trapezoidal patch bordered by the 2 circular arcs p = ρ0 and ρ = ρ2 (ϕ:ϕ0 → ϕ0 + ø1) and the 2 logarithmic spirals and will give rise to a telescopic conical helix formation truncated transversely at both the apical and base ends (
Referring now to
Referring now to
In use when supporting a tubular object, the scaffold 1, 101, 201, 301. spreads any bend to which the tubular object may be subjected over a longer longitudinal span. The reduction in curvature protects the tubular object and its contents from fatigue fracture.
Referring now to
By equation (23), for the same area of the regular scaffold strip Sw, the longitudinal span L, transverse diameter d and overlap ratio k (through the term l+k) are inversely related. If the overlap ratio k is also fixed, longitudinal deformation of the scaffold will result in and can only occur in the presence of opposite concomitant radial deformation (i.e. Poisson effect).
For the trapezoidal scaffold 201 (determined by A0 and b in equations (17) and (18); as shown in
The practical implications of the inverse relationship between longitudinal and radial deformations of the scaffold are:
Extending the scaffold does not only reduce its transverse diameter but also distributes its physical bulk over a longer longitudinal span, which makes the scaffold more flexible and deliverable along a tortuous anatomical course.
Radial expansion without longitudinal shortening (i.e. Poisson ratio = 0) of a telescopic cylindrical helix formation can be achieved by winding the scaffold membrane into a tighter roll and then unwinding it dunng deployment. Referring now to
The auxiliary splines 9 can also take the form of a wire 30 (circular, elliptical, rectangular or other geometric shape in cross-section) at one end and a matching receiving groove 31 at the other (
Referring now to
As k → 1 and k1 → 0, the maximum radial expansion that can achieved by this method is x2. For example, scaffold 601 has splines 603a, 603b and two pairs of grooves 604a-d. In the first rolled configuration, the splines 603a, 603b are engaged with the central grooves 604c, 604d that are furthest away from the splines 603a, 603b when in the flattened configuration Specifically, spline 603a is engaged with groove 604c, and spline 603b is engaged with groove 604d. The other grooves 604a, 604b remain free. In the second rolled configuration, the splines 603a, 603b are engaged with the grooves 604a, 604b that are adjacent to the splines 603a, 603b in the flattened configuration. Specifically, spline 603a is engaged with groove 604a, and spline 603b is engaged with groove 604b. Grooves 604c and 604d remain free.
Referring now to
where n is the width of a unit. The pitch angle α stays the same for the different transverse diameter telescopic helix formations.
The diameter of the telescopic cylindrical helix formation is smallest when p = 1 and largest when p = n, The radial expansion ratio possible of the scaffold takes the form p/q, where p>q are positive integers ≤n . The widened scaffold strips and telescopic helix formations possible for n = 2 and n = 3 are shown in
Referring now to
Radial expansion without longitudinal shortening through axial unwinding allows the scaffold for telescopic cylindrical helix formation to be positioned precisely in a collapsed state at the target site before deployment. However, the wound-up scaffold has increased physical bulk compacted into a smaller volume and may become stiffer and less deliverable along a tortuous course.
The scaffold 1 can be deployed simply by unwinding it and then wrapping it around a tubular object turn by turn, so that the splines 3a, 3b fall within their receiving grooves 4a, 4b. If the scaffold 1 is pre-shaped to a helical formation with a transverse diameter slightly smaller than the outer diameter of the tubular object, elastic recoil will ensure a good radial grip by the scaffold 1 and fix its position on the tubular object. If necessary, the scaffold 1 can be extended longitudinally along the tubular object, so that its transverse diameter will decrease and the scaffold 1 will grip the tubular object more tightly (
Assuming the scaffold 1 is applied to the outside of the tubular object 60 in the distal (further away from the user) to proximal (closer to the user) direction, the distal end of the next turn will be external to the proximal end of the last turn, the “proximal-external-to-distal” topology (
If the scaffold 1 is to line the inner surface (lumen) of the tubular object 60, it needs to have a transverse diameter larger than the diameter of the object’s lumen so that it can be held in place by friction against and/ or distortion of the lumen’s wall. Before the scaffold 1 can be introduced into the lumen of the object 60 through either of its ends or an opening on its side, the scaffold 1 needs to be collapsed into a transverse diameter smaller than the lumen’s. When the scaffold is retrieved out of the tubular object 60, it needs to be reduced back into a smaller transverse diameter.
Ideally, the deployment and retrieval apparatus (external tools and attachments to the scaffold 1) should be physically as small as possible. However, if the apparatus is too small, they may be challenging to handle and not strong enough to manipulate the scaffold 1 with. If the apparatus is too large, it may cause obstruction for the scaffold or be too bulky to be delivered to the target site through minimal remote access. The scaffold 1 is designed with dedicated features to enable lower profile delivery and easy reliable atraumatic, nondestructive retrieval through minimal access.
Assuming the scaffold 1 is applied to the tubular object 60 in the distal (further away from the user) to proximal (closer to the user) direction, the distal end of the next turn needs to be internal to the proximal end of the last turn, the “proximal-internal-to-distat” topology (
Referring now to
The most difficult step in scaffold retrieval is likely to be re-grasping the handle. If necessary, the grasping tool 68a can be left permanently in place (
Referring now to
Once positioned at the target site (
If the scaffold 1001 is made of malleable materials with no shape memory components, the scaffold 1001 relies on permanent non-elastic deformation of its components and the spline-groove locks to maintain shape after deployment. Alternatively, the scaffold may contain shape-memory materials and be mounted on the balloon 75 in a malleable state. Shape memory activation (e.g. by heat) is achieved by either using warm liquid (e.g. radio-opaque contrast warmed up to the transition temperature of the shape memory materials) or passing an electric current between the ends of the collapsed scaffold through electrodes on the balloon catheter or the guide wire passing through it.
The scaffold 1001 has two internal handles 1065a, 1065b at either longitudinal end of the scaffold 1001. The handles 1065a, 1065b are formed from auxiliary splines 1009a, 1009b made of shape memory materials such as nitinol. For retrieval, an inflatable balloon 75 with a transverse diameter the same as but a longitudinal span shorter than the deployed scaffold 1001 is inserted through its central lumen (
Only the proximal auxiliary spline 1009b is needed for scaffold retrieval by the method depicted in
Referring now to
Referring now to
If the object to which the scaffold 11 is applied externally is sufficiently flexible, the telescopic (cylindrical or conical) helix formation of the scaffold 11 may be able to distort the object into a helical formation as well (
Referring again now to
Referring now to
Suppose the scaffold 1 is deployed in a tubular object 60 with the proximal-intemal-to-distal topology and the tubular object 60 has a proximal-to-distal fluid flow in its lumen 61, the flow will tend to wash a scaffold 1 turn distally into the next turn, wedging it open wider (
Referring now to
A stent placed in a biological tubular object capable of peristalsis is inherently vulnerable to migration. However, the scaffold 1 is resistant to migration via peristalsis. When the peristaltic contraction is proximal to the deployed scaffold 1. the most proximal segment of the scaffold 1 is longitudinally compressed and expands radially as a result, effectively forming a “flared” end (
When the scaffold 1 is applied around an object, the radial grip by a helical spline 3a, 3b or receiving groove 4a, 4b of the scaffold 1 is distributed evenly over a longitudinal distance equal to its pitch along the object, so that no section of the object will face a concentrated or circumferential grip (
Unlike traditional stents with complete rings of struts, the scaffold 1 does not place circumferential radial stress on any segment of the wall of the tubular object 60 into which it is placed. Flat strip auxiliary splines 20 at the two ends of the scaffold 1 are intended to be malleable during scaffold deployment and not to exert any radial stress on the tubular object’s wall 60. The absence of circumferential radial stress should reduce or even prevent dissection or thickening of the tubular object’s wall 60 at the edges of the stent.
The struts of a stent may break over time due to fatigue fracture from repetitive flexing and unflexing. The sharp ragged ends of the fracture may perforate the wall of the blood vessel housing the stent. For the scaffold 1 of the present invention, even if the metallic or other rigid polymer components in the principal 3a, 3b or auxiliary 9 splines and/ or receiving grooves 4a, 4b do snap, the sharp ragged ends can be contained in the scaffold membrane 2 if it is made of a material with high tear strength (e.g. orthogonally laminated ePTFE layers).
Expanded PTFE has high tensile strength parallel to its polymer strands, is chemically very inert and will not significantly disintegrate inside the human or animal body. A deployed scaffold 1 made from a membrane 2 containing appropriately arranged ePTFE layers is likely to be retrieved (“explanted”) successfully by pulling without any fragments falling off (and causing embolism), even if the principal splines 3a, 3b and/ or receiving grooves 4a, 4b have fractured at places.
Because of the inherent helical shape of the deployed scaffold 1, it may induce spiral laminar flow within a blood vessel, resulting in physiologically advantageous fluid dynamics, especially at bifurcation sites (blood vessel branch points), and reduction of platelet adhesion (and hence thrombosis).
Referring now to
A scaffold (with or without an external handle for anchorage to an adjacent anatomical structure) can be applied from the side to a lead which has developed a breach in its external insulation, and will securely attach to the lead even without adhesive. (The current commercially available lead insulation repair kit requires sliding short lengths of silicone tubes over the lead body and fixing them in place with medical adhesives. The short silicone tube is generally oversized with respect to the lead body to be repaired as it has to slide over the connector pin, which is larger in calibre than the body of most leads. Medical adhesives take time to cure and generally do not give very strong bonds.)
A self-extracting lead sleeve can be externally applied to the entire length of a transvenous lead connecting a cardiac implantable electronic device (CIED) or neuro-stimulator to excitable biological tissues (the heart, a nerve, the brain, the spinal cord) to:
Once a transvenous lead has been implanted inside the human or animal body, it can become heavily encased in fibrous tissues and become difficult or even dangerous to extract.
The self-extracting lead sleeve is a scaffold 1401 as shown in
During lead extraction, the lead 74 is exposed at the surgical access site (usually just deep to the subcutaneous tissues in the shoulder or loin region,
A locking stylet or lead locking device 79 is inserted inside the lumen of the lead 74 to provide tensile strength and distal lead tip control. A sheath 73 is inserted around the lead 74 through the channel newly created within the radially expanded scaffold 1401 all the way to near the lead tip (
Referring now to
The pin plug 1590 consists of a central cylindrical core 1592 within a cylindrical shell 1593 mounted on a circular end plate 1594 (
Suppose it is anatomically more convenient, feasible, effective and safer to fix the tip of a transvenous lead to a target site from the groin (the “femoral” approach). After the lead’s tip position has been fixed, the connector pin of the lead needs to be transported from the femoral region, through the bloodstream, and out of the shoulder (“pectoral”) region when the pulse generator of the cardiac implantable electronic device (CIED) will be placed.
The scaffold 1501 which can be referred to as a lead pin plug-handle is externally applied to the lead pin 95 in the femoral region outside the human or animal body. The handle 1596 is then mounted on a “ramrod” dilator 97 with a hemi-spherical tip cut with a planar cleft that will fit snuggly around it (
The scaffold 201 shown in
For a stenosis in a tapering artery 50 (
A slanted ostium cannot be perfectly covered by a cylindrical stent for geometrical reasons: either the stent leaves a short segment of the side branch uncovered (provisional T stenting) or a short segment of the stent protrudes into the lumen (T stenting and small protrusion). A conical stent. e.g. scaffold 201, can be used in a novel way to overcome this geometric conundrum in the following manner:
The proximal end of the conical stent 201 is then tilted so that it becomes flush with the slant ostium. The technique differs depending on whether a wall opposing the slanted ostium is available in practice.
If an opposing wall is available:
If an opposing wall is unavailable:
A conical stent made out of the scaffold is especially advantageous for the technique described for several reasons.
A scaffold can form an ePTFE covered stent for the coronary, peripheral, carotid and vertebral arteries, and the aorta. If the ePTFE is infused with a perfluorocarbon, the scaffold will have a SLIPS. A SLIPS stent will resist, reduce or prevent:
A SLIPS stent should remain pristine long after implantation because of the biochemical inertness of perfluorocarbons. This will allow the stent to be retrieved using the auxiliary splines as internal handles on the stent (
The scaffold can form a vascular graft that can be rapidly externally applied to a leaking blood vessel (e.g. a ruptured aortic aneurysm). As the scaffold is self-assembling, the user only needs to wrap the scaffold strip roughly around the leaking blood vessel and the splines will slot into the receiving grooves semi-automatically. This is important as the leak in the blood vessel can often not be clearly visualised because of the amount of blood gushing out. Once the immediate blood loss has been staunched, the damaged blood vessel can be fixed permanently. The scaffold can be incorporated as part of the permanent surgical repair. If the scaffold is infused with perfluorocarbons to form a SLIPS, the resulting vascular graft may be resistant to thrombosis, infection and stenosis. Because of the biochemical inertness of ePTFE (with or without infusion with perfluorocarbons), the graft will probably never be endothelialised and incorporated into the body.
A SLIPS scaffold can be made into a flexible, kink resistant long term indwelling catheter (e.g. for haemodialysis, chemotherapy, urinary tract), a prosthetic vascular graft (e.g. between an artery and a vein in the formation of arterio-venous fistula for haemodialysis; between the aorta and the coronary arteries in coronary artery bypass surgery; for the carotid artery. or between the femoral and popliteal arteries) or plasticiser free flexible tubing (which can be used for liquid infusion in clinical practice) by putting in extra pairs of receiving grooves (to absorb compression and extension around bends and induce spiral laminar flow within) and sealing the spline-groove joints with a liquid proof adhesive (
The scaffold can be used to form a stent for tubular organs capable of peristalsis and carrying luminal flow (e.g. the bile duct, the oesophagus, the colon, the stomach, the ureters;
The scaffold can be wrapped externally around soft tubular organs of the pelvic floor (e.g. the vagina, the urethra, the rectum) that are prone to prolapse (with ageing, weakening of the pelvic floor from childbirth, previous surgery, previous radiation therapy) to provide flexible mechanical support. The scaffold can be pre-set to have an internal diameter that will not impede the flow of the contents of these soft tubular organs. The scaffold has intrinsic longitudinal and radial elasticity and should not feel rigid for the recipient. If the scaffold membrane is made of ePTFE (with or without infusion of perfluorocarbons), the scaffold should resist ingrowth by the surrounding tissues, making the scaffold easy to remove surgically if that proves necessary later.
The scaffold can be wrapped around an electric cable to:
The scaffold can be externally applied to an electric cable from the side even if both of its ends are attached to significantly larger objects (e.g. an integrated plug) without any other apparatus (e.g. a heat gun for heat-shrink tubing). Unlike other electric cable insulation repair kits, the scaffold will attach securely to an electric cable but can be easily dismantled from one electric cable and reused on another. A single scaffold can also be wrapped around multiple electric cables to organise them into a manageable bundle, and provide the means by which the cables can be tied down through one or more anchorable handles (
The scaffold can be wrapped around and then pulled tight around a leakage pipe. The splice-groove joints can be equipped with a liquid proof adhesive to produce a leak proof seal. The ends of the scaffold may be compressed with another pair of externally applied clamps to contain the hydraulic pressure. The scaffold can be left as a temporary, semi-permanent or permanent fix to the leak. The scaffold and deployment/ retrieval techniques from remote minimal access can be adapted in other internal liquid or gas pipe repair jobs.
Referring now to
In one embodiment, the scaffold may be referred to as a Self-Assembling Extendible Expandable Retrievable scaffold (i.e. SAFEER scaffold) that can be applied to and removed from a tubular object either on the external surface from the outside, or on the internal surface through an interior channel (the “lumen”); whether the tubular object is rigid or flexible, static or subjected to repetitive deformation; with relatively ease and minimal training of the operator; even when direct physical access to the object is restricted. The SAFEER scaffold can be used to provide mechanical support to the structural integrity of the object, which is flush with its ends (even if they are slanted with respect to its longitudinal axis), conforms to the object’s wall even if its cross-section profile, transverse diameters and curvature vary along its length, protect the tubular object and its contents from damage caused by repetitive flexing and unflexing (i.e. fatigue fracture), external or internal abrasion, or any other forms of physical and chemical insults. The SAFEER scaffold can be used to form a continuous surface lining the lumen or covering the external surface of the object that stops, prevents or reduces: leakage across the object’s wall out of or into the lumen; thrombus (blood clot) formation (if the object is a blood vessel); adhesion by biological entities (cells and micro-organisms) and their secretions, or other organic or inorganic particles. The SAFEER scaffold can produce a physical gap on demand (which may require the application of a stimulus or an energy source) separating the object from its surroundings (even against constricting and restricting influences), so that: another instrument can be inserted alongside or over the tubular object within the same surroundings; the object can be moved freely with respect to (and hence removed safely from) its surroundings. The SAFEER scaffold can be adapted to have one or more handles that can be used to: anchor the scaffold (and indirectly the tubular object) to the surroundings; provide purchase for a manipulation or retrieval tool, directly for the scaffold, or indirectly for the tubular object through the scaffold.
In relation to the detailed description of the different embodiments of the invention, it will be understood that one or more technical features of one embodiment can be used in combination with one or more technical features of any other embodiment where the transferred use of the one or more technical features would be immediately apparent to a person of ordinary skill in the art to carry out a similar function in a similar way on the other embodiment.
In the preceding discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of the values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of the parameter, lying between the more preferred and the less preferred of the alternatives, is itself preferred to the less preferred value and also to each value lying between the less preferred value and the intermediate value.
The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof.
Number | Date | Country | Kind |
---|---|---|---|
2002220.8 | Feb 2020 | GB | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2021/054081 | 2/18/2021 | WO |