A blood vessel harvesting device

Abstract

The invention provides a device for use in no-touch vein harvesting. The device includes a tissue separating and side branch cutting head having, a tubular body which has an inner surface and an outer surface, and which extends between a leading end and a trailing end, the leading end being adapted to separate or cut tissue surrounding a blood vessel to be harvested, a lumen defined within the inner surface, and which opens at the leading and trailing ends, and adapted to receive a part of the blood vessel, a plurality of slots formed through the body and extending in a longitudinal direction between an open end, and a closed end, each adapted to receive a side branch and to channel the side branch towards the closed end, a plurality of cutting devices, each associated with a respective slot, and each having a pair of dissectors adapted to sever the side branch, and a processing module. The processing module automates the device, enabling detection of a side branch between a pair of dissectors, and initiating an action to energise the pair of dissectors to sever the side branch without the need for visual detection which typically requires an endoscope.

Description

A BLOOD VESSEL HARVESTING DEVICEFIELD OF THE INVENTION

[0001] The invention relates to a blood vessel harvesting device.BACKGROUND OF INVENTION

[0002] Endoscopic vein harvesting (EVH) is a procedure to harvest the great saphenous vein (GSV), the most common graft used in coronary artery bypass surgery. This procedure has largely replaced the more invasive open vein harvesting technique.

[0003] In this procedure, a small incision is made, and an endoscopic camera is used as a blunt dissector to create a subcutaneous tunnel of tissue under the skin. The side branches of the GSV are usually cauterized and divided by means of a RF ablation using a separate device, typically a bipolar forceps.

[0004] The problem with this technique, and the use of the associated devices, is that, although less traumatic, it is not without trauma. Due to the prodding and poking required of the technique, the vein is often damaged, reducing the patency rate.

[0005] Furthermore, the technique requires a high degree of training to enable skilful manipulation of the ablation device, guided by the endoscopic camera imagery, which is an additional piece of equipment needed to employ the technique.

[0006] With vein grafts offering lower patency rates than artery grafts, as a start, and with evidence that the patency rate improves if the vein is harvested, covered by the surrounding tissue, it is important that the extractive procedure is such as to reduce damage to the vein and to include a predefined amount of surrounding tissue.

[0007] Furthermore, with current EVH devices, the vein is separated from the surrounding tissue and side branches and then removed. At this point, the vein might experience shear stress due to friction between the vein surface and surrounding tissue.

[0008] Another problem with current EVH is thermal damage. This damage occurs when the electrodes which are used to cut side branches are too close to the surface of the main vein to be harvested. This can potentially thermally damage the vein.

[0009] JP2016042987 addresses some of the aforementioned issues to a certain extent. The document outlines a blood vessel harvesting device featuring a leading tissue-separating head and a side branch cutting head. This cutting head is equipped with grooves through which a peripheral vessel passes during device operation, undergoing dissection by ablation.

[0010] However, a drawback of this device is its inability to detect when a peripheral vessel has entered a groove, preventing the activation of cutting mechanisms within that specific slot for dissecting the peripheral vessel.

[0011] In the absence of a detection mechanism, the only viable options are direct observation (requiring an endoscope and resulting in a less-minimally invasive procedure), initiating an ablation current flow on perceived mechanical resistance (risking the rupture of side branches), or constantly energizing all slots, potentially causing thermal damage to surrounding tissues or the main branch of the vein. Another shortcoming of JP2016042987 is a reliance on straightening the vein to be harvested. This involves inserting a reinforcing portion into the vein to prevent inadvertent dissection by the device. Unfortunately, this pre-procedure is potentially traumatic and poses the risk of puncturing the vein.

[0012] The invention at least partially solves the problems.SUMMARY OF INVENTION

[0013] In a first aspect, the invention provides a blood vessel harvesting device which includes: a tissue separating and side branch cutting head having: a tubular body which has an inner surface and an outer surface, and which extends between a leading end and a trailing end, the leading end being adapted to separate or cut tissue surrounding a blood vessel to be harvested, a lumen defined within the inner surface, and which opens at the leading and trailing ends, and adapted to receive a part of the blood vessel,a plurality of slots formed through the body and extending in a longitudinal direction between an open end, and a closed end, each adapted to receive a side branch and to channel the side branch towards the closed end, a plurality of cutting devices, each associated with a respective slot, and each having a pair of dissectors adapted to sever the side branch, and a processing module, characterised in that the processing module is adapted to detect a change in an electrical property across a pair of dissectors and, should the change exceed a limit which is indicative of the presence of a side branch between the pair of dissectors, to initiate an action to energise the pair of dissectors to sever the side branch.

[0014] The processing module may include a detector which is electronically connected to each pair of dissectors in a respective detection circuit, and which is adapted to measure the electrical property across a pair of dissectors, when the respective detection circuit is closed by a circuit specific switch and a first master switch.

[0015] The processing module may include a control unit which is adapted to sequentially close the detection circuit for each pair of dissectors at the circuit specific switch, facilitating the measurement of the electrical property, and to open the detection circuit at the circuit specific switch when the measurement received from the detector does not indicate the presence of a side branch.

[0016] The processing module may include an ablation generator which is electrically connected to each pair of dissectors in a respective dissection circuit, and which is adapted to energise a pair of dissectors, when the respective dissection circuit is closed by the circuit specific switch and a second master switch.

[0017] The control unit may be adapted to open all detection circuits at the first master switch, when the measurement received from the detector indicates the presence of a side branch between a pair of dissectors, and to close the respective dissection circuit at the second master switch to energise that pair of dissectors.

[0018] The processing module may include an alarm which is activated by the control unit to emit an alarm signal when the measurement received from the detector indicates the presence of a side branch between a pair of dissectors.

[0019] The processing module may include an actuator which is adapted to open all detection circuits at the first master switch, when actuated in response to an alarm signal, and to close the respective dissection circuit at the second master switch to energise the pair of dissectors.

[0020] Each circuit specific switch may comprise two switches, configured to interrupt both supply and return lines of the circuit.

[0021] Each pair of dissectors may be either a moveable pair of dissectors, adapted to move towards and away from one another, or an immoveable pair of dissectors.

[0022] The moveable pair of dissectors may include an actuator, which is electrically interposed in the respective dissection circuit between the ablation generator and the pair of dissectors, and which actuates the pair of movable dissectors to move when the dissection circuit is energised.

[0023] The tubular body may be comprised of half tubular sections defined between the leading end and the trailing end and a first and a second longitudinal edge.

[0024] Each half section maybe discrete, adapted to engage the other along the first and second longitudinal edges to form the tubular body.

[0025] The two half sections may be connected along respective first longitudinal edges to allow the half sections to move between an open position, in which the respective second longitudinal edges are spaced apart, and a closed position, in which the respective second longitudinal edges meet to form the tubular body.

[0026] Each slot may be tapered or partially tapered to guide the side branch to the closed end.

[0027] The slots may be equally radially spaced about the body.

[0028] The leading end may be adapted with a plurality of cutting edges, each between a pair of adjacent slots.

[0029] Each cutting device is radially spaced from a perimeter of the lumen.

[0030] In a second aspect, the invention provides a blood vessel harvesting device which includes:a blood vessel containing chain which extends between a leading end and a trailing end, and which comprises a plurality of segments pivotally connected to one another, each adapted to contain a section of a blood vessel to be harvested, and a tubular cutting head connected to the leading end of the chain which has a leading end which is adapted to separate or cut tissue surrounding the blood vessel, and a lumen which is adapted to receive passage of the blood vessel.

[0031] Each segment is a tubular segment may be comprised of two half tubular sections which engage one another along respective first longitudinal and second longitudinal edges and to form a tubular body.

[0032] The two half tubular sections may pivotally connect to one another along respective first longitudinal edges to move between an open position, in which respective second longitudinal edges are separated, and a closed position, in which the respective second longitudinal edges engage to form a tubular body.

[0033] Each segment may include a semi-circular base element that defines a channel and a closure engaged with the semi-circular element and which moves between a closed position, closing at least part of an opening to the channel, and an open position.

[0034] The closure may be a pair of resiliently deformable flaps situated on opposed sides of the opening to resiliently open and close the opening.

[0035] Alternatively, the closure may be a pair of toggle elements situated on opposed sides of the opening that rotate from an open to a closed position.

[0036] Alternatively, the closure may be an arcuate shutter which slidably engages with the base element to move between the open and the closed positions.

[0037] The base element may include an arcuate slot into which the arcuate shutter moves when moving to the open position.

[0038] The shutter may have a biasing element within the slot which biases the shutter to the closed position.

[0039] The biasing element may be a concertina element, or a spring loaded element.

[0040] In a third aspect, the invention provides a blood vessel harvesting device which includes: a blood vessel containing chain which extends between a forward end and a trailing end, and which comprises: a plurality of segments, each adapted to contain a section of a blood vessel to be harvested; a plurality of flexible connectors, each interposed between an adjacent pair of segments to flexibly connect the segments in the chain; and a tubular cutting head connected to the forward end of the chain which has a leading end which is adapted to separate or cut tissue surroundingthe blood vessel, and a lumen which is adapted to receive passage of the blood vessel.

[0041] Each flexible connector may have a composite body, comprised of a first flexible material and a second structural material.

[0042] The first material may be a flexible material and the second material may be less flexible than the first material, included to prevent excessive flexion of the connector.

[0043] The composite body may comprise alternating layers of the first material and the second material.

[0044] Alternatively, the composite body may comprise a spiral interengagement of the first and the second material. Preferably, the second material is a spirally arranged seam embedded within the first material.BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The invention is further described by way of an example, with reference to the accompanying Figures in which:Figure 1 is a view in perspective of a tissue separating and side branch cutting head for a blood vessel harvesting device (hereinafter referred to as a cutting head) in accordance with a first embodiment of a first aspect of the invention;Figure 2 is a view in longitudinal section of the cutting head of Figure 1 ;Figure 3 is a view in longitudinal section of A blood vessel harvesting device in accordance with a second embodiment of the first aspect of the invention;Figure 4 is a view in plan of the cutting head of Figure 1 ;Figure 5 diagrammatically illustrates a slot of the cutting head;Figures 6A and 6B diagrammatically illustrate a part of the slot of Figure 4, showing a cutting device; Figure 7 is a view in perspective of A blood vessel harvesting device in accordance with a third embodiment of the first aspect of the invention;Figure 8 is an exploded view in perspective of A blood vessel harvesting device in accordance with a fourth embodiment of the first aspect of the invention;Figure 9 is a circuit diagram that describes how each cutting device is powered and controlled;Figure 10A and 10B provide process flow diagrams detailing the method by which a cutting device is powered and controlled to execute its dissecting function;Figure 11 diagrammatically illustrates a blood vessel harvesting device in accordance with a second aspect of the invention which includes A blood vessel harvesting device and a chain comprising a plurality of interconnected vessel containing segments;Figures 12A and 12B diagrammatically illustrate the blood vessel harvesting device of Figure 11 being deployed in harvesting a blood vessel;Figures 13A and 13B isometrically illustrate a vessel containing segment of a blood vessel harvesting device (hereinafter referred to as a segment) of Figure 10 in an open configuration and a closed configuration respectively;Figures 14 and 15 isometrically illustrate a segment in accordance with a second and a third embodiment respectively of the second aspect of the invention;Figures 16 and 17 isometrically illustrate a segment in accordance with a fourth and a fifth embodiment of the second aspect of the invention;Figures 18A and 18B isometrically illustrate a segment in accordance with a sixth embodiment of the second aspect of the invention in an open configuration and a closed configuration respectively;Figure 19 isometrically illustrate a blood vessel harvesting device in accordance with a third aspect of the invention which includes A blood vessel harvesting device and a chain comprising a plurality of vessel containing segments interconnected by moveable joints;Figure 20 and 21 isometrically illustrate a blood vessel harvesting device in accordance with a second embodiment of the third aspect of the invention which includes A blood vessel harvesting device and a chain comprising a plurality of vessel containing segments interconnected with a plurality of flexible joints; andFigure 22 isometrically illustrates a first embodiment of a flexible joint of the blood vessel harvesting device, andFigure 23 isometrically illustrates a second embodiment of a flexible joint of the blood vessel harvesting device.DESCRIPTION OF PREFERRED EMBODIMENTS

[0046] Figure 11 illustrates a blood vessel harvesting device 10.1 in accordance with one aspect of the invention. The device 10.1 is adapted to harvest a vessel, preferably a vein such as the great saphenous vein, for use in coronary artery bypass surgery.

[0047] The device (of any of the embodiments 10.1 , 10.2... 10.3) comprises a leading tissue-separating and side branch cutting head 12 and a flexible trailing articulated train 14. This train consists of multiple vessel-containing elements, designated as 16.1 , 16.2, 16.3...16.N. Further details about the device will be provided later, with initial emphasis on the cutting head, the first aspect of the invention.

[0048] Figures 1 and 2 illustrate a first embodiment of the cutting head 12.1 . The cutting head includes a tubular body 18 which extends between a leading end 22 and a trailing end 24, which comprises a conical part 18.1 and a tubular part 18.2, and which has a tubular wall 20 defined between an inner surface 20.1 and an outer surface 20.2.

[0049] A lumen 26 extends through the tubular body 18 of the cutting head, defined within the inner surface 20.1 and opens at both the leading and trailing ends (22, 24).

[0050] The cutting head 12.1 includes a plurality of slots (respectively designated 28.1 , 28.2, 28.3...28.N) formed through the wall 20. Each slot extends longitudinally between an open end 32, at the leading end, and a closed(or base) end 34. Each slot has a respective cutting device at or towards the closed end 30 (see Figure 5).

[0051] Slots (28.1 , 28.2,...28.N) create a plurality of teeth-like projections (respectively designated 36.1 , 36.2, 36.3...36. N) between them. The outermost edge of these teeth-like projections determines the leading end 22.

[0052] The leading end is a cutting or separating edge 38, which is adapted to separate away, or cut through, fat tissue surrounding a blood vessel 40 to be harvested. The cutting edge can be adapted to cut through fat tissue but retain a core of this tissue around the blood vessel by having the adjacent inner surface 20.1 orientated aslant relative to the adjacent outer surface 20.2, as illustrated in Figures 1 , 2, and 4. Alternatively, the cutting edge can be adapted to separate away the fat tissue surrounding the blood vessel by having the adjacent outer surface 20.2 orientated aslant relative to the adjacent inner surface 20.1 , Figure 3 illustrates this embodiment. Another alternative is to have both surfaces aslant, positioning the cutting edge circumferentially in the middle of the wall.

[0053] In a third embodiment, illustrated in Figure 7, the cutting head 12.3 differs from the earlier described embodiments in that body 18 does not flare but remains cylindrically tubular, with a cylindrically tubular lumen. In this non-limiting example, the cutting head 12.3 has four slots (18.1 , 18.2, 18.3 and 18.4) and four teeth-like projections (36.1 , 36.2, 36.3 and 36.4). The cutting device 30 includes a pair of bipolar dissectors or forceps (64.1 , 64.2).

[0054] The embodiment 12.4 (see Figure 8) differs from the preceding embodiments of the cutting head in that the teeth-like projections 36.1 , 36.2, ... , 36. N are more pointed in shape with a narrower, more honed, and less planar separating edge 38.

[0055] Body 18 of the cutting head 12.4 comprises half-tubular sections 42.1 and 42.2 (see Figure 8). Each half section has a first 44 and a second 46 longitudinal edge. The half sections are joined along respective first edges about a hinge 48. This configuration allows the half tubular sections to pivot between an open position, where the respective second longitudinal edges 46 are apart, and a closed position, where the second edges 46 engage, taking on a tubular configuration. Opposed second 46 longitudinal edges have complementary locking formations (49.1 , 49.2), which inter-engage in the snap lock when the half tubular sections are moved to the closed position.

[0056] Each of the plurality of vessel containing elements (16.1 , 16.2, 16.3....) of the articulated train is, in one embodiment (designated 16A and illustrated in Figures 13A and 13B) like the head 12, comprised of arcuate half sections 42.1 and 42.2, which are hinged together in the same manner as described in respect of the cutting head 12 to move between an open and a closed position. Figures 13A and 13B illustrate this movement, which is necessary to enable the enclosure of the blood vessel that is being harvested.

[0057] The vessel-containing element may come in many embodiments. In describing these embodiments, like features bear like designations and, for ease of description, only the differences with other embodiments are described.

[0058] Figure 14 represents a second embodiment of the vessel containing element 16B. The arcuate half sections 42.1 and 42.2 are connected via hinges along edges 44. These edges 46 feature corresponding female and male locking configurations (49.1 , 49.2) that resiliently interlock and snap securely when the half sections are brought into the closed position.

[0059] A third embodiment of the element 16 is shown in Figure 15. This embodiment differs from the preceding embodiments in that it is comprised not of two half sections but of a semi-circular rigid base section 42.1 and a closure 42.2. The base section features a channel 26 and an opening 50 between its ends 51 . Closure 42.2 is connected to the base section and spans the opening. In this variant, the closure comprises a pair of resiliently deformable flaps (53.1 , 53.2) that connect to each end of the base section, extending into the opening to effectively seal it. However, these flaps have the flexibility to deform inwardly, allowing for the passage of a vein into the channel.

[0060] A fourth embodiment, 16D, shown in Figure 16, has a pair of toggle elements (53.1 , 53.2) instead of a pair of flaps. The toggle elements can be rotated between an open position (not illustrated), where the elements do not substantially extend across the opening 50, and a closed position (shown), where the elements extend across the opening in partial closure, necessary to retain a contained vein.

[0061] Figure 17 illustrates a sixth element embodiment 16E. The closure is an arcuate shutter 42.2, and the base section 42.1 is formed with a complementaryarcuate slot 55 into which the shutter slidably moves between an open and a closed position. The closed position is illustrated.

[0062] Spring-loaded modifications of the sixth embodiment are depicted in Figures 16F and 16G, representing the seventh and eighth embodiments. In these versions, the arcuate shutter 42.2 incorporates a biasing element - specifically, a spring-loaded bowed element 57.1 and a concertina element 57.2 - positioned along the inside edge of the shutter. This element engages an end of the slot, imparting a bias to keep the shutter in the closed position. This design ensures the opening is consistently closed, effectively containing the vein.

[0064] For the articulate traversal of the vessel harvesting device 10 along the winding path of the harvested vein, it is essential for the elements to be pivotally or flexibly interlinked. In one embodiment shown in Figure 19, and designated 10.2, the connections between elements and between the cutting head and the element are facilitated by a ball and socket joint (designated as 52.1 and 52.2, respectively). This joint permits elements to move relative to each other in a multiaxial manner, accommodating the variability required for the orientation of the longitudinal axis of the device.

[0065] In another embodiment, designated 10.3, represented in Figures 20 and 21 , the vessel harvesting device includes a plurality of connectors (designated 59.1 , 59.2, > 59. N), each interposed between an adjacent pair of vessel containing elements (16.1 , 16.2, 16.3) to provide a continuous interconnected articulated train wherein each connector provides the requisite flexibility.

[0066] Each connector (59.1 , 59.2, .... 59. N) mirrors the configuration of the adjacent vessel's base section 42.1 , exhibiting a semi-circular body 61 that seamlessly extends and aligns with the channel 26. In one embodiment of the connector 59A, the body is made of a laminar composite material, comprising of layers of a flexible material 63 alternating with layers of a less flexible material 65. This feature is best illustrated in Figure 22.

[0067] In an alternative embodiment, represented as 59B in Figure 23, the semicircular body is made from a composite material exhibiting a spiral arrangement. In this example, the structural material 65, possessing less flexibility, forms a spiral seam integrated within the flexible material 63. The seam runs continuously from end to end, connecting the base sections of adjacent vessel-containing elements (16.1 , 16.2). This spiral seam functions akin to a spring, ensuring the connector remains straight and preventing excessive flexion.

[0068] In use of the blood vessel harvesting device (10.1 , 10.2 or 10.3), a surgeon will first dissect the tissue of, say, the leg if the GSV is to be harvested, to reach the vein 40 and expose a few centimetres long segment of the vein. At the entry end 54 of the dissection (see Figure 12A), the cutting head, in the open configuration, is then placed beneath a section of the exposed vein before the two half sections (42.1 , 42.2) are closed about the vein 40 section to enclose the section, as illustrated in Figures 13A and 13B.

[0069] The diameter (D) of the cutting head (and of each of the vessel containing elements 16) can be significantly larger than the diameter (d) of the vein to provide for the passage of a retained cylindrical sheath of fatty / connectivetissue surrounding the vein after the tissue is cut by the cutting edges 38 of the cutting head 12.

[0070] The surgeon can subsequently advance the cutting head beneath the skin, as depicted in Figures 12A and 12B. During this process, the foremost cutting edges 38 of the cutting head will incise or separate tissue. In this specific scenario, as previously explained, a portion of the vein is preserved within a cylindrical mass of tissue. By enclosing the vein within the cutting head, the vein serves as a guiding element.

[0071] The flexible trailing articulated train 14 feature enables the device 10 to follow the tortuous path of the vein. Unlike alternative solutions, like JP2016042987, that address this problem by straightening of the vein, for example using a straight rod placed inside the vein itself, the articulated chain approach proves advantageous. These alternative methods are potentially more traumatic for the vein, they require an access into the lumen of the vein resulting in potential blood loss, a non-dry operating field, and higher risk of potential infections.

[0072] Enclosing the vein 40 within the device markedly diminishes or eliminates friction between the dissected vein and the adjacent tissue. This decrease in friction serves to minimize the potentially injurious shear stress encountered during vein removal. Having the vein 40 encased in a cylindrical tissue sheath improves the patency rates for vein grafts. By safeguarding a layer of surrounding tissue, known as "no-touch harvesting", thereby preserving the structural and functional integrity of the harvested vein, better outcomes andhigher patency rates in coronary bypass surgery have been scientifically observed when compared to traditional harvesting methods.

[0073] Moreover, to be fully encompassed within the cylindrical lumen of the device (10.1 , 10.2, 10.3), the vein would otherwise need to be cut at one end prior to insertion. This may result in the need for inflation of the vein and the concomitant risk of trauma due to overinflation, the risk of accidentally severing the vein due to under-inflation of the vein and consequent sliding of the vein into a side branch dissecting slots 22, and the risk of blood loss and infection.

[0074] As the cutting head 12 is pushed forward to disappear beneath the skin, the first vessel containing elements 16.1 (of any aforementioned embodiment) of the train are closed about a respective section of the vein in the manner described above. The surgeon continues to push it forward, and this sequence is iterated for each subsequent element (16.2, 16.3...16.N) until the complete section of the vein intended for harvesting is contained within the device 10.1 (refer to Figure 12B).

[0075] It is contemplated within the scope of the invention that additional vessel containing elements can be connected to an end of the existing articulated train 14 as needs be, dependent upon the length required of the vein 40. The ball and socket embodiment shown in Figure 19 will aid in this process with the ball 52.1 of each additional element being pushed into the socket 52.2 of the last element in the chain.

[0076] Finally, from an opposed exit end 56, the surgeon will dissect down to expose the cutting head 12. The vein is now ready to be severed at each end(57.1 , 57.2), ligated, and the device 10 pulled from the body to remove the device and the encapsulated vein graft segment.

[0077] The vein 40 will have numerous side branches 58 which laterally extend from the principal vein. For the cutting head to advance in cutting through the tissue surrounding the vein 40, these side branches need to be severed and the blood flow staunched.

[0078] The cutting head 12 does this by deflecting any side branch 58 it encounters off the cutting edge 38, as the head moves forward, and into an adjacent slot 28. Within the slot, the peripheral vein is directed towards a lower cutting region 60 of the slot by the tapered edges 62. This region 60 terminates at the closed end 34 and contains a respective cutting device 30.

[0079] In the example shown in Figures 6A and 6B, the cutting device 30 is equipped with a pair of electrodes or dissectors (these terms are used interchangeably), denoted as 64.1 and 64.2. The vein is directed and locates between these electrodes, which, in this instance, are mobile and form a pair of bipolar forceps. The bipolar forceps serves as the mechanical element within the cutting device 30, incorporating a magnetic or electro-magnetic actuator 92 for electrode movement.

[0080] As will be described below, the dissectors 64 can be automatically actuated, or actuated by an operator of the device, to close together, to pinch the vein (as illustrated in Figure 6B), and to energise. In energising the electrodes, electrical energy passes between the electrodes, generating heat which severs and staunches the side branch.

[0081] Alternatively, as illustrated in Figure 7, the pair of electrodes (64.1 , 64.2) may be immovable, set into respective sides of the slot. In this alternative, actuation only serves to energise the electrodes.

[0082] An energy source 82 supplies alternating current (AC) electrical energy oscillating at radiofrequency (RF-energy). This electrical energy is converted into thermal energy as it travels through the vessel via the electrodes 64. The generated heat serves the purpose of cutting through and sealing the vessel. To prevent potential thermal damage to the main vein or surrounding tissue due to heat conduction, the continuous application of RF-energy is to be avoided. Therefore, it becomes imperative to discern both the timing and location where RF-energy is required. In the context of this invention, it is necessary only when a side branch is detected within one of the dissection slots.

[0083] To prevent thermal damage to the vein 40, the cutting devices 30 are positioned at a distance X from the perimeter of the lumen containing the vein, as shown in Figure 4. This distancing is achieved by the particular configuration of the tubular body 18 in this embodiment. Specifically, the cutting devices are situated in the conical section 18.1 , located radially outward from the cylindrical section 18.2, as depicted in the initial embodiment of the cutting head 12.1 (Figures 1 to 3). Alternatively, in the case of the embodiment depicted in Figure 7, with a cylindrical body, the cutting devices are radially spaced from the inner surface in the cylindrical lumen, facing outwardly.

[0084] The use of movable electrodes presents a distinct advantage, as bringing the electrodes together to constrict the side branch allows for more focused passage of electrical energy. This targeted localization results in a reduction ofthe overall energy required, thereby minimizing the risk of thermal damage to the vein and surrounding tissue. Furthermore, the cauterization process for halting blood flow in the vessel becomes more efficient, leading to a decreased probability of hematomas. This holds particular significance considering the routine administration of blood thinners during bypass operations.

[0085] To prevent the need to continuously apply RF-energy, and only energise the electrodes when a side branch is present in a slot, the blood vessel harvesting device 10 includes a processing module 72 (Figure 9). The processing module, in electronic communication with each cutting device 30, is adapted to detect a change in an electrical property across a pair of electrodes (64.1 , 64.2) and, should the change exceed a limit indicative of the presence of a side branch between the electrode pair, to initiate an action which culminates in the severance of the side branch.

[0086] The preferred electrical property is impedance, although it could alternatively be resistance, capacitance, voltage, current, or conductivity. The selection of this property is based on the unique impedance characteristics exhibited by various tissues. Blood vessels, especially when filled with blood, demonstrate markedly distinct impedance levels compared to connective tissue.

[0087] In this example, the processing module 72 includes a control unit 74, a detector 76, a radiofrequency (RF) generator 78 and a power distribution module 80 which is electrically connected to a power source 82. The power distribution module 80 can be any electrical circuit or component which adapts or regulates parameters from power outlet to supply further components within the processing module and can be a voltage regulator, a transformer, or a power adapter.

[0088] An alarm 83, either visual or auditory, and a dissection activation button 84, which can be hand or foot operated, completes the processing module. Both these components are electronically connected to control unit 74.

[0089] Figure 20 illustrates the blood harvesting device 10.3, with the processing module 72, and the accessory nature of the alarm 83 and the button 84, connected to the flexible trailing articulated train 14. The conductive wiring runs through the train (not shown), terminating at electrode pair (64A, 64B, 64C..) of the cutting devices in the cutting head 12.3.

[0090] The RF generator 78 can be any electrical circuit that transforms an electrical input signal into a high-frequency and high voltage output signal. The RF generator can include a signal generator, an amplifier, a frequency tuning circuit, or voltage transformation circuit.

[0091] The detector 76 can be any electrical circuit or component that detects side branches by measuring the impedance, change of voltage, and / or current of tissue inside the electrode pairs. The detector can include an impedance analyser, a LCR circuit, a LCR meter, a Wheatstone Bridge, a voltage measurement circuit, or a current measurement circuit.

[0092] The control unit 74 can include a control unit (MCU), microprocessor, or System-on-Chip (SoC). The control unit is electronically connected to the detector 76, the RF generator 78, power distribution (80) and each electrode pair (64A, 64B, 64C) to control the activation and deactivation of each of these components.

[0093] Each pair of electrodes (designated 64A, 64B and 64C) is connected in a respective detection circuit to the detector 76. Each detection circuit is closed by a respective circuit specific switch 86 (designated 86 on the detection circuit including electrode pair 64C merely for ease of illustration) and a first master switch 88.

[0094] Each pair of electrodes is also connected in a respective dissection circuit to the RF generator 78. Each dissection circuit is closed by the circuit specific switch 86 and a second master switch 90.

[0095] It is preferable that each circuit specific switch 86 comprises a pair of switches (86.1 , 86.2), each associated with an electrode of the pair, interrupting both the “supply” and “return” lines. This configuration is advantageous because if only the supply line is interrupted without affecting the return line, there is a risk of current flow through all return lines of electrode pairs (and vice versa with supply lines). In simpler terms, given that the electrodes share the same medium, there is potential for current exchange between pairs.

[0096] A switch can be any of the following: a transistor (e.g. MOSFET), a relay (e.g. solid-state relay), a digital logic gate, a TRIAC, a thyristor, a solid-state switch, a programmable logic component, or an electromagnetic switch.

[0097] Following the sequence illustrated in Figure 10A, the detector and control unit systematically interrogate each electrode pair to ascertain the presence or absence of a side branch. Commencing with electrode pair 64A, for example, the control unit closes the circuit-specific switch 86 to activate the corresponding detection circuit. The detector gauges the impedance across the electrodes, and if there is no discernible change indicating the presence of a side branch, thecontrol unit opens the detection circuit. Subsequently, the detection circuit involving electrode pair 64B is engaged, with the circuit-specific switch being controlled by the control unit. This process repeats until a side branch is identified. Throughout this sequential detection cycle, the first master switch 88 remains closed.

[0098] Upon detecting a side branch, such as between electrode pair 64B, the control unit will deactivate all detection circuits by opening the first master switch 88 and activate a dissection circuit by closing the second master switch 90. The only energized dissection circuit will be the one containing electrode pair 64B, as only this circuit-specific switch remains in the closed position from the previous detection cycle. All other circuit-specific switches will be in the open position.

[0099] With energisation of the electrodes, and the heat generated, the side branch is severed and staunched.

[0100] As an alternative sequence, illustrated in Figure 10B, instead of an automated deactivation of the detection circuits by opening the first master switch 88 and activation of the dissection circuits by closing the second master switch 90, an operator controlled intervention is provided.

[0101] Upon detecting a side branch, the control unit triggers the alarm to produce an auditory or visual signal. This signal serves as feedback to alert the operator about the side branch's presence, prompting them to press the button. This action deactivates the detection circuits by opening the first master switch 88 and activates the dissection circuits by closing the second master switch. The outcome mirrors the initial sequence, with the electrodes being energized,generating heat, and resulting in the severance of a side branch located between electrode pair 64B, following the example.

[0102] By being configured in this manner, the invention's device (10.1 , 10.2, 10.3) holds a distinct advantage over existing minimally invasive vein harvesting devices in the market. Unlike its counterparts, it eliminates the need for an endoscope, as the design inherently enables the operator to determine the presence of a side branch within the dedicated RF-dissection element without additional visual aids.

Claims

CLAIMS1 . A blood vessel harvesting device (10) which includes: a tissue separating and side branch cutting head (12) having: a tubular body (18) which has an inner surface (20.1 ) and an outer surface (20.2), and which extends between a leading end (22) and a trailing end (24), the leading end being adapted to separate or cut tissue surrounding a blood vessel (40) to be harvested, a lumen (26) defined within the inner surface, and which opens at the leading and trailing ends, and adapted to receive a part of the blood vessel, a plurality of slots (28) formed through the body and extending in a longitudinal direction between an open end (32), and a closed end (34), each adapted to receive a side branch (58) and to channel the side branch towards the closed end, a plurality of cutting devices (30), each associated with a respective slot, and each having a pair of dissectors adapted to sever the side branch, and a processing module (72), characterised in that the processing module is adapted to detect a change in an electrical property across a pair of dissectors and, should the change exceed a limit which is indicative of the presence of a side branch between the pair ofdissectors, to initiate an action to energise the pair of dissectors to sever the side branch.

2. A blood vessel harvesting device according to claim 1 wherein the processing module includes a detector (76) which is electronically connected to each pair of dissectors in a respective detection circuit, and which is adapted to measure the electrical property across a pair of dissectors, when the respective detection circuit is closed by a circuit specific switch and a first master switch.

3. A blood vessel harvesting device according to claim 2 wherein the processing module includes a control unit(74) which is adapted to sequentially close the detection circuit for each pair of dissectors at the circuit specific switch, facilitating the measurement of the electrical property, and to open the detection circuit at the circuit specific switch when the measurement received from the detector does not indicate the presence of a side branch.

4. A blood vessel harvesting device according to claim 2 or 3 wherein the processing module includes an ablation generator (78) which is electrically connected to each pair of dissectors in a respective dissection circuit, and which is adapted to energise a pair of dissectors, when the respective dissection circuit is closed by the circuit specific switch and a second master switch.

5. A blood vessel harvesting device according to claim 4 wherein the control unit is adapted to open all detection circuits at the first master switch, when the measurement received from the detector indicates the presence of a side branch between a pair of dissectors, and to close the respective dissection circuit at the second master switch to energise that pair of dissectors.

6. A blood vessel harvesting device according to claim 4 wherein the processing module includes an alarm (82) which is activated by the control unit to emit an alarm signal when the measurement received from the detector indicates the presence of a side branch between a pair of dissectors.

7. A blood vessel harvesting device according to claim 6 wherein the processing module includes an actuator (84) which is adapted to open all detection circuits at the first master switch, when actuated in response to an alarm signal, and to close the respective dissection circuit at the second master switch to energise the pair of dissectors.

8. A blood vessel harvesting device according to anyone of claims 2 to 8 wherein each circuit specific switch comprises two switches, configured to interrupt both supply and return lines of the circuit.

9. A blood vessel harvesting device according to anyone of claims 1 to 8 wherein each pair of dissectors is either a moveable pair of dissectors, adapted to move towards and away from one another, or an immoveable pair of dissectors.

10. A blood vessel harvesting device according to claim 9 wherein the moveable pair of dissectors includes an actuator (86), which is electrically interposed in the respective dissection circuit between the ablation generator and the pair of dissectors, and which actuates the pair of movable dissectors to move when the dissection circuit is energised.1 1. A blood vessel harvesting device according to anyone of claims 1 to 10 wherein the tubular body (18) is comprised of half tubular sections (42.1 , 42.2)defined between the leading end and the trailing end and a first and a second longitudinal edge (44, 46).

12. A blood vessel harvesting device according to claim 1 1 wherein each half section (42.1 , 42.2) is discrete, adapted to engage the other along the first and second longitudinal edges to form the tubular body (18).

13. A blood vessel harvesting device according to claim 10 wherein the two half sections (42.1 , 42.2) are connected along respective first longitudinal edges (44) to allow the half sections to move between an open position, in which the respective second longitudinal edges (46) are spaced apart, and a closed position, in which the respective second longitudinal edges meet to form the tubular body (18).

14. A blood vessel harvesting device according to anyone of claims 1 to 13 wherein each slot (28) is tapered or partially tapered to guide the side branch to the closed end.

15. A blood vessel harvesting device according to anyone of claims 1 to 14 wherein the slots (28) are equally radially spaced about the body.

16. A blood vessel harvesting device according to anyone of claims 1 to 15 wherein the leading end is adapted with a plurality of cutting edges (38), each between a pair of adjacent slots.

17. A blood vessel harvesting device according to anyone of claims 1 to 16 wherein each cutting device is radially spaced from a perimeter of the lumen.

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