WO2009103951A2

WO2009103951A2 - Surgical tool and method of use

Info

Publication number: WO2009103951A2
Application number: PCT/GB2009/000412
Authority: WO
Inventors: Adam Paul Fitzpatrick
Original assignee: Central Manchester University Hospitals Nhs Foundation Trust
Priority date: 2008-02-20
Filing date: 2009-02-16
Publication date: 2009-08-27
Also published as: WO2009103951A3; GB0803055D0

Abstract

A surgical tool for use in upgrading an implantable pulse generator in a patient has an arm with a flesh-piercing head having a sheath adapted to mate with a terminal of an implantable electrical lead. When a further cardiac electrical lead needs to be implanted in a patient's heart, damage caused by earlier implantation of cardiac electrical leads from a first side of the heart can be avoided by implanting the new lead from the contralateral side. The head of the tool is used to form a tunnel through the subcutaneous flesh of the patient so that the new lead can pass from the contralateral side, through the tunnel, to the first side for connection to an implantable pulse generator. The tool has a sheath into which the terminal of a lead can be mated to allow the lead to be drawn through the tunnel by the tool or to be slid through the tunnel along a conduit in the tool. The tool may be adapted to provide local anaesthetic at the cutting head as the tunnel is formed, and may have a detachable cutting head to facilitate withdrawal of the tool after the tunnel has been cut.

Description

Surgical Tool and Method of Use

The present invention is concerned with tools for use in performing surgical operations on humans or animals, particularly humans. In particular, it relates to tools for use in surgical procedures related to the implantation of endocardial implantable cardiac electrical leads. More specifically, the invention relates to a surgical tool for use in procedures to supplement or upgrade an existing implanted endocardial stimulation system of a patient.

Implantable medical electrical leads for use in stimulation or sensing of heart activity are well known in the fields of cardiac stimulation and monitoring. For instance, the leads may be used for cardiac pacing (pacemakers) and cardioversion/defibrillation. In the field of cardiac stimulation and monitoring, endocardial electrical leads are generally put in place through a transvenous route to the heart in order to insert a sensing and/or stimulation electrode at the distal terminal of the electrical lead at a site in a chamber of the heart or a blood vessel of the heart. In order to achieve reliable sensing of the cardiac electrogram or to apply stimulation that effectively paces or cardioverts the heart muscles, it is necessary to fix the electrode surface against the endocardium or within the myocardium at the desired site. Following the operation to implant the electrical lead, fibrous tissue growth occurs, holding the electrode in place.

For pacemaking or cardioversion/defibrillation, an implantable pulse generator (IPG) or the monitor is typically coupled to the electrodes implanted in the heart tissue through one or more endocardial electrical leads. The ends of the leads for connection to the IPG typically are formed with a connector or terminal, which connects to an electrode or connector of the IPG. The endocardial electrical lead suitably comprises one or more insulated conductive wires surrounded by an electrically insulating outer sleeve.

An endocardial electrical lead having a single stimulation electrode at the heart or distal end of the lead and a single conductive wire with a single terminal for connection to the IPG is referred to as a unipolar lead. An endocardial electrical lead having two or more stimulation electrodes at the heart or distal end and two or more conductive wires for connection to the IPG is referred to as a bipolar lead or a multi-polar lead, respectively.

In order to implant an endocardial lead within a heart chamber, a transvenous approach is usually made, and the lead is inserted into and passed through the subclavian, jugular, or cephalic vein and through the superior vena cava into the right atrium or ventricle. An active or passive fixation mechanism is incorporated into the distal or heart end of the endocardial lead and deployed to maintain the distal end electrode in contact with the heart tissue. The most widely used active fixation mechanism employs a sharpened helix or screw as the electrode. The screw is shielded during the transvenous advancement into the heart chamber the helix then, once at the required site, unshielded advanced and rotated to give a penetrating, screw-in fixation of the electrode

Typically, simple, existing cardioverter defibrillator systems will have one or more endocardial electrical leads implanted through the left subclavian vein, into the left brachiocaphalic vein, through the right atrium and with an electrode embedded in the inner wall of the right atrium and/or right ventricle.

It has now been found that it is highly desirable, for patients with heart failure, to provide pacing of the left ventricle in addition to conventional cardioversion/defibrillation to the right side of the heart. The incorporation of the additional endocardial electrical lead to provide CRT (cardiac resynchronization therapy) can provide increased life expectancy for a heart failure patient having an existing implanted ICD which may provide only cardioversion/defibrillation.

One option would be to replace the existing ICD with a biventricular pacemaker (BVP) system. However, because of the scarring and fibrous tissue that will have arisen from the original implantation of endocardial leads for the existing ICD, it is highly desirable to leave these leads in place. Rather than removing and replacing the existing leads, resulting in further scarring and fibrous tissue generation, the existing leads may be left to function as previously, with a supplementary lead or leads being implanted to provide biventricular pacemaking for CRT.

Unfortunately, central venous occlusion or stenosis from the original lead implantation often means that the implantation of a supplementary left ventricular endocardial lead cannot be safely achieved in parallel with the existing implanted endocardial leads. Instead, it has been found that a safer route is to implant the new left ventricular lead from the contralateral side of the heart to the existing ICD system. This minimizes the peri- and post-operative risk to the patient. Such a surgical procedure is detailed in "Upgrading patients with chronic defibrillator leads to a biventricular system and reducing patient risk: contralateral LV lead placement" by DJ Fox, S Petkar, NC Davidson and AP Fitzpatrick in Pacing Clinical Electrophysiology, 2006, September, 29(9): 1025-7.

Conventionally, because most patients are right handed, and because it is desirable to minimize strain on the endocardial leads in the neighbourhood of the shoulder joint and clavicle, the left side of the heart (i.e. the patient's left side) is chosen as the implantation site for the IPG.

However, the shock vector for an ICD shock is more effective if delivered by an implanted lead in the right ventricle of the heart with the ICD generator placed on the left side under the skin or muscle. This is because more of the myocardial muscle will be "captured" between the shocking poles. If the lead is placed in the right ventricle from the right side, but the generator box is on the right side, the vector is far from ideal, although still effective.

It is thus desirable, when adding a supplementary endocardial lead or leads and/or IPG for CRT for a patient with an existing IPG implanted on the left of the patient's heart, for the supplementary endocardial lead to be guided into the heart from an incision on the right (contralateral) side, but for the IPG or replacement IPG to remain on the left side of the heart. Hence, there is a need for a means to allow the proximal terminal or terminals (i.e. intended for connection to an IPG terminal) of a supplementary endocardial lead or leads to reach the IPG terminal or terminals for connection when the lead terminals, immediately following implantation, are on the contralateral side of the heart to the IPG. For safety and health reasons, in addition to aesthetic reasons, it is desirable that the leads should be concealed under the skin of the patient.

Hence, one object of the invention, amongst others, is to provide a surgical tool which can be used to provide a route, under the skin of the patient, to allow the terminal or terminals of the supplementary endocardial lead or leads to be pulled or slid through from their initial location after insertion, on one side of the chest, to the location of an IPG on the other, contralateral side of the chest. It is another object of the invention to provide a tool that can be used to pull or to provide a route through which to slide the terminal or terminals of the supplementary endocardial lead or leads through the route, under the skin of the patient, from their initial location after insertion on one side of the chest to the location of the IPG on the other, contralateral side of the chest.

Hence, a first aspect of the invention provides a surgical tool comprising an arm having a proximal end and a distal end, the distal end comprising a head, the head comprising a base connected to the distal end of the arm and a tip adapted to pierce flesh, and the distal end of the arm further comprising a sheath adapted to mate with a terminal of an implantable electrical lead.

The sheath may comprise a gripping means adapted to releasably grip a terminal of an implantable electrical lead. Suitably, the sheath may form a conduit from an inlet aperture at the proximal end of the arm to an outlet aperture adjacent to the tip, whereby one or more implantable electrical leads may be slid along the conduit. The arm is suitably stiff so that it may be used to push the flesh-piercing tip through the patient's flesh. The tool is suitably formed from a non-corroding material such as surgical steel, which may be easily sterilised after use. The tool might also be formed from a rigid polymeric material. The tool may be a disposable tool, intended for single use only or it may be a multi-use tool.

The surgical tool may be used as follows in a surgical procedure to add a supplementary endocardial lead to a patient. The new lead will be inserted into the heart from a second contralateral pocket or incision in the patient, and positioned as required in the heart. A first incision or pocket will also be formed at the site of the existing implanted IPG. The flesh-piercing tip of the head the surgical tool may be inserted into the patient's skin at the side of the existing IPG, and pushed, suitably using the proximal end of the arm of , the surgical tool as a handle, through the patient's flesh, subcutaneously, to form a tunnel between the first pocket and the second, contralateral pocket, under the patient's skin. When the head of the tool is accessible at the second pocket, with the arm still in the tunnel, the proximal terminal of the supplementary endocardial lead may be placed in the sheath. The tool may then be drawn back through the tunnel, again suitably using the proximal end of the arm as a handle, acting to guide the proximal terminal of the supplementary endocardial lead through the tunnel. If no gripping means is provided, the lead can be pushed through the tunnel, keeping it mated in the sheath as the tool is withdrawn. Preferably, the sheath is provided with a gripping means and the gripping means configured to grip the terminal so that the lead can be dragged through the tunnel by the tool. As the head of the tool is pulled back to the first pocket, the terminal of the supplementary endocardial lead is also drawn back into that pocket, held in the gripping means. Once at the first pocket, the terminal can be released from the gripping means and attached to an appropriated terminal of the IPG located in the first pocket. This may be the existing IPG or a replacement IPG to be fitted during the same surgical procedure. The pockets may then be closed, leaving the supplementary endocardial lead connecting the IPG in the first pocket, through the tunnel and via the second pocket, to the heart. Clearly, if there are several endocardial leads or terminals, the surgical tool may be provided with a plurality of sheaths and optionally releasable gripping means. For example, some ICD leads have three terminal ends, one for pacing and sensing, and two for connections to mounted coils that form part of a shocking circuit. The head, sheath and optional gripping means of the device may be adapted to accommodate all these terminal ends if a new ICD lead is required on the first side, but the veins of the first side of the chest are occluded, preventing access.

In a preferred version of the tool, the sheath may form a conduit from an inlet aperture at the proximal end of the arm to an outlet aperture adjacent to the tip, whereby one or more implantable electrical leads may be slid along the conduit. This tool may be used as described above, but rather than using the tool to drag or guide the new endocardial lead through the tunnel formed by the tool, the lead or leads are slid along the conduit, through the tool, from the contralateral pocket to the first pocket. The tool can than be extracted from the tunnel, sliding past the new lead (or leads) and leaving it behind in the tunnel.

Suitably, as a second aspect of the invention according to the first aspect of the invention, the head of the tool may be removable. Suitably, the distal end of the arm comprises a connector means for connecting the head to the distal end of the arm, the connector means being adapted to releasably engage with an engagement means of the head, wherein the head is a detachable head having a base comprising the engagement means of the head, the engagement means being adapted to releasably engage with the connector means of the distal end of the arm, whereby the surgical tool has a first configuration with the detachable head rigidly attached to the distal end of the arm, and a second configuration with the detachable head removed from the distal end of the arm.

This second aspect of the tool has further advantages, in that it allows the flesh- piercing head of the tool to be removed prior to mating or connecting the terminal or terminals of the supplementary endocardial lead(s) and guiding or pulling the lead or leads back through the tunnel formed by the tool. Similarly, if the tool has a conduit for guiding the lead(s), the head can be removed prior to pulling the tool back through the tunnel. This provides the advantage that the head of the tool can be of a shape, such as an arrowhead or lanceolate shape, that is advantageous for forming the tunnel, but which might cause needless tearing when retracted back through the tunnel. Detaching the head avoids the risk of such tearing.

Suitably, for the second aspect of the invention, the engagement means comprises one or more male members and the connector means comprises one or more female members in the distal end of the arm adapted to mate with the male members. The female members may, for instance, have a tapped hole extending from an inside wall of each female member to an outside surface of the arm, and a screw fitting the tapped hole adapted to grip the respective male member when tightened.

Suitably, the surgical tool of the second aspect of the invention has a gripping means adapted to grip the terminal of the implantable electrical lead when the surgical tool is in the second configuration, i.e. with the detachable head removed.

A further advantage of this second aspect of the invention is that the sheath or conduit at the distal end of the tool may be covered by the detachable head when the tool is in the first configuration, and revealed when the tool is in the second configuration. This helps to prevent the sheath having the flesh of the patient unintentionally captured within it as the piercing head of the tool is advanced to form the tunnel.

For either the first or second aspects of the invention, the sheath in the distal end of the arm adapted to mate with the with said terminal of an implantable electrical lead may also comprise a gripping means. For instance the sheath may be provided with a tapped hole extending from an inside wall of the sheath to an outside surface of the arm and a screw fitting the tapped hole adapted to grip said terminal when tightened. The screw may typically be a grub screw or may be a countersunk screw. Preferably, the screw head does not project beyond the surface of the tool when the screw is fully tightened.

Suitably, the sheath or conduit may form or act as the female member of the connector means of the second aspect of the invention.

Hence, when the tool has been advanced through the tunnel from the first to the second pocket, the connector means in the distal end of the arm may act as a sheath for mating with and optionally gripping the terminal of the implantable lead, once the detachable head has been removed such that the tool is in its second configuration. This is advantageous in that only one means is needed to act as both the terminal for the lead and also to act as a connector means for the detachable head.

The following preferred features apply to both the first and second aspects of the invention, where appropriate.

The tool suitably has a length, measured from the tip to the proximal end of the arm, from 15 to 60 cm, preferably from 18 to 50 cm, more preferably from 20 to 40 cm. This allows for the tool to extend from a pocket on one side of the chest to a pocket in its other side without the tool being unwieldy. The maximum width of the tool, measured normal to its long axis, is suitably less than 15 mm, preferably less than 10 mm, more preferably less than 7mm and even more preferably less than 5 mm; this allows the tool to penetrate the flesh of a patient without excessive damage. The tool is suitably greater than 1mm in width to provide adequate stiffness for penetrating flesh.

The tool may be such that the distal end of the arm comprises a plurality of sheaths, each optionally with gripping means adapted to mate with a terminal of an implantable electrical lead. Suitably, the head may be substantially pyramidal or conical in shape, tapering from the base the tip. The tip may be substantially a point.

Suitably, the base of the head is of a shape to match the distal end of the arm of the tool, such that the base does not project beyond the outer surface of the distal end of the arm. This helps to prevent the tunnel being unnecessarily large and also helps to prevent tearing when the tool of the first aspect of the invention is retracted, or should the tool of the second aspect of the invention need to be retracted prior to reaching the second pocket. However, it is found that a lanceolate shape for the distal end of the tool is particularly effective. By lanceolate is meant a flattened ovoid shape with a point at the tip.

Suitably, the surgical tool of either aspect of the invention comprises a duct adapted to conduct fluid and extending from an inlet port at the proximal end of the arm to one or more outlet ports adjacent to the tip.

This feature allows a local anaesthetic to be pumped out of the one or more outlet ports as the flesh-piercing head of the tool is advanced under the patient's skin to form the tunnel. This gives the advantage that the tunnelling procedure may be carried out without the need to put the patient under general anaesthetic, using conscious sedation to supplement local anaesthetic instead. As the supplementary lead implantation and any IPG replacement may also generally be carried out under local anaesthetic, this feature of the tool allows for the entire surgical procedure to be carried out without need for general anaesthetic, making the procedure both more rapid and also safer for the patient, who does not need to undergo the risks of general anaesthesia. Such a procedure also obviates the need for a qualified anaesthetist to be present, reducing labour costs.

Suitably, the tool may have one or more outlet ports are situated at loci within 1 cm of the tip. The proximity of the outlet ports to the tip means that the local anaesthetic pumped out of the port can numb the patient locally as the piercing head of the tool is gradually and progressively advanced from the first pocket to the second pocket.

Suitably, the sheath may form part of the duct. The duct may comprise a first duct section inside the arm extending from the inlet port to a first aperture in the distal end of the arm and a second duct section inside the head extending from a second aperture in the base of the head to the one or more outlet ports adjacent to the tip, and wherein the first and second apertures are in fluid connection. The first and second duct sections are suitably connected at a fluid-tight joint between the first and second apertures.

The first duct section is suitably the conduit formed by the sheath when this forms a conduit from an inlet aperture at the proximal end of the arm to an outlet aperture adjacent to the tip, whereby one or more implantable electrical leads may be slid along the conduit. In this case, the inlet port of the first duct section is the inlet aperture of the conduit and first aperture of the first duct section is the outlet aperture of the conduit.

Suitably, the inlet port of the duct may be provided with a syringe whereby a fluid, such as a local anaesthetic composition, may be pumped from the syringe into the inlet port of the conduit, through the conduit and out of the one or more outlet ports. The syringe may be integral with the tool, but preferably the inlet port of the duct is provided with an inlet port engagement means adapted to lockingly engage with an outlet port connection means of a syringe to form a fluid-tight connection whereby a fluid may be pumped from the syringe into the inlet port of the conduit, through the conduit and out of the one or more outlet ports, whereby the syringe may be disengaged from the inlet port. Where the sheath forms a conduit extending along the length of the arm of the tool, such that a lead or leads can be slid through the tool, it is convenient to remove the syringe to provide access to the conduit for the lead(s). A suitable commercially available and standardized engagement means for allowing a syringe to lock with an inlet port engagement means is known as a Luer™ lock.

In order to assist in the handling of the tool, the proximal end of the tool is suitably provided with a handle adapted for gripping the tool.

A third aspect of the invention provides a detachable head for a surgical tool according to the second aspect of the invention. The preferred features detailed above also apply to the third aspect of the invention, where appropriate.

A fourth aspect of the invention provides an arm for a surgical tool of the second aspect of the invention! The preferred features detailed above also apply to the fourth aspect of the invention, where appropriate.

A fifth aspect of the invention provides a method for upgrading a cardiac pacemaker implant in a patient having a pulse generator assembly already implanted in a first pocket on a first side of said patient's chest, involving using the tool according to the invention to draw leads through a tunnel between the contralateral and first pockets by the tool.

The method comprises:

a) inserting and implanting one or more additional implantable electrical leads into the patient's heart through one or more blood vessels from a second side of the chest, contralateral to the first side, whereby the termini of the one or more additional implantable electrical leads are located in a contralateral pocket,

b) opening the first pocket to provide access to the implanted pulse generator assembly, c) pushing the tip of a tool according to the first aspect of the invention from the first pocket to the contralateral pocket through the subcutaneous flesh of the patient to form a tunnel between the first pocket and the contralateral pocket,

d) optionally providing a flow of a local anaesthetic fluid from the inlet port to the one or more outlet ports of the outlet port of the surgical tool, when the tool comprises a duct adapted to conduct fluid, such as local anaesthetic, as detailed hereinbefore,

e) mating and optionally releasably gripping the one or more termini of the one or more implantable electrical leads with the one or more sheaths of the tool, after first detaching the head of the surgical tool when this is a tool according to the second aspect of the invention,

f) drawing the surgical tool back though the tunnel, with the one or more implantable electrical leads guided through the tunnel from the contralateral pocket into the first pocket by means of their respective termini mated in the one or more sheaths,

g) unmating the termini from the sheaths, removing the tool from the patient and connecting the termini to either the existing implanted pulse generator, or to a second pulse generator which replaces or supplements the existing implanted pulse generator, and

h) closing the first and contralateral pockets.

A sixth aspect of the invention provides a method for upgrading a cardiac pacemaker implant in a patient having a pulse generator assembly already implanted in a first pocket on a first side of said patient's chest, involving using the tool according to the invention to slide leads, along a conduit in the tool, through a tunnel between the contralateral and first pockets by the tool. The method comprises;

b) opening the first pocket to provide access to the implanted pulse generator assembly,

c) pushing the tip of a tool according to the first aspect of the invention from the first pocket to the contralateral pocket through the subcutaneous flesh of the patient to form a tunnel between the first pocket and the contralateral pocket, wherein the tool has a sheath forming a conduit from an inlet aperture at the proximal end of the arm to an outlet aperture adjacent to the tip of the tool.

e) sliding the one or more implantable electrical leads along the conduit in the arm of the tool from the outlet aperture adjacent to the tip to the inlet aperture at the proximal end of the arm, after first detaching the head of the surgical tool when this is a tool according to the second aspect of the invention,

f) drawing the arm of the surgical tool back though the tunnel and removing it from the patient, leaving the one or more electrical leads in place in the tunnel,

g) connecting the termini to either the existing implanted pulse generator, or to a second pulse generator which replaces or supplements the existing implanted pulse generator, and h) closing the first and contralateral pockets.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a plan elevation of a first embodiment of a surgical tool according to the first aspect of the invention. The head of the tool is also shown enlarged in the figure.

Figure 2 shows a side elevation of the head and distal end of the arm of the first embodiment in cross section through the central long axis of the tool.

Figure 3 shows a plan elevation of a second embodiment of a surgical tool according to a second aspect of the invention. The head 10 of the tool, shown connected to the distal end 8 of the arm 1 is also shown enlarged in the figure.

Figure 4 shows a side elevation of the distal end of the arm 1 and the detachable head 10 of the second embodiment in cross section through the central long axis of the tool.

Figure 5 shows a plan elevation of a third embodiment of a surgical tool according to the second aspect of the invention. The third embodiment includes a conduit for delivery of local anaesthetic. The head 10 of the tool, shown connected to the distal end 8 of the arm 1 is also shown enlarged in the figure.

Figure 6 shows a side elevation of the distal end of the arm 1 and the detachable head 10 of the third embodiment in cross section through the central long axis of the tool.

Figure 7 shows a plan elevation of a fourth embodiment of a surgical tool according to the second aspect of the invention. The fourth embodiment includes a conduit for delivery of local anaesthetic. The head 10 of the tool, shown connected to the distal end 8 of the arm 1 is also shown enlarged in the figure.

Figure 8 shows a plan elevation of the distal end of the arm 1 and the detachable head 10 of the fourth embodiment in cross section through the central long axis of the tool.

Figure 9 shows a side elevation of the distal end of the arm 1 and the detachable head 10 of the fourth embodiment in cross section through the central long axis of the tool.

Figure 10 shows a schematic plan elevation of a fifth embodiment of a surgical tool according to the second aspect of the invention. The fifth embodiment includes a conduit 22 extending along the full length of the tool acting as a conduit for delivery of local anaesthetic and to allow a lead to be slid through the tool. A syringe 21 is also shown in the figure. The head 10 of the tool, shown connected to the distal end 8 of the arm 1 is also shown enlarged in the figure.

Figure 11 shows a schematic plan elevation of the distal end of the arm 1 and the detachable head 10 of the fifth embodiment in cross section through the central long axis of the tool.

Figure 12 shows a side elevation of the distal end of the arm 1 and the detachable head 10 of the fifth embodiment in cross section through the central long axis of the tool.

Turning now to the first embodiment as shown in figures 1 and 2, the tool has a stiff cylindrical arm 1 , 25 cm in length and 5 mm in diameter. The arm 1 is of surgical steel. At the distal end 8 a head 2 is formed as a cone ending in a flesh- piercing tip 3. A gripping means in the head 2 consists of a sheath or borehole 4 with a tapped hole 6 leading from the outer wall of the distal end 8 of the arm 1 to the inner wall of the borehole 4, and a grub screw 5 which engages with the tapped hole 6.

In use, the tool is gripped by a surgeon at the proximal end 7 and the tip 3 is pushed through a patient's flesh from a first pocket at one side of the patient's heart to a second contralateral pocket at the other side of the patent's heart, where a proximal end of an implantable electrical lead is located, following the earlier implantation of the distal end of the lead into the heart wall. The proximal terminal of the implantable electrical lead is inserted to mate into the borehole sheath 4 and then the grub screw 5 is tightened in the hole 6 in order to firmly grip the terminal. The surgeon, grasping the proximal end 7 of the tool then withdraws the head 2 back through the tunnel formed in the patient's flesh, pulling the proximal end of the implantable lead with it. When the head 2 is back at the first pocket, the grub screw 5 is loosened allowing the terminal to be removed from the borehole 4. The tool may then be set aside and the proximal terminal of the implanted lead connected to an IPG terminal on an IPG in the first pocket.

Turning now to the second embodiment, as shown in figures 3 and 4, the tool has a stiff cylindrical arm 1 , 25 cm in length and 5 mm in diameter. The arm 1 is of surgical steel. At the distal end 8 of the arm, a detachable head 10, also of surgical steel, is firmly attached to the distal end 8 of the arm. The detachable head 10 is formed as a cone ending in a flesh-piercing tip 3. The detachable head 10 has a male member 11 fitting into a borehole sheath 12 centrally positioned in the distal end 8 of the arm 1. A tapped hole 6 leads from the outer wall of the distal end 8 of the arm 1 to the inner wall of the borehole sheath 12, and a grub screw 5 engages with the tapped hole 6 so that it can be screwed into and out of the hole 6. The engagement means of the detachable head 10 is formed by the male member 11 , with the borehole sheath 2, tapped hole 6 and grub screw 5 forming the connector means of the distal end 8 of the arm 1. The detachable head is held firmly in place when grub screw 5 is tightened in tapped hole 6 to press against male member 11 , and the detachable head is released by unscrewing grub screw 5.

The connector means of the distal end 8 of the arm 1 also acts as the gripping means for this embodiment, as is explained below.

In use, the tool is first configured with the detachable head 10 firmly held in place on the distal end 8 of the arm 1 by tightening the grub screw 5 onto the male member 11. The tool is then gripped by a surgeon at the proximal end 7 and the tip 3 is pushed through a patient's flesh from a first pocket at one side of the patient's heart to a second contralateral pocket at the other side of the patent's heart, where a proximal end of an implantable electrical lead is located, following the earlier implantation of the distal end of the lead into the heart wall. The detachable head 10 is detached from the distal end 8 of the arm 1 by unscrewing the grub screw 5 in the tapped hole 6 such that the male member 11 is no longer gripped and can be pulled out of the borehole sheath 12 to remove the detachable head 10 from the distal end 8 of the arm 1. The proximal terminal of the implantable electrical lead is then inserted into the borehole 12 and the grub screw 5 is tightened in the hole 6 in order to firmly grip the terminal. The surgeon, grasping the proximal end 7 of the tool then withdraws the arm 1 back through the tunnel formed in the patient's flesh, pulling the proximal end of the implantable lead with it. When the distal end 8 of the arm 1 is back at the first pocket, the grub screw 5 is loosened allowing the terminal to be removed from the borehole 12. The tool arm 1 may then be set aside and the proximal terminal of the implanted lead connected to an IPG terminal on an IPG in the first pocket.

Turning now to the third embodiment, as shown in figures 5 and 6, the tool has a stiff cylindrical arm 1 , 25 cm in length and 5 mm in diameter. The arm 1 is of surgical steel. A first duct 22 in the form of a cylindrical borehole runs from an inlet port at the proximal end 7 to a first aperture in the distal end 8 of the arm 1. At the proximal end 7, the inlet port is provided with a Luer™ lock arrangement 20 connecting the duct 22 to a syringe 21 containing a liquid local anaesthetic solution.

At the distal end 8 of the arm, a detachable head 10, also of surgical steel, is firmly attached to the distal end 8 of the arm. The detachable head 10 is formed as a cone ending in a flesh-piercing tip 3. The detachable head 10 has a hollow male member 13 fitting into a first aperture of duct 22 centrally positioned in the distal end 8 of the arm 1. A tapped hole 6 leads from the outer wall of the distal end 8 of the arm 1 to the inner wall of the duct 22, and a grub screw 5 engages with the tapped hole 6 so that it can be screwed into and out of the hole 6.

The engagement means of the detachable head 10 is formed by the hollow male member 13, with the first duct 22, tapped hole 6 and grub screw 5 forming the connector means of the distal end 8 of the arm 1. The detachable head is held firmly in place when grub screw 5 is tightened in tapped hole 6 to press against hollow male member 15, and the detachable head is released by unscrewing grub screw 5.

The detachable head 10 has a second duct section 24 within it, extending from a second aperture in the end of the hollow male member 13 and leading to outlet ports 23 adjacent to the tip 3 of the detachable head. An o-ring seal 25 provides a fluid-tight connection where the male member 13 mates with the first duct 22 at the distal end 8 of the arm 1.

In use, the tool is first configured with the detachable head 10 firmly held in place on the distal end 8 of the arm 1 by tightening the grub screw 5 onto the male member 13. This results in the liquid anaesthetic in the syringe being put into fluid connection with the outlet ports 23 in the detachable head 10, via Luer™ lock 20, first duct 22, and second duct 24. The tool is then gripped by a surgeon at the proximal end 7 and the tip 3 is pushed through a patient's flesh from a first pocket at one side of the patient's chest towards a second contralateral pocket at the other side of the patent's chest, where a proximal end of an implantable electrical lead is located, following the earlier implantation of the distal end of the lead into the heart wall.

As the tip 3 is advanced through the patient's flesh, the surgeon may pause and pump anaesthetic solution from the syringe 21 to the outlet ports 23 in order to numb the patient's flesh, allowing the procedure to take place without need for general anaesthetic.

When the head eventually arrives at the contralateral pocket, the detachable head 10 is detached from the distal end 8 of the arm 1 by unscrewing the grub screw 5 in the tapped hole 6 such that the hollow male member 13 is no longer gripped and can be pulled out of the first conduit 22 to remove the detachable head 10 from the distal end 8 of the arm 1. The proximal terminal of the implantable electrical lead is then inserted into the first aperture of the conduit 22 in the distal end 8 of the arm 1 and the grub screw 5 is tightened in the hole 6 in order to firmly grip the terminal. The surgeon, grasping the proximal end 7 of the tool then withdraws the arm 1 back through the tunnel formed in the patient's flesh, pulling the proximal end of the implantable lead with it. When the distal end 8 of the arm 1 is back at the first pocket, the grub screw 5 is loosened allowing the terminal to be removed from the borehole 12. The tool arm 1 may then be set aside and the proximal terminal of the implanted lead connected to an IPG terminal on an IPG in the first pocket.

Turning now to the fourth embodiment, as shown in figures 7, 8 and 9, the tool has a stiff cylindrical arm 1 , 25 cm in length and 5 mm in diameter. The arm 1 is of surgical steel. A first conduit or duct 22 in the form of a cylindrical borehole runs from an inlet port at the proximal end 7 to a first aperture in the distal end 8 of the arm 1. At the proximal end 7, the inlet port is provided with a Luer™ lock arrangement 20 connecting the duct 22 to a syringe 21 containing a liquid local anaesthetic solution.

There are two boreholes 12 in the distal end 8 of the arm 1 arranged on each side of the first conduit 22. Male members 11 on the base of the detachable head 10 mate with the boreholes 12. Further tapped holes 6 lead from the outer wall of the distal end 8 of the arm 1 to the inner walls of the boreholes 12, and further grub screws 5 engage with the tapped hole 6 so that it they be screwed into and out of the holes 6 to engage with the male members 11.

The engagement means of the detachable head 10 is formed by the hollow male member 13 and the two male members 11 , with the first duct 22, two boreholes or sheaths 12, tapped holes 6 and grub screws 5 forming the connector means of the distal end 8 of the arm 1. The detachable head is held firmly in place when grub screws 5 are tightened in tapped holes 6 to press against hollow male member 13, and male members 11 respectively. The detachable head is released by unscrewing grub screw 5.

The connector means of the distal end 8 of the arm 1 also act as the gripping means for this embodiment, as is explained below.

In use, the tool is first configured with the detachable head 10 firmly held in place on the distal end 8 of the arm 1 by tightening the grub screw 5 onto the male member 13. This results in the liquid anaesthetic in the syringe being put into fluid connection with the outlet ports 23 in the detachable head 10, via Luer™ lock 20, first duct 22, and second duct 24.

The tool is then gripped by a surgeon at the proximal end 7 and the tip 3 is pushed through a patient's flesh from a first pocket at one side of the patient's chest towards a second contralateral pocket at the other side of the patent's chest, where proximal ends of three implantable electrical leads are located, following the earlier implantation of the distal ends of the three leads into the heart wall.

When the head eventually arrives at the contralateral pocket, the detachable head 10 is detached from the distal end 8 of the arm 1 by unscrewing the grub screws 5 in the tapped holes 6 such that the hollow male member 13 and the male members 12 are no longer gripped and can be pulled out of the first conduit 22 and the boreholes 12 in order to remove the detachable head 10 from the distal end 8 of the arm 1. The three proximal terminals of the implantable electrical leads are then inserted into the first aperture of the conduit 22 and the two boreholes 12 respectively, in the distal end 8 of the arm 1, and the grub screws 5 are tightened in the holes 6 in order to firmly grip the three terminals. The surgeon, grasping the proximal end 7 of the tool then withdraws the arm 1 back through the tunnel formed in the patient's flesh, pulling the proximal ends of the implantable leads with it. When the distal end 8 of the arm 1 is back at the first pocket, the grub screws 5 are loosened allowing the terminals to be removed from the borehole 12. The tool arm 1 may then be set aside and the proximal terminals of the implanted leads connected to respective IPG terminals on an IPG in the first pocket.

Turning now to the fifth embodiment, as shown in figures 10, 11 and 12, the tool has a stiff cylindrical arm 1 , which is 25 cm in length and 5 mm in diameter. The arm 1 is of surgical steel. A first conduit or duct 22 in the form of a cylindrical borehole runs from an inlet port the proximal end 7 to a first aperture in the distal end 8 of the arm 1. At the proximal end 7, the inlet port is surrounded by a hollow handle 30 fitted with a grub screw 31. A syringe 21 containing a liquid local anaesthetic solution can be slid into the hollow handle 30 such that it can engage to form a fluid-tight connection with the inlet port for pumping anaesthetic solution into the conduit 22. The screw 31 is used to hold the syringe in place.

At the distal end 8 of the arm, a detachable head 10, also of surgical steel, is firmly attached to the distal end 8 of the arm. The detachable head 10 is formed as a flattened lanceolate shape with cutting edges and a flesh-piercing tip 3. The detachable head 10 has a hollow male member 13 fitting into a first aperture of the conduit or duct 22 centrally positioned in the in the distal end 8 of the arm 1. A tapped hole 6 leads from the outer wall of the distal end 8 of the arm 1 to the inner wall of the conduit 22, and a grub screw 5 engages with the tapped hole 6 so that it can be screwed into and out of the hole 6.

The engagement means of the detachable head 10 is formed by the hollow male member 13, with the first duct 22 tapped hole 6 and grub screw 5 forming the connector means of the distal end 8 of the arm 1. The detachable head is held firmly in place when grub screw 5 is tightened in tapped hole 6 to press against hollow male member 13. The detachable head is released by unscrewing grub screw 5. The detachable head 10 has a second duct section 24 within it, extending from a second aperture in the end of the hollow male member 13 and leading to outlet ports 23 adjacent to the tip 3 of the detachable head. The head and duct are made to close tolerances to provide a fluid-tight connection where the male member 13 mates with the first duct 22 at the distal end 8 of the arm 1.

In use, the tool is first configured with the detachable head 10 firmly held in place on the distal end 8 of the arm 1 by tightening the grub screw 5 onto the male member 13. The syringe 21 with anaesthetic solution is locked into the handle 30. This results in the liquid anaesthetic in the syringe being put into fluid connection with the outlet ports 23 in the detachable head 10, via first duct 22, and second duct 24.

The tool is then gripped by a surgeon at the proximal end 7 using the handle 30 and the tip 3 is pushed through a patient's flesh from a first pocket at one side of the patient's chest towards a second contralateral pocket at the other side of the patent's chest, where the proximal end of a implantable electrical lead is located, following the earlier implantation of the distal end of the lead into the heart wall.

When the head eventually arrives at the contralateral pocket, the detachable head 10 is detached from the distal end 8 of the arm 1 by unscrewing the grub screw 5 in the tapped hole 6 such that the hollow male member 13 is no longer gripped and can be pulled out of the first duct or conduit 22 in order to remove the detachable head 10 from the distal end 8 of the arm 1.

At the proximal and 7 of the arm 1 the screw 31 is unfastened and the syringe 31 removed from the hollow handle 30. The proximal terminal of the implantable electrical lead is then inserted into the first aperture of the conduit 22 in the distal end 8 of the arm 1 , and the surgeon can then slide the implantable lead along the conduit 22 until the proximal terminal of the lead emerges from the conduit or duct 22 through the hollow handle 30. The surgeon, grasping the proximal end 7 of the tool using the handle 30 then withdraws the arm 1 back through the tunnel formed in the patient's flesh, resulting in the implantable lead remaining in the tunnel with its proximal end projecting into the first pocket. The tool may then be set aside and the proximal terminal of the implanted leads connected to respective IPG terminals on an IPG in the first pocket.

It will be appreciated that numerous modifications to the above described embodiments may be made without departing from the scope of the invention as defined in the appended claims. For example, in the fourth embodiment, there may be only one further male member 11 in addition to the hollow male member 13. For instance, in embodiments three and four, there may be only one outlet port 23 rather than a plurality of outlet ports 23.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. It should be understood that while the use of words such as "preferable", "preferably", "preferred" or "more preferred" in the description suggest that a feature so described may be desirable, it may nevertheless not be necessary and embodiments lacking such a feature may be contemplated as within the scope of the invention as defined in the appended claims. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

1. A surgical tool comprising an arm having a proximal end and a distal end, the distal end comprising a head, the head comprising a base connected to the distal end of the arm and a tip adapted to pierce flesh, and the distal end of the arm further comprising a sheath adapted to mate with a terminal of an implantable electrical lead.

2. A tool according to claim 1 wherein the sheath comprises a gripping means adapted to releasably grip a terminal of an implantable electrical lead.

3. A tool according to claim 1 or claim 2 wherein the sheath forms a conduit from an inlet aperture at the proximal end of the arm to an outlet aperture adjacent to the tip, whereby said implantable electrical lead may be slid along the conduit.

4. A tool according to any preceding claim wherein the distal end of the arm comprises a connector means for connecting the head to the distal end of the arm, the connector means being adapted to releasably engage with an engagement means of the head, and

wherein the head is a detachable head having a base comprising the engagement means of the head, the engagement means being adapted to releasably engage with the connector means of the distal end of the arm,

whereby the surgical tool has a first configuration with the detachable head rigidly attached to the distal end of the arm, and a second configuration with the detachable head removed from the distal end of the arm.

5. A tool according to any preceding claim wherein the engagement means comprises a male member and the connector means comprises a female member in the distal end of the arm adapted to mate with the male member.

6. A surgical tool according to claim 4 or claim 5 wherein the gripping means is adapted to releasably grip said terminal of said implantable electrical lead when the surgical tool is in the second configuration.

5

7. A tool according to any one of claims 4 to 6 wherein the sheath forms the female member of the connector means.

8. A tool according to claim 7 wherein the sheath is provided with a tapped io hole extending from an inside wall of the sheath to an outside surface of the arm, and a screw fitting the tapped hole adapted to grip the male member or said terminal of said implantable electrical lead when tightened.

9. A tool according to any preceding claim wherein the distal end of the arm 15 comprises a plurality of sheaths each adapted to mate with a terminal of an implantable electrical lead and each provided with respective gripping means adapted to releasably grip a terminal of an implantable electrical lead.

10. A tool according to any preceding claim wherein the distal end of the tool 20 is substantially lanceolate in shape.

11. A surgical tool according to any one of claims 1 to 10 wherein the tip is substantially a point.

25 12. A tool according to any preceding claim comprising a duct adapted to conduct fluid, the duct extending from an inlet port at the proximal end of the arm to one or more outlet ports adjacent to the tip.

13. A tool according to claim 12 wherein the sheath forms part of the duct.

30

14. A surgical tool according to any one of claims 12 to 13 wherein the one or more outlet ports are situated at loci within 1 cm of the tip.

15. A tool according to any one of claims 12 to 14 wherein the duct comprises a first duct section inside the arm extending from the inlet port to a first aperture in the distal end of the arm and a second duct section inside the head extending from a second aperture in the base of the head to the one or more outlet ports adjacent to the tip, and wherein the first and second apertures are in fluid connection.

16. A tool according to claim 15 wherein the first duct section is the conduit of claim 3 and wherein the inlet port of the first duct section is the inlet aperture of the conduit and first aperture of the first duct section is the outlet aperture of the conduit.

17. A tool according to any one of claims 12 to 16 wherein the inlet port of the duct is provided with a syringe whereby a fluid may be pumped from the syringe into the inlet port of the conduit, through the conduit and out of the one or more outlet ports.

18. A tool according to claim 17 wherein the inlet port of the duct is provided with an inlet port engagement means adapted to lockingly engage with an outlet port connection means of a syringe to form a fluid-tight connection whereby a fluid may be pumped from the syringe into the inlet port of the conduit, through the conduit and out of the one or more outlet ports, whereby the syringe may be disengaged from the inlet port.

19. A tool according to any preceding claim wherein the proximal end of the tool is provided with a handle adapted for gripping the tool.

20. A detachable head for a surgical tool as described in any one of claims 4 to 19.

21. An arm for a surgical tool as described in any one of claims 4 to 19.

22. A surgical tool, detachable head for a surgical tool or arm for a surgical tool substantially as hereinbefore described with reference to and as shown in the accompanying figures.

23. A method for upgrading a cardiac pacemaker implant in a patient having a pulse generator assembly already implanted in a first pocket on a first side of said patient's chest comprising;

c) pushing the tip of a tool according to any one of claims 1 to 19 from the first pocket to the contralateral pocket through the subcutaneous flesh of the patient to form a tunnel between the first pocket and the contralateral pocket,

d) optionally providing a flow of a local anaesthetic fluid from the inlet port to the one or more outlet ports of the surgical tool, when the tool is according to any one of claims 12 to 19,

e) mating the one or more termini of the one or more implantable electrical leads with the one or more sheaths of the tool, after first detaching the head of the surgical tool when this is a tool according to claim 4 or claims 5 to 18 when dependent on claim 4,

h) closing the first and contralateral pockets.

24. A method for upgrading a cardiac pacemaker implant in a patient having a pulse generator assembly already implanted in a first pocket on a first side of said patient's chest comprising;

c) pushing the tip of a tool according to any one of claims 3 to 18 from the first pocket to the contralateral pocket through the subcutaneous flesh of the patient to form a tunnel between the first pocket and the contralateral pocket,

d) optionally providing a flow of a local anaesthetic fluid from the inlet port to the one or more outlet ports of the outlet port of the surgical tool, when the tool is according to any one of claims 12 to 19,

e) sliding the one or more implantable electrical leads along the conduit in the arm of the tool from the outlet aperture adjacent to the tip to the inlet aperture at the proximal end of the arm, after first detaching the head of the surgical tool when this is a tool according to claim 4 or claims 5 to 19 when dependent on claim 4,

g) connecting the termini to either the existing implanted pulse generator, or to a second pulse generator which replaces or supplements the existing implanted pulse generator, and

h) closing the first and contralateral pockets.