AU5421701A - Lasing device - Google Patents

Description

S&FRef: 379459D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: United States Surgical Corporation 150 Glover Avenue Norwalk Connecticut 06856 United States of America Thomas J. Pacala, Michael S. Kolesa, James Correia, Oleg Shikhman and Barton C. Thompson Spruson Ferguson St Martins Tower,Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) Lasing Device The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c 1 Lasing Device Background 1. Technical Field The present disclosure relates generally to laser ablation devices for surgical use. More specifically, the present disclosure relates to laser ablation devices having a longitudinally advancing laser energy transmission mechanism to facilitate ablation of body tissue. The laser ablation device is particularly suited for use in performing transmyocardial revascularisation (TMR) and angioplasty.

2. Background of the Related Art A variety of procedures and apparatus have been developed to treat cardiovascular disease.

For example, minimally invasive surgical procedures such as balloon angioplasty and atherectomy have received extensive investigation and are in wide use. In some patients, however, circumstances still require conventional open heart bypass surgery to correct or treat advanced cardiovascular disease. In some circumstances patients may be too weak to undergo the extensive trauma of bypass surgery or repetitive bypasses may already have proved unsuccessful.

An alternative procedure to bypass surgery is transmyocardial revascularisation (TMR), wherein holes are formed in the heart wall to provide alternative blood flow channels for ischaemic heart tissue. This procedure can be done by laser. In early laser myocardial revascularisation, a C02 laser was used to produce holes in the heart wall. In this procedure, laser energy is transmitted from o o° the laser to the heart wall by an extemally located articulated support. Thus, some surgical opening of the chest wall is required to access the heart muscle. The entrance wound in the heart is closed by external pressure with the objective that the endocardial and myocardial layers remain open to permit blood flow from the ventricle to the heart muscle.

A less traumatic approach to laser myocardial revascularisation is disclosed in U.S. 5 380 316 and 5 389 096. These references disclose methods of myocardial revascularisation using a 25 deflectable elongated flexible lasing apparatus which is either introduced through a patient's vasculature or alternatively, directly into the patient's chest cavity. The intravascular method requires the direction of laser energy from inside the heart to form a bore in the heart wall while the other method requires introduction of the lasing apparatus through the patient's chest and into contact with S.the outer wall of the heart.

In both of these methods, the optical fibre conveying the laser energy is advanced and controlled by hand to form the bore. This manual advancement and control presents problems in that depth and rate of penetration are difficult to accurately reproduce for the multiple bores necessary in a myocardial revascularisation procedure.

In addition, if the advancement rate of the laser fibre is too slow, tissue damage from thermal and acoustic shock can result. On the other hand, if the advancement rate of the fibre is too fast (ie., faster than the laser ablation rate), the fibre itself, not the laser energy, can mechanically form at least a portion of the hole, which may be undesirable.

Similar problems are present in other cardiovascular procedures such as, eg. laser angioplasty wherein an optical fibre is inserted and manually advanced into a patient's vasculature to apply laser 2 energy to obstructions and/or restrictions typically caused by plaque build-up. Both continuous wave and pulsed high energy lasers have been used to provide the vaporising laser energy. Insuring the plaque is actually ablated and not just pushed aside is important to prevent or delay restenosis. Once again, because the fibre is manually advanced, the rate of advancement of the fibre through the obstruction is generally uncontrolled.

Summary In accordance with the present disclosure, a controlled advancement laser ablation device is provided for precise ablation of body matter. The laser ablation device includes a laser energy transmission mechanism such as, eg. an optical fibre device mounted for controlled longitudinal movement relative to a housing structure. A laser energy generator is optically connected to the laser energy transmission mechanism for initiating laser energy. A controlled advancement mechanism is provided in engagement with the laser energy transmission mechanism for advancing the mechanism through the housing structure at a controlled rate coordinated with the laser energy generator output to ablate body tissue. Controlled advancement mechanisms include constant and/or variable rate springs, motors, and other mechanisms which can be coordinated with the laser energy generator to advance the laser energy transmission mechanism during ablation.

Brief Description of the Drawings Various preferred embodiments are described herein with references to the drawings: FIG. 1 is a perspective view of one embodiment of the laser ablation device in association with 20 a control assembly; FIG. 2 is a perspective view of the handle and fibre optic portion of the laser ablation device shown in FIG. 1; FIG. 3 is a perspective view with parts separated of the handle and fibre optic portion shown in FIG. 2; S 25 FIG. 4 is a side cross-sectional view of the handle portion shown in FIG. 2 engaging body tissue with the optical fibre retracted within the housing of the device; FIG. 5 is a side cross-sectional view of the handle portion shown in FIG. 2 engaging body o .tissue with the optical fibre extended into body tissue; FIG. 5A is a side cross-sectional view of the handle portioh shown in FIG. 2 engaging body tissue with the optical fibre extended through the body tissue; FIG. 6 is a side cross-sectional view of the distal end of the optical fibre of the laser ablation device shown in FIG. 1 extending within vascular tissue; FIG. 7 is a side cross-sectional view of the distal end of the optical fibre of the laser ablation device shown in FIG. 1 extending into plaque within vascular tissue; FIG. 8 is a side cross-sectional view of vascular tissue having a channel formed in plaque by the laser ablation device shown in FIG. 1; FIG. 9 is a perspective view of an altemrnate embodiment of a handle portion of the laser ablation device; FIG. 10 is a perspective view of the handle portion shown in FIG. 9 with a half-housing section removed; FIG. 10A is a side cross-sectional view of the internal components of the handle portion shown in FIG. FIG. 11 is a side cross-sectional view of the handle portion shown in FIG. 9 positioned adjacent to body tissue with the optical fibre extended; FIG. 11A is a side cross-sectional view of the handle portion shown in FIG. 9 engaged with body tissue with the optical fibre retracted; FIG. 12 is a side cross-sectional view of the handle portion shown in FIG. 9 with the optical fibre extending through the body tissue; FIG. 13 is a perspective view of another alternate embodiment of the handle portion with the inner assembly in a fully extended position; FIG. 14 is a perspective view of the handle portion shown in FIG. 13 with the inner assembly in a partially retracted position; FIG. 15 is a perspective view with partial separation of parts of the handle portion shown in FIG.

13; FIG. 16 is a partial cross-sectional view in perspective of the housing and spring biasing member of the handle portion shown in FIG. FIG. 17 is a perspective view with parts separated of the internal assembly of the handle portion shown in FIG. 13; FIG. 18 is a partial side view in perspective of the housing and spring biasing member of the handle portion shown in FIG. 17; FIG. 19 is a partial perspective view of the handle portion shown in FIG. 13 with a half-housing section removed; 25 FIG. 20 is a partial side cross-sectional view of the handle portion shown in FIG. 13; FIG. 21 is a sectional view of the handle portion shown in FIG. 13 adjacent body tissue; FIG. 22 is a sectional view of the handle portion shown in FIG. 13 adjacent body tissue with the inner assembly and optical fibre retracted; FIG. 23 is a sectional view of the handle portion device shown in FIG. 13 adjacent body tissue with the inner assembly partially advanced and the optical fibre extending through body tissue; FIG. 24 is a sectional view of the handle portion shown in FIG. 13 adjacent body tissue with the outer housing partially extended, the inner assembly partially advanced, and the optical fibre extending through body tissue; FIG. 25 is a side partial cross-sectional view of the handle portion shown in FIG. 13 and a heart during a TMR procedure with the optical fibre extending through the myocardium.

FIG. 26 is a perspective view of an alternate embodiment of a laser ablation device wherein the control module and fibre advancing assembly have been combined into a single unit.

FIG. 27 is a partial perspective view of the fibre control assembly of FIG. 26.

FIG. 28 is a partial perspective view of the fibre control assembly of FIG. 27 with the optical fibre and fibre casing mounted to the fibre control assembly.

4 FIG. 29 is a cross sectional view of the optical fibre, fibre coating, fibre casing and upper retaining clip taken from FIG. 28.

FIG. 30 is a cross sectional view of the optical fibre, fibre coating and lower retaining clip taken from FIG. 28.

s FIG. 31 is a partial view of the fibre control assembly and a side cross-sectional view of the handle portion shown in FIG. 2 engaging body tissue with the optical fibre retracted within the housing of the device; and FIG. 32 is a partial view of the fibre control assembly and a side cross-sectional view of the handle portion shown in FIG. 2 engaging body tissue with the optical fibre advanced into the body tissue.

Detailed Description of Preferred Embodiments Preferred embodiments of the laser ablation device will now be described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views.

One embodiment of the presently disclosed laser ablation device will now be described with reference to FIGS. 1-8. FIG. 1 illustrates a laser ablation device shown generally at 10. Device preferably includes handle portion 11, an optical fibre advancing mechanism 12, a laser generator 14, a foot operated actuator 16, and a control module 17. The optical fibre advancing mechanism 12 is of the type capable of precisely transmitting longitudinal motion and optionally, rotational motion, to an 20 optical fibre, optical fibre bundle or other laser energy transmission mechanism. The controlled longitudinal and/or rotational motion can be provided by one or more motors and preferably by one or more stepper motors. The stepper motors can be of the type commercially available from Haydon .****,Switch and Instrument, Inc. of Waterbury, Connecticut or Eastem Air Devices, Inc. of Dover, New Hampshire. The laser generator 14 may be either a continuous wave laser or a pulsed, high energy S 25 laser; such as, for example, an excimer, CO 2 Yag, or an alexandrite laser. Preferably, a pulsed high energy xenon chloride excimer laser is used, such as those available from Spectranetics of Colorado Springs, Colorado, or Medolas of Germany.

The optical fibre advancing mechanism 12 and the laser generator 14 are operably connected S -to foot switch 16. By depressing foot switch 16, laser energy is transmitted through the optical fibre by laser generator 14 while fibre advancing mechanism 12 advances the laser fibre relative to handle portion 11. As shown, the signal from foot switch 16 actuates control module 17 which communicates with fibre advancing mechanism 12. Control module 17 is programmable and controls the motors or similar advancing structure in advancing mechanism 12 upon actuation of foot switch 16. Control module 17 is shown with a receptacle 19 adapted to engage a terminal of a programmable computer to interface control module 17 with the computer. As such, instructions required to operate advancing mechanism 12 can then be stored in control module 17. Such instructions are commercially available, for example, through Intelligent Motions Systems, Inc. of Taftville, Connecticut. A toggle switch may be provided on the control module 17 to switch from an operation mode to a test mode. In a particular test mode, when the foot actuator 16 is acted upon, the flexible optical fibre is moved sequentially from a retracted position, to a predetermined extended position, and back to the retracted position.

Fibre advancing mechanism 12 is preferably equipped with two internal limit switches (not shown). The first limit switch is preferably positioned to be activated when the optical fibre is at a desired retracted position a "home" position), wherein the mechanism that is retracting the fibre is caused to stop. The second limit switch limits/controls the maximum distance that the optical fibre can extend from handle portion 11. Most preferably, an external selector 21 is provided so that the operator can select the desired maximum extension of the distal end of the optical fibre from the handpiece. For example, selector 21 can be in the form of a rotatable knob that can be set at 0lo selectable positions, wherein each position corresponds to a predetermined maximum longitudinal position of the optical fibre. When the fibre reaches the selected position, a limit switch can automatically terminate the fibre's advancement. In a most preferred embodiment, the operator can select fibre extension positions so that the distal end of the fibre extends from the distal end of the hand piece from between about 0.5cm and about 5.0cm, with the ability to select in increments of about 0.25cm to about 0.5cm. In the embodiment shown in FIGS. 26-32, the fibre preferably extends form the handpiece from between about 0.2cm and about 4.0cm, with the ability to select in increments of about 0.2cm. The minimum and maximum extensions and the selected incremental values therebetween can be varied as desired.

FIG. 2 illustrates a perspective view of the handle portion 11 of laser ablation device 10. Briefly stated, handle portion 11 includes housing 20 formed from moulded housing half-sections 20a and Housing 20 has an elongated body 22 with a conically tapered section 24. An optional locater ring 26 is provided at the distal end of conically tapered section 24 that can be positioned in engagement with body tissue, ie., the wall of the heart during a TMR procedure, to facilitate proper orientation of the handle portion with respect to the body tissue. Locater ring 26 can be formed 25 integrally with housing half-sections 20a and 20b or can be removably fastened to tapered section 24.

A ridged surface 28 is formed on an outer wall of housing half-sections 20a and 20b to facilitate grasping of the device FIG. 3 illustrates laser ablation device 10 with housing half-sections 20a and 20b and the internal components of the handle portion 11 separated. Housinq half-sections 20a and 20b define a central bore 30, a proximal recess 32, and a distal recess 34. The proximal recess 32 is configured to receive a swivel connector 36 which is fastened to the optical fibre casing 38. The swivel connector 36 has an annular flange 40 dimensioned to be received within an increased diameter section 42 of proximal recess 32 to permit rotation of housing 20 with respect to optical fibre casing 38.

As shown, the locater ring 26 has a cylindrical body portion 44 having an annular flange 46 formed at its proximal end. The cylindrical body portion 44 includes a central bore 50 and is configured to be received within the distal recess 34 defined by housing half-sections 20a and Central bore 50 of cylindrical body portion 44 is aligned with a central opening 48 formed in the distal end of the housing 20 and the central bore 30 of housing 20. Locater ring 26 can either swivel, to allow independent rotation of the handle portion relative thereto, or be fixed in place. The optical fibre 18 is slidably positioned within central bores 30 and 50 such that it can be advanced through opening 48 in housing 20. Pins or screws 49 can be used to fasten the housing half-sections 20a and together to secure the locater ring 26 and the swivel connector 36 to the housing FIGS. 4-5A illustrate laser ablation device 10 during use in a TMR procedure. Locater ring 26 has been positioned against the epicardium 54 of the heart 56. Because the heart may be beating during a TMR procedure, the locater ring 26 greatly enhances the surgeon's ability to position and stabilise the laser ablation device 10 with respect to the heart 56. In Fig. 4, the foot operated actuator 16 (FIG. 1) has not been actuated and the optical fibre 18 is in a retracted position with its distal end positioned in central bore 50 of locater ring 26.

Referring now to FIGS. 5 and 5A, foot operated actuator 16 (FIG. 1) has been actuated to initiate operation of laser generator 14 and the advancing mechanism 12 to ablate tissue and advance optical fibre 18. The distal end 60 of optical fibre 18 has been advanced in the direction indicated by arrow to produce a channel 57 from the epicardium through to the myocardium 58 in the ventricle of the heart 56. During the TMR procedure, 1 or more channels can be ablated into the heart to facilitate blood delivery to ischaemic areas of the heart. The distal end 60 of the optical fibre 18 which can be a single fibre or a bundle or fibres, is preferably advanced at a rate that is coordinated with the power level and the frequency of pulsing of the laser generator to form channels in the heart. For example, optical fibre 18 can be advanced at a rate of between about 0.5mm/sec to about 12.7mm/sec with a laser power level of about 10mJ/mm 2 to about 60mJ/mm 2 and a pulsing frequency of about 5Hz to about 100Hz. Preferably, the optical fibre is advanced at a rate of about 1.0mm/sec to 20 about 2.0mm/sec with a laser power level of between about 30mJ/mm 2 to about 40mJ/mm 2 and a pulse frequency of about 50Hz. In a most preferred embodiment, the rate of advancement of the optical fibre is no greater than the rate of ablation of tissue in order to minimise mechanical tearing by the fibre. Alternatively, if some degree of mechanical tearing is desired, the advancing mechanism can be set to advance the fibre at a rate greater than the ablation rate. Studies have shown that a 25 xenon chloride excimer laser operating at a power level of about 35mJ/mm 2 can ablate about of animal heart tissue per pulse.

In one study, channels were successfully created in canine heart tissue using a xenon chloride excimer laser (308nm) optically connected to a 1.8mm solid fibre bundle. The laser was set to provide about 30mJ/mm 2 at a rate of about 50Hz, while the advancing mechanism was set to advance the laser fibre bundle at various constant speeds between about 1.3mm/sec and about 13mm/sec. In a clinical trial on a human heart, the laser was set to provide about 35mJ/mm 2 at a rate of about with a feed rate of about 0.95mm/sec advancing the fibre at approximately 31.75jim per pulse).

Typically, a healthy heart has a wall thickness of 10-15mm. A diseased heart may be as thick as 40mm (measured from the outer surface of the epicardium to the inner wall of the myocardium). At a minimum, the laser ablation device 10 and control assembly should be capable of advancing the optical fibre 18 through a stroke having a length at least as great as the thickness of the heart being treated. Alternately, it is possible to create channels in the myocardium from within the heart by introducing the laser fibre into the patient's vasculature or through an opposing heart wall and directing the fibre tip to the desired location. See, for example, U.S. 5 389 096. In this approach, once the fibre is properly placed, controlled advancement of the fibre can be achieved as described above. However, with this approach the fibre preferably will not penetrate the epicardium.

Referring now to FIGS. 6-8, laser fibre 18 and fibre advancing mechanism 12 (FIG. 1) can also be used to perform laser angioplasty. During the laser angioplasty procedure, the optical fibre 18 is inserted into a blood vessel 62 such that the distal end 60 of the optical fibre 18 is positioned adjacent a plaque obstruction 64 (FIG. as is known in the art. The foot operated actuator 16 (FIG. 1) is actuated to initiate operation of the advancing mechanism 12 and the laser generator 14 to simultaneously advance, in the direction indicated by arrow and ablate plaque 64 to produce a channel 66 through the obstruction. As discussed above, the rate of advancement of the optical fibre 18 and the power level and frequency of pulsing of laser energy are coordinated, via control module 17, to form the channel 66 through the plaque. By precisely controlling the rate of advancement of the laser fibre, the user can ensure that the plaque is truly ablated by the laser energy and not just pushed aside. Ablation/removal of plaque reduces the likelihood of or delays restenosis as compared to mere mechanical manipulation of the plaque.

An alternate, preferred embodiment of the presently disclosed laser ablation device will now be described with reference to FIGS. 9 to 12. The handle portion of the laser ablation device shown in this embodiment has a self-biasing advancing mechanism incorporated therein. FIGS. 9 and illustrate the handle portion of the laser ablation device shown generally as 100. Briefly described, handle portion 100 includes a housing 120 formed from moulded housing half-sections 120a and 20 120b. The housing half-sections 120a and 120b are formed with mating recesses 114 configured to slidably receive the intemrnal components. A proximal opening 115 and a distal opening 116 are formed in housing 120 to permit an optical fibre 118 to extend through the housing 120. A swivel connector (such as 36 in Figs. 3-5A) and fibre casing (such as 38 in Fig. 3) can also be included.

An engagement assembly 113 is slidably positioned within a channel 122 defined by mating 25 recesses 114 formed in housing half-sections 120a and 120b. The engagement assembly 113 includes a cylindrical cap 124, a flexible engagement washer 128, and a compression screw 130. The cylindrical cap 132 has a threaded blind bore 126 dimensioned to receive the flexible engagement washer 128. The compression screw 130 has a threaded end 134 dimensioned to be threaded into the blind bore 126. The cylindrical cap 124, the engagement washer 128 and the compression screw 130 all have a central throughbore to permit the optical fibre 118 to extend through the housing 120.

Referring to FIG. 10A, the engagement washer 128 is positioned in the blind bore 126 of cylindrical cap 124 and compression screw 130 is threaded into the blind bore 126. As the engagement washer 128 is compressed between the compression screw 130 and the base of blind bore 126, the washer 126 deforms inwardly into frictional engagement with the optical fibre 118 to fasten the optical fibre 118 to the engagement assembly 113.

The advancing assembly 112 includes a guide member 136 and a biasing member 138. The guide member 136 is positioned in abutting relation with the proximal end of the cap 124 of engagement assembly 113. An elongated rib 140 extends along the longitudinal periphery of guide member 136 and is configured to be received within a longitudinal slot 142 formed on an internal wall of the housing 120. The rib and slot engagement limits rotation of the guide member 136 with respect to the housing 120 to avoid inadvertent disengagement of the guide member 136 and biasing member 138.

The biasing member 138 is positioned to engage the proximal end of the guide member 136 as to bias the guide member 136 distally into the engagement assembly 113 to move the engagement assembly 113 distally in channel 122. The biasing member 138 preferably includes a constant force spring having a first end 144 connected through an opening 146 to the housing 120 and a body portion 148 positioned in a recess 150 formed in the proximal end of the guide member 136. The constant force spring allows for controlled advancement of the laser fibre, which has advantages in TMR and angioplasty procedures, similar to those previously described.

FIGS. 11-12 illustrate the handle portion 100 of laser ablation device during use in a TMR procedure. FIG. 11 illustrates the handle portion 100 prior to engagement with heart 152. The biasing member 138 has moved the guide member 136 into abutment with the engagement assembly 113 to advance the engagement assembly distally in channel 122. Because of the frictional connection between washer 128 and optical fibre 118, optical fibre 118 has been advanced distally with the engagement assembly 113 and extends through opening 116 in housing 120.

Referring now to FIG. 11A, the handle portion 100 of laser ablation device has been pushed i against the epicardium 154 of the heart 152. The force on the distal end of the optical fibre 118 is sufficient to overcome the force of the biasing member 138 to retract the optical fibre 118, in the direction indicated by arrow to a position within housing 120. It is noted that the strength of the biasing member should be less than that capable of puncturing the heart 152, eg., the optical fibre 118 should not pierce the heart when the distal end of the optical fibre is pushed against the epicardium.

In FIG. 12, laser energy has been conducted to the optical fibre 118 to ablate heart tissue adjacent the distal end 160 of the optical fibre 118. As the heart tissue adjacent the distal end 160 of the optical fibre is ablated, biasing member 138 continually advances the optical fibre 118 through the 25 heart tissue until a channel 162 is formed in the ventricle of the heart from the epicardium through the myocardium 156. The laser energy level and pulse frequency are coordinated with the rate of advancement provided by the biasing member 138. A similar biasing mechanism can be used to controllably advance the laser fibre during laser angioplasty.

A further alternate, preferred embodiment of the presently disclosed laser ablation device is shown in FIGS. 13-25. The handle portion 200 of the laser ablation device in this embodiment includes a self-biasing advancing mechanism substantially identical to that incorporated in the handle portion 100 described above. The device further includes a compensating mechanism suitable for use in performing a TMR procedure on a beating heart.

FIGS. 13 and 14 illustrate the handle portion of laser ablation device shown generally as 200.

Briefly, handle portion 200 includes an outer housing 210 formed from moulded housing half-sections 210a and 210b and an inner housing 220formed from moulded housing half-sections 220a and 220b.

The inner housing 220 is slidably positioned within outer housing 210, as indicated by arrow and includes a distal conical portion 222 having an opening 224 dimensioned to permit passage of an optical fibre 218.

Referring now to FIGS. 15 and 16, the outer housing half-sections 210a and 210b have recesses which together form a channel 226 in which the inner housing 220 is slidably positioned.

Proximal and distal openings 228 and 230 are also formed in the outer housing 210 and are dimensioned to permit passage of the optical fibre 218 and the inner housing 220, respectively. As with the previous embodiment, a swivel connector (such as 36 in FIGS. 3-5A) and fibre casing (such as 38 in FIG. 3) can also be included but are not shown. A biasing member 232 is positioned within the outer housing 210 to engage and urge the inner housing 220 towards the distal end of channel 226. The biasing member 232 can be a spring having a first portion retained in a slot 234 formed in the outer housing 220 and a second portion engaging a retainer 236 secured to the inner housing 220. The outer housing half-sections 220a and 220b can be fastened together with pins or screws 238 to secure inner housing 220 within channel 226.

FIGS. 17-20 illustrate the inner housing 220 with parts separated. The internal components of the inner housing 220 include an engagement assembly and an advancing mechanism, which are similar to those disclosed with respect to the housing portion 100 and will only be briefly discussed herein. The engagement assembly includes a cylindrical cap 240, a flexible engagement washer 242, and a compression screw 244. The cylindrical cap 240 has a threaded blind bore 245 which is adapted to receive a threaded end 246 of compression screw 244. The compression screw 244 is threaded into blind bore 245 to compress and deform the engagement washer 242 into frictional engagement with optical fibre 218, which extends through a central bore formed in the engagement 20 assembly.

The advancing mechanism includes a guide member 248 and a biasing member 250. The guide member 248 is positioned in abutting relation to the proximal end of cap 240. The biasing member 250 is positioned to engage and bias the guide member 248 distally within a channel 252 formed in the inner housing 220 to move the engagement assembly towards the distal end of the 25 channel 252. An elongated rib 254 is formed on the outer periphery of the guide member 248 and is received in a slot 256 formed along channel 252 to prevent the guide member 248 from rotating and becoming disengaged from the biasing member 250. The inner housing half-sections can be fastened together with pins 258 to secure the engagement assembly and the advancing mechanism within channel 252.

FIGS. 21-25 illustrate a handle portion 200 of a laser ablation device during use in a TMR procedure. FIG. 21 illustrates the handle portion 200 after the optical fibre 218 has been pressed against the epicardium 262 of the heart 260 but before laser energy has been conducted to the optical fibre 218. Engagement between the distal end 264 of optical fibre 218 creates a compressive force in the optical fibre 218 that overcomes the force of biasing member 250 to cause retraction of the optical fibre 218 in the direction indicated by arrow Referring to FIG. 22, the distal end 266 of the inner housing 220 is positioned in abutting relation with the heart 260. If the heart 260 and the handle portion 200 move towards each other with the handle portion 200 in this position, such as when the heart beats or the patient breathes, the force on the distal end 264 of inner housing 220 overcomes the force of biasing member 232 (FIG. 19), to permit the inner housing 220 to move proximally within channel 252, in the direction indicated by arrow Outer housing 210 and biasing member 232 form a compensation assembly in this respect.

Referring now to FIGS. 23-25, laser energy has been conducted to the optical fibre 218 to ablate heart tissue adjacent to the distal end 264 of the optical fibre 218. As the heart tissue is ablated, biasing member 250 controllably advances distal end 264 of optical fibre 218, in the direction indicated by arrow through the heart tissue until a channel 268 is formed from the epicardium 262 through the myocardium 270. Once again, the power output of the laser generator conducting energy to optical fibre 218 is coordinated with the advancement mechanism to provide channels 268 in the heart.

Referring now to FIGS. 26-32, an alternate laser ablation device is shown, wherein the control module (generally shown as 17 in FIG. 1) and fibre advancing assembly (generally shown as 12 in FIG. 1) have been combined into a single unit refereed herein as fibre control assembly 312. Fibre control assembly 312 is shown on top of laser energy generator 314 and is positioned to receive an optical fibre that serves to transmit laser energy from laser 314 to body tissue. Laser 314 is preferably an excimer laser, however, other laser energy sources that can be coupled to an optical fibre can also be used. Laser 314 is also shown with a control pad 316 and a monitor 318. Footswitch 320 is also shown and serves to actuate the laser and fibre control assembly.

9*:With reference to FIGS. 27-30, fibre control assembly 312 is shown in greater detail. Fibre control assembly houses motor 322 (preferably a stepper motor) that serves to move lower fibre 20 securing plate 324 relative to upper fibre securing plate 326. Upon actuation, motor 322 rotates screw 328 relative to threads disposed in lower plate 324 (not shown) to move the lower plate relative to the upper plate. Both the upper plate and the lower plate have clip recesses 341 and 343, respectively, and clips 342 and 344, respectively, that serve to hold portions a disposable lasing assembly, discussed in greater detail below. The motor and plates are disposed in housing portion 330 that o 25 includes movable access door 332 and upper fibre exit opening 334 and lower fibre entrance opening 336. Fibre control assembly also includes rotatable depth selector 338 that allows the user to select the desired movement of lower plate 324 relative to upper plate 326. As discussed in greater detail, °below, movement of the lower plate relative to the upper plate controls movement of the optical fibre relative to a handle portion. Preferably, the selected depth is displayed on digital display panel 340 and is selectable in 0.2cm increments in a range between about 0.2cm to about Turning to FIGS. 28-30, a disposable lasing assembly, generally designated as 400, is shown connected to fibre control assembly 312 and laser energy generator 314. Disposable lasing assembly 400 includes coupler 402, optical fibre 404, fibre casing 408 and handle portion 410. Coupler 402 is configured and dimensioned to be connected to laser generator 314 at laser output 342, wherein energy emitted from the laser is directed into the proximal end of optical fibre 404. Optical fibre 404 is shown as a bundle of fibres but can also be a single fibre. Optical fibre 404 preferably has fibre coating 406 (see FIGS. 29 and 30) that is preferably at least partially stripped away from the distal end of the fibre (see FIGS. 31 and 32) so that only the fibre touches body tissue. Fibre casing 408 serves to provide a fixed distance between handle portion 410 and upper plate 326. The casing can be ratably connected to either or both the handle portion (as described above) and the upper plate.

Optical fibre 404 is movable within casing 408. Handle portion 410 is similar handle portion 11, described above.

To connect disposable lasing assembly 400 to the laser and fibre control assembly, the surgeon or operator will attach coupler 402 to laser output 342, pass optical fibre 404 (and coating 406 disposed about the fibre, if included) through lower fibre entrance opening 336, secure the fibre to lower plate 324 by means of clip 344, secure fibre casing 408 to upper plate 326 by means of clip 342 and direct the fibre casing and fibre out of the control assembly through upper fibre exit opening 334.

These steps of connecting the disposable lasing assembly to the control assembly need not be performed in any particular order. Because the disposable lasing assembly passes through openings 336 and 334, door 322 can be closed during operation.

During operation, with reference to FIGS. 31 and 32, the surgeon or operator will use depth selector 338 to select the desired depth that the distal end of optical fibre 404 will feed into the body tissue 500. Next the surgeon places the distal end of handle portion 410 at a desired location against the tissue heart tissue) and activates foot switch 320 (FIG. 26). The foot switch aciivates motor 322 and laser generator 314. Motor 322 rotates screw 328 to move lower plate 324 towards upper plate 326 in the direction of arrow A. Because fibre casing 408 is secured at both ends (one end to handle portion 410 and the other to upper plate 326) and the optical fibre is secured to the lower plate, movement of the lower plate a distance X causes the distal end of the optical fibre to move a distance X relative to the distal end the handle portion. Once the desired distance X has been travelled, laser i: 20 energy transmission is stopped and motor 322 reverses direction to bring the optical fibre to its initial or "home" position. The procedure can be repeated according to the discretion of the surgeon.

After the surgeon has finished with a particular patient, disposable lasing assembly 400 can be discarded and laser generator 314 and fibre control assembly 312 can be cleaned for the next patient.

Disposable lasing assembly 400, in combination with the relatively quick and easy to use connection to the laser generator and fibre control assembly, provides for a convenient and safe method of performing laser surgery, such as TMR.

It will be understood that various modifications can be made to the embodiments disclosed herein. For example, in the first embodiment, any type of motor, such as air, hydraulic, pneumatic or o.eo other electrical motor can be used in place of a stepper motor. 0n addition, altemrnate devices can be 3o used to actuate the laser advancing device and the laser energy source, such as a trigger mechanism associated with the handle portion. Also, various other structures for securing the optical fibre and fibre casing to the fibre control assembly can be used. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended thereto.

Claims (24)

1. A laser ablation device comprising: a handle portion having proximal and distal openings; a laser energy transmission mechanism having first and second ends, the first end being extendible through the handle portion; a laser energy generator optically connected to the laser energy transmission mechanism second end; and an advancing mechanism operably connected to the laser energy transmission mechanism, the advancing mechanism being operable to advance the laser energy transmission mechanism through the distal opening of the handle portion at a rate coordinated with the laser generator output to ablate body tissue.

2. A device according to claim 1, wherein the laser energy transmission mechanism is at least one optical fibre.

3. A device according to claim 1, wherein the advancing mechanism is a motor.

4. A device according to claim 3, wherein the motor is selected from the group of motors consisting of electric motors, air motor, hydraulic motors and pneumatic motors.

5. A device according to claim 3, wherein the motor is an electrical stepper motor.

6. A device according to claim 1, further including a control module, the control module for controlling the advancement rate of the laser energy transmission mechanism. 20

7. A device according to claim 1, wherein the laser generator is a pulsed high energy laser generator.

8. A device according to claim 1, wherein the laser generator is selected from the group consisting of excimer, CO 2 Yag, and Alexandrite lasers.

9. A device according to claim 8, wherein the laser pulse frequency and energy level are 25 coordinated with the advancement rate of the laser energy transmission mechanism.

10. A device according to claim 1, wherein the advancement mechanism is positioned within the handle portion.

11. A device according to claim 10, wherein the advancement mechanism includes a biasing member, and wherein the advancement rate of the laser energy transmission mechanism is coordinated with the laser generator output.

12. A device according to claim 11, wherein the laser generator is a pulsed, high energy laser and the advancement rate of the laser energy transmission mechanism is coordinated with the pulse frequency and the energy level of the laser generator.

13. A device according to claim 1, further comprising a compensation assembly operably connected to the handle portion.

14. A device according to claim 13, wherein the compensating assembly includes an outer housing operably connected to the handle portion by a biasing member, the biasing member permitting relative movement between the handle portion and the outer housing.

A device according to claim 1, wherein the advancing mechanism comprises a constant force spring.

16. A method of ablating body matter with a laser comprising: a) providing a laser energy source; b) providing at least one optical fibre having proximal and distal ends; c) disposing the optical fibre distal end adjacent body matter; d) directing laser energy through the optical fibre to ablate the body matter; and e) advancing the optical fibre into the body matter at a controlled and constant rate.

17. The method according to claim 16, wherein the optical fibre is advanced at a rate less than or equal to the ablation rate of the body matter.

18. The method according to claim 16, wherein the optical fibre is advanced at a rate greater 1o than the ablation rate of the body matter.

19. A method of performing transmyocardial revascularisation comprising: a) providing a xenon-chloride excimer laser energy source; b) providing at least one optical fibre having proximal and distal ends; c) disposing the optical fibre distal end adjacent heart tissue; is d) transmitting laser energy through the optical fibre to ablate the heart tissue, the laser energy being transmitted at a power level of between about 1 OmJ/mm 2 and about 60mJ/mm 2 and e) advancing the optical fibre into the heart tissue at a constant rate of between about 9*9*9* to about 12mm/sec. S.i

~20. A method of ablating body tissue comprising the steps of: providing a laser ablation device having a linearly advanceable laser energy transmission mechanism; providing a laser generator to deliver laser energy to the laser ablation device; positioning the laser ablation device adjacent body tissue; advancing the laser energy transmission mechanism into body tissue; and coordinating the advancement rate of the laser energy transmission mechanism with the output of laser generator to ablate body tissue.

21. A method according to claim 20, wherein the laser generator is a pulsed high energy laser generator, and the step of coordinating includes coordinating the pulse frequency and energy level of the output of the laser generator with the advancement rate of the laser energy transmission mechanism to ablate body tissue.

22. A method according to claim 20 wherein the body tissue is heart tissue, and the step of advancing the laser energy transmission mechanism includes advancing the laser energy transmission mechanism into the heart tissue to provide at least one channel in the heart tissue.

23. A method according to claim 20, wherein the body tissue is vasculature, and the step of advancing the laser energy transmission mechanism includes advancing the laser energy transmission mechanism through the vasculature to ablate obstructions within the vasculature.

24. A laser ablation device comprising: a handle portion having proximal and distal openings; a fibre advancing device having a stationary member and a movable member, the movable member being movable towards and away from the stationary member; a fibre casing having proximal and distal ends, the distal end being secured to a proximal end of the handle portion and the proximal end being secured to the stationary member of the fibre advancing device; at least one optical fibre having proximal and distal ends, the distal end being extendible through the handle portion and a portion of the fibre defined between the proximal and distal ends being secured to the movable member of the fibre advancing device; and a laser energy generator optically connected to proximal end of the at least one optical fibre. A laser ablation device, substantially as hereinbefore described with reference to the accompanying drawings. Dated 4 July, 2001 United States Surgical Corporation Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON :i 555@