Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
  • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
  • A61B18/14—Probes or electrodes therefor
  • A61B18/1477—Needle-like probes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B2018/00636—Sensing and controlling the application of energy
  • A61B2018/00773—Sensed parameters
  • A61B2018/00791—Temperature
  • A61B2018/00809—Temperature measured thermochromatically
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
  • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
  • A61B18/14—Probes or electrodes therefor
  • A61B2018/1472—Probes or electrodes therefor for use with liquid electrolyte, e.g. virtual electrodes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
  • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
  • A61B2090/3937—Visible markers
  • A61B2090/395—Visible markers with marking agent for marking skin or other tissue

Definitions

• the present invention relates generally to the field of devices for cardiac surgery, and more specifically to devices for ablation of cardiac tissue.
• the present invention is directed toward treatment of tachyarrhythmias, which are heart rhythms in which a chamber or chambers of the heart exhibits an excessively fast rhythm.
• the present invention is directed toward treatment of tachycardias, which are due to the presence of ectopic foci within the cardiac tissue or due to the presence of aberrant condition pathways within the cardiac tissue.
• SA node sinoatrial node
• the impulse causes adjacent myocardial tissue cells in the atria to depolarize, which in turn causes adjacent myocardial tissue cells to depolarize.
• the depolarization propagates across the atria, causing the atria to contract and empty blood from the atria into the ventricles.
• the impulse is next delivered via the atrioventricular node (or "AV node") and the bundle of HIS (or "HIS bundle”) to myocardial tissue cells of the ventricles. The depolarization of these cells propagates across the ventricles, causing the ventricles to contract.
• This conduction system results in the described, organized sequence of myocardial contraction leading to a normal heartbeat.
• aberrant conductive pathways develop in heart tissue, which disrupt the normal path of depolarization events.
• anatomical obstacles in the atria or ventricles can disrupt the normal propagation of electrical impulses.
• These anatomical obstacles can cause the electrical impulse to degenerate into several circular wavelets that circulate about the obstacles. These wavelets, called “reentry circuits,” disrupt the normal activation of the atria or ventricles.
• arrhythmias The aberrant conductive pathways create abnormal, irregular, and sometimes life- threatening heart rhythms, called arrhythmias.
• An arrhythmia can take place in the atria, for example, as in atrial tachycardia, atrial fibrillation or atrial flutter.
• the arrhythmia can also take place in the ventricle, for example, as in ventricular tachycardia.
• the lesions used to treat atrial fibrillation are typically long and thin and are carefully placed to interrupt the conduction routes of the most common reentry circuits. More specifically, the long thin lesions are used to create a maze pattern that creates a convoluted path for electrical propagation within the left and right atria. The lesions direct the electrical impulse from the SA node along a specified route through all regions of both atria, causing uniform contraction required for normal atrial transport function. The lesions finally direct the impulse to the AV node to activate the ventricles, restoring normal atrioventricular synchrony.
• Several surgical approaches have been developed with the intention of treating atrial fibrillation.
• the "maze procedure” is known as the "maze procedure,” as is disclosed by Cox, XL et al. in "The surgical treatment of atrial fibrillation. I. Summary” Thoracic and Cardiovascular Surgery 101(3), pp. 402-405 (1991); and also by Cox, JL in “The surgical treatment of atrial fibrillation. IV. Surgical Technique", Thoracic and Cardiovascular Surgery 101(4), pp. 584-592 (1991), both of which are incorporated by reference herein in their entireties.
• the "maze” procedure is designed to relieve atrial arrhythmia by restoring effective atrial systole and sinus node control through a prescribed pattern of incisions about the tissue wall.
• the surgical "maze procedure" as performed in the left atrium generally includes forming vertical incisions from the two superior pulmonary veins and terminating in the region of the mitral valve annulus, traversing the inferior pulmonary veins en route.
• An additional horizontal line also connects the superior ends of the two vertical incisions.
• the atrial wall region bordered by the pulmonary vein ostia is isolated from the other atrial tissue.
• the mechanical sectioning of atrial tissue eliminates the precipitating conduction to the atrial arrhythmia by creating conduction blocks within the aberrant electrical conduction pathways.
• Alcohol may be delivered to blood vessels supplying the tissue to be ablated, as described in “Transcoronary Chemical Ablation of Arrhythmias", by Nellens et al, Pace Vol. 15, pages 1368-1373, September 1992.
• Alcohol can be delivered directly to the tissue to be ablated by means of a needle inserted through a catheter, as described in "Chemical Ablation by Subendocardial Injection of Ethanol via Catheter— Preliminary Results in the Pig Heart", by Weismuller et al, European Heart Journal,
• This invention relates to a device and method for ablation of cardiac tissue in which a hand-held instrument having a hollow needle is used to deliver precise amounts of liquids into cardiac tissue for purposes of ablation of the tissue along a desired lesion line.
• a reciprocating needle device like that disclosed in U.S. Patent 4,204,438, which is incorporated by reference in its entirety, is used to repeatedly penetrate cardiac tissue and deliver a cytotoxic agent to the cardiac tissue.
• the cytotoxic agent is used to "draw" a lesion on the myocardium by the repeated introduction of the needle and injection of cytotoxic fluid while moving the tip of the device along the desired lesion pattern. Because of the motor-driven reciprocating action of the device, the lesion pattern can be completed rapidly by the surgeon.
• a manually operated switch on the housing of the device is capable of energizing and de-energizing the device as desired by the operator and an eccentric drive advances and retracts the needle from the housing.
• the depth of needle penetration can be adjusted to control the depth at which the cytotoxic fluid is delivered to the tissue but preferably the depth of needle penetration enables the cytotoxic fluid to be injected into the tissue so that it extends through the entire thickness of the tissue.
• the hollow needle is filled with the cytotoxic agent.
• the cytotoxic fluid can be loaded into the needle a little at a time or it can be filled by means of a fluid reservoir.
• the delivery of the fluid can occur passively as the needle is inserted into the tissue or it can be actively injected into the tissue according to needle position.
• the fluid delivery can be performed endocardially, epicardially, and epicardially on a beating heart.
• a non-reciprocating metering needle assembly like that disclosed in U.S. Patent 4,719,825, which is incorporated by reference in its entirety, is use to repeatedly penetrate cardiac tissue and deliver a cytotoxic agent to the cardiac tissue.
• the device is activated by the operator to deliver a predetermined, metered amount of the cytotoxic agent into the myocardium.
• the needle is then withdrawn from the cardiac tissue and advanced to a second location along the desired lesion pattern where it is inserted into the myocardium and another predetermined metered amount of cytotoxic agent is dispensed into the myocardial tissue. In this manner, the device is advanced stepwise along the desired lesion line by the operator in order to complete the lesion.
• a device as described above is utilized in combination with radiofrequency ablation.
• the needle can be connected to one pole of a radiofrequency generator while the other pole of the generator is connected to a large indifferent electrode.
• the needle delivers a conductive liquid such as a saline solution that creates an ablative virtual electrode when delivered into the tissue through the needle.
• the device is advanced along a desired lesion line on the tissue as the needle is advanced into and retracted from the tissue. Delivery of the conductive liquid and the ablative radiofrequency energy is synchronized to form the virtual electrode and ablate the tissue along the desired lesion line.
• a device as described above is utilized in combination with a conventional radiofrequency ablation device such as the Cardioblate ® pen sold by Medtronic, Inc.
• a conventional radiofrequency ablation device such as the Cardioblate ® pen sold by Medtronic, Inc.
• the needle delivers a conductive liquid such as a hypertonic saline solution to the tissue.
• the device is advanced along a desired lesion line on the tissue as the needle is advanced into and retracted from the tissue. Delivery of the conductive liquid is made into the tissue along the desired lesion line.
• the conductive tip of the Cardioblate pen is then drawn along the desired lesion line while applying radiofrequency energy to the tissue.
• the hypertonic saline solution that creates a low impedance electrical pathway to ground such that the resultant lesion is deeper and narrower than would normally result from the use of the conventional radiofrequency ablation device.
• a device as described above is utilized in order to deliver a protective fluid in order to protect certain areas of cardiac tissue, such as tissue near vessels and valves.
• a hypotonic fluid can be used as a protective fluid in order to increase the electrical impedance of the tissue to be protected relative to the surrounding tissues, essentially insulating the protected tissue from the electrical current of the radiofrequency ablation device.
• This aspect of the invention can be combined with one or more of the other aspects of the invention in which a conductive liquid is delivered to a first portion of cardiac tissue along a desired lesion line and a protective fluid is delivered to a second portion of cardiac tissue spaced apart from the desired lesion line.
• a device having a plurality of spaced-apart needles with centrally located needles delivering the conductive liquid and other needles on one or both sides of the centrally located needles which deliver the protective fluid.
• the radiofrequency ablation device such as the Cardioblate pen
• a device as described above is utilized in order to deliver an ink or dye to the cardiac tissue in order to identify the position of the lesion line on the cardiac tissue and to identify portions of tissue along the lesion line where the lesion has been completed.
• the ink or dye can be added to the cytotoxic fluid in order to identify portions of tissue which have received the cytotoxic fluid and that those portions create a complete lesion along the desired lesion line.
• the ink or dye can be added to the conductive liquid in order to identify the portions of tissue which has been ablated by the radiofrequency energy of a virtual electrode. Again the completeness of the lesion line is indicated by the presence of the ink or dye.
• the ink or dye can be added to the conductive liquid in order to identify the position of the desired lesion line so that the Cardioblate pen or other radiofrequency ablation device can be guided along the line that has been established by the delivery of the conductive fluid.
• the ink or dye can be thermochromic such that it changes color when heated to a temperature which indicates that a lesion has been formed by the application of radiofrequency energy.
• temperatures above about 50 to 55 degrees C are required to cause cell death in an ablative lesion made by radiofrequency ablation and the photochromic material would preferably change color in that temperature range.
• Fig. 1 is a perspective view of a prior art device suitable for use in the present invention
• Fig. 2 is a perspective view of a prior art device suitable for use in the present invention.
• Fig. 3 is a schematic view of a device with a reciprocating needle operating according to the invention.
• Fig. 4 is a side sectional view of a needle delivering a fluid into tissue according to the invention.
• Fig. 5 is a side sectional view of fluid delivered according to the invention that has diffused into tissue near its point of delivery.
• Fig. 6 is a side sectional view showing needles delivering fluid according to the invention into tissue at varying depths.
• Fig. 7 is a side sectional view of a needle delivering fluid according to the invention during reciprocation of the needle.
• Fig. 8 is a side view of a distal portion of a needle showing multiple fluid openings for delivery of fluid according to the present invention.
• Fig. 9 is a side sectional view of a lesion created by the application of radiofrequency energy according to the invention.
• Fig. 10 is a fragmentary, schematic, side sectional view of a linear array of needles which can be used for delivering protective fluid about a delivered cytotoxic and/or conductive fluid.
• Fig. 11 is a schematic view of the heart showing various maze lesions that can be formed according to the invention.
• FIG. 1 shows a reciprocating needle device 1 as disclosed in U.S. Patent 4,204,438.
• the reciprocating needle device 1 includes a motor housing 10 and a needle housing 12.
• the needle housing 12 has an opening 14 through which a needle reciprocates.
• the device 1 may be held by hand by a surgeon and used to repeatedly penetrate cardiac tissue by a reciprocating action of the needle and deliver a cytotoxic agent to the cardiac tissue.
• FIG. 2 shows a non-reciprocating metering needle device 20 like that disclosed in U.S. Patent 4,719,825.
• the metering needle device 20 has a barrel portion 22 that can be held by hand, a tip portion 24 through which a needle 26 extends and a switch 28.
• a surgeon can advance the needle 26 into myocardial tissue and then deliver a metered amount of a cytotoxic agent from the needle 26 by activating the switch 28 on the metering needle device 20.
• Some tattoo pens are also believed suitable for practicing the present invention.
• the tattoo pens preferably provide a longer than conventional needle travel path and also provide a stronger than conventional driving force for driving the needle or needles through the longer path.
• the cytotoxic agent is an agent which has cytotoxic properties and can be delivered as an injectable liquid or a liquid suspension.
• the cytotoxic substance has potent cytotoxic properties that destroys cell function without affecting protein structure and scaffolding.
• the cytotoxic agent has limited and controllable diffusion properties through extracellular spaces.
• the cytotoxic agent has a fleeting effect such that the compound washes out of the systemic circulation quickly.
• Alkylating agents such as cytotaxan or melphalan or their active metabolites are preferred.
• the cytotoxic agent is used to "draw" a lesion on the myocardium by the repeated introduction of the needle and injection of cytotoxic fluid while moving the tip of the device along the desired lesion pattern.
• FIG 11 shows some possible generally linear lesion patterns 110 that are capable of interrupting conductive pathways 112 and 114.
• a reciprocating needle device 30 can have a reservoir 32 and a hollow, reciprocating needle 34 through which the fluid 36 can be delivered into myocardial tissue 38.
• the needle 34 may be tapered to allow for easy penetration of the tissue 38 and delivery of fluid 36 into the tissue 38. Following delivery of the fluid, the needle is withdrawn and the fluid 36 diffuses into the tissue 38.
• Needles 34a-34c also represent varying depth needles included within an array or linear array of needles.
• the needle array can be advanced along the desired lesion path and the needles inserted together, insuring multiple fluid delivery depths along the path.
• Such a phased linear array of needles also can reduce the force required to enter the myocardium, relative to a constant dept array, as the time of entry into the tougher outer layer occurs at different times.
• the depth of penetration for needles 34a-c can be adjusted to control the depth at which the cytotoxic fluid 36 is delivered to the tissue 38 through injection ports or orifices 37.
• the needle 34d can also be adjusted to deliver the cytotoxic fluid as the needle 34d is inserted and/or withdrawn in order to provide delivery of fluid 36 at various depths.
• the needle may be provided with injection ports or openings 42 which will deliver fluid from a plurality of side openings or ports along the length of the needle 34e. The delivery of the fluid can therefore occur passively as the needle is inserted into the tissue or it can be actively injected into the tissue according to needle position.
• an ablative lesion 44 can be created in tissue 48 by a needle connected to a radiofrequency generator (not shown) as a conductive fluid 46 is delivered through the needle 49 into the tissue 48.
• the needle delivers a conductive liquid such as a saline solution that creates an ablative virtual electrode when delivered into the tissue through the needle.
• the device is advanced along a desired lesion line on the tissue as the needle is advanced into and retracted from the tissue. Delivery of the conductive liquid and the ablative radiofrequency energy can be synchronized to form the virtual electrode and ablate the tissue along the desired lesion line.
• Figure 10 illustrates a linear array of needles 50 including an injection manifold 52.
• Linear array 50 includes outer needles 54, 56, 58, and 60, and inner needles 62 and 64.
• Inner needles 62 and 64 are fed by a first fluid delivery lumen 66 while outer needles 54- 60 are fed by a second fluid delivery lumen 68.
• the inner needles can deliver a conductive and/or cytotoxic fluid, while the outer needles can deliver a protective fluid, described below.
• some possible generally linear lesion patterns 110 are shown that are capable of interrupting conductive pathways 112 and 114.
• the lesion patterns can be made as described above or in combination with a conventional radiofrequency ablation device such as the Cardioblate pen sold by Medtronic, Inc. (not shown).
• the needle delivers a conductive liquid such as a hypertonic saline solution to the tissue.
• the device is advanced along a desired lesion line 110 on the tissue as the needle is advanced into and retracted from the tissue. Delivery of the conductive liquid is made into the tissue along the desired lesion line 110.
• the conductive tip of the Cardioblate pen is then drawn along the desired lesion line 110 while applying radiofrequency energy to the tissue.
• the hypertonic saline solution that creates a low impedance electrical pathway to ground such that the resultant lesion is deeper and narrower than would normally result from the use of the conventional radiofrequency ablation device.
• a protective fluid can also be used when making the linear lesions 110 in order to protect certain areas of cardiac tissue, such as tissue near vessels and valves like the pulmonary veins 116.
• a hypotonic fluid can be used as a protective fluid in order to increase the electrical impedance of the tissue to be protected relative to the surrounding tissues, essentially insulating the protected tissue from the electrical current of the radiofrequency ablation device.
• the protective fluid can be a thermally protective fluid such as a chilled fluid which protects tissue adjacent to the intended lesion from being overheated.
• This aspect of the invention can be combined with one or more of the other aspects of the invention in which a conductive liquid is delivered to a first portion of cardiac tissue along a desired lesion line and a protective fluid is delivered to a second portion of cardiac tissue spaced apart from the desired lesion line.
• a device having a plurality of spaced-apart needles with centrally located needles delivering the conductive liquid and other needles on one or both sides of the centrally located needles which deliver the protective fluid, as discussed with respect to Figure 10.
• the radiofrequency ablation device such as the Cardioblate pen
• the device as described above can be utilized in order to deliver an ink or dye to the cardiac tissue in order to identify the position of the lesion line 110 on the cardiac tissue and to identify portions of tissue along the lesion line 110 where the lesion has been completed.
• the ink or dye can be added to the cytotoxic fluid in order to identify portions of tissue which have received the cytotoxic fluid and that those portions create a complete lesion along the desired lesion line.
• the ink or dye can be added to the conductive liquid in order to identify the portions of tissue which has been ablated by the radiofrequency energy of a virtual electrode. Again the completeness of the lesion line is indicated by the presence of the ink or dye.
• the ink or dye can be added to the conductive liquid in order to identify the position of the desired lesion line so that the Cardioblate pen or other radiofrequency ablation device can be guided along the line that has been established by the delivery of the conductive fluid.
• Dyes such as those used for tattoos are believed suitable, as are some tissue dyes. Toluene blue and methylene blue are examples of dyes believed suitable for use in the present invention.
• the ink or dye can be thermochromic such that it changes color when heated to a temperature which indicates that a lesion has been formed by the application of radiofrequency energy.
• temperatures above about 50 to 55 degrees C are required to cause cell death in an ablative lesion made by radiofrequency ablation and the photochromic material would preferably change color in that temperature range.
• the injected fluid can include a viscous enhancing agent or fluid added to reduce or retard fluid diffusion after delivery. Reducing the diffusion of a cytotoxic and/or conductive fluid can reduce the width of the resulting lesion. Reducing the diffusion of a protective fluid can maintain the protective fluid in a desired position adjacent the cytotoxic and/or conductive fluid, to serve its protective function. Viscous fluids such as dextrose or glycerol maybe added to increase the viscosity of a delivered fluid. The viscous fluids or agents can provide a fluid viscosity of at least about twice that of water.

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Applications Claiming Priority (3)

Publications (1)

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• 2003
  • 2003-05-15 WO PCT/US2003/015549 patent/WO2005034782A2/fr not_active Application Discontinuation
  • 2003-05-15 AU AU2003304495A patent/AU2003304495A1/en not_active Abandoned

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