MXPA99005713A

MXPA99005713A - Device for the treatment of infarcted tissue and method of using the device

Info

Publication number: MXPA99005713A
Application number: MXPA/A/1999/005713A
Authority: MX
Inventors: D Laufer Michael
Original assignee: Hearten Medical Inc
Priority date: 1996-12-08
Filing date: 1999-06-18
Publication date: 2000-05-01

Abstract

This invention is a device and method for treating myocardial infarction by selectively heating the infarct scar to reduce the size of the scar tissue area (18) by shrinking the tissue in the heart (10), stiffen the floppy portion of the scar tissue, reduce the ventricular systolic wall tension, and increase the overall pumping efficiency of the infarcted heart (10) by eliminating a ventricular aneurysm, if present. The heat can be applied to, or induced in, the infarct scar. Force can also be applied to assist the reduction of the size of the scar (18) using the device of the present invention which has a heating element (24), and a scissor-like clamp (26) for squeezing two portions of the infarct scar together.

Description

DEVICE FOR THE TREATMENT OF INFRARED TISSUE AND METHOD FOR USING THE DEVICE FIELD OF THE INVENTION The present invention relates generally to the modification of cardiac tissue for the treatment of myocardial infarction.

BACKGROUND OF THE INVENTION As is well known, the heart has four chambers for receiving and pumping blood to various parts of the body. During normal heart function, oxygen-poor blood returning from the body enters the right atrium. The right atrium fills with blood and eventually contracts to expel blood through the tricuspid valve into the right ventricle. The contraction of the right ventricle injects blood similarly to a pulsation to the pulmonary artery and to each of the lungs. Oxygenated blood leaves the lungs through the pulmonary veins and fills the right atrium. The left atrium fills with blood and eventually contracts to expel blood through the mitral valve into the left ventricle. The contraction of the left ventricle pushes the blood through the aorta to eventually supply the blood P1379 / 99MX oxygenated to the rest of the body. Myocardial infarction (ie, heart attack) can result in a heart failure. Congestive heart failure is a condition where the heart can not pump enough blood. When patients have a heart attack, part of the circulation to the muscle of the heart wall is usually lost due to a blood clot that is dislodged from a larger artery and obstructs a coronary artery. If the clot does not dissolve within approximately 3 to 4 hours, the muscle that loses its blood supply becomes necrotic and subsequently becomes a scar. The scarred muscle is not contractile, therefore it does not contribute to the pumping capacity of the heart. In addition, the scarred muscle is elastic (ie, flexible) which also reduces the efficiency of the heart because a portion of the force created by the remaining healthy muscle forms a pocket with the scar tissue (ie, a ventricular aneurysm) instead of pumping the blood out of the heart. Congestive heart failure is usually treated with a lot of rest, a low-salt diet, and medications such as A. CE inhibitors, digitalis, vasodilators, and diuretics. In some cases, of myocardial infarction, the scarred muscle is cut and separated from the heart P1379 / 99MX and the remaining portions of the heart are sutured (ie, aneurysm). In limited circumstances, a heart transplant may be performed. Collagen-containing tissue is found everywhere in the human body and forms an important portion of the scar. Collagen demonstrates several unique characteristics not found in other tissues. Intermolecular crosslinks provide tissue containing collagen with unique physical properties of high tensile strength and considerable elasticity. A property of collagen is the shrinkage or shrinkage of the collagen fibers when the temperature is raised. It is believed that this molecular response to the rise in temperature is the result of the breakdown of transverse collagen stabilizing bonds and the immediate contraction of collagen fibers to approximately one third of their original linear dimension or the result of a change in the tissue hydration. Another property of collagen is that the size of the individual fibers increases enormously, more than four times, without changing the structural integrity of the connective tissue. It has been analyzed in the existing literature regarding the tissue that contains collagen, in various parts of the body. A technique known for the effective use of this knowledge of the properties of P1379 / 99MX collagen is through the use of infrared laser energy to effect tissue heating. The use of infrared laser energy as a tool for shrinkage of the cornea of the eye cornea has been described and is related to laser keratoplasty, as set forth in U.S. Patent No. 4,976,709. The importance of controlling the location, timing, and intensity of the laser energy supply is recognized as paramount in providing the desired effects of soft tissue shrinkage without creating excessive damage to surrounding non-target tissues. Another known technique for altering collagen is described in U.S. Patent No. 5,458,596 for treating joints. U.S. Patent No. 5,437,664 describes the use of a catheter for occlusion of the veins and blood coagulation. Thermal destruction (i.e., ablation) of myocardial tissue presenting problem (ie, arrhythmiogenic focus) is a therapeutic procedure used increasingly frequently for the treatment of cardiac arrhythmias (eg, ventricular tachycardia), as described in U.S. Patent No. 5,246,438. The treatment of cardiac arrhythmias involves electrically treating problematic tissue, except otherwise healthy tissue. As a result, one goal of the P1379 / 99MX ablation is to locate the heat as much as possible to restrict ablation to problematic healthy tissue only.

SUMMARY OF THE INVENTION The present invention provides a device and method for treating scar tissue from heart infarction of a mammal by selectively heating the infarct scar to reduce the size of scar tissue surface area, increase cross section of scar tissue, stiffening the flexible portion of the scar tissue, reducing systolic ventricular wall tension and increasing the overall pumping efficiency of the infarcted heart by eliminating the ventricular aneurysm, if present. The present invention, preferably, does not affect healthy heart tissue or softens infarcted tissue. In addition, the present invention preferably diffuses the heat over the infarcted area. The method is similar to an annealing process where the scar tissue undergoes heating after it is allowed to cool slowly. The heat can be applied or induced in the infarction scar. Force may also be applied in accordance with the present invention, to assist in reducing the size of the scar. Generally speaking, P1379 / 99MX in addition to reducing the surface area of the scar tissue, the present invention alters the material properties of the infarct scar as making it more rigid and less elastic. In one aspect of the invention, there is provided an apparatus for heating an infarct scar in a heart, having a thermal element with a projection to penetrate the scar and a mechanism for pressing at least two portions of the scar against each other. In another aspect of the invention, there is provided a method for treating an infarct scar in a heart, which includes the step of energizing a thermal element to raise the temperature of the infarct scar to a temperature sufficient to reduce the surface area of the heart. infarct scar. In still another aspect of the invention, there is provided a method for training a person to carry out a method to treat a heart attack scar, which includes the steps of demonstrating or instructing how to do the next step of energizing an element. term to raise the temperature of the infarct scar to a temperature sufficient to reduce the superficial area of the infarct scar. In still another aspect of the invention, P1379 / 99MX will provide a modified mammalian heart with a portion of contracted infarct scar tissue, decreased in its surface area and stiffened. In yet another aspect of the invention, there is provided a method for treating a heart infarction scar, which includes the step of energizing a term element to raise the temperature of the infarct scar at a temperature sufficient to reduce wall tension. ventricular systolic BRIEF DESCRIPTION OF THE DRAWINGS As used herein, similar reference numerals will designate similar elements in the various embodiments of the present invention, and wherein: Figure 1 is the heart of a mammal, with electrodes inserted into an infarcted area; Figure 2 is the heart of a mammal with a radio frequency thermal element in contact with the infarcted area; Figure 3 is a front view of a device for heating and pressing together, portions of the infarcted area; Figure 4 is a side view of the device of Figure 3; and Figure 5 is a top view of the device of Figure 2 during the treatment of P1379 / 99MX infarcted area.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention provides a device and a method for altering the material properties of collagen-containing infarcted tissue in the heart of a patient. A method for training a person to develop a method for treating an infarcted scar in a mammalian heart is also provided. The invention is used to accurately control the induction of heat or the application of heat within a specific thermal range, and supply thermal energy to the infarcted tissue containing collagen to reduce the size of the scar tissue area by means of the shrinkage of the tissue. tissue infarcted in the heart and by stiffening the flexible portion of the scar tissue without ablating the tissue. As a result, the overall pumping efficiency of the infarcted heart is increased. Similarly, it results the heart or a mammal with a portion of contracted infarct scar tissue, decreased in its surface area and reduced ventricular systolic wall tension. Referring initially to Figure 1, a heart 10 having an infarcted region or portion 12 is illustrated. The infarcted portion 12 of the heart can be accessed with conventional surgery at P1379 / 99MX open chest or with arthroscopic techniques. A positive electrode 14 and a negative electrode 16 are inserted into a portion of the infarcted portion 12 to induce heat by resistances in the infarct scar in the desired treatment area 18 when energy is applied through the electrodes. Alternatively, the positive and negative electrodes can be contacted with the infarcted scar. The positive and negative electrodes function as a term element while they are energized to raise the temperature of the scar in the desired treatment area 18 at a temperature sufficient to reduce the surface area of the scar without ablating the scar tissue or damaging the tissue healthy surrounding of the infarcted portion 12. The term "thermal element" as used herein encompasses elements that apply energy thereby inducing heat in the tissue as well as elements that apply heat to the tissue. In a preferred embodiment, the scar is heated to a temperature in the range of about 40 degrees Celsius to about 75 degrees Celsius, more preferably from about 60 degrees Celsius to about 65 degrees Celsius. After the desired treatment area 18 has been heated, it is allowed to cool. The energy is no longer applied after there has been sufficient shrinkage of the scar tissue. Enough shrinkage P1379 / 99MX can be detected visually, mechanically, echocardiographically, ventriculographically with x-rays, fluoroscopic or with appropriate feedback variables, such as, for example, impedance monitoring, temperature monitoring or any other suitable method. The elements or thermal element can then be moved to another portion of the infarcted portion 12 for treatment. It is believed, without being limited to a particular theory, that while the infarcted scar is heated, the collagen fibers are then straightened while the collagen fibers are cooled, they become interlaced or folded around each other becoming shorter, narrower, thicker, stronger, stiffer, or with some combination of these characteristics. It is contemplated that the method will be used with any suitable device to apply radiant energy, thermal energy, or to otherwise heat the infarcted tissue and reduce the area of the infarcted tissue. For example, a radio frequency generator 20 and an applicator 22 of the thermal element can be used (Figure 2). When the thermal element 24 of the applicator 22 is placed at the desired treatment site, the radio frequency generator 20 is activated to provide adequate power, preferably at a selected frequency in the range of 10 megahertz to 1000 megahertz, for P1379 / 99MX heat the scar tissue at a temperature sufficient to reduce the surface area of the scar without ablating the scar tissue or damaging the healthy tissue surrounding the infarcted area 12. Preferably, the emitted energy is converted into the tissue of scar, in heat in the range of about 40 degrees Celsius to about 75 degrees Celsius, more preferably in the range of about 60 degrees Celsius to about 65 degrees Celsius. Radio frequency energy is preferably applied at low power levels (for example, 1 to 20 watts). The appropriate radio frequency energy sources are already available in the market. In one embodiment, the radio frequency generator 20 has a single channel, which supplies approximately 1 to 20 watts of power and which has continuous supply capacity. The thermal element 24 of the applicator 22, as shown in Figure 2, functions as a unipolar electrode. An outer electrode (not shown) with a much larger surface area than the thermal element 24 is placed on the exterior surface of the patient's body. For example, a mesh or external metal plate is placed on the skin. Both electrodes are connected to a radio frequency generator 20, which produces an electric field at a high frequency within the body of the patient. Due P1379 / 99MX because the surface area of the thermal element 24 is much smaller than that of the outer electrode, the density of the high frequency electric field is much higher around the thermal element. The electric field reaches its highest density between the two electrodes in the region near the thermal element 24. The increased density of the field around the thermal element 24 produces localized heat of the scar tissue in the treatment area 18. Alternatively, they can place two electrodes on the scar and energize in a bipolar mode. Referring to Figures 3-5, another embodiment for a thermal device is shown. The thermal device of Figures 3-5 comprises: scissors-like jaws 26 having transverse arms 28 and 30 which are connected by the pin 32 near the midpoint of the arms. At the proximal end of the arms 28 and 30 are the handles 34 and 36, respectively, and at their distal ends 38 and 40, respectively, a plurality of projections 42 spaced apart from elongate members 44 and 46, respectively. An optional releasable pin 48 is located between the arms 28 and 30. Similarly, an optional fixed force spring can be located between the arms. Attached to the arm 28 is a positive electrode 50 and attached to the arm 30 is the negative electrode 52. Each of the arms 28 and 30 are P1379 / 99MX are free to rotate around a pin 32 and are electrically isolated from each other so that when a potential is applied between the electrodes 50 and 52, no cutting occurs between the arms. The jaw 26 is used by a surgeon (or by a demonstrating individual) to press and shrink a portion of the infarcted scar tissue area 12. (Similarly, a person can instruct a surgeon on how to carry out the method of the present invention with the jaw 26 or other embodiments described herein). The surgeon grasps or cuts the infarct tissue with the protuberances 42, if present, and presses the two portions of scar tissue against each other by actuating the jaw with the handles 34 and 36 (Figure 5). The protuberances 42 when present, are conductive elements. The positive and negative electrodes are then energized by the surgeon to function as a thermal element to raise the temperature of the scar in the desired treatment area 18, at a temperature sufficient to reduce the surface area of the scar without ablating the scar tissue or damage the healthy tissue surrounding the infarcted portion 12. The lumps can be used to treat endocardial, sub-endocardial and transmural infarcted areas. The protuberances may have isolated close portions so that the portions Distal P1379 / 99MX are used to treat infarcted areas of the endocardium. Alternatively, the protrusions may have isolated distal portions so that proximal portions are used to treat sub-endocardial infarcted areas. The protuberances may be uninsulated to treat transmural infarcted areas. Similarly, only a portion of one side of a protrusion can be isolated. The clamp 26 is beneficial in applying force to the infarcted tissue to aid in the shrinkage process. The releasable latch 48 or fixed force spring can be used to preset the distance at which the two portions of the scar will move towards each other. Alternatively, the releasable latch 48 can be used to maintain the two constant portions at a certain distance during the heating process. The elongated members 44 and 46 generally do not come together so that a larger area of scar can be treated. Generally, the elongated members 44 and 46 are driven towards each other to apply a relatively small amount of force to assist the shrinking process. The jaw 26 illustrated in Figures 3 to 5 uses heating of the scar tissue by resistors, but it is also within the scope of the invention that a radio generator P1379 / 99MX frequency and electrodes, as well as other means that will be described later, may be used. The thermal element of any of the embodiments can be made to provide protection against overheating of the scar tissue. Techniques, for example, temperature monitoring or monitoring of electrical characteristics (e.g., impedance), can be used in a system that interrupts the application of energy to the thermal element to avoid ablating the tissue or damaging healthy tissue. The surgeon can, if desired, override the feedback control system. A microprocessor can be included and incorporated into the feedback control system to switch the power on and off, as well as modulate the power. The microprocessor can serve as a control to observe the temperature and modulate the energies so as to avoid overheating of the tissue. The thermal element can be synchronized with the ECG (electrocardiogram) so that the heart wall is in diastole. In addition, the system may include auditing or visual power indicators to signal when shrinkage, temperature or other variables are occurring, and also when any have reached or exceeded the desired conditions. It will be understood that other P1379 / 99MX energy forms, in addition to those analyzed in the above, such as microwaves, ultrasound and light (both coherent and incoherent sources), and that the thermal energy generated from a hot fluid element (for example, liquids, gases , combinations of liquids and gases, etc.), a Curie point element or similar elements can also be used. The thermal element 42 in accordance with any of the embodiments may be a number of diverse materials including, but not limited to, conductive polymer, stainless steel, platinum, or other noble metals. While various particular embodiments of the invention have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. Consequently, the invention is not intended to be limited, except for the attached clauses.

P1379 / 99MX

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. An apparatus for heating an infarct scar in a heart, comprising: thermal element; and means for contacting and pressing at least two portions of the same surface of the scar, one against the other.
2. The apparatus according to claim 1, wherein the thermal element comprises electrodes for heating the scar.
3. The apparatus according to claim 1, further comprising a radio frequency generator for energizing the thermal element.
4. The apparatus according to claim 1, further comprising a projection for cutting the scar.
The apparatus according to claim 4, wherein the projection comprises a plurality of conductive elements.
The apparatus according to claim 4, wherein a portion of the projections is isolated.
The apparatus according to claim 1, wherein the means for contacting and pressing P1379 / 99MX comprises a scissor-like jaw.
The apparatus according to claim 7, wherein the scissor-like jaw further comprises a releasable latch.
The apparatus according to claim 7, wherein the scissor-like jaw further comprises a fixed force spring.
10. The apparatus according to claim 1, wherein the thermal element comprises microwave means for heating the infarct scar.
The apparatus according to claim 1, wherein the thermal element comprises ultrasound means for heating the infarct scar.
12. The apparatus according to claim 1, wherein the thermal element comprises light means for heating the infarct scar.
The apparatus according to claim 1, wherein the thermal element comprises a hot fluid element.
The apparatus according to claim 1, wherein the thermal element comprises a unipolar electrode.
15. The apparatus according to claim 1, further comprising means for synchronizing the thermal element with the ECG.
16. The apparatus according to claim 1, further comprising a feedback indicator. P1379 / 99MX
17. The apparatus according to claim 16, wherein the feedback indicator is an audit signal.
18. The apparatus according to claim 16, wherein the feedback indicator is a visual signal.
19. The apparatus according to claim 16, wherein the feedback indicator is shrinkage indicator.
20. The apparatus according to claim 16, wherein the feedback indicator is a temperature indicator.
21. The apparatus according to claim 16, wherein the feedback indicator is an indicator of electrical characteristics.
22. A method for treating an infarct scar in a heart, comprises the step of: energizing a thermal element to raise the temperature of the infarct scar at a temperature sufficient to reduce the superficial area of the infarct scar.
The method according to claim 22, further comprising the step of: pressing at least two portions of the infarcted scar against each other.
The method according to claim 22, further comprising the steps of: P1379 / 99MX cut the scar; and pressing at least two portions of the scar against each other.
The method according to claim 22, further comprising the steps of: providing an apparatus having a thermal element with a projection for cutting the scar and means for pressing at least two portions of the scar, one against the other; cut the scar; and pressing at least two portions of the scar against each other.
26. The method according to claim 22, wherein the thermal element is energized by the application of radiofrequency energy.
27. The method according to claim 22, wherein the thermal element is energized by heating by resistors.
The method according to claim 22, wherein the scar is energized at a temperature in the range of about 40 degrees Celsius to about 75 degrees Celsius.
29. A method for training a person to carry out the method for treating a heart infarction scar, comprising the step of: demonstrating or providing instructions for developing the next step of: P1379 / 99MX energize a thermal element to raise the temperature of the infarct scar to a temperature sufficient to reduce the superficial area of the infarct scar.
30. The method according to claim 29, further comprising the step of: pressing at least two portions of the infarct scar, one against the other.
The method according to claim 29, further comprising demonstrating or providing instructions for developing the following steps of: cutting the scar; and press at least two portions of the scar, one against the other.
The method according to claim 29, further comprising the steps of: providing an apparatus with a thermal element having a projection for cutting the scar and means for pressing at least two portions of the scar, one against the other; and demonstrate or provide instructions for the development of the following stages of: cutting the scar; and press at least two portions of the scar, one against the other.
33. The method according to claim 29, in P1379 / 99MX where the thermal element is energized by applying radiofrequency energy.
34. The method according to claim 29, wherein the thermal element is energized by heating with resistors.
35. The method according to claim 29, wherein the scar is energized at a temperature in the range of about 40 degrees Celsius to about 75 degrees Celsius.
36. A modified mammalian heart, which has a portion of reduced infarct scar tissue in its surface area.
37. A method for treating an infarct scar in a heart, comprising the steps of: energizing a thermal element to raise the temperature of the infarcted scar to a temperature sufficient to reduce ventricular systolic wall tension. P1379 / 99MX