Abstract:
A method for treating Chronic Obstructive Pulmonary Disease (COPD) or chronic bronchitis to alleviate the discomforts of breathing by using non-thermal electroporation energy to ablate diseased portions of the lung including the bronchus, airways and alveoli which, in effect, opens the restrictive diseased portions thereby maximizing the overall surface area thereof causing improved airflow and uninhibited breathing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. patent application Ser. No. 12/754,210, which claims priority to U.S. Provisional Application No. 61/166,386 filed Apr. 3, 2009, both of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to advances in medical procedures aimed at improving the quality and length of life of individuals with Congestive Obstructive Pulmonary Disease (COPD). More particularly, the present invention relates to a method of using Irreversible Electroporation (IRE) to ablate diseased portions of the lung to further enhance lung functions while reducing complications associated with conventional procedures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Chronic Obstructive Pulmonary Disease; hereinafter, COPD is a disease of the lungs wherein the airways become narrowed which leads to a restriction in the flow of air into and out of the lungs causing shortness of breath. COPD includes both chronic emphysema and chronic bronchitis and is mainly caused by noxious particle or gases, most commonly from smoking, which initiates an abnormal inflammatory response in the lung. Other causes of COPD are intense or prolonged exposure to workplace dusts and particles found in coal and gold mining, in the cotton textile industry with chemicals such as cadmium and isocyanates, fumes from welding, and non-smokers being exposed to the noxious particles and gases emitted from smokers. Lung damage, inflammation of the lung airways (alveoli), and clogged mucus in the bronchial tubes are conditions associated with bronchitis and emphysema. 
         [0004]      FIG. 1  shows a view of a lung ( 10 ) depicting an enlarged bronchus ( 12 ) and alveoli ( 14 ) which are microscopic grape-like clusters of air sacs at the end of the smallest bronchiole (airways) ( 12 ). The alveoli ( 14 ) are where gas exchange takes place, and are regarded as the primary functional units of the lungs. Alveoli ( 14 ) are densely covered with capillaries [for sake of clarity, too small to show about the alveoli ( 14 ), but are extensions to the capillaries ( 16 ) about the bronchus ( 12 )] wherein blood is brought to the capillaries ( 16 ) by the pulmonary artery (not shown) and carried away by the pulmonary vein (not shown). When the alveoli ( 14 ) inflate with inhaled air, oxygen diffuses into the blood in the capillaries ( 16 ) to the tissues of the body, and carbon dioxide diffuses out of the blood into the lungs ( 10 ), where it is exhaled. 
         [0005]    Bronchitis is an inflammation of the bronchial tubes ( 12 ), or bronchi, that bring air into the lungs ( 10 ). When the cells lining the bronchi are irritated, the tiny hairs (cilia) that normally trap and eliminate particulates from the air stop working. Formation of material (mucus and phlegm) associated with irritation (inflammation) also increases; causing the passages to become clogged. Mucus/phlegm and the inflamed bronchial lining ( 18  of  FIGS. 2A and 2B ) constrict the airways causing them to become smaller and tighter which makes it difficult to get air into and out of the lungs. As an attempt to rid the constricted airways of the mucus/phlegm, the body responds with persistent, intense and severe coughing spells. Chronic bronchitis is often either misdiagnosed or neglected until it is in advanced stages. 
         [0006]      FIGS. 2A and 2B  are cross-sectional views of a normal bronchus ( 12 ) and a bronchus ( 12 ) affected by chronic bronchitis, respectively.  FIG. 2A  depicts the bronchus ( 12 ) with an inner bronchial wall ( 18 ) having a thickness (T1), and the airway (A1) of the bronchus ( 12 ) having a diameter (D1).  FIG. 2B  depicts the bronchus ( 12 ) having an inner bronchial wall ( 18 ) with a thickness (T2), and the airway (A2) of the bronchus ( 12 ) having a diameter (D2). In comparison to a normal bronchus ( 12 ), as shown in  FIG. 2A , the inner bronchial wall ( 18 ) of the bronchus ( 12 ) affected by chronic bronchitis has an increased thickness (T2) which creates the decreased diameter (D2) airway (A2). The inner bronchial wall ( 18 ) becomes enlarged or swollen due to irritants within the air when air is taken in. Once the inner bronchial wall ( 18 ) is irritated, the small hairs (cilia) that normally protect the bronchus ( 12 ) from foreign matter stop working. As a result, (mucus and phlegm) associated with irritation (inflammation) forms; thereby decreasing the diameter of the airway (D2) and causing the passages to become clogged and restricted. The decreased diameter (D2) airway (A2) prevents the proper flow of air into and out of the lung inhibiting the natural functions of the lung. 
         [0007]    Emphysema is defined as a breakdown or destruction in the walls of the alveoli causing them to become abnormally enlarged. A lung ( 10 ) affected by emphysema has enlarged and engorged alveoli ( 14 ). The breakdown or destruction of the alveoli ( 14 ) reduces the surface area available for the exchange of oxygen and carbon dioxide during breathing resulting in poor oxygenation (low oxygen and high carbon dioxide levels within the body). Also, elasticity of the lung ( 10 ) itself is decreased leading to the loss of support of the airway embedded in the lung ( 10 ) which often times leads to collapse of the airway thereby further limiting airflow. 
         [0008]      FIGS. 3A and 3B  are cross-sectional views of normal alveoli ( 14 ) and alveoli ( 14 ) affected by emphysema, respectively.  FIG. 3A  depicts and enlarged view of normal alveoli ( 14 ) showing the grape-like configurations or individual alveolus ( 20 ) and surrounding tissue ( 22 ). The individual alveolus ( 20 ) is tightly compacted together and is clearly defined by the surrounding tissue ( 22 ). However, with emphysema, as the alveoli ( 14 ) deteriorates or is destroyed, the surrounding tissue ( 22 ) loses its elasticity thereby causing the individual alveolus ( 20 ) to expand and become engorged, see  FIG. 3B .  FIG. 3B  also shows that the individual alveolus ( 20 ) is much less compacted and has reduced amounts of surrounding tissue ( 22 ). Due to the inelasticity of the surrounding tissue ( 22 ), the abnormally enlarged alveoli ( 14 ) fill easily with air during inhalation/inspiration, but lose the ability to empty the lung during exhalation/expiration. 
         [0009]    In both cases of COPD, chronic bronchitis and emphysema, the greatest reduction in airflow occurs when breathing out (exhalation/expiration) because the pressure in the chest tends to compress rather than expand the airways. A person with COPD may not be able to completely finish breathing out before needing to take another breath. A small amount of the air from the previous breath remains within the lungs when the next breath is started. Easy filling and poor emptying of the lungs leads to progressive hyperexpansion or dynamic hyperinflation of the lungs resulting in inefficient breathing mechanics. Hyperexpansion/hyperinflation of the lungs, in addition to the poor oxygenation capability, makes it progressively difficult to breathe. 
         [0010]    In order to compensate for the breathing deficiencies, some people with advanced COPD manage to breathe faster; however, as a result, they usually develop dyspnea (chronic shortness of breath). Others, who may be less short of breath, tolerate the low oxygen and high carbon dioxide levels in their bodies, but eventually develop headaches, drowsiness and even heart failure. Advanced COPD can lead to complications beyond the lung such as depression, muscle loss, weight loss, pulmonary hypertension, osteoporosis and heart disease. 
         [0011]    Currently, there is no cure available for chronic bronchitis; most treatment is focused on making the symptoms less severe and trying to prevent further damage. The most common types of treatment involve changes in lifestyle, medication and supplemental oxygen supply. Examples of medications are bronchodilators to open airways; corticosteroids to reduce inflammation, swelling and phlegm production; and expectorants to stop the cough that often accompanies chronic bronchitis. 
         [0012]    Lung Volume Reduction Surgery; herein after (LVRS), is a treatment option for patients with severe emphysema. In LVRS, a physician removes approximately 20-35% of the damaged lungs or of the poorly functioning space occupying the lung tissue from each lung. By reducing the lung size, the remaining lung and surrounding muscles are able to work more efficiently, making breathing easier. 
         [0013]    LVRS is typically performed by techniques such as thoracoscopy, sternotomy and thoracotomy. Thoracoscopy is a minimally invasive technique where three small (approximately 1 inch) incisions are made in each side, between the ribs. A video-assisted thoracic surgery (VATS) or video-scope is placed through one of the incisions which allows the surgeon to see the lungs. A special surgical stapler/grasper is inserted in the other incisions and is used to cut away the damaged areas of the lung, reseal the remaining lung from leaking blood and air, and dissolvable sutures are used to close the incisions. Thoracoscopy can be used to operate on either one or both lungs and allows for assessment and resection of any part of the lungs. Thorascopic laser treatment of portions of the lung can also be performed using this technique. In contrast, thorascopic laser treatment, although capable of ablating emphysematous tissue only at the lung surface, prohibits simultaneous bilateral lung applications. 
         [0014]    Sternotomy or open chest surgery involves an incision being made through the breastbone to expose both lungs. Both lungs are reduced in this procedure, one after the other. The chest bone is wired together and the skin is closed. This is the most invasive technique and is used when thoracoscopy is not appropriate. This approach is usually used only for upper lobe disease of the lung. 
         [0015]    Thoracotomy is a technique often used when the surgeon is unable to see the lung clearly through the thoracoscope or when dense adhesions (scar tissue) are found. A 5 to 12 inch long incision is made between the ribs; and the ribs are separated, but not broken, to expose the lungs. With this procedure only one lung is reduced and the muscle and skin are closed by sutures. 
         [0016]    Although the goal of surgical therapy of COPD is to prolong life by relieving shortness in breath, preventing secondary complications, and enhancing quality of life by improving functional status, LVRS for COPD has higher surgical risks than heart surgery. Other risks associated with LVRS involve, but are not limited to: air leakage from the lung tissue at the suture line and into the chest cavity, pneumonia, bleeding, stroke, heart attack and death (resulting from worsening of any of the aforementioned complications). Because of the dangers associated with LVRS and despite advances in medical therapy, a significant number of patients with advanced COPD face a miserable existence and are at an extremely high risk for death. Over the years, a number of minimally invasive methods have been developed to address the concerns related to LVRS and to focus on the selective destruction of specific areas of undesirable tissue as an alternative to LVRS. Some of these methods include cryosurgery, non-selective chemical ablation, and ablation through radiofrequency or (RF), ultrasound, microwave, laser and thermal electric methods. However, these developments are associated, as well, with a fair amount of surgically related setbacks including complications such as large and difficult to manipulate operating mechanisms and the inability to control therapy to the affected area. This is due to the fact that ablation techniques used historically have been non-selective in that they mediate cell death with methods such as extreme heat or cold temperatures. The aforementioned methods of focal destruction of affected areas have been proven to non-selectively and adversely affect blood vessels, nerves, and connective structures adjacent to the ablation zone. Disruption of the nerves locally impedes the body&#39;s natural ability to sense and regulate homeostatic and repair processes at and surrounding the ablation region. Disruption of the blood vessels prevents removal of debris and detritus. This also prevents or impedes repair systems, prevents homing of immune system components, and generally prevents normal blood flow that could carry substances such as hormones to the area. Without the advantage of a steady introduction of new materials or natural substances to a damaged area, reconstruction of the blood vessels and internal linings become retarded as redeployment of cellular materials is inefficient or even impossible. Therefore historical ablation treatments do not leave tissue in an optimal state for self-repair in regenerating the region. 
         [0017]    Improvements in medical techniques have rekindled interest in the surgical treatment of COPD, wherein the effects highly resemble that of LVRS but without much of the associated risks and complications of conventional LVRS techniques. These recent developments offer an opportunity to advance the regenerative process following ablation treatments. Irreversible Electroporation or (IRE) is one such technique that is pioneering the surgical field with improved treatment of tissue ablation. IRE has the distinct advantage of non-thermally inducing cell necrosis without raising/lowering the temperature of the ablation zone, which avoids some of the adverse consequences associated with temperature changes of ablative techniques such as radiofrequency (RF) ablation, microwave ablation, or even cryo-ablation. IRE also offers the ability to have a focal and more localized treatment of an affected area. The ability to have a focal and more localized treatment is beneficial when treating the delicate intricacies of organs such as the lung. 
         [0018]    IRE is a minimally invasive ablation technique in which permeabilization of the cell membrane is effected by application of micro-second, milli-second and even nano-second electric pulses to undesirable tissue to produce cell necrosis only in the targeted tissue, without destroying critical structures such as airways, ducts, blood vessels and nerves. More precisely, IRE treatment acts by creating defects in the cell membrane that are nanoscale in size and that lead to a disruption of homeostasis while sparing connective and scaffolding structure and tissue. Thus, destruction of undesirable tissue is accomplished in a controlled and localized region while surrounding healthy tissue, organs, etc. is spared. This is different from other thermal ablation modalities known for totally destroying the cells and other important surrounding organs and bodily structures. 
       BRIEF SUMMARY OF THE DISCLOSURE 
       [0019]    The present invention relates to methods for treating tissue, more particularly to treating lung tissue, through utilization of Irreversible Electroporation (IRE) to non-thermally ablate diseased tissue and enhance lung functions in patients with Congestive Obstructive Pulmonary Disorder (COPD). 
         [0020]    It is a purpose of this invention to successfully treat target regions of diseased lung tissue affected by chronic bronchitis and emphysema through IRE ablation. IRE involves the application of energy sources capable of generating a voltage configured to successfully ablate tissue through the utilization of electrode balloons, flexible devices, probes such as monopolar, bipolar, or multiple probes (i.e. combinations of monopolar or bipolar probes arranged in a variety of configurations, monopolar and bipolar probes used together, or a series of separate or mixed groups of monopolar or bipolar probes), electrode arrays, and other devices available in electro-medicine. IRE ablation devices are available in various combinations and configurations in order to accommodate the ablation of multiple shapes, sizes and intricate portions of the diseased tissue. Examples of IRE probes applicable to this invention are described in U.S. patent application Ser. No. 12/413,332 filed Mar. 27, 2009 and 61/051,832 filed May 15, 2008, both of which are incorporated herein. 
         [0021]    The present invention involves the method of treating COPD using IRE through open surgical, percutaneous, laparoscopical, or endotracheal procedures including the steps of obtaining access to the diseased area by positioning one or more energy delivery devices coupled to an IRE device within a target region of diseased tissue; applying IRE energy the target region to ablate the tissue; disconnecting the energy source from the IRE probe and withdrawing the probe. More specifically, the invention involves ablating diseased portions of lung tissue. Although the method of the present invention is directed towards treatment of a diseased lung, the method can also be used to treat other organs or areas of tissue to include, but not limited to areas of the digestive, skeletal, muscular, nervous, endocrine, circulatory, reproductive, lymphatic, urinary, or other soft tissue or organs; and more particularly, areas of the fiver, prostate, kidney, pancreas, uterus and brain, among others. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view of a lowermost portion of the lung depicting an enlarged bronchus and alveoli. 
           [0023]      FIG. 2A  is an enlarged cross-sectional view of a normal bronchus. 
           [0024]      FIG. 2B  is an enlarged cross-sectional view of a bronchus affected by chronic bronchitis. 
           [0025]      FIG. 3A  is an emerged cross-sectional view of normal alveoli. 
           [0026]      FIG. 3B  is an enlarged cross-sectional view of alveoli affected by emphysema. 
           [0027]      FIG. 4  is a perspective view of the endotracheal procedure for performing IRE on a lung affected by chronic bronchitis showing a catheter passed through the trachea and positioned within the bronchus. 
           [0028]      FIG. 5A  is a perspective view of the endotracheal procedure for performing IRE on a lung affected by chronic bronchitis showing an IRE electrode balloon positioned within the bronchus. 
           [0029]      FIG. 5B  is an enlarged cross-sectional view of a deflated IRE electrode balloon positioned within the bronchus prior application of IRE energy. 
           [0030]      FIG. 5C  is an enlarged cross-sectional view of an inflated IRE electrode balloon positioned within the bronchus during the application of IRE energy. 
           [0031]      FIG. 5D  is an enlarged cross-sectional view of the bronchus post-treatment showing the restored diameter of the bronchus. 
           [0032]      FIG. 6A  is a perspective view of the percutaneous procedure of performing IRE detailing the use of an IRE probe to ablate the diseased region of the lung. 
           [0033]      FIG. 6B  is a perspective view of the percutaneous procedure of performing IRE detailing the use of two IRE probes to ablate the diseased region of the lung. 
           [0034]      FIG. 7  is a flowchart showing the method of treating patients with COPD or chronic bronchitis using IRE ablation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]      FIG. 4  shows the endotracheal method of performing IRE on a lung ( 10 ) affected by chronic bronchitis. A catheter ( 24 ) is advanced through the trachea ( 26 ) to a diseased region ( 28 ) of the bronchus ( 12 ). Advancement through the trachea ( 26 ) is relatively simple and will optionally require a guidewire to select the advancement route through to the branching bronchus ( 12 ). Steering of the catheter ( 24 ) may be effected under real time imaging using video assisted thoracic surgery (VATS). Once the catheter ( 24 ) is in place inside the diseased region ( 28 ), a flexible IRE device ( 25 ) is inserted through the catheter ( 24 ) to the diseased region ( 28 ) of the bronchus ( 12 ). The flexible IRE device is used in the endotracheal method because it allows for the device to be easily steered through and properly positioned within the delicate intricacies of the lung ( 10 ) and into the bronchus ( 12 ). With the flexible IRE device ( 25 ) within the diseased region ( 28 ) of the lung ( 10 ), an IRE power source (not shown) is powered on and IRE energy is applied to ablate the inflamed bronchial tissue of the diseased region ( 28 ). To treat multiple bronchi, the IRE device ( 25 ) may then be retracted back into the catheter ( 24 ) and redeployed in an adjacent bronchus ( 12 ). 
         [0036]    The endotracheal method of performing IRE can be executed endo-bronchially or exo-bronchially.  FIG. 5A  shows a more detailed view of the flexible IRE device ( 30 ) in place within the diseased region ( 28 ) of the lung ( 10 ) wherein the IRE device ( 30 ) includes an electrode balloon ( 36 ). Although an electrode balloon is shown, the endotracheal procedure is not limited to such, other devices may be employed.  FIG. 5B  details the electrode balloon ( 36 ), in a deflated state, in place within the decreased diameter airway (A2) of the inflamed inner bronchial wall ( 18 ) of the bronchus ( 12 ). The electrode balloon ( 36 ) includes a plurality of electrodes  37  positioned on the surface of the deflated balloon. Prior to application of IRE energy, the IRE power source ( 32 ) is powered on, the electrode balloon ( 36 ) is inflated as shown in  FIG. 5C . The expansion of the balloon results in a partial increase in bronchial airway diameter. Electrodes  37  are shown in contact with the inner bronchial wall ( 18 ) of the bronchus. As IRE energy is then applied to the inner bronchial wail ( 18 ) of the bronchus, electrical current ( 39 ) flows from the electrodes ( 37 ) into the bronchial wall ( 18 ) tissue. The inflamed portion of the bronchus is ablated, reducing the thickness of the bronchus wall. After treatment, the diameter (D1) of bronchial airway (A1) increases as shown in  FIG. 5D . The airflow is restored and breathing functions improve. 
         [0037]    A percutaneous method of treating a lung affected by chronic bronchitis may also be used. Very much similar to the endotracheal method, the percutaneous method may be executed both endo-bronchially and exo-bronchially. The probe, with increased rigidity and strength relative to an IRE catheter probe, is inserted into the lung tissue through the skin using a direct stick approach. The distal end section of the probe is then advanced through a wall of the bronchus into the lumen. IRE energy is applied to ablate the tissue of the diseased region such that inflammation of the bronchus is decreased and breathing functions are enhanced. 
         [0038]      FIGS. 6A and 6B  show a method of perforating IRE on an emphysemic lung ( 10 ) using a percutaneous approach. Although not shown, the endotracheal approach previously described may also be used.  FIG. 6A  details a bipolar IRE probe ( 50 ) inserted through the skin ( 46 ) to the target area of the lung ( 10 ) near the alveoli ( 14 ). Advancement and positioning of the probe ( 50 ) may be effected under real time imaging modalities such as ultrasound or CT. Once the probe ( 50 ) is in place in the targeted lung region, the IRE power source ( 32 ) is powered on and IRE energy is applied to the probe. Electrical current flows between distal electrode ( 56 ) and proximal electrode ( 54 ), creating a zone of ablation ( 52 ). 
         [0039]    Alternatively, as shown in  FIG. 6B , two IRE probes of opposite polarity may be used to ablate a desired lung tissue volume. Electrode probe ( 58 ), which may be of positive polarity, is positioned within the lung tissue a selected distance away from negative electrode probe ( 59 ). The application of electrical energy from power source ( 32 ) creates an electrical field between the two electrodes  61  and  62  as shown by ablation zone ( 52 ). In another embodiment (not shown), an electrode probe with deployable electrode tines may be used to apply IRE energy to lung tissue. In all these embodiments, the ablated tissue dies, thereby reducing the overall lung volume. For larger target areas, sequential ablations may be performed. As with LVRS, up to approximately 20-35% of the damaged lung may be non-surgically ablated. By reducing the lung volume, the remaining lung tissue and surrounding muscles are able to work more efficiently, improving air flow. 
         [0040]    Ablation of the targeted region of diseased tissue is achieved with an IRE generator as the power source, utilizing a standard wall outlet of 110 volts (v) or 230 v with a manually adjustable power supply depending on voltage. The generator should have a voltage range of 100 v to 10,000 v and be capable of being adjusted at 100 v intervals. The applied ablation pulses are typically between 20 and 100 microseconds in length, and capable of being adjusted at 10 microsecond intervals. The preferred generator should also be programmable and capable of operating between 2 and 50 amps, with test ranges involving an even lower maximum where appropriate. It is further desired that the IRE generator includes 2 to 6 positive and negative connectors, though it is understood that the invention is not restricted to this number of connectors and may pertain to additional connector combinations and amounts understood in the art and necessary for optimal configurations for effective ablation. Preferably, IRE ablation involves 90 pulses with maximum field strengths of 400V/cm to 3000V/cm between electrodes. Pulses are applied in groups or pulse-trains where a group of 1 to 15 pulses are applied in succession followed by a gap of 0.5 to 10 seconds. Pulses can be delivered using probes, needles, and electrodes each of varying lengths suitable for use in not only with percutaneous and laparoscopic procedures, but with open surgical procedures as well. In endotracheal procedures, due to the delicate intricacies and general make-up of the lung, it is preferable that a flexible device be used to ensure proper placement and reduced risk of perforation, abrasion, or other trauma to the lung tissue. 
         [0041]    Although preferred specifics of IRE ablation devices are set forth above, electro-medicine provides for ablation processes that can be performed with a wide range of variations. For instance, some ablation scenarios can involve 8 pulses with maximum field strengths between electrodes of 250V/cm to 500V/cm, while others require generators having a voltage range of 100 kV-300 kV operating with nano-second pulses with maximum field strengths of 2,000V/cm to, and in excess of, 20,000V/cm between electrodes. Electrodes can be made using a variety of materials, sizes, and shapes known in the art, and may be spaced at an array of distances from one another. Conventionally, electrodes have parallel tines and are square, oval, rectangular, circular or irregular shaped having a distance of 0.5 to 10 centimeters (cm) between two electrodes; and a surface area of 0.1 to 5 cm2. 
         [0042]      FIG. 7  is a flowchart detailing the basic method of performing IRE ablation on bronchitis or COPD patients. As detailed above, access to the diseased region is gained through open surgical, laparoscopical, percutaneous or endotracheal procedure. Once the IRE device is connected and in proper position, the IRE parameters are set. These parameters may vary and are selected depending upon several factors such as the diseased state, patient health and anatomy, and other considerations. After establishing and setting the required IRE energy parameters, the diseased region of the lung is ablated and the IRE device is removed. Thus, focal tissue ablation of the lung is achieved without causing harm to surrounding tissue and/or organs. 
         [0043]    An unlimited number of variations and configurations for the present invention could be realized. The foregoing discussion describes merely exemplary embodiments illustrating the principles of the present invention, the scope of which is recited in the following claims. Those skilled in the art will readily recognize from the description, the claims, and drawings that numerous changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited to the foregoing specification.