Abstract:
A method for treating a patient is provided where a sensed cardiac rhythm is used to adjust electrical stimulation that is used to activate a diaphragm to cause contraction. A cardiac rhythm management device in combination with a diaphragm stimulation device is also provided which includes a cardiac stimulation device configured to provide stimulation to control cardiac rhythm of a subject; and an electrical stimulation device configured to provided electrical stimulation to a subject to activate a diaphragm to increase functional residual capacity of the subject.

Description:
[0001]    This application claims priority of Provisional Application No. 60/931,205 and; and is a continuation in part of U.S. application Ser. No. 12/082,057 entitled: DEVICE AND METHOD FOR TREATING CARDIOVASCULAR DISORDERS OF THE CARDIOVASCULAR SYSTEM OR HEART filed Apr. 8, 2008; and is a continuation in part U.S. application Ser. No. 12/069,823 filed Feb. 13, 2008, and of U.S. application Ser. No. 12/004,932 filed Dec. 21, 2007; and of U.S. application Ser. No. 11/981,342 filed Oct. 31, 2007; and of U.S. application Ser. No. 11/480,074 filed Jun. 29, 2006 and of U.S. application Ser. No. 11/271,315 filed Nov. 10, 2005; and of U.S. application Ser. No. 11/271,554 filed Nov. 10, 2005; and of U.S. application Ser. No. 11/271,353 filed Nov. 10, 2005; and of U.S. application Ser. No. 11/271,264 filed Nov. 10, 2005; and of U.S. patent application Ser. No. 10/966,487 filed Oct. 15, 2004; and of U.S. application Ser. No. 11/480,074 filed Jun. 29, 2006 which is a continuation in part of U.S. application Ser. No. 11/271,726 filed Nov. 10, 2005 which is a continuation in part of U.S. application Ser. No. 10/966,484 filed Oct. 15, 2004; U.S. application Ser. No. 10/966,474, filed Oct. 15, 2004; U.S. application Ser. No. 10/966,421, filed Oct. 15, 2004; and U.S. application Ser. No. 10/966,472 filed Oct. 15, 2004 which are continuations in part of U.S. application Ser. No. 10/686,891 filed Oct. 15, 2003 entitled: BREATHING DISORDER DETECTION AND THERAPY DELIVERY DEVICE AND METHOD all of which are incorporated in their entirety herein by reference without limitation. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a device and method for providing diaphragm stimulation in cardiovascular and heart failure (or dysfunction) patients. 
       BACKGROUND OF THE INVENTION 
       [0003]    In copending Application entitled DEVICE AND METHOD FOR TREATING DISORDERS OF THE CARDIOVASCULAR SYSTEM OR HEART, filed on even date herewith and incorporated in its entirety herein by reference without limitation, electrical stimulation is described to elicit a diaphragm response to provide therapy to patients with heart failure, heart dysfunction or other cardiovascular related disease. Such stimulation may be provided to treat heart failure/dysfunction or other cardiovascular disease and/or may be provided to treat disordered breathing that frequently is associated with heart failure. Such patients may be using a cardiac rhythm management device such as a pacemaker, CRT or ICD or may at some time be a candidate for such device. Accordingly, it would be desirable to provide a device that provides stimulation to elicit a diaphragm response that may work in concert with one or more such devices. 
         [0004]    It would further be desirable to provide a device that may control the diaphragm stimulation in response to one or more cardiac conditions. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with one aspect of the invention, a diaphragm stimulation device, i.e., configured to stimulate tissue to elicit a diaphragm response, is provided with an cardiac electrogram sensor. The diaphragm stimulator is configured to control or adjust stimulation in response to cardiac electrogram sensed by the cardiac electrogram sensor. The sensed cardiac electrogram may provide information on a cardiac condition or event and may control stimulation to avoid device-device interaction at the occurrence of a cardiac event. According to one variation, stimulation may be turned off when a cardiac event or condition is present for purposes of safety and to allow other intervention. The stimulator may also provide or adjust stimulation based on a cardiac event or condition, to therapeutically benefit the patient during such event or condition. 
         [0006]    In accordance with one aspect of the invention, stimulation is provided to the diaphragm or phrenic nerve to elicit a diaphragm response to thereby provide a therapeutic effect for a heart failure or other cardiac or cardiovascular patient. 
         [0007]    In accordance with one aspect of the invention, stimulation to elicit a diaphragm response is provided to increase or normalize lung volume and in particular to increase functional residual capacity. It is believed that stimulation to increase or to normalize lung volume or functional residual capacity may have one or more effects that may be therapeutic to cardiovascular or heart failure patients. Normalizing herein may include for example, bringing a physiological parameter into a normal or healthy region for patients or for a particular patient, or to a level appropriate for a condition or state of a patient. 
         [0008]    In accordance with another aspect of the invention stimulation is provided to control breathing to reduce respiration rate and thereby reduce hypertension, reduce sympathetic nerve bias, and/or provide improved blood gas levels. 
         [0009]    In accordance with another aspect of the invention stimulation is provided to control minute ventilation to therapeutically effect blood gas levels. 
         [0010]    In accordance with another aspect of the invention, stimulation is provided to create a deep inspiration or an increased tidal volume to thereby reduce sympathetic nerve bias, improve blood gas levels, stimulate reflexes for example the Hering-Bruer reflex related to activating stretch receptors, increase lung volume, normalize or reset breathing or provide other beneficial therapies to improve cardiovascular function or heart failure condition. 
         [0011]    In accordance with another aspect of the invention stimulation may be provided to manipulate intrathoracic pressure to thereby produce a therapeutic effect. According to one embodiment, stimulation is provided to reduce intrathoracic pressure to thereby increase ventricular filling. 
         [0012]    In accordance with another aspect of the invention stimulation is provided to reduce breathing disorders to thereby improve condition of a heart failure patient. 
         [0013]    In accordance with another aspect of the invention a combined cardiac rhythm management device and diaphragm/phrenic nerve stimulation device is provided to provide an enhanced combined treatment device. 
         [0014]    In accordance with another aspect of the invention the stimulation device may be used to treat one or more diseases, disorders and conditions that may relate to, have co-morbidities with, affect, be affected by respiratory or lung health status, respiration, ventilation, or blood gas levels. Such diseases and disorders may include but are not limited to obstructive respiratory disorders, restrictive respiratory disorders, vascular respiratory disorders, upper airway resistance syndrome, snoring, obstructive apnea; central respiratory disorders, central apnea; hypopnea, hypoventilation, obesity hypoventilation syndrome other respiratory insufficiencies, inadequate ventilation or gas exchange, chronic obstructive pulmonary diseases; asthma; emphysema; chronic bronchitis; circulatory disorders; hemodynamic disorders; hypertension; heart disease; chronic heart failure; cardiac rhythm disorders; neurodegenerative disorders; ALS; MS; obesity or injuries in particular affecting breathing or ventilation. 
         [0015]    These and other aspects of the invention are set forth herein in the abstract, specification and claims. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a front schematic view illustrating a device in accordance with an aspect of the invention. 
           [0017]      FIG. 2A , illustrates a composite sensed signal including diaphragm EMG and CARDIAC ELECTROGRAM. 
           [0018]      FIG. 2B  illustrates a diaphragm EMG signal filtered from the composite signal of  FIG. 2A . 
           [0019]      FIG. 2C  illustrates and CARDIAC ELECTROGRAM signal filtered from the composite signal of  FIG. 2A . 
           [0020]      FIGS. 3A ,  3 B, and  3 C illustrate respectively, an CARDIAC ELECTROGRAM signal in which an arrhythmia event occurs, a schematic illustration of lung volume and a therapeutic stimulation signal configured elicit a diaphragm response. 
           [0021]      FIGS. 4A ,  4 B, and  4 C illustrate respectively, an CARDIAC ELECTROGRAM signal in which an arrhythmia event occurs, a schematic illustration of lung volume and a therapeutic stimulation signal configured elicit a diaphragm response. 
           [0022]      FIG. 5  is a flow chart illustrating an example of use of a method and device in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Examples of various devices for and uses of diaphragm stimulation are described in related applications set forth above and in copending patent application entitled: DEVICE AND METHOD FOR TREATING DISORDERS OF THE CARDIOVASCULAR SYSTEM OR HEART, filed on even date herewith, all of which are incorporated herein by reference without limitation. A diaphragm stimulator in accordance with the invention also includes a cardiac electrogram sensor which may be used in conjunction with any diaphragm stimulation therapy. 
         [0024]      FIG. 1  illustrates a diaphragm stimulator  100  in accordance with the invention positioned on the diaphragm  10 . The stimulator may be positioned from an abdominal approach or a thoracoscopic approach as described, for example, one or patent applications set forth herein. The diaphragm stimulator  100  includes an implantable pulse generator  110  and leads  120  extending to electrode assemblies  130  positioned on the hemidiaphragms  20 . The electrode assemblies  130  include at least one electrode  140  positionable on the diaphragm  10 . The electrode assemblies  130  are coupled to a signal processor  150 , e.g., located with the pulse generator  110 , configured to process a composite signal, for example as shown in  FIG. 2A  to obtain a diaphragm EMG signal and/or an cardiac electrogram as shown in  FIGS. 2B and 2C  respectively. The stimulator  100  may further be programmed to control stimulation in response to cardiac electrogram information sensed by one or more electrodes  140 . The electrode assembly  130  includes an electrode  135  that acts as a stimulation electrode as well as a sensor for sensing EMG and cardiac electrogram. The cardiac electrogram sensor described herein includes the electrode  135  and signal processing, for example as described herein. The EMG sensor and/or the cardiac electrogram sensor may be separate from the electrode  135  as well. Examples of programmable diaphragm are set forth in one or more of the related patent applications set forth herein. 
         [0025]      FIG. 1  further illustrates a CRM device  160  implanted with leads in the heart  155 . The CRM device comprises a subcutaneously implanted pulse generator  165  with intravenous lead  170  extending into heart and terminating in atrial electrode  175  and ventricular electrode  180 . The diaphragm stimulator  100  is configured to avoid device-device interaction with CRM device  160 . For example, defibrillation therapy produces a strong electric field in the body that may be sensed by at least one  140  electrode on the diaphragm. The electrode  140  may be arranged, for example, with a far reference such that it more effectively picks up a global signal such as the defibrillation therapy as sensed at the diaphragm. When the diaphragm stimulation device senses that defibrillation is occurring stimulation is adjusted or turned off to allow for defibrillation without interference from diaphragm stimulation, and to lower the risk of noise detection which may interfere with cardiac therapies. Antitachycardia pacing which treats lower rate tachycardias may also be detected by the diaphragm stimulation device, and trigger a halting or change of diaphragm based therapy. 
         [0026]    According to another aspect of the invention, the CRM device  160  is configured to avoid negative device/device interaction with a diaphragm stimulator  100 . Diaphragm stimulation produces a characteristic electric field in the body that may be sensed by a sensing electrode component of a CRM device, for example, based on a known stimulation signal characteristics such as frequency, amplitude and/or duration of the stimulation. The CRM device may be programmed to recognize one or more of these characteristics. Programming and detection may occur, for example, when the diaphragm stimulation device is implanted so that the precise characteristics of the actual stimulation as seen by the CRM device can be recognized. The sensing electrode of the CRM device  160  may be arranged, for example, with a far reference such that it more effectively picks up a global signal such as the diaphragm stimulation. If a CRM device senses that diaphragm stimulation is occurring then it may be configured to adjust it&#39;s sense algorithms for reduced sensitivity to a diaphragm stimulation artifact. In accordance with another aspect of the invention, the CRM device may be configured as a defibrillator where the defibrillator is configured to avoid entering a noise detection state during a time in which diaphragm stimulation is occurring. Often defibrillation therapy is not allowed during noise detection. Accordingly turning off noise detection during diaphragm stimulation permits pacing or defibrillation to occur during diaphragm stimulation. 
         [0027]    While  FIG. 1  illustrates a diaphragm stimulator positioned in a specific location, a diaphragm stimulator in accordance one or more aspects of the invention may be positioned in other locations, for example on the phrenic nerve, subcutaneously, transvenously or externally. Such stimulator may include a stimulation electrode and an cardiac electrogram sensor and may be programmed in accordance with the invention to control stimulation based on sensed cardiac electrogram information. 
         [0028]      FIG. 2A  illustrates a composite signal  210  including a diaphragm EMG and an cardiac electrogram sensed at one or more electrodes of a diaphragm stimulator in accordance with the invention. This signal  210  as illustrated is representative of a diaphragm EMG and cardiac electrogram sensed at a stimulator configured to be positioned on the diaphragm of a subject.  FIG. 2B  illustrates a signal  220  comprising an EMG signal  220  processed from the signal  210  of  FIG. 2A  where the signal has been processed through a 4-40 Hz notch filter.  FIG. 2C  illustrates a signal  230  comprising an ECG signal  230  processed through a 4-40 Hz bandpass filter. 
         [0029]      FIGS. 3A-3C  illustrate a device and method in accordance with an aspect of the invention.  FIG. 3C  schematically illustrates a stimulation signal  380  to stimulate tissue to elicit a diaphragm response. The signal  380  is configured to increase functional residual capacity. Stimulation such as a bias stimulation to increase FRC is described for example in one or more related patent applications set forth herein. As illustrated by the lung volume  381  in  FIG. 3B , the stimulation in  FIG. 3C  causes a functional residual capacity FRC 2  which is greater than a baseline functional residual capacity FRC 1 . The cardiac electrogram (EGM), EGM 1  during stimulation signal  380 , is normal. EGM 2  indicates an arrhythmia. The sensor that senses cardiac electrogram may also be configured to identify an irregular cardiac electrogram, such as, for example, an arrhythmia. The stimulation signal  380  is turned off by a controller when the cardiac electrogram signal is identified as an irregular cardiac electrogram. 
         [0030]      FIGS. 4A-4C  illustrate a device and method in accordance with an aspect of the invention.  FIG. 4C  schematically illustrates a stimulation signal  480  to stimulate tissue to elicit a diaphragm response. The signal  480  is configured to increase functional residual capacity (FRC). Stimulation such as a bias stimulation to increase FRC is described for example in one or more related patent applications set forth herein. As illustrated by the lung volume in  FIG. 4B , the stimulation in  FIG. 4C  causes a functional residual capacity FRC B  which is greater than a baseline functional residual capacity FRC A . The cardiac electrogram, EGM A  during stimulation signal  480 , is normal. EGM B  indicates an arrhythmia. The sensor that senses cardiac electrogram may also be configured to identify an irregular cardiac electrogram, such as, for example, an arrhythmia. The stimulation signal  480  is turned off by a controller when the cardiac electrogram signal is identified as an irregular cardiac electrogram. A stimulation signal  490  is delivered to stimulate a deep inspiration or a breath with an increased tidal volume when the controller identifies the irregular cardiac electrogram, EGM B  as an arrhythmia. An increase in FRC to FRC c  is shown resulting from deep inspiration therapy from stimulation signal  490 . 
         [0031]      FIG. 5  illustrates a device used in accordance with an aspect of the invention. A cardiac electrogram signal is obtained  510  with a cardiac electrogram sensor on a diaphragm stimulation device. (The sensor may use separate electrode or may use the same electrode that is used for stimulation.) The signal is used by a processor to check cardiac rhythm  520 . The processor determines whether or not the rate is high  530 . If it is not the device continues to check cardiac rhythm  520 . If the rate is high, then the processor determines if the high rate is a tachycardia without ventricular fibrillation or if ventricular fibrillation is occurring  540 . Such cardiac electrogram processing techniques are generally known in the art. If ventricular fibrillation is detection, then one or more programmable actions may follow at step  550 . For example, sleep apnea therapy comprising diaphragm stimulation may be stopped or controlled to reduce the level of stimulation. The sleep apnea therapy may also be changed to a different therapy such as breathing control where breathing is paced. If at step  540  ventricular fibrillation is not detected, the one or more programmable actions may follow at step  560 . For example, the sleep apnea therapy comprising diaphragm stimulation may be stopped or controlled to reduce the level of stimulation. The sleep apnea therapy may also be changed to a different therapy such as deep inspiration which may affect the tachycardia. If a sinus rhythm is not detected as step  570  then cardiac rhythm is checked again at step  520 . If a sinus rhythm is detected at step  570 , then the appropriate sleep apnea therapy is reinitiated at step  580 .