Abstract:
A patient-controlled system for temporarily disabling an electrical cardioverting therapy in order to prepare the patient psychologically and physiologically for the pain associated with electrical cardioversion therapy. In an example embodiment, the system includes a capacitive circuit capable of charging and discharging in order to apply the electrical therapy. The implanted medical device automatically causes the capacitive circuit to charge and discharge at least once within a selected period. The system includes a patient activator device that communicates with the implanted device. A disabling circuit is also included within the implanted medical device that temporarily disables the electrical therapy application in response to the patient activator device. The system further includes an alerting arrangement that alerts the patient activator device in response to the disabling circuit. An override circuit overrides the temporary disabling of the electrical therapy application in response to the patient being in a relaxed mode.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to the management of pain associated with applying electrical cardioversion therapies. In particular, the invention relates to patient preparation in advance of application of the electrical cardioversion therapy. 
     BACKGROUND OF THE INVENTION 
     Implanted medical devices are capable of detecting and treating an arrhythmia (i.e., irregular heartbeats) in a patient. In one example, the implanted medical device includes a defibrillator that applies an electrical pulse therapy to a patient&#39;s heart upon detecting fibrillation (i.e., high, irregular heartbeat), a form of arrhythmia. Cardioverters or defibrillators discharge relatively high energy electrical shocks or pulses into or across cardiac tissue to arrest a life-threatening atrial or ventricular fibrillation upon detection by the implanted medical device. Defibrillation shocks, while highly effective at arresting the fibrillation, may occur suddenly and can cause considerable patient discomfort. 
     The level of discomfort that a patient experiences with defibrillation shocks is affected by many psychological factors, among which are fear and anxiety of the impending shock therapy. In one instance, the patient becomes highly distressed because the patient must rush through current activities in order to find an area for treatment, and await the application of the pre-programmed shock therapy. Patients can reduce the impact of these psychological factors by taking control over the time that the shock is applied and by physiologically preparing the body in advance of the shock delivery. 
     The implanted device is programmed by a physician using a programming head that is electrically connected to a programming unit similar to a personal computer. The programming of the implanted device is usually limited to the physician or a trained technician. To safeguard the patient&#39;s health, the physician programs the implanted device to automatically deliver at least one electrical shock therapy in a 24-hour period. Therefore, patient control over the application time of the shock treatment is not usually available to ambulatory patients because the patient is not authorized to program his own implanted device. 
     Patients can also reduce the impact of psychological factors by using any one of a number of sedatives prior to the shock delivery. Although sedation therapy may be helpful in reducing shock discomfort, sedation therapy is also impractical when the patient is traveling or when the patient needs to be alert and cannot be incapacitated by the sedative for a prolonged time period. 
     Accordingly, patients would be able to better manage the pain associated with electrical cardioversion therapy if they had the time to psychologically and physiologically prepare in advance of the therapy. An approach that addresses the aforementioned problems, as well as other related problems, is therefore desirable. 
     SUMMARY OF THE INVENTION 
     Various embodiments of the present invention are directed to addressing the above as well as other needs in connection with enabling a patient to control the pain associated with an electrical cardioverting therapy, by allowing the patient to control the timing of the electrical therapy. In one such embodiment, an implanted medical device is configured to automatically cause the application of an electrical therapy at least once within a selected period (e.g., 24-hour period), includes a circuit arrangement for temporarily disabling the electrical therapy application responsive to a patient activated device that is carried by the patient. 
     According to another embodiment of the invention, a system for temporarily disabling an electrical therapy application by an implanted medical device includes a capacitive circuit capable of charging and discharging in order to apply the electrical therapy. The implanted medical device automatically causes the capacitive circuit to charge and discharge at least once within a selected period. The system includes a patient activator device that communicates with the implanted device. A disabling circuit is also included within the implanted medical device that temporarily disables the electrical therapy application in response to the patient activator device. The system further includes an alerting arrangement that alerts the patient activator device in response to the disabling circuit. The system also includes an override circuit that overrides the temporary disabling of the electrical therapy application in response to the patient being in a relaxed mode. 
     According to yet another embodiment of the present invention, an implanted medical device that automatically applies an electrical therapy to a patient&#39;s heart at least once within a selected period includes a communications circuit that enables telemetric communications from the implanted medical device in response to an external patient activator device. A disabling circuit is disposed within the implanted medical device that temporarily disables the electrical therapy application. An alerting arrangement is also include that alerts the patient activator device in response to the disabling circuit. The implanted medical device further includes an override circuit that overrides the temporary disabling of the electrical therapy application in response to the patient being in a relaxed mode. 
     The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures in the detailed description that follow more particularly exemplify these embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
     FIG. 1 illustrates a block diagram of a patient-controlled system for temporarily disabling an electrical therapy provided by an implanted device according to an example embodiment of the invention; and 
     FIG. 2 is a flow diagram illustrating the manner of using a patient activator device to control the time that an electrical therapy is applied according to another example embodiment of the invention. 
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     The present invention is generally directed to a patient-controlled system that enables a patient to control the pain associated with an electrical cardioverting therapy by controlling the time that the electrical therapy is applied. While the present invention is not necessarily limited to such an application, the invention will be better appreciated using a discussion of example embodiments in such a specific context. 
     In an example embodiment, a system for delivering an electrical cardioverting therapy to a heart of a patient experiencing atrial fibrillation includes an implanted medical device that delivers the electrical cardioverting therapy within a predetermined time period upon detecting the fibrillation. The implanted medical device includes a capacitive circuit that can be charged and discharged in response to a first and a second signal, respectively. The implanted device automatically transmits the signals at least once within a predetermined time period (e.g., 24-hours) causing the capacitive circuit to charge and discharge and transmits the signals in response to the detected fibrillation. The system includes a patient activator device (PAD) that is carried by the patient and that communicates an instruction to the implanted device to temporarily disable the implanted device&#39;s control over the timing of the electrical therapy. The PAD device includes an alert feature that advises the patient that the electrical therapy is temporarily disabled. 
     In a related embodiment, the system includes a sleep monitor that is activated by the PAD and ensures that the patient is at least relaxed or asleep when he receives the electrical therapy. In another related embodiment, the sleep monitor is automatically activated when the implanted device detects an arrhythmia. The sleep monitor is programmable by the patient via the PAD. 
     FIG. 1 illustrates a block diagram of a patient-controlled system  100  for temporarily disabling an electrical therapy provided by an implanted device according to an example embodiment of the invention. A patient  102  has an implanted medical device  103  that is configured to detect an abnormal body function, such as an arrhythmia (irregular heartbeat) of a heart  105 . In this example, a detection circuit  104  detects an atrial fibrillation of the heart and transmits a warning signal via a communications module  108  to a patient activator device (PAD)  110 . PAD  110 , which can be carried, sounds an audible alarm (or emits a vibration) via an alert unit  113 , in response to the warning signal from implanted device  103  alerting patient  102  that his heart is in atrial fibrillation. 
     Patient  102  uses PAD  110  to instruct implanted device  103  to temporarily disable the implanted device&#39;s automatic atrial fibrillation response. In this example, the automatic response is application of an electrical cardioverting therapy or shock via a charge/discharge circuit  109  to heart  105 . Alert unit  113  advises the patient that the electrical therapy is temporarily disabled. System  100  also includes an override circuit in the form of a sleep monitor circuit  107 A (with sensor  107 B) that is activated by PAD  110  and, in conjunction with PAD  110 , ensures that the patient is at least relaxed or asleep when he receives the electrical therapy. 
     To induce relaxation or sleep prior to the application of the electrical therapy, patient  102  can choose to take a sedative. After taking the sedative, the patient activates sleep monitor circuit  107 A, which monitors the patient&#39;s physiological condition. If the patient decides not to take a sedative, the patient activates the sleep monitor when he is reclined or seated. Charge/discharge circuit  109  applies the electrical therapy to the patient upon detecting that the patient is in a relaxed mode or is asleep. In a related embodiment, a timing circuit is activated as part of the sleep monitor to ensure that the patient is asleep for a select period of time before applying the electrical therapy. 
     Heart conditions detectable by detection circuit  104  include, but are not limited to, ventricular fibrillation, tachycardia, bradycardia and eventual heart failure. In a related embodiment, a logic unit  106  in conjunction with detection circuit  104 , evaluate the severity of the detected heart condition. Logic unit  106  continues to monitor the general condition of heart  105  before triggering detection circuit  104  to warn patient  102  of a detected arrhythmia. Implanted device  103  is also programmed to automatically deliver additional electrical therapies or shocks if a preceding shock was either ineffective or an atrial tachyarrhythmia prematurely re-occurred. 
     In the present embodiment, PAD  110  is comprised of a communications module  114  that communicates bi-directionally with implanted device  103  via communications module  108 . PAD  110  also includes a logic unit  112  (e.g. microprocessor) that configures the electrical therapy that is applied by implanted device  103 . Unit  112  also processes warning signals from implanted device  103  and transmits them to an alert unit  113  that audibly advises patient  102  of the bi-directional communication occurring between implanted device  103  and PAD  110 . In this example, PAD  110  also includes a display  16  for reading alphanumeric messages from implanted device  103  and a keypad  118  for facilitating programming of implanted device  103 . 
     In another example embodiment, implanted device  103  is an implantable cardiac defibrillator (ICD) having programmable atrial tachyarrhythmia therapies with the capability to accept programmed commands from the PAD. The ICD also includes a PAD programming capability with several automatic shock and patient activated shock therapy options. A programmable option in the ICD will allow the patient to suspend therapy for a programmable duration (e.g., one-day). ICD is also capable of delivering an electrical therapy on patient-command via PAD  110 . A first signal from PAD  110  charges circuit  109  and a second signal from PAD  110  discharges circuit  109  into heart  105 . The override circuit (e.g., sleep monitor circuit) of implanted device  103  is also programmable and PAD includes additional features to assist the patient to include: a query function to determine status of atrial rhythm status; immediate delivery of an electrical therapy; an atrial defibrillation deactivation button; and a programmable delay function that can suspend therapy for up to a selected period of time (e.g., 24-48 hours). 
     With respect to sleep monitor  107 A, factors such as respiration rate, heart rate and patient activity are highly affected by sleep and are monitored by sleep monitor  107 A. Once activated, monitor  107 A attempts to detect a patient&#39;s state of relaxation or sleep. An example algorithm used by monitor  107 A for detecting sleep requires detecting a low activity level and a 15%-25% reduction in respiration and/or heart rate (suggested physiological measures). If monitor  107 A does not detect sleep within two hours, then the electrical therapy will be canceled. In another embodiment, the physiologic measures are combined with a timing circuit to ensure a steady state of sleep for a certain period of time before delivering the electrical therapy. This approach prohibits delivering the electrical therapy when the patient has just fallen asleep and is not yet entered REM sleep. 
     In a related embodiment, the patient is audibly warned (or via a vibration or light signal) by PAD  110  that the electrical therapy is to be administered shortly. In another related embodiment, PAD  110  has a programmable delay with a locking feature to ensure that the patient cannot alter the delay. The time delay can be based on the peak effect of the sedation therapy. 
     In a related embodiment, implanted device  103  comprises a neurological implant or nerve stimulator that includes a stimulator circuit. Logic unit  106  with detection circuit  104  and at least one sensor  107 B coordinates the detection of irregular body functions at or near the area of the implant. Upon detecting an irregularity at the implant area, PAD  110  receives telemetric communications from implanted device  103  of the irregularity and provides an alert to the patient. The stimulator circuit delivers the electrical therapy to the area upon sensing that the patient is in a relaxed mode. 
     In the various embodiments described herein, PAD  110  is configured to operate in harmony with implanted device  103 . For more information regarding the functionality of PAD  110  and IMD  103 , reference may be made to U.S. Pat. No. 5,987,356 to De Groot, which is assigned to the assignee of the present invention and incorporated herein by reference. 
     In the various embodiments described herein, modules  108  and  114  are configured to telemetrically communicate with each other using various techniques, including magnetic-field coupling, reflected impedance coupling and radio-frequency (RF) coupling. For more information regarding magnetic-field coupling, reference may be made to U.S. Pat. No. 3,311,111 to Bower and U.S. Pat. No. 3,805,796 to Terry et al., which are assigned to the assignee of the present invention and incorporated herein by reference. For more information regarding reflected-impedance coupling, reference may be made to U.S. Pat. No. 4,223,679 to Schulman et al., which is assigned to the assignee of the present invention and incorporated herein by reference. For more information regarding RF coupling, reference may be made to U.S. Pat. No. 5,843,139 to Goedeke et al., which is assigned to the assignee of the present invention and incorporated herein by reference. 
     FIG. 2 is a flow diagram  200  that illustrates the logic in the use of a patient activator device to control the time that an electrical therapy is applied according to another example embodiment of the invention. At step  202 , implanted device  103  detects the presence of arrhythmia, which in this case is atrial fibrillation. At step  204 , implanted device  103  determines the type of therapeutic mode: automatic atrial defibrillation or patient-activated atrial defibrillation. At step  206  of the patient activated atrial fibrillation path, implanted device  103  determines if the patient activated the therapy via a delay timer or sleep monitor  107 A. If the sleep monitor is activated at step  208 , the sleep monitor determines at step  210  if the sleep criterion for the patient is met. At step  212 , if the sleep criterion is met implanted device  103  determines whether a delay entered on PAD  110  is still engaged. If the therapy delivery time is exceeded in step  214 , then implanted device  103  determines whether the patient canceled the therapy. At step  218 , the implanted device applies the electrical therapy because the therapy was not actually canceled. 
     At step  206 , implanted device  103  determines that the patient did not activate a therapy, and device  103  continues to monitor for ongoing AF (atrial fibrillation) at step  220 . At step  208 , if implanted device  103  determines that the sleep monitor is not on then implanted device  103  verifies whether a delay is engaged. If no delay is detected, then at step  216 , implanted device  103  determines that the therapy was indeed canceled and continues to monitor for ongoing AF. Device  103  also continues to monitor for AF when the implanted device determines that at step  214  the therapy time delay has been exceeded. At step  210 , implanted device  103  determines that the sleep criterion is not met and continues to monitor for ongoing AF. 
     At step  222  on the automatic atrial defibrillation path, device  103  determines whether the patient has suspended the atrial defibrillation therapy for a fixed time period. If at step  223 , implanted device  103  determines that the suspended time is exceeded then device  103  continues to monitor for AF. At step  224 , implanted device  103  determines if there is a pre-programmed window for therapy (e.g., 4AM-6AM, daily). If there is no therapy pre-scheduled, at step  226  device  103  determines whether the sleep monitor is on. If at step  228 , device  103  determines that the sleep monitor is on and the sleep criteria is met device  103  delivers the shock therapy to heart  105  at step  230 . 
     Device  103  delivers a shock to the heart at step  224  if there is no therapy window and at step  226  if sleep monitor circuit  107 A is not on. Device  103  will continue to monitor for ongoing AF whenever device  103  determines that the sleep criterion is not met. 
     Various modifications, equivalent processes, as well as numerous applications to which the present invention may be amenable will be readily apparent to those of skill in the art to which the present invention is directed, upon review of the present specification. The claims are intended to cover such modifications and devices.