Abstract:
Devices, systems, and methods for leadlessly stimulating the heart. Through a magnetic signal generator positioned outside or inside the thoracic cavity, a magnetic signal is transmitted through the chest to stimulate electrical activity within the myocardial muscles. The magnetic signal may function as a pacemaker, cardioverter or defibrillator. Advantages of magnetic stimulation include, without limitation, non invasiveness, a reduction or even elimination in pain, and access to tissues covered by poorly conductive structures.

Description:
RELATED APPLICATIONS 
       [0001]    This U.S. Utility Patent Application claims priority to U.S. Provisional Patent Application Ser. No. 60/817,424, filed on Jun. 30, 2006. 
     
    
     BACKGROUND 
       [0002]    Despite advances in techniques of resuscitation, cardiac arrest and related cardiac problems are associated with significant morbidity and mortality. Moreover, due to the incidence of sudden cardiac death (“SCD”) and other life threatening cardiac ailments, cardiac dysfunction remains a major public health problem, especially for developed countries. For example, it is estimated that between 250,000 and 300,000 SCDs occur per year in the United States; an undoubtedly conservative estimate due to the fact that these figures are exclusively based on the assumption that about 50% of 600,000 cardiovascular deaths occur suddenly. (Myerburg and Spooner, 2001; Danieli G A, 2006). Moreover, according to recent trials, up to 50% of the deaths in patients with coronary artery disease and left ventricular systolic dysfunction are sudden or arrhythmic in nature. (Cannom D S, 2006). While the incidence of sudden or arrhythmic deaths is lower in patients with heart failure due to non-ischemic aetiologies, there is currently no way to detect which heart failure patients will die from an arrhythmia rather than progressive left ventricle systolic dysfunction. Although certain clinical markers such as greater age, degree of left ventricle systolic dysfunction, and severity of heart failure can predict general mortality, there is low specificity in detecting the mode of death. 
         [0003]    A healthy cardiac rhythm not only consists of a heart that beats at the proper pace, but the muscular contractions of the four chambers of the heart must also be properly mediated such that they can contract in a coordinated fashion. The heart has specialized conduction pathways in both the atria and the ventricles that enable the rapid conduction of excitation (i.e. depolarization) throughout the myocardium. Normally, the sinoatrial node (“SA node”) initiates each heart-beat cycle by depolarizing so as to generate an action potential. This action potential propagates relatively quickly through the atria, which react by contracting, and then relatively slowly through the atrio-ventricular node (“AV node”). From the AV node, activation propagates rapidly through the His-Purkinje system to the ventricles, which also react by contracting. This natural propagation synchronizes the contractions of the muscle fibers of each chamber and synchronizes the contraction of each atrium or ventricle with the contralateral atrium or ventricle. 
         [0004]    The rate at which the SA node depolarizes determines the rate at which the atria and ventricles contract and thus controls the heart rate. The pace at which the SA node depolarizes is regulated by the autonomic nervous system which can alter the heart rate so that the heart, for instance, beats at a faster rate during exercise and beats at a slower rate during rest. The above-described cycle of events holds true for a healthy heart and is termed normal sinus rhythm. 
         [0005]    The heart, however, may have a disorder or disease that results in abnormal activation that preempts sinus rhythm, and results in an irregular heartbeat, i.e. an arrhythmia. Individuals with cardiac ailments, and especially those at risk of SCD, may suffer from an irregular pace and/or uncoordinated mechanical activity wherein the myocardial depolarization and contraction of the chambers do not occur simultaneously. Without the synchronization afforded by the normally functioning specialized conduction pathways or the proper pacing by the SA node, the heart&#39;s pumping efficiency is greatly diminished and can thus compromise a patient&#39;s cardiac output. Several different factors may lead to the development of an arrhythmia, including atherosclerosis, thrombosis, defects in electrogenesis and nerve impulse propagation, influences of the sympathetic and parasympathetic systems, ischemia (inadequate oxygen supply to the cells due to lack of blood flow), and/or poor vascular control. 
         [0006]    A variety of techniques are practiced to minimize the uncoordinated motion patients with cardiac ailments exhibit. Such current therapies can generally be divided into pharmacological, surgical, and electrical methods. While each of these therapies may be used individually, it is not uncommon for physicians to concurrently employ more than one. In addition, the physician&#39;s decision as to which type of therapy(ies) to employ depends, in large part, on the type of arrhythmia that the patient exhibits. 
         [0007]    With respect to electrical therapy, catheter ablation and cardiac rhythm management devices have particularly evolved as the gold standard therapies for patients at high risk for ventricular and supraventricular tachyarrhythmia (i.e. abnormally rapid beating of the heart). Catheter ablation is an invasive procedure used to remove the faulty electrical pathways from the heart. The procedure consists of inserting several flexible catheters into the patient&#39;s blood vessels, typically into the femoral, internal jugular, or subclavian veins. The catheters are then advanced towards the heart and high-frequency electrical impulses are used to induce an arrhythmia, and then ablate (destroy) the abnormal tissue that is causing the arrhythmia. While catheter ablation of most arrhythmias has an extremely high success rate, the procedure is highly invasive and requires direct contact with the region of interest. 
         [0008]    Cardiac rhythm management devices are implantable devices that provide electrical stimulation to selected chambers of the heart in order to treat cardiac rhythm disorders. There are numerous types of cardiac rhythm management devices, the most notable of which include pacemakers and implantable cardioverter defibrillator (“ICD”) devices. 
         [0009]    A pacemaker is a cardiac rhythm management device that paces the heart with timed pacing pulses. The simplest configuration of a pacemaker is a power source with a timing circuit and an electrical lead designed to carry electrical energy to the heart. The most common condition for which pacemakers are used is in the treatment of bradycardia, where the ventricular rate is slow. Pacing therapy may also be applied in order to treat cardiac rhythms that are too fast, termed anti-tachycardia pacing. 
         [0010]    If functioning properly, the pacemaker makes up for the heart&#39;s inability to pace itself at an appropriate rhythm by enforcing a normal heart rate. It does this by using electrical energy to cause the myocardium to contract when necessary, as determined based off of a normal sinus rhythm. Currently, pacemakers are capable of “dual-chamber pacing”, which initiates a contraction in the atrium, the ventricle, or both. When enough energy is sent down through the lead to cause depolarization in the myocardium, and therefore a contraction, “capturing” of the heart occurs and the depolarization effect can be observed on an electrocardiogram (“ECG”). As the term is used herein, “capture threshold” is the minimum amount of energy necessary to capture the heart. 
         [0011]    An ECG of a normal sinus rhythm is characterized by a P wave, which corresponds with atrial depolarization and contraction of the atria, followed by the QRS complex, which corresponds with depolarization and contraction of the ventricles. Due to size differences between the atria and the ventricles, the P wave is considerably smaller than the QRS complex. A T wave follows the QRS complex and corresponds to ventricular repolarization. Atrial repolarization is difficult to detect with an ECG as the atrial repolarization signal has a small amplitude and is mainly hidden by the much larger QRST complex. In addition to the P wave and the QRST complex, a normal ECG is also characterized by a PR interval, defined as the time between atrial and ventricle contractions, of about 0.12 to 0.20 sections and regular R-R intervals, defined as the time between QRST complexes, of about 0.60 to 1 second. 
         [0012]    The pacing rate of a pacemaker consists of the average number of pulses delivered from the power source over a specified period of time, usually one (1) minute. The length of time from one pacing impulse to the next is termed the pacing interval. It is the goal of using a pacemaker that the pacing interval eventually corresponds to the normal sinus rhythm discussed above. The pulse width, (measured in milliseconds), is the length of time that the current flows through the lead when the pacemaker delivers an energy pulse. Conventional pacemakers typically contain an internal timing clock to measure time in thousandths of a second, or milliseconds (ms), to ensure the pacing impulses are delivered correctly. The pacemaker&#39;s output is equal to the amount of energy delivered with each energy pulse. Energy can be considered as “voltage over time” or voltage at a certain pulse width. The optional capture thresholds can be calculated by varying the pulse width while maintaining a constant voltage. 
         [0013]    Economically, cardiac pacemakers account for more than 50% of worldwide expenditure in the electrophysiology market, which includes cardiac pacemakers, ICDs, and radiofrequency ablation devices. (ANAES, 1999). In 1998, the percentage accounted for approximately $2.5 billion in sales, or approximately 540,000 implanted pacemakers. (ANAES, 1999). The number of cardiac pacemakers inserted continues to increase over time, especially in light of the ever-increasing elderly population. 
         [0014]    Pacemaker implantation is a common surgical procedure that is performed under local anesthesia and requires only a short hospitalization time. A lead catheter is inserted into the chest, through the subclavian vein, which is located below the collarbone and above the heart. The pacemaker&#39;s leads are then threaded through the catheter and adhered to the appropriate chamber or chambers of the heart. The electrodes are typically positioned in contact with the inner surface of the right atrium or ventricle. The pacemaker&#39;s leads are then tested to guarantee that there is consistent capture with a sufficiently low energy level to ensure that the pacemaker can function properly over an extended period of time. Finally, a small pocket is created subcutaneously on the upper portion of the chest wall to hold the power source, which is thereafter closed with stitches. It is not uncommon for the power source—typically a conventional lithium battery—to be easily felt through the skin. Such lithium batteries typically exhibit a battery life of eight (8) to ten (10) years and are easily replaced by performing a relatively minor surgery where the subcutaneous pouch is reopened under local anesthesia. 
         [0015]    A common problem with cardiac pacemaker implantation is dislocation of the leads, which typically occurs in 1.1% to 6% of all cases. (ANAES, 1999). This complication generally takes place within two (2) months of insertion and requires additional surgery to relocate the leads. In addition, the implantation of a pacemaker also carries the risks of developing haematoma, hemorrhage, perforations of the heart and the pleura, infection (more specifically, endocarditis), and symptomatic and asymptomatic venous thrombosis. Electrophysiological complications may also include pacemaker syndrome, an atrial fibrillation considered to be less common with single chamber atrial inhibited pacing mode cardiac pacemakers. In addition, the implantation procedure is invasive and requires direct contact with the region of interest. 
         [0016]    In about 30% of chronic heart failure patients, the disease process compromises the myocardium&#39;s ability to contract, which thereby alters the conduction pathways through the heart and causes a delay in the beginning of right or left ventricular systole. (Abraham et al., 2002). On an ECG, such a desynchronization is manifested as a QRS complex interval lasting more than 120 ms. It has been proposed that intraventricular conduction delay may compromise the ability of the failing heart to eject blood and may consequently increase the severity of the mitral valve regurgitant flow. In patients with heart failure, the intraventricular conduction delay leads to clinical instability and an increased risk of death. These uncoordinated contractions cannot be remedied by a conventional pacemaker alone, as simple pacemakers merely address pacing issues. Currently, there are several devices that make use of atrial-synchronized biventricular pacing in order to coordinate right and left ventricular contraction. 
         [0017]    A cardiac resynchronization therapy (“CRT”) device, also known as a biventricular pacemaker, is a type of pacemaker that can pace both ventricles (right and left) of the heart. As noted above, by pacing both sides of the heart, the pacemaker can resynchronize a heart that does not beat in synchrony, which is common in patients at risk for SCD. After the Food and Drug Administration approved CRT in 2001, approximately 271,000 heart failure patients in the United States have received CRT for moderate to severe heart failure. (Aranda et al., 2005). 
         [0018]    Conventional CRT devices closely resemble pacemakers, except that a typical CRT device has three (3) electrical leads which are coupled to cardiac tissue. The first lead is typically coupled to the right atrium, a second lead is typically coupled to the right ventricle, and a third lead is typically coupled to the left ventricle (often via the coronary sinus or great vein). Implantation and maintenance of a CRT device are linked to greater risks than conventional pacemaker devices. This is because a device delivering CRT requires that the third lead is inserted through the coronary sinus and advanced into the cardiac vein to pace the left ventricle. As a result, the risk of an unsuccessful implantation of the device or even dissection or perforation of the coronary sinus or cardiac vein is increased significantly. Erroneous efforts to implant the third lead or the device may also have severe complications, including complete heart block, hemopericardium, and even cardiac arrest. In addition, it is not uncommon for the left ventricular lead to become dislodged during long-term pacing, which necessitates repositioning or replacement of the lead. 
         [0019]    An additional cardiac rhythm management device that is closely related to a pacemaker is the ICD device. Like CRT, ICDs resemble pacemakers and are often used in the treatment of patients at risk for SCD. An ICD is a small, battery powered electrical impulse generator which is typically implanted in patients who are at risk of SCD due to ventricular fibrillation. The principles of cardiac arrhythmia detection and treatment are incorporated into the implantable device, such that the ICD can monitor the heart&#39;s sinus rhythm and deliver the proper electrical treatment automatically. 
         [0020]    An ICD has the ability to treat many types of heart rhythm disturbances (including uncoordinated cardiac activity) by means of pacing, cardioversion, or defibrillation. ICDs are capable of constantly monitoring the rate and rhythm of the heart and delivering therapies, by way of electrical shock, when the heart activity is not in accordance with the optimal sinus rhythm. In this manner, ICDs are able to offer joined therapy with programmable anti-arrhythmia pacing schemes, as well as low and high energy shocks in multiple ranges of tachycardia rates. Conventional ICD devices are considerably smaller than the first prototypes of the early 1980s and can easily be positioned under the skin in the left chest. The majority ICD generators must be replaced every four (4) to five (5) years. 
         [0021]    In the United States in 2002, 415,780 ICD devices were implanted. (Wilkoff B L, 2007). The process of implantation of an ICD is similar to implantation of a pacemaker. Similar to CRT devices, these devices typically include electrode leads which pass through the coronary sinus and into the cardiac vein. Accordingly, the same risks that apply to the implantation and maintenance of pacemakers, and specifically CRT devices, are applicable to ICD devices. 
         [0022]    Due to the growing number of patients requiring some form of cardiac rhythm therapies, there is a need for a technique that benefits from the advantages of ICDs and pacemakers without suffering the problems associated with such devices. Furthermore, such novel techniques should be easy to understand and implement, universally adoptable, and have competitive advantages over conventional heart treatment devices, such as ICDs and pacemakers. 
         [0023]    Articles discussing cardiac disease and treatment include: 
         [0024]    Abraham W T et al. Cardiac resynchronization in chronic heart failure.  N Engl J Med  2002; 346(24):1845-1853. 
         [0025]    Agence Nationale d′Accréditation et d&#39;Évaluation en Santé. Evaluation clinique et économique des endoprothèses aortiques. Paris: ANAES; 1999. 
         [0026]    Aranda et al. Management of heart failure after cardiac resynchronization therapy: integrating advanced heart failure treatment with optimal device function.  J Am Coll Cardiol  2005; 46(12): 2193-98. 
         [0027]    Cannom D S. “After DEFINITE, SCD-HeFT, COMPANION: Do We Need to Implant an ICD in All Patients With Heart Failure?” Cardiac Arrhythmias Proceedings of the 9th International Workshop on Cardiac Arrhythmias. A. Raviele. Venice 425-434 (2005). 
         [0028]    Danieli G A. “Sudden Arrhythmic Death: Which Genetic Determinants?” Cardiac Arrhythmias Proceedings of the 9th International Workshop on Cardiac Arrhythmias. A. Raviele. Venice 385-392 (2005). 
         [0029]    Myerburg R J, Spooner P M. Opportunities for sudden death prevention: directions for new clinical and basic research.  Cardiovasc Res  2001; 50: 177-85. 
         [0030]    Wilkoff B L. Pacemaker and ICD malfunction—an incomplete picture. JAMA 2007; 295(16): 1944-1946. 
       SUMMARY 
       [0031]    Devices, systems, and methods for the magnetic resynchronization of a heart are provided. Embodiments of the device include an external source of magnetic energy to resynchronize the heart to initiate or correct proper sinus rhythm. By determining the proper level of energy required to resynchronize the sinus rhythm, devices transmit a magnetic energy wave to the heart to retrigger the electrical pattern necessary to re-initiate the pattern for contraction. 
         [0032]    An additional embodiment comprises a device for stimulating the heart. The device comprises a magnetic signal generator positioned outside of a chest cavity. When the magnetic signal generator produces a magnetic signal external to the chest cavity, the heart receives the magnetic signal and resets its electrical activity accordingly. 
         [0033]    To prevent attenuation and loss of energy when the device is situated externally of the chest cavity, the device may be implanted adjacent to the heart using a minimally invasive procedure, and/or the standard cardiac surgical procedure. Standard thorascopic techniques can be employed to implant and anchor the device onto the pericardium immediately near the heart. 
         [0034]    An additional embodiment comprises a method for determining treatment for a heart. The method includes determining the heart rate and arrhythmia information; analysis of the information to determine best therapeutic strategy; and applying magnetic stimulus that corresponds with the determined best therapeutic strategy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  shows a partial cross-section view of an implantable cardioverter defibrillator of the PRIOR ART. 
           [0036]      FIG. 2A  shows a front view of a magnetic cardioverter defibrillator device. 
           [0037]      FIG. 2B  shows a schematic diagram of the magnetic cardioverter defibrillator device of  FIG. 2A . 
           [0038]      FIG. 3  shows a schematic diagram of one embodiment of a circuitry of the magnetic cardioverter defibrillator device of  FIG. 2A . 
           [0039]      FIG. 4A  shows a bottom view of one embodiment a coil configuration for use with the magnetic cardioverter defibrillator device of  FIG. 2A . 
           [0040]      FIG. 4B  shows a bottom view of an additional configuration of the coil of  FIG. 4A . 
           [0041]      FIG. 4C  shows a bottom view of an additional configuration of the coil of  FIG. 4A . 
           [0042]      FIG. 4D  shows a side view of the coil configuration of  FIG. 4B . 
           [0043]      FIG. 5  shows a schematic diagram of one embodiment of a magnetic cardioverter defibrillator device and system. 
           [0044]      FIG. 6A  shows a schematic diagram of a robotic arm for use with the magnetic cardioverter defibrillator device and system of  FIG. 5 . 
           [0045]      FIG. 6B  shows a perspective view of the robotic arm of  FIG. 6A . 
           [0046]      FIG. 7  shows a flow chart showing logic and functions steps of a method for treating arrhythmias over time. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]    Reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of scope is intended by the description of these embodiments. 
         [0048]      FIG. 1  shows a partial cross-section view of an implantable cardioverter defibrillator  10  (“ICD  10 ”) of the prior art. The ICD  10  of the prior art comprises a pulse generator  16 , at least one shock coil  12 , and at least one spacing electrode  14 . The pulse generator  16  is capable of generating the electrical pulse that is used to deliver therapy to the heart  50  through the shock coil  12 . The pulse generator  16  comprises a circuitry  20  and a battery  22  encased within a hermetically sealed, biologically inert outer casing  24  and is typically implanted either beneath the skin in the subcutaneous space or beneath the pectoral muscles, adjacent to the heart  50 . 
         [0049]    One or more shock coils  12 , collectively identified with reference to numeral  12  in  FIG. 1 , are electrically coupled to the pulse generator  16  in a conventional manner and extend transvenously between the implant site of the pulse generator  16  to the heart  50 . Disposed near the distal end of the shock coils  12  are one or more exposed spacing electrodes  14  for receiving electrical cardiac signals and/or delivering electrical pacing stimuli to the heart  50 . The shock coils  12  of the ICD  10  are implanted with their distal end(s) situated in the atrium and/or ventricle of the heart  50 . In addition, at least one of the shock coils  12  is typically advanced into the cardiac vein such that the ICD  10  to pace the left ventricle. In operation, the ICD  10  of the prior art delivers electrical stimuli directly to the heart  50  through the shock coils  12  and, ultimately, the pacing electrodes  14 . While the application of direct-electrode stimulation does not present many difficulties with respect to localizing the proper area of the heart to be stimulated, the direct-electrode treatment is often considerably painful for the patient. 
         [0050]    To implant the ICD  10  into a patient, the shock coils  12 , and therefore the pacing electrodes  14 , must be inserted into various veins associated with the heart, including the cardiac vein. Insertion of a lead into the cardiac vein is a particularly invasive procedure, as the shock coil  12  must first be inserted through the coronary sinus and thereafter advanced into the cardiac vein. As previously noted, the pulse generator  16  is also implanted into the patient, either subcutaneously in between the skin and the ribs, or in the proximity of the heart  50  itself. In the event the pulse generator  16  is implanted adjacent to the heart  50 , the battery  22  is typically implanted subcutaneously so that the battery  22  can be easily accessed and replaced upon failure. When the battery  22  is implanted subcutaneously and independent of the pulse generator  16 , an additional lead is run from the battery  22  to the pulse generator  16 . 
         [0051]    Now referring to  FIGS. 2A and 2B , a novel magnetic cardioverter defibrillator  100  (the “MCD device  100 ”) is shown. The MCD device  100  is capable of implementing leadless magnetic therapy to a heart, even when positioned externally of the patient&#39;s chest cavity. Accordingly, the MCD device  100  offers a less invasive alternative to conventional devices and methods. Moreover, because the therapy is delivered by magnetic stimulation, the use of the MCD device  100  may reduce the amount of pain felt by a patient when the therapy is applied. This is because with direct-electrode stimulation, the current required to stimulate a region of the myocardium must pass through the highly resistive myocardial muscle cells, which contain numerous pain fiber endings. However, with the magnetic stimulation delivered by the MCD device  100 , the electric field is circumferential and tangential to the myocardial muscle, thereby necessitating less current density, therefore resulting in less sensation. 
         [0052]    The MCD device  100  comprises a pulse generator  116  having a power supply  120  and circuitry  122 , both of which are encased within a casing and shield  123 . The casing and shield  123  are hermetically sealed and biologically inert, such that the casing and shield  123  protect the components contained therein, and do not interfere with the magnetic stimulation generated by the pulse generator  116 . 
         [0053]    The power supply  120  may comprise any power supply known in the art, so long as power supply  120  is capable of providing sufficient power to the pulse generator  116  over a period of time. In one embodiment, the power supply  120  comprises a lithium battery. The circuitry  122  is electronically coupled with the power supply  120  and comprises a magnetic stimulation system having a magnetic stimulator  135  and at least one coil  140 . The magnetic stimulator  135  and the at least one coil  140  form a circuit  122 , which in one embodiment is a series resonant or RLC circuit (as shown in  FIG. 3 ). While the RLC circuit of  FIG. 3  is offered by way of an example, it will be understood that any type of circuit may be used in conjunction with the magnetic stimulation system, including more complicated circuits. The magnetic stimulation system, by way of the magnetic stimulator  135  and the coils  140 , produces magnetic stimulation in cardiac muscle through the transmission of electromagnetic fields. 
         [0054]    The magnetic stimulator  135  is capable of generating pulse fields by delivering current into the coil  140 . The configuration of the coil  140  and the magnetic stimulator  135  may affect the different values of capacitance available. For example, in one embodiment the magnetic stimulator  135  further comprises a high-powered thyristor and can thereby control the capacitor discharge. When the number of coils  140  (inductors) are increased (see  FIG. 4C ), the magnetic stimulator  135  may further comprise parallel capacitors to generate high magnetic localization. 
         [0055]    Now referring to  FIGS. 4A-4D , different configurations of the coils  140  are shown. The coils  140  of the circuitry  122  may comprise several possible configurations. Numerous factors may influence the optimal coil  140  configuration, such as the placement of the MCD device  100  relative to the heart, the patient&#39;s body composition, and/or specific details with respect to the arrhythmia being treated. Different coil configurations can create different stimulation on the epicardium. In addition, the numerous muscles and bones located in the chest can reflect and refract the electromagnetic fields produced by the magnetic stimulation system. Therefore, the adaptation of the magnetic coils  140  to aid in the localization of the electromagnetic field is beneficial. Alternatively, implantation of the MCD device  100  adjacent to the heart circumvents issues of refraction and reflection while nonetheless having the less invasive advantage of remaining outside of the heart or vessels. 
         [0056]    In one embodiment of the MCD device  100 , the coils  140  are individually configured into circular flat-spiral coils, as shown in  FIG. 4A . While a single coil  140  may be used in this configuration in the magnetic stimulation system to produce a magnetic signal, a plurality of coils  140  arranged in various configurations relative to each other may also be employed.  FIGS. 4B ,  4 C, and  4 D illustrate two (2) possible configurations of the at least one coil  140  that is used in the MCD device  100 . While only two configurations are discussed herein, it will be recognized that any number of coil designs may be used with the magnetic stimulation system of the MCD device  100 . In  FIGS. 4B and 4D , two of the coils  140  are arranged in a two-leaf, butterfly configuration. In  FIG. 4C , four of the coils  140  are arranged in a four-leaf, cloverleaf configuration. As previously noted, these different coil configurations create different stimulus on the epicardium. For example, the flat-spiral coil (shown in  FIG. 4A ) induces currents similar to those induced by the larger coil configurations, but more focally. The butterfly-shaped coil (shown in  FIGS. 4B and 4D ) induces the largest currents in its center, where the circumferences of the two component coils  140  adjoin. In addition, the butterfly-shaped coil configurations ( FIGS. 4B and 4D ) and the cloverleaf-shaped coil configurations ( FIG. 4C ) are more efficient than a single circular coil, such as the one shown in  FIG. 4A . In short, the different geometries of the coils  140  affect the values of the magnetic induction and electric field induced by the MCD device  100 . 
         [0057]    The MCD device  100  may either be implanted within a patient&#39;s thoracic cavity, or positioned externally. In both locations, the MCD device  100  is capable of leadlessly transmitting an electric pulse to the myocardial fiber by inducing time-varying magnetic fields. Referring back to  FIG. 2A , the MCD device  100  is positioned external to the patient&#39;s body. The external MCD device  100  may be employed in clinical settings or may be affixed to the exterior of a patient&#39;s chest for outpatient therapy. In this manner, the patient can benefit from the therapy delivered by the MCD device  100  without undergoing invasive surgery and risking the numerous complications associated therewith. Moreover, because the MCD device  100  is external to the patient&#39;s body, the power supply  120  can be easily replaced and recharged. 
         [0058]    In an alternative embodiment, the MCD device  100  may be implanted within the patient&#39;s thoracic cavity to provide more comfort and security to the patient. Because the MCD device  100  does not require direct contact with the heart, the MCD device  100  may be implanted subcutaneously in between the patient&#39;s skin and ribs, on the surface of the heart or pericardium, or any other location within the body where the MCD device  100  can effectively transmit the generated electric pulses to the heart. In any of the embodiments where the MCD device  100  is internal to the patient&#39;s body, the power supply  120  may be attached to the MCD device  100  through a wire and subcutaneously implanted independently of the MCD device  100  such that the power supply  120  can be easily accessed and replaced or recharged when necessary. 
         [0059]    In operation, the MCD device  100  is capable of treating arrhythmias through the use of localized magnetic stimulation. The magnetic stimulation system of the circuitry  122  may either be programmed to initiate stimulus at a specific time or, in the embodiment where the MCD device  100  is located outside of the patient&#39;s body, the magnetic stimulation system of the circuitry  122  may be manually activated. When the MCD device  100  is activated, the electric current in the myocardial fibers of the patient&#39;s heart are induced by the magnetic coils  140  within the circuitry  122 . If the circuitry  122  comprises an RLC circuit (as shown in  FIG. 3 ), the optimal amount of current i(t) to run through the coil(s)  140  can be determined by the ordinary differential equation associated with an RLC circuit, as given in Equation 1. The duration of the first phase of di(t)/dt is denoted as the pulse width of a magnetic stimulus. 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       i 
                        
                       
                         ( 
                         
                           r 
                           , 
                           t 
                         
                         ) 
                       
                     
                     = 
                     
                       
                         V 
                         0 
                       
                        
                       C 
                        
                       
                           
                       
                        
                       
                         ω 
                         2 
                       
                        
                       
                         
                            
                           
                             
                               - 
                               
                                 ω 
                                 1 
                               
                             
                              
                             t 
                           
                         
                          
                         
                           ( 
                           
                             
                               
                                 ( 
                                 
                                   
                                     ω 
                                     1 
                                   
                                   
                                     ω 
                                     2 
                                   
                                 
                                 ) 
                               
                               2 
                             
                             + 
                             1 
                           
                           ) 
                         
                       
                        
                       
                         sinh 
                          
                         
                           ( 
                           
                             
                               ω 
                               2 
                             
                              
                             t 
                           
                           ) 
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   where 
                    
                   
                     
 
                   
                    
                   
                     
                       ω 
                       1 
                     
                     = 
                     
                       
                         
                           R 
                           
                             2 
                              
                             
                                 
                             
                              
                             L 
                           
                         
                          
                         
                             
                         
                          
                         and 
                          
                         
                             
                         
                          
                         
                           ω 
                           2 
                         
                       
                       = 
                       
                         
                           
                             
                               ( 
                               
                                 R 
                                 
                                   2 
                                    
                                   
                                       
                                   
                                    
                                   L 
                                 
                               
                               ) 
                             
                             2 
                           
                           - 
                           
                             1 
                             LC 
                           
                         
                       
                     
                   
                 
               
               
                 
                   [ 
                   1 
                   ] 
                 
               
             
           
         
       
     
         [0000]    and C and R are the default capacitance and inductance, respectively, and V 0  is the initial voltage. The total resistance of the RLC circuit includes the default and coil resistances. 
         [0060]    As the current flows through the coil(s)  140 , the induced electric field E(r, t) and magnetic induction B(r,t) can be calculated from the ‘coil current and the geometry of the coil(s)  140  by Equation 2. 
         [0000]    
       
         
           
             
               
                 
                   
                     E 
                      
                     
                       ( 
                       
                         r 
                         , 
                         t 
                       
                       ) 
                     
                   
                   = 
                   
                     
                       ( 
                       
                         
                            
                           
                             i 
                              
                             
                               ( 
                               
                                 r 
                                 , 
                                 t 
                               
                               ) 
                             
                           
                         
                         
                            
                           t 
                         
                       
                       ) 
                     
                      
                     
                       ( 
                       
                         
                           - 
                           
                             
                               
                                 μ 
                                 0 
                               
                                
                               N 
                             
                             
                               4 
                                
                               
                                   
                               
                                
                               π 
                             
                           
                         
                          
                         
                           ∫ 
                           
                               
                           
                            
                           
                             
                                
                               
                                 l 
                                 ′ 
                               
                             
                             
                                
                               
                                 r 
                                 - 
                                 
                                   r 
                                   ′ 
                                 
                               
                                
                             
                           
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   [ 
                   2 
                   ] 
                 
               
             
             
               
                 
                   
                     B 
                      
                     
                       ( 
                       
                         r 
                         , 
                         t 
                       
                       ) 
                     
                   
                   = 
                   
                     ∇ 
                     
                       × 
                       
                         ( 
                         
                           
                             
                               
                                 μ 
                                 0 
                               
                                
                               
                                 Ni 
                                  
                                 
                                   ( 
                                   
                                     r 
                                     , 
                                     t 
                                   
                                   ) 
                                 
                               
                             
                             
                               4 
                                
                               
                                   
                               
                                
                               π 
                             
                           
                            
                           
                             ∫ 
                             
                                 
                             
                              
                             
                               
                                  
                                 
                                   l 
                                   ′ 
                                 
                               
                               
                                  
                                 
                                   r 
                                   - 
                                   
                                     r 
                                     ′ 
                                   
                                 
                                  
                               
                             
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   [ 
                   3 
                   ] 
                 
               
             
           
         
       
     
         [0000]    where 
         [0061]    μ 0  is a constant (4 π×10 −7  V·s/AM); 
         [0062]    N is the number of turns in the coil  140 ; 
         [0063]    i(r,t) is the coil current; 
         [0064]    r is the position where the electric field is calculated; 
         [0065]    r′ is the position of the differential element of the coil dl′. 
         [0000]    The induced electric field can be expressed as the product of a function of time and space without considering the electrostatic potential. Once the coil geometry has been prescribed, the spatial distribution of the electric field can be determined independently of the current using the integral of Equation 2. In addition, Equations 1 and 2 are used to determine any term in the magnetic stimulation system when other values are defined. 
         [0066]    As previously noted, the MCD device  100  can be programmed to implement various designed programs to deliver timed magnetic stimulation by controlling the circuitry  122  in the MCD device  100 . Antitachycardia pacing (“ATP”) is a conventional electrophysiological technique that is commonly used for terminating monomorphic tachycardias. The ATP techniques can be delivered by the MCD device  100  and involve lowest-energy short pacing pulse (synchronized stimuli) delivered with a cycle length of approximately 80-90% of that of the tachycardia. By delivering pulses at a pace slower than the heart is beating, the ATP attempts to terminate the ventricular and supraventricular tachycardia. In practice, dual pacing has been shown to result in significant haemodynamic improvement. 
         [0067]    The two basic modes of antitachycardia pacing include 1) overdrive burst pacing, and 2) autodecremental (“ramp”) pacing. For these two major modes of ATP, different features can be added, such as the coupling interval scan, start interval scan, programmed extrastimulus, and additional extra pulses. Ramp pacing has been reported to be more efficacious than burst pacing in terminating sustained monomorphic ventricular tachycardia and has exhibited a low incidence of accelerating ventricular tachycardia. In addition, antibradycardia pacing can also be implemented by the MCD device  100  via ATP. 
         [0068]    The ATP current used to depolarize the heart is generally &lt;5 mA for the ventricles, which can be up to 20 mA. The pulse width, or the duration which the voltage is applied to the heart thereby causing current flow, is determined by the length of time it takes for the capacitor to discharge. In the MCD device  100 , the pacing pulse corresponding to the induced electrical field (E(r,t) in Equation 2) is controlled by the pulse of a magnetic stimulus (di(r,t)/dt). The pulse width is generally around 1 ms because the longer the pulse width, the greater discharge of energy per pulse and the shorter the battery life. The pulse amplitude (potential) required to capture the heart is about 200 mV on the epicardium. The potential gradient (the electric field intensity) is generally 100 mV/cm. 
         [0069]    Given the necessary pacing parameters (e.g., pulse current, pulse width, pulse amplitude), the required current in the magnetic coil(s)  140  can be inversely computed using Equations 1, 2, and 3. From Equation 2, the electric current (i(r,t)) in the magnetic coil(s)  140  can be calculated to equal approximately 1-10 A if a circular coil configuration is considered with N=30 turns, having an inner and outer radius of about 3 cm with butterfly configuration. From Equation 1, the battery potential V 0  can be calculated to equal approximately 20-50 V, assuming that C=200 μF and R=3Ω. C and R are the default capacitor and inductance, respectively, which are used to control the pulse width. 
         [0070]    In the event that the tachycardia does not respond to ATP, the MCD device  100  is also capable of implementing low energy shocks, or cardioversion, in an initial attempt to terminate ventricular and supraventricular tachycardia while inducing minimal pain to the patient (as some patients remain conscious despite rapid tachycardia). Synchronized cardioversion is shock delivery that is timed (synchronized) with the QRS complex. Low energy cardioversion consists of synchronized shocks with energies of 1 J or less and may exhibit very short charge times. The corresponding electric field intensity is about 1 V/cm, which is ten times larger than pacing. Like pacing, every synchronized shock is controlled by the magnetic stimulus (di(t)/dt). The parameters associated with di(t)/dt are also C, R, and V 0  of Equation 1. The electric current (i(r,t)) and potential V 0  in the magnetic coils are respectively about 10-100 A and 200 V if the same RLC circuit is selected as was in pacing. However, low energy cardioversion delivered by the conventional direct-electrode devices may accelerate the tachycardia and is uncomfortable for the patient. As previously indicated, when the MCD device  100  is employed, the pain to the patient may be significantly reduced due to the use of magnetic stimulation as opposed to the electric stimulation of the prior art devices. 
         [0071]    When low energy cardioversion fails, defibrillation may be delivered by the MCD device  100  to correct the serious tachycardia such as rapid ventricular tachycardia. In defibrillation delivered by conventional direct-electrode devices, four to eight non-synchronized shocks are applied and maximum shock energies range between 25 and 42 J with biphasic waveforms. When the MCD device  100  is used to deliver defibrillation, the corresponding electric field intensity is about 6 V/cm and 4 V/cm for a typical monophasic waveform and biphasic waveform, respectively. Like the low energy therapies, the non-synchronized shocks are also controlled by the magnetic stimulus (di(t)/dt). The parameters associated with di(t)/dt are also C, R, and V 0  of Equation 1. The electric current (i(r,t)) and potential V 0  in the magnetic coils are about 500 A and 1000 V, respectively, if the same RLC circuit is selected as was in pacing. More exact values for current and voltage may be determined based on the geometry of the coils  140  and the characteristics of the patient (for example, age, weight, thickness of chest, etc.), and will be apparent to one of ordinary skill in the art in view of the present disclosure. 
         [0072]    Now referring to  FIG. 5 , a schematic diagram is shown of a magnetic cardioversion defibrillator system  200  (the “MCD system  206 ”). The MCD system  200  comprises an echo and adjustment system  250  and a magnetic cardioversion defibrillator device  223  (the “MCD device  223 ”), which comprises a pulse generator  216  and a plurality of leads  218 . The echo and adjustment system  250  is capable of recording the position and motion of the walls and/or internal structures of the heart by the echo obtained from beams of ultrasonic waves directed through the chest wall. 
         [0073]    In one embodiment, the echo and adjustment device  250  further comprises an x-ray device (not shown). In this embodiment, the x-ray device detects the position and motion of the heart walls and/or the internal structures using electromagnetic radiation. Using the information determined by the x-ray device, the echo and adjustment system  250  is capable of accurately calculating the optimal stimulation position in the beating heart by determining the simple geometrical computation |r−r′| of Equations 2 and 3. In this manner, the echo and adjustment system  250  allows for a user to determine if optimal levels of localization have been reached upon magnetic stimulation the tissue, or if the MCD device  223  needs to be redirected or modified in some way. 
         [0074]    The pulse generator  216  comprises a power supply  120 , circuitry  122 , a microprocessor  224  for signal filtering and analysis, and at least one memory device  226  for data storage. Similar to the MCD device  100  previously discussed, all of the various components of the MCD device  223  may be encased within a casing and shield  123  (not shown). The casing and shield  123  are hermetically sealed and biologically inert, such that the casing and shield  123  protect the components contained therein, and do not interfere with the magnetic stimulation generated by the pulse generator  216 . However, it is understood that the microprocessor  224 , the plurality of leads  218 , and/or the at least one memory device  226  may each comprise an independent device, separate and apart from the MCD device  223 , so long as such devices are capable of being in communication with the MCD device  223 . 
         [0075]    The circuitry  122  and the power supply  120  may be identical to the components of the MCD device  100  shown in  FIGS. 1-4D , and as such, will not be discussed in detail with respect to the MCD device  223 . The microprocessor  224  is electronically coupled with the power supply  120  and the memory storage device  226 . The microprocessor  224  may be any microprocessor known in the art that is capable of receiving and processing electrogram data. The memory device  226  is coupled with the microprocessor  224  and may be any memory device  226  known in the art that comprises an accessible database or other storage medium. In addition, the memory device  226  is capable of storing information collected from the heart and/or information stored therein by a user, such as therapeutic algorithms and/or an individual&#39;s cardiac sinus rhythm characteristics. In one embodiment, the memory device  226  comprises a plurality of memory chips to store the collected electrograms. In addition, in this embodiment, the memory device  226  is telemetrically accessible by a user, as is known in the art, such that a user may remotely access the collected electrograms stored within the memory device  226  even when the MCD device  223  is implanted in the patient&#39;s thoracic cavity. 
         [0076]    The microprocessor  224  further comprises a plurality of leads  218 , each lead  218  comprising at least one electrode  219  that functions as a sensor for detecting the electrical activity of the heart. The leads  218  and electrodes  219  may be any leads and electrodes known in the art that are capable of transmitting a continuous uptake of sinus rhythm information from a heart being monitored. The electrodes  219  may comprise any single electrode or combination of electrodes conventionally used to generate an electrogram and/or pacing signals, or the electrodes  219  may comprise other types of skin electrodes. The electrodes  219  produce electrical signals based on the electric fields generated by the heart and the leads  218  transmit these signals back to the microprocessor  224  for analysis. In this manner, the microprocessor  224  is able to track and analyze the condition of the heart in an automated fashion solely from the information received from the leads  218 . While the leads  218  and electrodes  219  of the MCD device  223  are in close proximity to the cardiac muscle, it is not necessary for the leads  218  or electrodes  219  to be inserted into the cardiac muscle or veins, and the leads  218  and electrodes  219  are not required to deliver pacing and shocking pulses to the myocardium. 
         [0077]    In one embodiment of the MCD system  200 , the information collected through the leads  218  and electrodes  219  is used to create a real-time display of the intracardiac electrograms, which are thereafter used to assess the effect of body position and maneuvers on the electrical signals of the heart. In the event an abnormal sinus rhythm is observed, the echo and adjustment system  250  scans the heart using the x-ray device and automatically responds and redirects the MCD device  223  to the optimal stimulating position. 
         [0078]    Similar to the MCD device  100 , the MCD device  223  may be implanted within a patient&#39;s thoracic cavity, or the MCD device  223  may be positioned externally. The placement of the leads  218  and corresponding electrodes  219  relative to the heart depend on whether the MCD device  223  is positioned internally or externally relative to the patient&#39;s body. In one embodiment, the MCD device  223  is implanted in the patient&#39;s chest and the leads  218  extend to the pericardium between the pulse generator  216  and the patient&#39;s heart. 
         [0079]    In an alternative embodiment where the MCD device  223  is implanted in the patient&#39;s chest, the leads  218  and electrodes  219  are implanted subcutaneously, but are not in direct contact with the heart. In this manner, the leads are not placed within the coronary sinus, cardiac vein, or any other vein of the heart, which results in a much less invasive procedure and significantly decreases the risk of complications. In yet another embodiment, both the MCD device  223  and the leads  218  are positioned outside of the patient&#39;s chest cavity. In this embodiment, the electrodes  219  of the leads  218  comprise, for example, skin electrodes, and the leads  218  are removably applied to the external portion of the patient&#39;s chest in a manner commonly known in the art. 
         [0080]    In operation, the MCD device  223  is used to leadlessly transmit magnetic stimulation to initiate a reaction in the myocardium. The MCD device  223  generates the magnetic stimulation identically to the MCD device  100  of  FIGS. 2A and 2B . In addition, optimal placement and configuration of the coil(s)  140  of the MCD device  223  is important to achieving an optimally localized magnetic field. For example, the MCD device  223  may be used to deliver continuous antitachycardia or antibradycardia pacing and defibrillation shock. Accordingly, when the optimal positioning is located, the signal is “localized” and the MCD device  223  need only use a minimum amount of energy to produce the desired effect. Generally, the optimal positioning of the MCD device  223  is perpendicular to the stimulation site. However, because of the likelihood of physical variation between individual patients, the MCD device  223  may be positioned such that the magnetic waves are focused, or localized, on the desired site of the heart. In this manner, the MCD system  200  may be optimally “tuned” to minimize the overall energy expenditure of the system. 
         [0081]    Unlike the MCD device  100 , the MCD device  223  of the MCD system  200  is employed in connection with the echo and adjustment system  250 . Through the assistance of the echo and adjustment system  250 , the MCD system  200  can automatically adjust the magnetic stimulation to modify the location and direction of the strongest portion of the electric pulse directed at the myocardium. As is the case with the MCD device  100 , the direction of the electric pulse can be changed by adjusting the RLC circuit. For example, when defibrillation is applied to cardiac tissue, the efficacy rate of defibrillation in ventricular and supraventricular fibrillation by the use of biphasic waveforms is known to be higher than 98%, maximum shock energies range between 25 J and 42 J, and the mean energy needed for successful defibrillation is approximately 10 J. The preferred biphasic waveform is controlled by the duration of the first phase of di(t)/dt. When the energy requirement for electric shock is known from the detection procedure in the MCD system  200 , the initial charged voltage (V 0 ) in the power supply  120  can be calculated with Equations 1 and 2, the capacitor and inductance (C and R) can be determined from the geometry, position, and direction of the coil(s)  140  in the RLC circuit, and further, if the number of turns of the coils  140  are optimally designed. Therefore, through the use of the echo and adjustment system  250  and Equations 1 and 2, the optimal localization of the MCD device  223  may be determined. 
         [0082]    In one embodiment of the MCD device  223 , the circuitry  122 —and more specifically the coils  140 —may be fixed on a robotic arm  400  that is controlled by an electric motor (not shown). One embodiment of the robotic arm  400  is shown in  FIGS. 6A and 6B .  FIG. 6A  depicts a two dimensional, schematic representation of the robotic arm  400 , and  FIG. 6B  shows a three dimensional perspective view of the robotic arm  400 . In this embodiment, the robotic arm  400  has seven (7) degrees of freedom. A shoulder  402  gives pitch, yaw and roll, an elbow  404  allows for pitch, and a wrist  406  allows for pitch, yaw and roll. As used herein, pitching is defined as tilting up and down, yawing is defined as turning left and right, and rolling is tilting from side to side. In one embodiment where the MCD device  223  is positioned externally, the MCD device  223  is coupled with the wrist  406  of the robotic arm  400  such that the robotic arm  400  is capable of automatically adjusting the position of the MCD device  223  relative to a heart to be treated. The robotic arm  400  may also be used in conjunction with the echo and adjustment system  250  and the detection algorithms to achieve optimal localization of the magnetic stimulus on the heart. 
         [0083]      FIG. 7  shows a flow chart of one embodiment of a magnetic cardiac stimulation method  300  (the “method  300 ”) for providing noninvasive magnetic stimulation to cardiac muscle. For ease of understanding, the steps of the related methods described herein will be discussed relative to components of the MCD system  200  shown in  FIG. 5 , but it will be appreciated by one skilled in the art that any such system can be used to perform these methods so long as it is capable of leadlessly transmitting magnetic stimulation to cardiac tissue. 
         [0084]    Generally, a user (for example, a physician) can utilize the MCD system  200  shown in  FIG. 5  to perform at least three major functions: 1) arrhythmia detection; 2) arrhythmia treatment (for example, pacing, resynchronization, and defibrillation) with echo adjustment; and 3) episode data storage. As shown in  FIG. 7 , the leads  218  and corresponding electrodes  219  continuously collect electrogram information from the patients being monitored and/or treated by the MCD device  223  at step  302 . As the leads  218  and electrodes  219  collect the information, the data is transferred to the microprocessor  224 . In one embodiment, the leads  218  and electrodes  219  collect two main rhythm characteristics—heart rate and arrhythmia duration. 
         [0085]    At step  304 , the microprocessor  224  analyzes the collected data using established algorithms loaded on the microprocessor  224 . In one embodiment, proper heart rate characteristics are programmed on the microprocessor  224  such that the microprocessor  224  simply compares the collected data against the program standard. Especially in the embodiment where the two rhythm characteristics are collected, the standard heart rate criterion can aid the microprocessor  224  in distinguishing an arrhythmia from a normal sinus rhythm. In addition, in view of the arrhythmia duration data, the microprocessor  224  is able to avoid falsely taking into account and initiating magnetic stimulation for a non-sustained arrhythmic episode. 
         [0086]    When the microprocessor  224  identifies the specifics of the arrhythmia, the method  300  proceeds to step  306  and a decision is made with respect to the appropriate therapeutic response for the patient being monitored. In one embodiment of the method  300 , this decision making step  306  is solely automated and performed by the microprocessor  224 . For example, if the microprocessor  224  determines after analyzing the data received from the leads  218  that the patient is suffering from tachycardia and fibrillation, the microprocessor  224  automatically determines that the proper response to tachycardia and fibrillation is to either employ ATP, cardioversion (synchronized shocks), or defibrillation (non-synchronized shocks). The microprocessor  224  is capable of utilizing the therapeutic algorithms to determine what the most appropriate therapy is to employ. In an alternative embodiment, the decision may be made wholly by a user, or the microprocessor  224  may analyze the data and present a recommended therapeutic strategy to a user based on the analysis results. In this embodiment, the user ultimately decides which course of therapy to pursue. 
         [0087]    Depending on what therapeutic decision is made, the method  300  proceeds to step  307 , step  308 , or step  309 . For example, in the event a tachyarrhythmia in the ventricular-fibrillation range is detected at step  306 , the method  300  proceeds directly to step  308 , wherein the arrhythmia is treated by immediate defibrillation delivered by the MCD device  223 . However, if tachycardia—particularly a slower one—is detected at step  306 , the method  300  proceeds to step  307  and the arrhythmia is treated by sequences of overdrive pacing or low-energy cardioversion through the MCD system  200 . However, if bradycardia is detected at step  306 , the method  300  proceeds to step  309  and the MCD device  223  delivers antibradycardia pacing. While steps  307 ,  308 , and  309  are illustrated as examples of therapeutic strategies, it will be recognized that the microprocessor  224  may be programmed by way of algorithms and other logic-based instructions to execute any desired therapeutic strategy using the MCD system  200 . 
         [0088]    After at least a small amount of magnetic energy has been applied to the myocardium at step  307 ,  308 , or  309 , the method  300  proceeds to step  310  wherein the echo and adjustment system  250  evaluates if the optimal therapeutic levels have been reached through feedback control. The use of the echo and adjustment system  250  in addition to the detection algorithm (e.g., Equations 1 and 2 where the geometrical positions of the MCD device  223  and coils  140  are known) initially utilizes a small amount of energy to stimulate the myocardial tissue and any resulting changes in the cardiac rhythm are evaluated. For example, depending on the feedback received through the leads  218  after the transmission of the first round of magnetic stimuli to the myocardium, the position and direction of the coils  140 , the capacitor, and inductance may be adjusted to achieve optimal signal localization in the heart. Accordingly, at step  310 , the echo and adjustment system  250  and the detection algorithm are used to assess the effects on the myocardial tissue of the magnetic stimuli delivered in step  307 ,  308 , or  309 . If the effects are not optimal, the placement of the MCD device  223  may be gradually adjusted until the optimal defibrillation level is achieved. In one embodiment, the robotic arm  400  may be used to automatically adjust the MCD device  223 . 
         [0089]    Once the MCD device  223  is optimally positioned and the appropriate parameters have been established, the therapy selected at step  306  is delivered by the MCD system  200  to correct the arrhythmia. At step  312 , each of the electrograms collected by the leads  218  and analyzed by the microprocessor  224  are transferred to the memory device  226  for storage. 
         [0090]    The foregoing embodiments have been presented for purposes of illustration and description and are not intended to be exhaustive or to limit the disclosed devices, systems, and methods to the precise forms disclosed. Many variations and modifications of the embodiments described herein will be apparent to one of ordinary skill in the art in view of this disclosure. 
         [0091]    Further, in describing representative embodiments of the devices, systems and methods, the specification may have presented a method and/or process as a particular sequence of steps. However, to the extent that a method or process described herein does not rely on the particular order of steps set forth, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth should not be construed as limitations on the claims. In addition, the claims directed to a method and/or process described herein should not be limited to the performance of its steps in the order written, and one skilled in the art can readily appreciate that the sequences may be varied and still remain within the spirit and scope of the disclosure.