Abstract:
An implantable defibrillator having programmable shock waveforms and paths where each successive waveform may be of a different shape and form, and delivered to and through an area of the human heart in a desired sequence. The shock waveforms can be delivered independently through certain areas of the heart or through different areas of the heart to the can electrode or to a patch electrode at a computed common time. Alternatively, a first shock waveform or set of shock waveforms can be delivered through one or more areas of the heart followed by a delivery of time sequenced delayed shock waveform or forms through specific areas of the heart to the can electrode or patch electrode.

Description:
CROSS REFERENCES TO CO-PENDING APPLICATIONS 
     This is a Continuation of Ser. No. 08/856,982, now abandoned, filed Mar. 24, 1992. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the field of heart defibrillators, and more particularly, relates to delivery of programmable and sequenced waveforms to areas of the heart by the components of a defibrillator. 
     2. Description of the Prior Art 
     Prior art defibrillators deliver a number of successive shocks for heart defibrillation. The same waveform in these devices is repeated in succession usually to deliver four shock waveforms. The particular handicap or drawback with these devices is that the repeated similar waveforms are determined by the manufacturer, and cannot be changed unless a reimplant of the device is accomplished. The prior art devices used only a repeated similar waveform instead of waveforms of different magnitudes and shapes to accomplish the defibrillation process. 
     The present invention overcomes the inadequacies of the prior art by providing a programmable defibrillator which can deliver shock waveforms of different shapes and magnitude in different combinations of sequences which are field programmable by a physician. 
     SUMMARY OF THE INVENTION 
     Once an implantable defibrillator has determined that the heart is in fibrillation, it begins a sequence of activities that involve charging the output capacitors and verifying that fibrillation is still present before delivering the first shock pulse. After a shock pulse is delivered, the device continues to monitor the heart rate, and if it determines that the shock was unsuccessful in terminating the fibrillation, the implanted defibrillator will deliver a second shock, at the same or higher energy. This sequence can be repeated several times up to four times in currently available devices, after which the device terminates further attempts at conversion. The rationale for terminating therapy after four shocks is that further attempts are unlikely to be successful in that conversion thresholds tend to increase with time in a fibrillation episode, and after fibrillating for long periods, the patient is likely to have suffered irreversible brain damage. In addition, if the shocks are being delivered inappropriately due to noise on the leads or component failure, the patient will receive no more than four unnecessary shocks. The device resets itself after the heart rate has slowed to a normal level for a prescribed length of time. 
     There is considerable evidence in the literature that some shock waveforms have generally lower defibrillation thresholds than others. However, there are many exceptions to the general rule and for any given patient and/or for different electrode configurations, the most efficient shock waveform may not be the one installed in the implanted prior art device. 
     The general purpose of this implantable defibrillator is that the shock waveform is programmable so that the implanting physician can select the waveform that yields the lowest threshold for a given patient and electrode configuration. 
     Further, the invented implantable defibrillator allows the physician to program the device such that each successive shock waveform may be programmed independently. The rationale is that if the first and earliest shock failed, it would be better to try a new waveform on the next shock rather than to repeat a shock waveform that has just demonstrated failure to defibrillate. 
     According to one embodiment of the present invention, there is provided an implantable defibrillator including a patch electrode for application to the heart, and another lead having sensing electrodes and defibrillation electrodes which are aligned in the right atrium and the right ventricle. A physician-programmable computer, including a memory for storing programmable waveform information, is included in the can of the defibrillator. 
     One significant aspect and feature of the present invention is a defibrillator which is physician programmable. 
     Another significant aspect and feature of the present invention is a defibrillator which has a variety of waveforms which can be sequentially applied in the defibrillation process. 
     A further significant aspect and feature of the present invention is the selective steering of desired waveforms through the heart to the components of the defibrillator. 
     Still another significant aspect and feature of the present invention is time-sequenced delays of waveform application. 
     Having thus described one embodiment of the present invention, it is the principal object hereof to provide a programmable defibrillation for the delivery of sequenced, independently shaped and time-sequenced defibrillation shock waveforms to the human heart. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
     FIG. 1 illustrates an implantable programmable defibrillator, the present invention, connected to a heart; 
     FIG. 2 illustrates a representative waveform; 
     FIG. 3 illustrates another representative waveform; 
     FIG. 4 illustrates another representative waveform; 
     FIG. 5 illustrates another representative waveform; 
     FIG. 6 illustrates shock waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 7 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 8 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 9 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 10 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 11 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 12 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 13 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 14 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 15 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 16 illustrates another set of waveform paths from the heart to the Implantable programmable defibrillator; 
     FIG. 17 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator; 
     FIG. 18 illustrates another set of waveform paths from the heart to the implantable programmable defibrillator. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates an implantable defibrillator 10 and associated components connected to a heart 12. The implantable defibrillator 10 includes a can 14, which is an electrode, a physician-programmable computer 16, including a memory 17 for storing programmable waveform information, a lead 18 connecting a patch electrode 20 to the implantable defibrillator 10, and a lead 22 having second electrodes connecting to the heart 12. Lead 22 extends through the superior vena cava 24, the right atrium 26, and to the lower region of the right ventricle 28. Also illustrated are the left atrium 30 and the left ventricle 32. Sense electrodes 34 and 36 are located at the distal end of the lead 22, and align in the lower region of the right atrium 26. The lead 22 also includes shock electrodes 38 and 40. The shock electrode 38 aligns in the upper portion of the right atrium 26 and a portion of the superior vena cava 24. Shock electrode 40 aligns centrally in the right ventricle 28. 
     FIGS. 2, 3, 4, and 5 illustrate representative waveforms that can be formed by the physician-programmable computer 16 of FIG. 1. The formation of these waveforms is the subject matter of a patent entitled IMPLANTABLE DEFIBRILLATOR SYSTEM EMPLOYING CAPACITOR SWITCHING NETWORK, Ser. No. 07/704,619, filed May 23, 1991, now issued as U.S. Pat. No. 5,199,429 having the same assignee. Although FIGS. 2, 3, 4 and 5 illustrate useful waveforms, it is appreciated that any other waveforms can also be incorporated within the teachings of the present invention. 
     FIG. 2 illustrates a truncated shock waveform 42 formed by two capacitors in series. 
     FIG. 3 illustrates a truncated shock waveform 44 formed by two capacitors in series and having the polarity reversed. 
     FIG. 4 illustrates a truncated shock waveform 46 formed by two capacitors in parallel, and have the polarity reversed and series connected. 
     FIG. 5 illustrates a truncated shock waveform 48 formed by two capacitors sequential, truncated, polarity reversed, and series connected. 
     MODE OF OPERATION 
     The waveforms 42-48 illustrated in FIGS. 2-5 can be programmed to be delivered as shock waves in almost any number of sequential arrangements such as four identical sequential shock waveforms such as four successive applications of truncated shock waveform 42, or four sequential truncated shock waveform 44 and following in the same sequential pattern application for identical truncated shock waveforms 46 and 48. 
     In the alternative, any combination of shock waveforms, such as sequence incorporating a sequence of shock waveforms such as 42, 44, 46, 48. Even a shock waveform sequence where certain shock waveforms are repeated such as 42, 46, 46, 48 can be used. Any desirable sequence can be used whether only one type of waveform is sequentially repeated or whether two or more waveforms are repeated. Any combination or permutation of the sequences may be used as desired. 
     FIGS. 6-8 illustrate the principle of successive changeable pathways for detected and programmed delivery of simultaneous or delayed shock sequenced delivery to and about various areas of the heart. The physician-programmable computer 16 detects fibrillation, and from that criteria decides within programmed limits and parameters as set by a physician where and when to deliver defibrillation shocks. All numerals in FIGS. 6-19 correspond to those elements previously described. Shock waveforms sent directly to, from or through a heart area to a defibrillator component are indicated by a path arrow having a solid shaft, such as arrow 50 in FIG. 6. Shock waveforms which are delayed are represented by a path arrow having a dashed shaft such as arrow 52 in FIG. 6. The shock waveforms which are sent are those shock waves such as described in FIGS. 2, 3, 4 and 5. Again, any of the shock waveforms such as waveforms 42-48 can be incorporated and sent directly or delayed across any of the paths whether the path is a directly-sent path or a time-delay path. The shock waves emanate from the shock electrode 40 in the right ventricle 28 in FIGS. 6-19, and travel through ports of the heart to either shock electrode 38, can electrode 14, or patch electrode 20. 
     FIG. 6 illustrates directly sent shock waveform path 50 traveling through the right ventricle 28 to the patch electrode 20, and delayed shock waveform paths 52 and 54 traveling from the right ventricle 28 to the can electrode 14 and to the shock electrode 38 in the superior vena cava 24. 
     FIG. 7 illustrates a directly sent shock waveform path 56 traveling through right ventricle 28 to the patch electrode 20 where the can electrode 14 is off. 
     FIG. 8 illustrates directly sent shock waveform paths 58 and 60 traveling, respectively, through the right ventricle 28, to the patch electrode 20 and the can electrode 14, and a delayed shock waveform path 62 traveling from the right ventricle 28, to the electrode 38 in the superior vena cava 24. 
     FIG. 9 illustrates a directly sent waveform path 64 traveling through the right ventricle 28, to the patch electrode 20, and a delayed shock waveform path 66 traveling from the right ventricle 28, to the can electrode 14. The shock electrode 38 is not connected. 
     FIG. 10 illustrates directly sent waveform paths 68 and 70 traveling, respectively, through the right ventricle 28, to the patch electrode 20, and to the can electrode 14. The shock electrode 38 is not connected. 
     FIG. 11 illustrates directly sent waveform paths 72, 74 and 76 traveling, respectively, through the right ventricle 28, to the patch electrode 20, to the can electrode 14, and to the electrode 38 in the superior vena cava 24. 
     FIG. 12 illustrates directly sent waveforms paths 78 and 80 traveling, respectively, through the right ventricle 28, to the can electrode 14 and to the superior vena cava 24. The patch electrode is not connected. 
     FIG. 13 illustrates a delayed shock waveform path 82 traveling through the right ventricle 28, to the can electrode 14, and a directly sent wave path 84 traveling from the right ventricle 28, to the electrode 38 in the superior vena cava 24. The patch electrode 20 is not connected. 
     FIG. 14 illustrates a directly sent shock waveform path 86 traveling through the right ventricle 28, to the can electrode 14. The shock electrodes 38 and the patch electrode 20 are not connected. 
     FIG. 15 illustrates a delayed shock waveform path 88 traveling through the right ventricle 28, to the patch electrode 20, and a directly sent shock waveform path 90 traveling through the right ventricle, to the can electrode 14. The shock electrode 38 is not connected. 
     FIG. 16 illustrates delayed shock waveform paths 92 and 94 traveling, respectively, through the right ventricle 28, to the patch electrode 20, and the can electrode 14, and a directly sent shock wave path 96 traveling through the right ventricle 28, to the electrode 38 in the superior vena cava 24. 
     FIG. 17 illustrates a delayed shock waveform path 98 traveling through the right ventricle 28, to the patch electrode 20, and directly sent shock waveform paths 100 and 102 traveling, respectively, through the right ventricle 28, to the can electrode 14 and the electrode 38 in the superior vena cava 24. 
     FIG. 18 illustrates a directly sent waveform path 110 traveling through the right ventricle 28, to the patch electrode 20, and a delayed shock waveform path 112 traveling through the right ventricle, to the electrode 38 in the superior vena cava 24. The patch electrode 20 is not connected. 
     
                       TABLE 1______________________________________Atrial area(SVC etc.) SubQ patch  Can       FIG______________________________________delayed    direct (full)                  delayed    6zero       direct (full)                  zero       7delayed    direct (full)                  direct (full)                             8zero       direct (full)                  delayed    9zero       direct (full)                  direct (full)                            10direct (full)      direct (full)                  direct (full)                            11direct (full)      zero        direct (full)                            12direct (full)      zero        delayed   13zero       zero        direct (full)                            14zero       delayed     direct (full)                            15direct (full)      delayed     delayed   16direct (full)      delayed     direct (full)                            17delayed    zero        direct (full)                            18zero       direct (full)                  zero      Not showndelayed    direct (full)                  zero      Not showndirect (full)      zero        zero      Not showndirect (full)      delayed     zero      Not showndirect (full)      direct (full)                  zero      Not showndirect (full)      direct (full)                  delayed   Not showndelayed    delayed     direct (full)                            Not shown______________________________________ 
    
     Table 1 sets forth the atrial area, the sub Q patch, the can and the corresponding figure. The pulse is either a monophasic pulse or biphasic pulse. 
     Various modifications can be made to the present invention without departing from the apparent scope hereof.