WO2002013902A1

WO2002013902A1 - Adapter and method for connecting percutaneous electrode to defibrillator

Info

Publication number: WO2002013902A1
Application number: PCT/US2001/011306
Authority: WO
Inventors: Rodney A. Brenneman; Jay A. Lenker; Robert S. Booker, Iii; Joe A. Ortiz
Original assignee: Theracardia, Inc.
Priority date: 2000-07-28
Filing date: 2001-04-06
Publication date: 2002-02-21
Also published as: AU2001251412A1

Abstract

The present invention provides methods, systems, and apparatuses for resuscitating patients in cardiac arrest, including patients suffering from ventricular fibrillation (VF), ventricular tachycardia (VT), arrhythmias, asystole, pulseless electromechanical activity (PEA), and the like. Specialized adapters (100) simultaneously connect a low energy minimally invasive direct cardiac massage (MID-CM) device with internal defibrillation capabilities (150), and conventional external gel pad electrodes (130, 132) to a standard portable defibrillation unit (12). The MID-CM device is operated in monopolar fashion and requires an external electrode to be engaged against the patient's skin. Circuitry within the adapter eliminates electrical activity in one of the gel pad electrodes (130, 132).

Description

ADAPTER AND METHOD FOR CONNECTING PERCUTANEOUS ELECTRODE TO DEFIBRILLATOR

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to medical devices and methods. More particularly, the present invention relates to devices and methods for performing cardiac defibrillation, pacing, monitoring and massage utilizing a surface electrode and a minimally invasive direct cardiac massage device. Sudden cardiac arrest is a leading cause of death in most industrial societies. While in many cases it is possible to re-establish cardiac function, irreversible damage to vital organs, particularly the brain and the heart itself, may occur during the period between cardiac arrest and restoration of normal cardiac activity. Therefore, a number of techniques have been developed to provide artificial circulation of blood to oxygenate the heart and brain during this period.

Patients in sudden cardiac arrest have various states of dysfunction including ventricular fibrillation, ventricular bradycardia, ventricular tachycardia, electromechanical dissociation, and asystole. In addition, patients suffering from heart arrhythmia may enter states of similar dysfunction, such as ventricular fibrillation. In many of these cases, direct current defibrillation may be required to effect cardioversion to a more stable heart rhythm. Direct current defibrillation is typically performed using electrical countershock by placing defibrillating pads on the patient's chest. When ventricular fibrillation or other arrhythmia is observed, the patent is treated with a countershock typically in the range from 200 to 300 joules. If the initial countershock is unsuccessful, a second shock in the same energy range is given. If the arrhythmia persists, a third countershock at a higher energy level, typically about 360 joules, is used.

The availability of direct current defibrillation has enabled the saving of thousands of lives each year. It is effective in treating patients for whom no alternative therapies would be available. Despite such success, the need to use such high energy levels can itself cause injury to the patient. Many patients who have been successfully revived using defibrillation suffer damage to the electrical pathways in the heart and require pacemakers and/or internal cardiac defibrillators for the rest of their lives. Conversely, even the very high energy levels which are used in cardiac defibrillation are not effective for all patients. The significant electrical resistance and broad electrical dispersivity of the patient's chest greatly reduces the energy which is actually delivered to the heart tissue. Thus, a practical limit exists on the ability to deliver effective direct current defibrillation to the heart using external pads. The excessive energy levels required for external defibrillation may be reduced with the use of an internal defibrillation electrode. Even if only one electrode is placed internally, all or most of the energy is routed through the heart as opposed to the patient's chest. Consequently, defibrillation thresholds are much lower than for external defibrillation. Energy requirements are expected to be close to those of completely internal defibrillation systems.

Internal defibrillation may be performed with the use of a minimally invasive direct cardiac massage device (MID-CM). The devices and methods have been described by Buckman et al. and by Drs. Filiberto and Giorgio Zadini in the patent and literature publications listed in the Description of the Background Art below. While the methods of Buckman et al. and the Zadinis differ in a number of respects, they generally rely on introducing a balloon, shoe, or other deployable member to engage the heart through a small incision through an intercostal space above the pericardium. The heart may then be pumped by directly engaging and compressing the pericardium, either by inflating and deflating the member or by reciprocating a shaft attached to the member. In addition, internal cardiac defibrillation, pacing, and/or monitoring of the patient's heart rhythm may be provided by the deployable member for simultaneous performance with direct cardiac massage. Improved devices for performing such procedures are described in copending, commonly assigned application nos. 09/087,665, 09/344,440, and 09/502311, the full disclosures of which are incorporated herein by reference. Internal defibrillation through the MID-CM device has been shown to allow for defibrillation thresholds that were approximately 10-15% of those obtained using external defibrillation with the same waveform.

Despite the great promise of percutaneous internal defibrillation via intercostal access, it is unlikely that systems developed particularly for such protocols will replace systems intended for external defibrillation in the immediate future. Thus, it is likely that presently available external defibrillators will remain in widespread use for some time and it would therefore be desirable to provide methods, apparatus and kits which would allow for the performance of percutaneous intercostal defibrillation while utilizing presently available external defibrillation equipment. Thus, it would be desirable to provide improved methods, apparatus, systems and kits, to facilitate the defibrillation of patients in sudden cardiac arrest using reduced defibrillation energy levels. In particular, it would be desirable to provide such methods and apparatus which enable and facilitate the utilization of an internal electrode in combination with presently available commercial external electrodes. It would be particularly desirable to provide for the usage of a percutaneous cardiac electrode together with a single pre-gelled self-adhesive patch derived from a conventional two patch system. More particularly, it would be desirable to provide for the simultaneous usage of commercially and clinically available electrodes in a hybrid type system of external and internal defibrillation. Such methods, systems and devices should be highly portable, easy to use and should provide quick access to a procedure that maximizes the chance of survival for the patient. At least some of these objectives will be met by the inventions described hereinafter.

2. Description of the Background Art U.S. Patent Nos. 5,582,580; 5,571,074 and 5,484,391 to

Buckman, Jr. et al. and 5,683,364 and copending application no. 09/287,230 to Zadini et al., licensed to the assignee of the present application, describe devices and methods for minimally invasive direct cardiac massage through an intercostal space, which optionally incorporate electrodes for defibrillation, pacing, ECG monitoring, and cardioversion. Published PCT application WO 98/05289 and U.S. Patent Nos. 5,466,221 and 5,385,528 describe an inflatable and other devices for performing direct cardiac massage. U.S. Patent No. 3,496,932 describes a sharpened stylet for introducing a cardiac massage device to a space between the sternum and the heart. Cardiac assist devices employing inflatable cuffs and other mechanisms are described in U.S. Patent Nos. 5,256,132; 5,169,381; 4,731,076; 4,690,134; 4,536,893; 4,192,293; 4,048,990; 3,613,672; 3,455,298; and 2,826,193. Dissectors employing inflatable components are described in U.S. Patent Nos. 5,730,756; 5,730,748; 5,716,325; 5,707,390; 5,702,417; 5,702,416; 5,694,951; 5,690,668; 5,685,826; 5,667,520; 5,667,479; 5,653,726; 5,624,381; 5,618,287; 5,607,443; 5,601,590; 5,601,589; 5,601,581; 5,593,418; 5,573,517; 5,540,711; 5,514,153; and 5,496,345. Use of a direct cardiac massage device of the type shown in the Buckman, Jr. et al. patents is described in Buckman et al. (1997) Resuscitation 34:247-253 and (1995) Resuscitation 29:237-248. External and internal defibrillators and defibrillation waveforms are described in U.S. Patent Nos. 5,913,877; 5,908,442; 5,899,924; 5,833,712; 5,824,017; 5,725,560; 5,634,938; 5,605,158; 5,591,209; 5,514,160; 5,447,518; 5,413,591; 5,411,525; 5,184,616; 5,083,562; and 5,014,701.

SUMMARY OF THE INVENTION The present invention provides methods, systems, and apparatuses for resuscitating patients in cardiac arrest, including patients suffering from ventricular fibrillation (VF), ventricular tachycardia (VT), cardiac arrhythmias, cardiac asystole, pulseless electromechanical activity (PEA), and the like. Specifically, the present invention facilitates the usage of a low energy internal defibrillation device, particularly a minimally invasive direct cardiac massage device with internal defibrillation capabilities, in a pre-hospital setting. Such a device is operated in a monopolar fashion and requires an external electrode to be engaged against the patient's skin. Since external gel pad electrodes are commonly available for use with standard portable defibrillation units, one of the gel pads may be used as the external electrode when using the internal defibrillation device. This may be possible with a specialized adapter of the present invention which simultaneously connects a set of commercially available external gel pad electrodes and a minimally invasive internal defibrillation device to a standard portable defibrillation unit. Circuitry within the adapter eliminates electrical activity in one of the gel pads. An additional benefit of this approach is that a reduction in defibrillation energy thresholds may be achieved compared to external defibrillation systems. In a first aspect of the present mvention, an apparatus is provided to enable the simultaneous connection of external and internal defibrillation devices with a standard portable defibrillation unit. The apparatus may be an adapter comprising an adapter structure, input terminals which removably couple to the defibrillation unit, output terminals which removably couple to a set of external gel pads and a connection to a percutaneous electrode structure for internal defibrillation. Such a percutaneous electrode structure is preferably a minimally invasive direct cardiac massage (MID-CM) device with defibrillation capabilities. A full description of exemplary MID-CM device for this purpose is described in co-pending application serial number 09/502311, assigned to the assignee of the present invention and incorporated by reference for all purposes. Such an adapter may consist of the adapter body having all input and output terminals formed therein or thereon. In this case, the adapter may be used alone for direct connection to the defibrillator and the defibrillation devices, or the adapter may be similarly connected with various commercially available connection cables. In general, the adapter may have specific circuitry to allow simultaneous usage of coupled devices. The positive input and output terminals on the adapter structure may be electrically coupled and the negative input and output terminals may not be electrically coupled. This circuitry may allow the negative input terminal to be coupled to a comiection on the adapter structure to a percutaneous electrode structure. Thus, input current from the defibrillator may connect to a terminal leading to an external gel pad and a connection leading to a percutaneous electrode structure. It may be appreciated that identification of positive and negative charges of the terminals and connections are provided for descriptive purposes only. Charges may be reversed and may change for biphasic defibrillation.

In a second aspect of the present invention, the adapter may comprise an adapter body as described above, however the comiection to the percutaneous electrode structure may be a cable. The percutaneous electrode structure may removably attach to the cable by coupling to a percutaneous electrode structure terminal at the end of the cable. Alternatively, the cable may be permanently affixed to the percutaneous electrode structure. Thus, the adapter may be provided by the percutaneous electrode structure itself for connection to the defibrillator and a set of external gel pads.

In a third aspect of the present invention, the adapter may comprise an adapter body as described above, however a gel pad cable may be present having the positive and negative output terminals disposed on its end. Thus, any commercially or clinically available external gel pads may be connected to the adapter via the output terminals. In addition, the connection to the percutaneous electrode structure may also be a cable. As previously described, the percutaneous electrode structure may removably attach to the cable by coupling to a percutaneous electrode structure terminal at the end of the cable. Alternatively, the cable may be permanently affixed to the percutaneous electrode structure.

In a fourth aspect of the present invention, the adapter may comprise an adapter body as described above, however an input cable may be present having the positive and negative input terminals disposed on its end. Thus, the adapter may be connected to any commercially or clinically available defibrillator via the input terminals. In addition, the connection to the percutaneous electrode structure may also be a cable. As previously described, the percutaneous electrode structure may removably attach to the cable by coupling to a percutaneous electrode structure terminal at the end of the cable. Alternatively, the cable may be permanently affixed to the percutaneous electrode structure.

In a fifth aspect of the present mvention, the adapter may comprise a bifurcated cable. The three branches of the cable may include: an input branch, a gel pad branch and a percutaneous electrode structure branch. The input branch may have the positive and negative input terminals disposed on its end for connection to the defibrillator. The gel pad branch may have the positive and negative output terminals disposed on its end for connection to the external gel pads. And, the percutaneous electrode branch may be comprised of the percutaneous electrode structure connection. As previously described, the percutaneous electrode structure may removably attach to connection by coupling to a percutaneous electrode structure terminal on its end. Alternatively, the percutaneous electrode structure may be permanently affixed to the connection.

Thus, the adapter design may take a variety of forms. As described, the adapter may removably connect directly to all of the defibrillation devices, may removably connect via extension cables to the defibrillation devices, and/or may provide one or more permanent cables for removable connection to each the defibrillator, external gel pads and the percutaneous electrode structure. Thus, systems of the present invention may include an adapter in any of these forms and a percutaneous electrode structure. In addition, the adapter may be permanently affixed to a percutaneous electrode structure. In these cases, the adapter may removably connect directly to the other defibrillation devices, may removably connect via extension cables to the other defibrillation devices, and/or may provide one or more permanent cables for removable connection to each the defibrillator and external gel pads. In a sixth aspect of the present invention, the adapter may comprise a high energy output limiter. As previously described, external defibrillation systems typically deliver 200-360 joules of energy to the patient. Thus, currently available defibrillators provide settings to output energy at these high levels. With the use of an internal defibrillation system, as described above, only approximately 20-50 joules of energy are typically necessary for delivery to the patient. In the event that too high an energy setting is used on the defibrillator, it is desirable that the output energy be limited before reaching the patient. This may be achieved with the use of a high energy output limiter provided by the adapter. Such a limiter may comprise a variety of circuit designs. According to the methods of the present invention, a pair of external gel pads and a percutaneous electrode structure may be connected to a defibrillator via an adapter so that they may be used to treat a patient simultaneously. The adapter may be attached to the positive and negative electrode terminals on the defibrillator to supply an electrical input current. External gel pads may be attached to the adapter so that one of the gel pads is electrically coupled to one of the electrode terminals on the defibrillator and the other of the gel pads remains unconnected to the defibrillator. The percutaneous electrode structure may also be attached, unless it is provided in an attached configuration to the adapter, to the other of the electrode terminals on the defibrillator. The electrically coupled gel pad may be applied to the skin of the patient to provide external defibrillation. The percutaneous electrode structure may be percutaneously introduced to a region over the heart of the patient to provide internal defibrillation. Upon energizing the defibrillator, defibrillation energy may be applied to the heart to provide countershock therapy via a dual internal-external approach. Such an approach may provide a much lower level of defibrillation energy compared to traditional external methods leading to reduced negative functional and morphologic damage to the body tissues of the patient. Other objects and advantages of the present invention may become apparent from the detailed description to follow, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic illustration of traditional external gel pads traditionally connected to a power supply or defibrillator as in the prior art.

Fig. 2A illustrates an exemplary percutaneous electrode structure in a retracted position connected to a power supply or defibrillator as in the prior art. Fig. 2B illustrates the percutaneous electrode structure of Fig. 2A in a deployed configuration. Fig. 3 depicts the percutaneous electrode structure of Figs. 2A and 2B engaged against the heart in use according to prior art methods.

Fig. 4 is a schematic illustration of an adapter of the present invention directly connectable to a defibrillator, pair of gel pads and a percutaneous electrode structure. Fig. 5 illustrates circuitry of an adapter of the present invention such that positive input and output terminals on the adapter structure are electrically coupled and the negative input terminal is coupled to a connection to a percutaneous electrode structure. Figs. 6 A and 6B are schematic illustrations of an adapter of the present invention having a cable connected or connectable to a percutaneous electrode structure.

Fig. 7 is a schematic illustration of an adapter having a cable connectable to a pair of external gel pads. Fig. 8 is a schematic illustration of an adapter having a cable connectable to a pair of external gel pads and a cable connected or connectable to a percutaneous electrode structure.

Fig. 9 is a schematic illustration of an adapter having a cable connectable to a defibrillator and a cable connected or connectable to a percutaneous electrode structure.

Fig. 10 is a schematic illustration of an adapter comprised of a bifurcated cable.

Fig. 11 is a schematic illustration of an adapter of the present invention having a high energy output limiter. Figs. 12A-B, 13, and 14 illustrate embodiments of a high energy output limiter which delivers a fixed percentage of an input energy level.

Figs. 15-16 illustrates an embodiment of a high energy output limiter which delivers output energy at a desired maximum value of energy which is less than an input energy level. Fig. 17 illustrates an embodiment of a high energy output limiter which delivers output energy at a level substantially similar to an input energy level or a level having a desired maximum value of energy which is less than an input energy level.

Fig. 18 illustrates the devices and systems of the present invention in use according to the methods of the present invention. Fig. 19 is a schematic illustration of an adapter of the present invention having a cable connectable to a percutaneous electrode structure.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS According to the present invention, methods, devices, systems and kits are provided for treating patients suffering from cardiac failure. As previously described, in such situations, direct current defibrillation is typically performed to induce a more stable heart rhythm. This is traditionally performed with the use of electrical countershock by placing defibrillating pads on the patient's chest. Such pads, commonly referred to as gel pads, are externally placed self-adhesive conductive electrodes for the application of an electric current to the chest area. Gel pads may also include pacing and monitoring capabilities as well. Typically, one external pad is placed anteriorly or posteriorly on the patient's skin and one pad is placed close to the apex of the heart on the anterior thorax or left lateral thorax. As shown in Fig. 1 (prior art), the pads 10 are traditionally connected to a power supply or defibrillator 12, which supplies defibrillation energy current, by a connection or therapy cable 14. This cable 14 is reusable and pairs with a single two pole connector on the defibrillator 12. The opposite end of the cable 14 attaches to conductive posts on the gel pads 10. Thus, the gel pads 10 may be removed from the cable 14 and disposed of after use. Percutaneous defibrillation devices have been developed for use in applying defibrillation energy more directly to the heart in the pre-hospital setting. Specifically, minimally invasive direct cardiac massage (MID-CM) devices have been developed to provide direct cardiac massage with "percutaneous" defibrillation, pacing, cardioversion, and/or monitoring. An exemplary MID-CM device 40 is shown in Fig. 2A (prior art) and comprises a sleeve 30, a shaft 32 slidably mounted in a central lumen of the sleeve 30, and a handle 34 attached to a proximal end of the shaft 32. The sleeve 30 includes a positioning flange 36 near its distal end, typically spaced proximally of the tip 38 of the device by an optimum distance. A blunt cap 41 is positioned at the distal-most end of the device 40 and facilitates entry of the device into the chest cavity. The device 40 may be percutaneously introduced, usually through an intercostal access hole, and contacted against the heart or pericardium. At this time, the sleeve 30 may be retracted and a flared bell structure 44, as shown in Fig. 2B (prior art), may be deployed to assume a trumpeted configuration. The flared bell structure 44 may comprise a plurality of outwardly curving struts 46 preferably formed from a resilient metal, such as a superelastic alloy. The distal tips of the struts 46 are preferably connected by a fabric electrode structure 48 having an edge which is folded over and stitched to hold the cover in place.

Once the device 40 is in place and the bell structure 44 fully deployed, the handle 34 may be manually grasped and the shaft 32 pumped through the sleeve 30. As shown in Fig. 3 (prior art), this will cause the deployed flared bell structure 44 to engage the electrode structure 48 surface against the heart H. As the structure 44 is advanced in a posterior direction, the heart H is compressed as generally shown in broken line H'. In this manner of pumping, direct cardiac massage is performed. Defibrillation energy or pacing is applied using a power supply or defibrillator 12 connected via a cable 52 to the device 40, as illustrated in Fig. 2 A and 3 (prior art). The device 40 is intended for "monopolar" operation. That is, the electrode structure 48 will be connected to one pole of the defibrillator 12 while the other pole will be connected to an external electrode 55 engaged against the patient's skin. Once resuscitation has been completed, the device 40 may be withdrawn by retracting the shaft 32 relative to the sleeve 30 to draw the flared bell structure 44 back into the sleeve 30. Once the structure 44 is retracted, the device may be proximally withdrawn through the incision and the incision closed in a conventional manner.

Since devices such as the MID-CM device provide internal defibrillation capability, the energy required for defibrillation is approximately an order of magnitude less than that required of external defibrillation devices, such as external gel pads. This is because current is applied directly to the heart. This benefit may be afforded to the patient when at least one electrode is placed on the heart through a device such as the MID-CM. If one electrode, such as an external gel pad, is placed externally and one electrode, such as with an MID-CM device, is placed internally, all or most energy is routed through the heart requiring a significantly lower defibrillation energy level.

Currently, as illustrated in Figs. 1, 2A, 2B and 3 (all prior art), such MID- CM devices are not designed to be used with commercially available external gel pad pairs. The present invention overcomes such difficulty, shown in Fig. 4, by providing an adapter 100 which simultaneously connects a defibrillator 12 to a standard pair or set of external gel pads 10 (comprised of an anterior or posterior gel pad 130 and an apex gel pad 132) and a percutaneous electrode structure 150. In a preferred embodiment, shown in Fig. 5, the adapter 100 may be comprised of an adapter structure 102, a positive input terminal 104, a negative input terminal 106, a positive output terminal 108, a negative output terminal 110, and a MID-CM device connector terminal 112. The adapter 100 may be connected to the defibrillator 12, as shown in Fig. 4, by removably coupling the positive and negative input terminals 104, 106 to positive and negative connection terminals 120, respectively, on the defibrillator 12. Similarly, the input terminals 104, 106 may fit existing cables and connectors (not shown) which in turn may connect to the connection terminals 120 on the defibrillator 12. The adapter 100 may be connected to the set of gel pads 10, as shown in Fig. 4, by removably coupling the positive and negative output terminals 108, 110 to positive and negative connection terminals 122, respectively, on the gel pads 10. Similarly, the output terminals 108, 110 may fit existing cables and connectors (not shown) for connection to the connection terminals 122 on the gel pads 10.

To provide current flow from the defibrillator 12 a gel pad 10, the positive input teπninal 104 and the positive output terminal 108 in the adapter structure 102 may be electrically coupled, as depicted by a coupling line 116 in Fig. 5. Such coupling may provide a live lead to the anterior or posterior gel pad 130. However, current flow to the other gel pad, the apex gel pad 132, may be obstructed to allow such current to be redirected to the percutaneous electrode structure 150. Thus, the negative input terminal 106 and the negative output terminal 110 may not be electrically coupled, as depicted by a terminal coupling line 118 in Fig. 5. Such termination may provide a dead lead to the apex gel pad 132. Instead, the negative input terminal 106 may be coupled with the connector terminal 112, such coupling depicted by a coupling line 119. The connector terminal 112 may be used to removably connect the adapter 100 to the percutaneous electrode structure 150 via a MID-CM device comiector 124 on the electrode structure 150, as shown in Fig. 4. As before, the connector terminal 112 may fit existing cables and connectors (not shown) for connection to the connector 124 on the electrode structure 150. Such circuitry may supply input current to both the anterior/posterior gel pad 130 and the percutaneous electrode structure 150 simultaneously.

It may be appreciated that male and female depictions of the input and output terminals, connection terminals and connections are provided for illustrative purposes. Such terminals and connections may be of either male or female configuration for coupling with the opposite configuration. Likewise, depictions of positive and negative charges of the terminals and connections are provided for descriptive purposes only. Charges may be reversed and do change for biphasic defibrillation. In addition, terminals and connections may include locking features at each connection to prevent separation.

Embodiments of the adapter 100 may take a variety of forms. To begin, the adapter structure 102 may be comprised of an adapter body 200 having all input and output terminals formed therein or thereon. Such an embodiment is depicted in Figs. 4-5. Additional embodiments may include various cables that are incorporated into the adapter design which are used to connect to the defibrillation system devices, namely the defibrillator 12, the gel pads 10 and the percutaneous electrode structure 150. When a cable is present, a connection terminal is typically located at the end of such a cable, rather than on the adapter body itself, for removably coupling to the desired defibrillation system device. Alternatively, the adapter and cable may be fixedly attached to a system device wherein no such terminal is necessary.

Referring to Figs. 6A and 6B, embodiments may provide that the adapter 100 be comprised of an adapter structure 102 with input terminals 104, 106, for connection to the defibrillator 12, and output terminals 108, 110, for connection to the gel pads 10, formed on the structure 102 itself. However, in these embodiments, the percutaneous adapter structure connector terminal 112 may be comprised of a cable 202 attached to the adapter body 200. Such a cable 202 may have a percutaneous electrode structure terminal 204 formed at its end to removably couple a percutaneous electrode structure 150, as shown in Fig. 6A. A similar embodiment is also shown in Fig. 19.

Alternatively, such a cable 202 may be permanently affixed to the percutaneous electrode structure 150, as shown in Fig. 6B.

In another embodiment, shown in Fig. 7, the adapter 100 may be comprised of an adapter structure 102 with input terminals 104, 106, for connection to the defibrillator 12, and a connector terminal 112, for connection to the percutaneous electrode structure 150, formed on the structure 102 itself. However, in these embodiments, the positive and negative output terminals 108, 110 may be disposed on the end of a gel pad cable 210 which is attached to the adapter body 200. As previously described, the output terminals 108, 110 may be configured to removably couple with the external gel pads 10, as shown in Fig. 7. Additional embodiments, one such shown in Fig. 8, may also include the percutaneous electrode structure connector terminal 112 comprising a cable 202 connecting the percutaneous electrode structure 150 to the adapter body 200. The cable 202 may have a percutaneous electrode structure terminal 204 at its end for removably coupling to the electrode structure 150, as depicted in Fig. 8. Alternatively, such a cable may be permanently affixed to the electrode structure 150, as previously depicted in Fig. 6B.

In another embodiment, shown in Fig. 9, the adapter 100 may be comprised of an adapter structure 102 with output terminals 108,110, for connection to the gel pads 10, and the connector terminal 112 comprising a cable 202 connecting the percutaneous electrode structure 150 to the adapter body 200. The cable 202 may have a percutaneous electrode structure terminal 204 at its end for removably coupling to the electrode structure 150, as depicted in Fig. 9. Alternatively, such a cable may be permanently affixed to the electrode structure 150, as previously depicted in Fig. 6B. However, in this embodiment, the adapter structure 102 may be further comprised of an input cable 220 attached to the adapter body 200 which has the positive and negative input terminals 104, 106 disposed thereon. Thus, the adapter structure 102 may be connected to the defibrillator 12 via the input cable 220.

Further, as shown in Fig. 10, adapter 100 may be comprised of a bifurcated cable 300. The cable 300 may be comprised of an input branch 302 having the positive and negative input terminals 104, 106 formed at its end for comiection to the defibrillator 12. Further, the cable 300 may be comprised of a gel pad branch 304 having the positive and negative output terminals 108, 110 formed at its end for connection to the gel pads 10. And, the cable 300 may also be comprised of a percutaneous electrode structure branch 306 comprising the percutaneous elecfrode structure connector terminal 112. The branch 306 may have a percutaneous electrode structure terminal 204 at its end for removably coupling to the electrode structure 150, as depicted in Fig. 10. Alternatively, such a branch 306 may be permanently affixed to the electrode structure 150, as previously depicted in Fig. 6B. Referring to Fig. 11, a high energy output limiter 500 may be included in any embodiment of the adapter 100. Such a limiter 500 may comprise a variety of circuit designs and components. Energy in electric circuits is the work done in moving a charge between two points with a potential difference between them. Power is the rate at which work is done; therefore, power is the derivative of energy. The power received or delivered by a component is the voltage multiplied by the current. Thus, energy output may be limited by limiting the voltage or limiting the current.

It may be appreciated that identification of positive and negative charges of the terminals and connections in the circuit diagrams are provided for descriptive purposes only. Charges may be reversed and may change for biphasic defibrillation. This applies to all embodiments of the high energy output limiter 500.

In a number of embodiments of the high energy output limiter 500, the resulting energy output level is a fixed reduced percentage, for example 10%, of the applied energy or input energy level. Fixed output circuits are presented by Kallock et al. in U.S. Patent No. 4,499,907, the full disclosure of which is incorporated herein by reference. Referring to Figs. 12A and 12B, embodiments of a limiter 500 may comprise a voltage divider. A voltage divider may be achieved by positioning resistors 502, as shown in Fig. 12 A. Similarly, a circuit comprising resistors 502 and zener diodes 503 may be used, as shown in Fig. 12B. In addition, output of the defibrillator may be monitored by comparators to effect different forms of voltage dividers. For example, Fig. 13 illustrates an embodiment of a high energy output limiter 500 which delivers output energy (E_out) at a fraction of the input energy (E;_n), depending on peak voltages of the input. If the input peak voltage is low, transistor (Q₀) 600 is turned on by a Q₀ driver 601, delivering full energy to the output terminals. If the input peak voltage is sufficiently high to trip a first comparator 602, Q_o 600 is turned off and a first transistor (Q ) 602 is turned on, forming a voltage divider between a first resistor (R-_.) 604 and the resistance of the body (R_b). This delivers an output energy at a fraction of the input energy according to the following equation: E_out = E;_n * [ R_b / ( Ri + R ) ]. If the input peak voltage is sufficiently high to trip a second comparator 606, then Q₀ 600 is turned off, Q 602 is turned off, and second transistor (Q₂) 608 is turned on, forming a voltage divider between a second resistor (R₂) 610 and the resistance of the body (R_b). This delivers an output energy at a fraction of the input energy according to the following equation: E_out = E^* _n * [ R / ( R₂ + R_b ) ]. A diode bridge 612 may be present to allow the comparators 602, 606 to switch AC energy using DC devices. Fig. 14 illustrates a similar circuit design with n additional transistors (Q_n) 622, resistors (R_n) 624 and comparators 620. Significantly finer resolution of output energy is obtained as n is increased.

Alternatively, energy output may be reduced or limited to a maximum value deemed safe and appropriate for the treatment protocol. For example, Fig. 15 illustrates an embodiment of a high energy output limiter 500 which uses linear regulation to control output energy. Here, a first transistor (Q**) 630 is used as a linear pass element. The linear control loop 632 is used to control O 630. Therefore, the loop 632 limits the output voltage to a predetermined value. Again, a diode bridge 634 may be present to allow control of AC output with a DC switch.

An additional embodiment of such a high energy output limiter 500 comprises an analysis block 510 and a load 512, as illustrated in Fig. 16. The analysis block 510 comprises a means for current sensing, a means for voltage sensing, and a timing mechanism. Measurements of voltage, current and elapsed time from the beginning of a freahnent shock are analyzed to determine the delivered energy. If the delivered energy exceeds a maximum value (e.g. 50 or 100 Joules), the output is switched so that the additional or excess energy is transmitted to the load 512. The load 512 may comprise a resistor or similar component. Such a resistor may be comprised of wire wound on a non-conductive cone and covered with an insulation to dissipate heat. The resistor may be similar to that disclosed in O'Phalen U.S. Patent No. 5,312,442, the full disclosure of which is incorporated herein by reference. However, the resistor of the current embodiment is not intended for implantable use or flex-circuit use and is intended for higher energy. This embodiment of the high energy output limiter 500 effectively limits delivered energy to a maximum value which is less than the input energy level, however waveform shape may not be preserved.

A further embodiment of the high energy output limiter 500 involves analyzing a defibrillation pulse and storing it. If the pulse is within energy limits, the original pulse is delivered to the patient at the same or substantially similar energy level. If the pulse exceeds energy limits, the pulse is transmitted through a limiting circuit which limits the delivered output energy to a maximum value. Referring to Fig. 17, such an embodiment of the high energy output limiter 500 comprises an analog storage block 520, an analysis block 522, a switch 530, a switch control 524, a follower circuit 526, a limiting output circuit 528, and a load 529. The switch 530 directs the output of the storage block 520 under the control of the switch control 524. Therefore, if a defibrillation pulse is within allowable energy limits, it is first stored in the analog storage block 520, analyzed in the analysis block 522 and transmitted to the follower circuit 526 for output. If a defibrillation pulse exceeds allowable energy limits, it is transmitted to the limiting output circuit 528 which outputs a fixed energy level, such as 50 or 100 Joules. In this case, an indicator may warn the operator that a high energy pulse was ^' attempted.

Referring to Fig. 18, pre-hospital or in-hospital treatment of a patient P suffering from cardiac arrest or other cardiac conditions requiring defibrillation may be aided with the simultaneous use of external and internal defibrillation devices. As shown, such devices may be simultaneously connected to a defibrillator 12 with the use of an embodiment of the adapter 100 of the present invention. According to the methods of the present invention, a standard defibrillator 12 may be used having positive and negative elecfrode terminals 120 configured to removably connect to a set of external gel pads 10. The adapter 100 may be attached to the electrode terminals 120 on the defibrillator 12. Likewise, the adapter 100 may be connected to the positive and negative connection terminals 122 of the external gel pads 10 such that one of the gel pads, for example the anterior/posterior gel pad 130, is electrically coupled to one of the electrode terminals on the defibrillator 12 and the other of the gel pads, for example the apex gel pad 132, remains electrically uncoupled. The electrically coupled pad, in this case gel pad 130, may be externally applied to the skin of the patient P, as shown in Fig. 18. The other pad, in this case gel pad 132, may be unused. In addition, a percutaneous electrode structure 150 may be electrically coupled to the opposite elecfrode terminal on the defibrillator 12 by connecting to the adapter 100 via the percutaneous elecfrode structure connector terminal 112. The percutaneous elecfrode structure 150 may be introduced to a region over the heart H of the patient P to access the heart H for direct internal defibrillation and/or massage.

Such methods, systems and devices for the simultaneous usage of internal and external defibrillation devices may used by both surgeons and other clinicians, such as paramedics, to provide improved resuscitation of patients in cardiac arrest. Such a dual defibrillation system may require a much lower defibrillation threshold than traditional external defibrillation systems, allowing less energy to be applied to the patient and therefore less functional and morphologic damage to the heart and surrounding tissues. In addition to resuscitation, such methods could provide a bridge to cardiopulmonary bypass and certain restorative therapies, such as angioplasty, stents and implantable cardioverter defibrillators.

Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be obvious that various alternatives, modifications and equivalents may be used and the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An adapter for simultaneously connecting a defibrillator having positive and negative connection terminals to external gel pads and a percutaneous electrode structure, said adapter comprising: an adapter structure; a positive input terminal and a negative terminal on the adapter structure which removably couple to the positive and negative connection terminals or the defibrillator, respectively; a positive output terminal and a negative output terminal on the adapter structure which removably couple to positive and negative connection terminals on the gel pads, respectively, wherein positive input and output terminals on the adapter structure are electrically coupled and the negative input and output terminals on the adapter structure are not electrically coupled; and a connection on the adapter structure to the percutaneous elecfrode structure, wherein said connection electrically couples the negative input terminal on the adapter structure to the percutaneous electrode structure.

2. An adapter as in claim 1, wherein the adapter structure consists of an adapter body having all input and output terminals formed therein or thereon.

3. An adapter as in claim 1, wherein the adapter structure comprises an adapter structure comprising an adapter body and the percutaneous electrode structure connection comprises a cable attached to the adapter body.

4. An adapter as in claim 3, further comprising a percutaneous electrode structure terminal on the cable to removably couple a percutaneous electrode structure.

5. An adapter as in claim 3, further comprising a percutaneous electrode structure permanently affixed to the cable.

6. An adapter as in claim 1, wherein the adapter structure comprises an adapter body and a gel pad cable attached to the adapter body and having, the positive and negative output terminals disposed thereon.

7. An adapter as in claim 6, wherein the percutaneous electrode structure connection comprises a cable attached to the adapter body.

8. An adapter as in claim 7, further comprising a percutaneous electrode structure terminal on the cable to removably couple a percutaneous electrode structure.

9. An adapter as in claim 1, further comprising a percutaneous elecfrode structure permanently affixed to the cable.

10. An adapter as in claim 1, wherein the adapter structure comprises an adapter body and the percutaneous electrode structure connection comprises a cable attached to the adapter body and having the percutaneous elecfrode structure terminal disposed thereon, and input cable attached to the adapter body and having the positive and negative input terminals disposed thereon.

11. An adapter as in claim 1, wherein the adapter comprises a bifurcated cable having an input branch with the positive and negative input terminals disposed thereon, a gel pad branch having the positive and negative output terminals disposed thereon, and a percutaneous electrode structure branch comprising the percutaneous electrode structure connection.

12. An adapter as in claim 11, further comprising a percutaneous electrode structure terminal on the percutaneous elecfrode structure branch to removably couple a percutaneous electrode structure.

13. An adapter as in claim 11 , further comprising a percutaneous electrode structure permanently affixed to the percutaneous electrode structure branch.

14. An adapter as in claim 1, further comprising a high energy output limiter.

15. An adapter as in claim 14, wherein the high energy output limiter comprises circuitry which delivers output energy at a level comprising a fixed reduced percentage of an input energy level.

16. An adapter as in claim 14, wherein the high energy output limiter comprises circuitry which delivers output energy at a level comprising a desired maximum value of energy which is less than an input energy level.

17. An adapter as in claim 16, wherein the circuitry optionally delivers output energy at a level substantially similar to an input energy level.

18. A system comprising: an adapter as in any of claims 1-4, 6-8, 10-12, and 14; and a percutaneous elecfrode structure connectable to the connection on the adapter structure.

19. A method for connecting electrodes to a defibrillator, said method comprising: providing a percutaneous electrode structure; providing a pair of external gel pads; providing a defibrillator having a positive and negative elecfrode terminals configured to removably connect to the external gel pads; attaching an adapter to the positive and negative elecfrode terminals on the defibrillator; and attaching the external gel pads to the adapter, wherein one of the gel pads is electrically coupled to one of the electrode terminals on the defibrillator and the other of the gel pads remains unconnected to the defibrillator; wherein the percutaneous elecfrode structure is connected or connectable to the other of the electrode terminals on the defibrillator.

20. A method as in claim 19, further comprising attaching the percutaneous electrode structure to the adapter to provide a connection to the other of the electrode terminals on the defibrillator.

21. A method as in claim 19, wherein the percutaneous electrode structure is preattached to the adapter.

22. A method as in claim 19, further comprising percutaneously introducing the percutaneous elecfrode structure to a region over the heart of the patient and externally applying the electrically coupled gel pad to skin of the patient.

23. A method as in claim 22, further comprising energizing the defibrillator to apply defibrillation energy to the heart.