Source: https://patents.google.com/patent/WO2002064205A2/en
Timestamp: 2019-12-06 19:01:09
Document Index: 710719262

Matched Legal Cases: ['art 20', 'art 20', 'art 20', 'art 20', 'art.\n39', 'art.\n44', 'art.\n49']

WO2002064205A2 - Multi-electrode apparatus and method for treatment of congestive heart failure - Google Patents
Multi-electrode apparatus and method for treatment of congestive heart failure Download PDF
WO2002064205A2
WO2002064205A2 PCT/US2002/004330 US0204330W WO02064205A2 WO 2002064205 A2 WO2002064205 A2 WO 2002064205A2 US 0204330 W US0204330 W US 0204330W WO 02064205 A2 WO02064205 A2 WO 02064205A2
PCT/US2002/004330
WO2002064205A3 (en
2001-02-13 Priority to US26844901P priority Critical
2001-02-13 Priority to US60/268,449 priority
2002-02-13 Application filed by Quetzal Biomedical, Inc. filed Critical Quetzal Biomedical, Inc.
2002-08-22 Publication of WO2002064205A2 publication Critical patent/WO2002064205A2/en
2003-03-20 Publication of WO2002064205A3 publication Critical patent/WO2002064205A3/en
206010007559 Cardiac failure congestive Diseases 0 abstract claims description title 22
201000006233 congestive heart failure Diseases 0 abstract claims description title 22
230000000638 stimulation Effects 0 abstract claims description 145
230000000747 cardiac Effects 0 abstract claims description 139
210000002216 Heart Anatomy 0 abstract claims description 134
239000011133 lead Substances 0 abstract claims description 119
230000002861 ventricular Effects 0 abstract claims description 63
206010027727 Mitral valve incompetence Diseases 0 abstract claims description 17
210000004115 Mitral Valve Anatomy 0 abstract claims description 9
230000001595 contractor Effects 0 claims description 56
210000001308 Heart Ventricles Anatomy 0 claims description 31
206010056370 Congestive cardiomyopathy Diseases 0 abstract description 6
201000010046 dilated cardiomyopathy Diseases 0 abstract description 6
206010015856 Extrasystoles Diseases 0 claims description 2
230000010247 heart contraction Effects 0 description 14
238000007634 remodeling Methods 0 description 5
206010000059 Abdominal discomfort Diseases 0 description 1
230000003828 downregulation Effects 0 description 1
An apparatus (100) and method for treatment of congestive heart failure from the right side of the heart. An implantable cardiac stimulation system (10) with a multi-electrode lead (14) having three or more selectable electrodes (E1, E2....En), together with apparatus for identifying an optimal subset of electrodes (114, 120, 124, 104), apparatus for shaping a propagating wave front, and apparatus for modifying the intrinsic ventricular cardiac activation sequence (104, 108, 118, 122, 126), or generating simultaneous or near simultaneous pacing pulses to the septum or right ventricular outflow tract during ventricular systole in order to improve left ventricular cardiac efficiency and reduce mitral regurgitation in patients with dilated cardiomyopathy. A three dimensional map of electrode placement may be calculated. A sub set of the available electrodes in the right side of the heart is selected for stimulation such that septal motion during systole is reduced or the mitral valve area is stiffened to reduce mitral regurgitation.
MULTI-ELECTRODE APPARATUS AND METHOD FOR TREATMENT OF
The heart is a mechanical pump that is stimulated by electrical impulses. The mechanical action of the heart results in the flow of blood. During a normal heartbeat, the right atrium (RA) fills with blood from the returning veins. The RA then contracts and this blood is moved into the right ventricle (RV), When the RV contracts it pumps that blood to the lungs. Blood returning from the lungs moves into the left atrium (LA), and after LA contraction, is pumped into the left ventricle (LV), which then pumps it throughout the body. Four heart valves keep the blood flowing in the proper directions.
The electrical signal that drives this mechanical contraction starts in the sino- atrial node, a collection of specialized heart cells in the right atrium that automatically depolarize (change their voltage potential). This depolarization wave front passes across all the cells of both atria and results in atrial contraction. When the advancing wave front reaches the A-V node it is delayed so that the contracting atria have time to fill the ventricles. The depolarizing wave front then passes over the ventricles, causing them to contract and pump blood to the lungs and body. This electrical activity occurs approximately 72 times a minute in a normal individual and is called normal sinus rhythm.
Fig. 12 is a cross section of the multi-electrode lead of Fig. 8. Fig. 13 is a flow chart for the development of a 3-D model of electrode position.
Fig. 24 is a flow chart of a program for gathering data concerning cardiac wave fronts and providing therapy. DETAILED DESCRIPTION OF THE INVENTION
The subject invention pertains to an implantable cardiac stimulation system 10 including a cardiac stimulator 12 with various electronic circuits, and a multi- electrode lead 14 attached to the stimulator 12, as shown. The lead 14 has a distal end 16 disposed, for example, in one of the cardiac chambers such as the right ventricle 18 of heart 20. In Fig.1 , end 16 is shown having a general spiral shape. The system 10 is'adapted to deliver therapy in the form of electrical pulses. The therapy may include GCV (greater cardiac vein) resynchronization therapy, treatment of conduction pathway abnormalities, bardycardia pacing, etc. The cardiac stimulator 12 contains electronic components common to current cardiac stimulators such as a battery, microprocessor control circuit, ROM, RAM, an oscillator, reed switch and antenna for communication, output circuits, and sense circuits. These components are well known to those of skill in the art. In addition the cardiac stimulator 12 has a plurality of independent sensing and stimulating circuits for each heart chamber, as will be explained below.
Fig. 2 illustrates important elements of the cardiac stimulator 12 in block diagram. The cardiac stimulator 12 comprises a logic control and timing circuit 22, which may include a microprocessor and memory, but which could also be implemented in a specialized circuit. The logic control and timing circuit 22 receives input from a sense detection circuit 24 and issues control instructions to an output control circuit 26. To accommodate the many electrodes used in the apparatus, multiple sense amplifiers 28a, 28b ... 28n are provided, each in electrical communication with an electrode through the lead 14 and with the sense detection circuit 24. Similarly, the output control circuit 26 is electrically connected to a plurality of output circuits 30a, 30b ... 30n. The output circuits 30a, 30b ... 30n produce stimulating pulses or high frequency, non-simulating signals at electrodes in the heart through the lead 14. The logic control and timing circuit 22 may operate in accordance with a program stored into memory. The programming in memory is received through a transceiver 25 (for instance from programmer 100). As part of this programming, the electrodes designated for stimulation, as described below, are stored in memory. During its operation, the microprocessor of the logic control and timing circuit 22 sets the output control circuit 26 and the sense detection circuit 24 in accordance with the appropriate electrode designations. Thereafter, the sensing detection circuit 24 senses intrinsic activity and other signals within the heart 20 and provides corresponding indication signals to the microprocessor. The Logic control and timing circuit 22 then issues appropriate commands to the output control circuit 26. The output control circuit 26 generates appropriate stimulation pulses. These pulses are steered to the designated electrode or electrodes.
Figures 3 and 4 show two embodiments of output control circuits 26 and output circuits 30a, 30b ... 30n. The embodiment of Fig. 3 comprises a communications controller that receives control signals from the logic control and timing circuit 22 (Fig. 2). Output of the communications controller 32 is sent to an amplitude controller 34 that controls the voltages produced by a plurality of voltage amplifiers 36a, 36b ... 36n. In parallel, the communications controller 32 also regulates a pulse timing controller 38. Signals from the pulse timing controller 38 close and open switches 40a, 40b ... 40n, thereby delivering stimulation pulses or high frequency signals to the heart through electrodes on the lead 14. The embodiment of Fig. 4 also uses a communication controller 32 and pulse timing controller 38, but the amplitude controller 34 and plurality of voltage amplifiers 36a, 36b ... 36 n are replaced by a single voltage amplifier 42. To achieve the same effect of multiple pulses to selected electrodes, the signals from the pulse timing controller are sent to a multiplexer 44, comprising a switch matrix controller 46 and a plurality of switches 48a, 48b ... 48n. The switches 48a, 48b ... 48n must be opened and closed in a synchronized manner. It may be necessary to open all switches before and after closing a selected switch. Thus the embodiment of Fig. 4 gains simplicity and energy efficiency by minimizing the number of voltage amplifiers, but sacrifices flexibility in potential output patterns.
A variety of apparatus may also be used to sense signals from multiple electrodes through the sense detection circuit 24. A first embodiment is illustrated in Fig. 5. In the embodiment of Fig. 5, a communication controller 50 in the sense detection circuit 24 communicates with the logic control and timing circuit 22 (Fig. 2). The communication controller 50 is in electrical communication with a sense amp controller 52 and a sense event timing analysis unit 54. The sense amp controller 52 regulates amplification levels on the sense amps 36a, 36b ... 36n such that significant signals are detected and noise is rejected. Each amplifier has independent sensitivity (gain) and filter characteristics. The sense event timing analysis unit 54 receives output from the sense amps 36a, 36b ... 36n and collects that information into a description of a moving wave front. Both intervals between sensed events and the sequence of channels or electrodes are used to describe the wave front. The description of the wave front is communicated to the logic control and timing circuit 22 for use in determining the appropriate therapy. A second embodiment, illustrated in Fig. 6, employs a multiplexer in a manner similar to the second embodiment of the output control circuit, described in connection with Fig. 4, above. In this second embodiment of the sense detection circuit 24, the sense amp controller 52 controls a single amplifier 56. The sense event timing analysis unit 54 analyses the output of the single amplifier 56 and produces the description of the moving wave front. A sense timing controller 58, in electrical communication with both the communication controller 50 and the sense event timing analysis unit 54, controls a multiplexer 60 through a switch matrix controller 62. The switch matrix controller 62 opens and closes a plurality of switches 64a, 64b ... 64n, selectively connecting the electrodes of the lead 14 to the sense amplifier 56. As explained above, replacing multiple dedicated sense amplifiers 36a, 36b ... 36n with a single amplifier 56 exchanges flexibility and simplified control for energy efficiency.
The multiplexers 44, 60 of the embodiments of the output control circuit of Fig. 4 and of the sense detection circuit of Fig. 6 may be combined externally to the cardiac stimulator 12 in an alternative configuration, illustrated in part in Fig. 7. Fig. 7 shows an adapter 66 for a connecting a multi-electrode lead to a cardiac stimulator having an IS-1 connector in the header of the stimulator 12. IS-1 connectors are well known and many physicians are familiar with their operation and use. For the adapter 68 a male IS-1 connector 68 is connected to the multiplexers 44, 60 in an independent package. The multiplexers are connected either directly to the lead 14 or indirectly through a multi-electrode connector 70. Dual chamber pacemakers having two IS-1 connectors in a single header are well known. In cardiac stimulators 12 according to the present invention using IS-1 connectors rather than a specialized multi-electrode connector, a first IS-1 connector might be used to carry both the voltage from the voltage amp 42 and signals from the pulse timing circuit 38 and a second IS-1 connector might be used to carry both the signals to the sense amplifier 56 and the control signals from the sense timing controller 58. Alternatively, one IS- 1 connector might be dedicated to the control signals from the sense timing controller 58 and the pulse timing circuit 38 while another IS-1 connector might be dedicated to the signals delivered to and received from the heart, that is, to pulses from the voltage amp 42 and to sensed events.
Details of the multi-electrode lead 14 are shown in Fig. 8. In a second embodiment, the lead 14 includes an external biocompatible polymer tube 72 having a straight portion 74 and a shaped portion 76. The tube may be made of polyurethane or other similar materials that may be thermally shaped so that the shaped portion 76 retains any desired configuration. In Figs.1 and 8, the shaped portion 76 is shown as having a spiral shape, but many other shapes may be selected as well. The spiral or coil shaped lead of Fig. 1 and 8 places electrodes around the entire chamber of the heart. This embodiment allows complete sensing and stimulating control around the entire chamber.
Yet another possible embodiment of Fig. 10 uses a serpentine shape to place electrodes along a wall of a chamber of the heart. These and other configurations may be combined and used in one or more chambers of the heart. Fig. 11 , for example, shows a lead having a folded configuration in the right ventricle and a coiled or spiral configuration in the atrium. Such a configuration may have particular advantages for so-called single pass, dual chamber applications.
Attached to tube 72 of the lead 14 of any configuration, there are provided a plurality of electrodes E1 , E2, E3, E4, E5, ...En. Preferably electrodes E1... En are formed of coils of bare wire or cable wound about the tube 72. Each electrode is connected to corresponding wires W1 , W2, W3 ... Wn which extend through the length of tube 72 and which are shown exiting through end 80 for the sake of clarity.
Wires W1 , W2, W3...Wn are insulated, so that they are not shorted to each other within the tube 72. The electrode 14 and its method of manufacture are disclosed in co-pending commonly assigned application S.N. 09/245,246 filed February 5,1999, and incorporated herein by reference. Preferably the end 80 of tube 72 and the ends of wires W1 , W2, W3, etc. are coupled to a connector 82 for attaching the lead 14 to the cardiac stimulator 12. The connector 82 may have a plurality of pins Pi. Each wire W1 ... Wn is associated with a pin. As explained below, however, it is not necessary to connect the electrodes E1 ... En through the wires W1 ... Wn to any specific pin. Because the lead may assume different configurations in the heart, it is the relative location of the electrodes in the heart that is important for application of an appropriate therapy, not the placement of the electrodes along the lead. This apparatus, therefore, assigns a functionality to an electrode and its pin after implantation of the lead.
In addition to spiral coil or ring electrodes E1 ... En, a distal tip electrode Ed may also be provided. The distal tip electrode Ed may also have an active fixation mechanism, for example a helical screw 84 or tines, to secure the lead to the interior wall of the heart.
The lead 14 can be constructed with the tube 72 extending relatively straight or can be customized to any shape to fit any pre-selected location within the heart 20 dependent on each particular patient's pathology. For example, if the lead 14 is to be placed in the greater cardiac vein, then its end 16 (consisting of tube portion 76 and electrodes E1 , E2, E3 ...etc.) is shaped to form a small helix, so that it will fit into the grater cardiac vein.
The tube 72 can be formed with a longitudinal cavity 86, as shown in the cross sectional view of Fig. 12. Cavity 86 holds the wires W1 , W2, W3 etc. The lead 14 could be straightened by inserting a substantially straight stylet 90 into cavity 86. The stylet 90 is also flexible but is less flexible than the lead 14 so that as it is inserted into the cavity 86, it forces the tube 72 to straighten. The lead 14 is then inserted into the heart or into a vein near the heart. After implantation of the lead 14, the stylet 90 is withdrawn and the lead 14 flexes back and takes a configuration shown, for example, in Fig. 8, 9, 10, or 11. Programmer
The process of identifying the optimum electrode or electrodes or a pattern of electrodes may be performed using several different approaches. For treatment of congestive heart failure, as well as for more traditional pacing modalities for bradycardia and tachycardia, the location of the electrode in the heart is important, not necessarily the position of any given electrode along the lead. As is apparent from Figures 8, 9, 10 and 1 , an implanted lead may assume many configurations. The lead may overlap itself, whereby electrodes proximal on the lead are closer to the venticular apex than are more distal electrodes. However, in many cases, the relative location of the electrodes in the heart may be determined by inspection under fluoroscopy by visual approximation. This information or mapping would be used either in the programmer or the cardiac stimulator or both. The mapping could be used as a starting point for additional location algorithms or as a model for measuring cardiac performance or providing appropriate therapy.
The connection between electrodes and pins may be determined either by manufacturing such that the first electrode is connected to the first pin, the second electrode to the second pin, and so on, or by measurements. A test apparatus may be provided wherein an electrical signal is supplied to each electrode in turn and the pins sampled to identify the pin receiving the signal. The mapping of electrodes to pins would then be communicated to a cardiac stimulator at the time of implantation so that the lead and cardiac stimulator could function together as a unit. The relative position of the electrodes can also be determined by measuring certain phenomenon and calculating a three dimensional position for each electrode, or by sensing the progression of an intrinsic wave front propagating through the heart, or by sensing the progression of a stimulated wave front, moving through the heart, as described below.
To determine the relative positions of the electrodes in three-dimensional space, calculations can be performed either in an external device such as the programmer 100, or in the cardiac stimulator 12. Because such calculations may be relatively energy expensive, calculation in an external device may be preferred. As described above, after implantation, the free end of lead 14 is connected to programmer 100, as shown in dotted line 102 in Fig. 1. Next, in step 300 (See Fig. 13) a high frequency test signal is fed to one of the electrodes, Ei, such as the electrode disposed at the tip of the lead 14. Preferably this test signal has a frequency in a range that is known to have no effect on the heart 20. For example, the test signal may have a frequency of about 200 kHz. This test signal is generated by a high frequency or HF generator 124 and applied to the lead 14 by a multiplexer 126 that selects different electrodes. While this HF test signal is applied to the one lead electrode, a sensor 124 within the programmer 100 is used to detect 302 the HF signals in the remaining electrodes. In step 304, a microprocessor 104 is used to determine the voltage amplitude of the detected signals at each electrode. If a signal has not been injected at each of the n electrodes (step 306), a new electrode i is selected (step 308), and a new set of data is recorded. Selecting all n electrodes will produce a more accurate determination of the position of the electrodes, however, positions can be determined by selecting as few a five electrodes (step 308). Using this information, the microprocessor 104 then determines (step 310) the position of each electrode in step 300. Details of the algorithms used to make this determination are provided in commonly assigned co-pending application SN 60/288,358 filed May 3, 2001 and entitled "Implantable Electrode System To Map Electrical Activity In 3-Dimensions And Deliver Multifocal Pacing Therapy For Atrial Fibrillation", incorporated herein by reference. Briefly, as described in that application, a 3D electrode positioning system operates by applying a periodic voltage to several subgroups of the electrodes and measuring the signal induced on selected remaining electrodes. The number of subgroups employed is sufficient to over-determine a system of non-linear equations representing the distribution of the voltage (or potential) at each of the electrodes and in the surrounding tissue. Several means are available to extract the electrode positions relative to tissue boundaries from such models. One of these, the method of non-linear least squares, is well known in the literature, (e.g. Golub and Van Loan, Matrix Computations.1989. Johns Hopkins)
Information on the relative three dimensional location of electrodes in the heart and with relationship to the heart wall may be valuable in specifying a therapy for the diseased heart or for interpreting phenomenon detected in the heart. Such information is not absolutely necessary for providing therapy for congestive heart failure. A set of ordered time delays as a function of the n electrodes implanted in the heart may be sufficient to provide a clinical benefit. The order of the electrodes and their associated time delays may be determined in several ways. Two such ways are illustrated in Figures 14 and 15.
When the preferred sample is identified, the associated set of ordered pairs of electrodes and time delays is set 342 as an initial preferred condition. This set of electrodes will usually approximate a desirable wave front preceding from the sinoatrial node down through the heart to the apex of the ventricle. In particular, the first electrode E1 in this series located in a given chamber of the heart, for example, in the right ventricle, is taken as the first approximation of the optimum electrode for stimulation in that chamber. Under appropriate circumstances, the heart is stimulated at E1 (step 344). The resulting contraction is sensed at the remaining n-1 electrodes, and the resulting vector (that is, set of ordered pairs of electrodes and time delays) is compared 346 to the stored pattern. A search is performed to confirm that stimulation at E1 is superior to any electrodes within a predetermined proximity to E1. Since the actual physical location of the electrodes is unknown, this is a logical proximity, that is, for example, the first P electrodes in order of time delay from E1. If stimulation at one (Ei) of these P electrodes is superior to E1 (step 348), Ei replaces E1 as the preferred electrode E[Best] (step 350). The counter is reset 352 and the search proceeds in the proximity of the new preferred electrode. Otherwise, the counter is incremented 354. When the counter reaches the preselected number P (step 356) the search halts and E[Best] has been identified 360.
It may also be necessary to identify the optimum electrode E[Best] when there is no intrinsic waveform or when the intrinsic waveform is so unpredictable or sporadic that meaningful information cannot be derived from it. In such conditions, a system 380 illustrated in Fig. 15 may be used. As mentioned above, a multi- electrode lead used with this apparatus may be constructed such that the electrical communication between an electrode and a pin in the lead connector is essentially randomly determined at the time of manufacture. That is, the electrodes may be connected to the pins in any order. However, if the distal tip of the lead is both a fixation device, such as a helical screw, and an electrode, the distal tip will preferably be provided with an identifiable electrical connection, probably physically different from the other wires in the lead. For example, the other electrodes may be mechanically continuous with their electrical connector or wire, while the distal tip or distal electrode may be connected to a conducting wire through a mechanical connection, such as a crimp joint or laser weld. This difference would allow the distal electrode to be electrically connected to a specific pin in the lead connector. Inserting the electrical conductor for the distal electrode into the lead either first or last could also aide in identifying this connection. In addition, the conductor connected to the distal tip could be physically different from other conductors, for example in type, color or thickness of wire or insulation. The conductor connected to the distal tip might also be identified electrically.
When the lead is implanted, the distal tip or distal electrode can usually be located physically in the heart. For instance, the distal electrode may be implanted low in the heart at the apex of the right ventricle. The system 380 can begin 382 to identify an optimum stimulation pattern. A signal may be emitted 384 through the distal electrode E[Distal]. The signal may be either a high frequency, non-stimulating signal, or a stimulating pulse that causes the ventricle to contract. The propagation of this signal through the heart is sensed 386 at all electrodes and elapsed times Delta T for each electrode are recorded 388. It may be expected that the electrode associated with the largest Delta T would be located relatively high in the ventricle. It may not be the optimum electrode, but it represents a good candidate for beginning a search for the optimum electrode. Therefore, Ei is set 390 equal to E[max T], and the heart is stimulated at step 392. The resulting waveform is sensed 394 either by the implantable device or externally. A physiologic performance parameter is also sensed 396 during the cardiac contractions affected by the stimulation. The sensed parameter Pi is compared 398 with a standard P[Best]. If Pi exceeds P[Best], P[Best] is replaced by Pi in step 400. The next potential electrode is identified by incrementing i [step 402]. A new set of ordered pairs associating each electrode (or pin) to a Delta T resulting from the stimulation. If i has been incremented to Q (step 404) the set of ordered pairs or Delta T values is stored 406. Q is a pre-selected number equal to of less than the total number of electrodes. If i is less than Q, a new stimulation 392 is produced at the next Ei electrode. When the optimum electrode EfBest] has been electrode, a physician may choose to modify the shape of the waveform by adding additional stimulations at other electrodes, in the manner described above.
Using the multi-electrode lead and capabilities of the apparatus described above, it is possible to map cardiac electrical activity. For example, in Fig. 16, a series of sense events is illustrated at electrodes numbered in order of physical location within the heart from electrode 1, which is the electrode nearest the relevant focus for a particular chamber of the heart. The wave front proceeds across the heart in an orderly fashion, corresponding to the surface ECG also shown in Fig. 16. The progress and shape of the wave front may be represented by a series of ordered pairs, each pair comprising a number of an electrode and a time delay in milliseconds, representing elapsed time from the prior sensing point or electrode. As an example, the wave front series or matrix for the samples of Fig. 16 might be: Electrode 1 2 3 4 5 ... N
Electrode 4 5 3 2 1 ... N
Sweet-spot pacing involves the determination of the optimal stimulating location within the heart chamber. As described above, the optimum electrode may be determined at the time of implantation. After implantation, similar search algorithms may be used either through the cardiac stimulator 12 or with the programmer 100 to confirm or modify the selection of the optimum electrode, as conditions change over time. Current pulse generators stimulate from an electro- physiologically arbitrary point determined by implant technique. Stimulation at a conventionally implanted electrode may produce a wave front similar to that illustrated in Fig. 18. Like the ectopic wave of Fig. 17, the wave front propagates across the heart in a less natural manner. Longer intervals between sensed events and an extended QRS signature may be due to the fact that the wave front follows cellular conduction rather than the faster Purkinje fibers. Where the optimum electrode has been identified, as described above, pacing at the optimum electrode may produce the more natural and efficient contraction illustrated in Fig. 19.
An important aspect of this invention comprises modifying the intrinsic ventricular cardiac activation sequence and generating simultaneous or near simultaneous pacing pulses to the septum or the right ventricular outflow tract during ventricular systole in order to improve left ventricular cardiac efficiency and reduce mitral regurgitation in patients with dilated cardiomyopathy. It is asserted that specialized stimulation from the right side of the heart can so improve left side performance that left ventricular output can be improved. Cardiac remodeling may also take place. One source of left ventricular inefficiency may be increased mitral valve regurgitation. A second source may be increased septal motion. In the weakened heart, the right and left ventricles may become dysynchronus. In the healthy heart, the septal wall remains relatively straight, balanced between pressures of the contracting right ventricle and the contracting left ventricle. In the ailing heart, the right ventricle may first push the septum into the left ventricle and the left ventricle, contracting later, may then push the septum back into the right ventricle. The septum oscillates back and forth and the energy of the heart is used up in this motion, rather than in pushing blood out of the heart and through the circulatory system. Both sources of left ventricular inefficiency may be treated by appropriate stimulation to contract or stiffen heart muscles. Stimulation through at least one and preferably two or more electrodes lying along the septal wall in the right ventricle may so stiffen the septum that flutter or oscillation is reduced and cardiac performance is improved. Similarly, stimulation through at least one electrode in or near the right ventricular outflow tract may propagate into the base of the left ventricle, stiffening the muscular structures around the mitral valve and increasing left ventricular output. Achieving these results requires selecting an electrode or set of electrodes from a set of electrodes located along the right ventricular septal wall and extending into the right ventricular outflow tract. Preferably the lead 14 is deployed in the right ventricle as shown in Fig. 11. Preferably sufficient electrodes are disposed along the septal wall a sufficient probability of stimulating the heart at an effective region within a selected period of time. The selected period of time is believed to be the first 20% of right ventricular contraction time, more preferably 10% or less of the right ventricular contraction time. The probability of stimulating at or near an ideal sport should be at least 25%, more preferably at least 50 %, yet more preferably 100 %. At least 3, more preferably 5, and yet more preferably 12, electrodes are disposed along the lead in the region of the septal wall.
The number of electrodes to be deployed for a given patient may be determined as follows. It will be recognized that any number of electrodes exceeding calculated number will meet the selected conditions of stimulation time and coverage probability. The conduction velocity of a contraction wave form through a ventricle is on the order of 500mm/sec or 0.5 mm/ms. The ventricular contraction takes about 40 ms and it is desirable to have the septum rigid within the first 10% of the contraction time, or within 4 ms. At the given conduction velocity, the effects of stimulation from a given electrode would travel about 2 mm in 4 ms. For complete coverage, adjacent electrodes would be about 4 mm apart.
d = e + 2*cv*t*(100/c)
where e is the electrode length, cv is the conduction velocity, t is the maximum conduction time and c is the selected percent coverage. For example, if the electrode length is 2 mm, and 100% coverage is desired, the electrode center-to- center distance is 6 mm. The number of electrodes deployed along a septum 5 cm (50 mm) long would be twelve. If 50% coverage were desired, 5 electrodes must be deployed on the same septum. If 25% coverage is desired, 3 electrodes would be deployed on the 5 cm septum. The distance d is not necessarily the spacing of the electrodes along the lead 14, except in configurations such as shown in Fig. 9. In lead configurations such as Fig. 10, additional electrodes must be provided to increase the probability that electrodes that fall on the septal wall are separated by the desired distance d.
The number and spacing of electrodes on the septal wall may also be affected by the number (n) of desirable pacing locations on a particular patient's septal wall. One or more "sweet" spots may be located by selective stimulation as described herein. If there are more than one sweet spots, but only one of the spots needs to be stimulated within the desired time to achieve septal rigidity, the probability or likelihood (I) of stimulation is
1 = 1 - ((100- c)/100)n
I = (1-((100-c)/100)n)p
where p is the number of sweet spots that must be stimulated. These equations may be reversed to determine the desired spacing of electrodes along the septal wall, which will aide the physician in selecting the appropriate multi-electrode lead and lead configuration. For example, if a particular patient is expected to have 5 sweet spots on the septal wall, 2 of which must be stimulated with a 75% certainty (I = 0.75) to achieve septal rigidity, then coverage c is
For the selected parameters this would be c = 0.33 or 33%. The center-to-center distance would be 14 mm, or 4 electrodes for a 50 cm septal wall. The number of electrodes would be rounded up to the nearest whole number of electrodes.
Where the preferred configuration of the lead 14 shown in Fig. 9 or 11 is used, most of the electrodes will fall on or near the right ventricular septal wall or in the right ventricular outflow tract. In other lead configurations, such as Fig. 8 or 10, the step 412 of identifying electrodes near the septum or RV outflow tract may be more difficult. A line of electrodes lying on the septum may be selected where two electrodes on the septum are known. The most distal or tip electrode on the lead is usually secured to the heart near the right ventricular outflow tract or the septal wall near the base of the right ventricular chamber and its location is known by reason of fluoroscopic observation during implantation. A second electrode may be located by observation of a radio opaque marker proximally on the lead. An electrode near the radio opaque marker may be determined to lie sufficiently near the apex of the heart and close to the septal wall. Alternatively, a temporary lead may be inserted in the heart and a distal electrode advanced to the septal wall near the apex of the right ventricular chamber. A grid mapping of the electrodes may then be developed, as described below. The desired set of electrodes on the septal wall are those electrodes on the shortest path containing the two known electrodes. As shown in Fig. 22 a program 460 begins by stimulating 462 the heart at a known electrode, preferably the distal electrode on the lead 14. A set of adjacent electrodes 464 is identified, comprising the first electrode sensing the stimulating pulse and all electrodes sensing the pulse within a pre-selected time t thereafter. In Fig. 23, this set comprises electrodes A, B and C, adjacent electrode 1 , which is the known distal electrode. The apparatus then stimulates the heart from each electrode in the set ABC, step 466 and forms (step 468) additional subsets, for example, A1 , A2 and B from electrode A; A2, B1 and C1 from electrode B; and B, C1 and C2 from electrode C. Unless all electrodes have acted as a stimulating electrode (step 470), this process is repeated until a complete map ordering the electrodes has been developed, as suggested in Fig. 23. The electrodes on or near the septum will be selected (step 472) as those electrodes in the shortest temporal path from electrode 1 to the other known electrode, electrode 2, which may be an electrode on the lead 14 or an electrode on a temporary lead, as explained above. In Fig. 23, this set of septal electrodes would be electrodes 1 , B, B1 , and B2. Electrode 2 would be included if it is an electrode on the multi-electrode lead. If electrode 2 is on a temporary lead, it would not be included in the set of septal electrodes. The set of septal electrodes is then set 474 for use in identifying the optimum electrodes for stiffening the septum or the mitral valve, as explained above.
Figure 21 illustrates an algorithm 410 for providing a stimulation therapy for congestive heart failure by stimulation from the right ventricle and right ventricular outflow tract. First, a set of electrodes on the multi-electrode lead is identified 412. This set of electrodes lies on or near the right ventricular septal wall or in the right ventricular outflow tract. A first effort may be made to identify a subset of electrodes that stimulate the heart at locations such that the muscles around the mitral valve will stiffen and mitral regurgitation will be reduced. The heart is stimulated 414 through an electrode located near the right ventricular outflow tract. Data is acquired 416 indicative of the effectiveness of the stimulation in reducing mitral regurgitation. The cardiac imaging device 101 is usually employed. Data acquired by Doppler echocardiogram may indicate a reduced or eliminated backflow through the mitral valve. This data may be communicated across the link 105 to the programmer 100. Alternatively, an attending health care provider may observe the output of the cardiac imaging device 101 and enter a determination of the effect of a stimulus on mitral regurgitation into the programmer 100. The programmer 100 (or cardiac stimulator 12) compares 418 regurgitation information for the present stimulation electrode or electrodes with information from previous electrode or sets of electrodes. If no improvement is noted, the program inquires 422 if there is another electrode or set of electrodes in or near the right ventricular outflow tract that is a candidate for stimulation. If there is another electrode or set of electrodes, those electrodes are selected 420, and the heart is stimulated 414 again. If not, the program 410 will locate an electrode or set of electrodes that stiffen the septum in such a way that septal motion is reduced. If there is an improvement at step 418, the current set of electrodes is set as optimum 419 and the test for other candidate electrodes 420 is performed.
When the cardiac contraction takes a longer, less efficient form, the event timer will expire at step 446 before the wave front is sensed at the next electrode in series. The program checks 458 if the wave front is following an intrinsic pattern, as explained above, that is that the wave front is proceeding generally from a focus through a chamber of the heart. If not, the wave front and contraction are considered ectopic, and the program compares the pattern to previously detected ectopic beats or contractions, for diagnostic purposes. If a new pattern is detected, a record is made of the form of the ectopic contraction, and therapy is applied 462. This may include stimulation at a particular electrode to drive the wave front back into a more efficient form. If the ectopic pattern has previously been recorded, a counter for that pattern is incremented and therapy is applied 464. On the other hand, if the wave front matches an intrinsic pattern (step 458), an intrinsic wave front counter is incremented and therapy applied 466 as above. After therapy in each of these three cases, the program returns 456, 468 to sensing 442. Data acquired by the cardiac stimulator 12 on the frequency and form of ectopic and intrinsic wave fronts can be used to refine the form of therapy applied. The matrix of ordered pairs representing the desired wave front for an efficient contraction can be modified in response to the particular needs of a patient. The apparatus described herein allows for stimulation of the heart at a location likely to produce an efficient contraction and for subordinate stimulation to reshape a contraction waveform that has started spontaneously or from an initial stimulating pulse. Improved cardiac efficiency reduces the effects of congestive heart failure.
1. A method for treating congestive heart failure comprising implanting a multi-electrode lead in at least the right ventricle of the heart of a patient, said multi-electrode lead having at least three selectable electrodes, implanting a cardiac stimulator in the body of said patient, said cardiac stimulator being connected to said multi-electrode lead, selecting a subset of said electrodes for stimulating the heart such that stimulation through said set of electrodes improves cardiac performance, and stimulating the heart through said set of electrodes.
2. The method of claim 1 wherein the step of selecting a set of electrodes further comprises selecting a set of electrodes lying on the right septal wall.
3. The method of claim 2 wherein the step of selecting said set of electrodes further comprises selecting a set of electrodes to stiffen the septum during systole.
4. The method of claim 2 wherein the step of selecting said set of electrodes comprises selecting a set of electrodes to reduce motion of the septum during systole.
9. The method of claim 2 wherein said multi-electrode lead is implanted from the right ventricular outflow tract along the right ventricular septal wall to the right ventricular apex.
10. The method of claim 2 wherein the set of electrodes lying on the septal wall is selected by identifying a set of electrodes close to a line connecting two electrodes that are known to lie on the septal wall.
26. The method of claim 1 further comprising developing a plurality of template patterns of wave fronts passing said electrodes and distinguishing between intrinsic and ectopic wave fronts by comparing sensed wave fronts to said template patterns.
27. An apparatus for treating congestive heart failure comprising a multi-electrode lead, said multi-electrode lead having at least three selectable electrodes, a cardiac stimulator in the body of said patient, said cardiac stimulator being connected to said multi-electrode lead, means for selecting a subset of said electrodes for stimulating the heart such that stimulation through said set of electrodes improves cardiac performance, and means for stimulating the heart through said subset of electrodes.
28. The apparatus of claim 27 further comprising means for selecting a set of electrodes lying on the right septal wall.
29. The apparatus of claim 28 further comprising means for selecting a set of electrodes to stiffen the septum during systole.
30. The apparatus of claim 28 further comprising means for selecting a set of electrodes to reduce motion of the septum during systole.
31. The apparatus of claim 30 further comprising a cardiac imaging apparatus.
32. The apparatus of claim 29 further comprising means for stimulating the septum within at least the first 10 per cent of ventricular contraction time.
33. The apparatus of claim 29 further comprising means for stimulating at said set of electrodes to stiffen the septum substantially simultaneously.
34. The apparatus of claim 29 further comprising means for stimulating at said set of electrodes to stiffen the septum in a sequence such that substantially all of the septum stiffens substantially simultaneously.
35. The apparatus of claim 28 wherein said multi-electrode lead is configured is an extended J shape such that said lead may be implanted from the right ventricular outflow tract along the right ventricular septal wall to the right ventricular apex.
36. The apparatus of claim 28 further comprising means for selecting a set of electrodes lying on the septal wall by identifying a set of electrodes close to a line connecting two electrodes that are known to lie on the septal wall.
37. The apparatus of claim 27 further comprising means for selecting a set of electrodes to stiffen the heart around the mitral valve during systole.
38. The apparatus of claim 37 further comprising means for minimizing mitral regurgitation by stimulation from the right side of the heart.
39. The apparatus of claim 38 further comprising an echo cardiogram for imaging mitral regurgitation.
40. The apparatus of claim 27 wherein said multi-electrode lead has sufficient electrodes deployable on the right ventricular septal wall such that at least fifty per cent of the right ventricular wall could be stimulated within the first ten percent of the ventricular contraction time.
41. The apparatus of claim 40 wherein said electrodes are within 8 mm of each other.
42. The apparatus of claim 41 wherein the electrodes are within 4 mm of each other.
43. The apparatus of claim 27 further comprising means for locating an electrode lying near a sweet spot in the heart.
44. The apparatus of claim 43 further comprising at least one sensor of a physiologic parameter correlated to cardiac output, and means for selecting an electrode or electrodes from the selectable electrodes on said multi-electrode lead such that said cardiac output is maximized when the heart is stimulated at said electrode or electrodes.
45. The apparatus of claim 27 further comprising means for determining a three dimensional position for each electrode.
46. The apparatus of claim 27 further comprising means for mapping the progress of a wave front through at least a portion of the heart past at least some of said electrodes.
47. The apparatus of claim 46 further comprising means for mapping an intrinsic contraction wave front.
48. The apparatus of claim 46 wherein said means for mapping further comprises means for stimulating the heart at at least one electrode and means sensing a resulting wave front propagating through the heart.
49. The apparatus of claim 27 further comprising means for sequentially stimulating at a plurality of electrodes.
50. The apparatus of claim 49 further comprising means for stimulating at said electrodes to cause the contraction wave form to conform to a selected normal wave form.
51. The method of claim 27 further comprising means for developing a plurality of template patterns of wave fronts passing said electrodes and means for distinguishing between intrinsic and ectopic wave fronts by comparing sensed wave fronts to said template patterns.
52. An implantable cardiac stimulator for treating congestive heart failure comprising an implantable lead having at least three electrodes, a cardiac stimulator connectable to said lead to place said electrodes in electrical communication with said stimulator; at least one detector coupled to said electrodes for detecting electrical phenomenon in the patient's body; a timer connected to said detector for timing at least one elapsed time between electrical phenomena detected at said electrodes; at least one logical template of an expected pattern of detected electrical phenomenon at said electrodes, a comparator comparing said detected electrical phenomenon and said elapsed times associated with said phenomenon to said logical template, and an output circuit providing a therapy to said patient in response to said comparison.
53. The implantable cardiac stimulator of claim 52 further comprising a logical model in said cardiac stimulator representing locations of said electrodes in a patient's body.
54. The implantable cardiac stimulator of claim 52 further comprising a trigger connected to said electrodes and said timer, said trigger turning said timer on in response to a detected electrical phenomenon.
55. The implantable cardiac stimulator of claim 52 further comprising a time-out circuit, said time out circuit turning off said timer whenever a second electrical phenomenon has not occurred within a selected period of time after a first phenomenon.
56. The implantable cardiac stimulator of claim 55 wherein the selected period of time is set based on electrode spacing and on expected conduction velocities.
57. The implantable cardiac stimulator according to claim 52 further comprising a logical template of a normal pattern and at least one logical template of an ectopic pattern.
58. The implantable cardiac stimulator according to claim 57 further comprising a circuit identifying an ectopic beat whenever a series of electric phenomenon is first detected at an electrode other than a selected first electrode.
59. The implantable cardiac stimulator according to claim 58 further comprising memory storing a template for identified ectopic beats.
60. The implantable cardiac stimulator of claim 59 wherein said comparator further matches said pattern to a template and further comprising a diagnostic counter counting the number of times a pattern matching said template matched to said pattern has been detected.
61. The implantable cardiac stimulator of claim 60 wherein a new template is created whenever a new pattern does not match an existing normal or ectopic template.
62. The implantable cardiac stimulator of claim 52 further comprising circuit means for stimulating the heart through at least some of said at least three electrodes and means for selecting as a stimulating electrode that electrode which produces a pattern of electric phenomenon most closely resembling a normal template.
63. The implantable cardiac stimulator of claim 62 further comprising means for producing a sequenced pacing train and wherein said stimulating electrode comprises a sequence of electrodes.
64. The implantable cardiac stimulator of claim 62 further comprising means for identifying fast conduction associated with stimulation through a patient's Purkinje system.
66. The implantable cardiac stimulator of claim 62 further comprising means for measuring cardiac output and means for comparing relative cardiac output resulting from stimulation at each of said at least some electrodes and wherein said means for selecting a stimulating electrode is responsive to said means for measuring cardiac output to select as stimulating electrode the electrode optimizing cardiac output.
67. The implantable cardiac stimulator of claim 66 wherein said means for measuring cardiac output measures blood oxygenation.
68. The implantable cardiac stimulator of claim 67 wherein said means for measuring cardiac output is a pulse oxymeter.
69. The implantable cardiac stimulator of claim 66 wherein said means for measuring cardiac output measures QRS width.
PCT/US2002/004330 2001-02-13 2002-02-13 Multi-electrode apparatus and method for treatment of congestive heart failure WO2002064205A2 (en)
US26844901P true 2001-02-13 2001-02-13
US60/268,449 2001-02-13
AU2002240363A AU2002240363A1 (en) 2001-02-13 2002-02-13 Multi-electrode apparatus and method for treatment of congestive heart failure
WO2002064205A2 true WO2002064205A2 (en) 2002-08-22
WO2002064205A3 WO2002064205A3 (en) 2003-03-20
PCT/US2002/004330 WO2002064205A2 (en) 2001-02-13 2002-02-13 Multi-electrode apparatus and method for treatment of congestive heart failure
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2002-02-13 US US10/075,808 patent/US6643546B2/en not_active Expired - Fee Related
2002-02-13 WO PCT/US2002/004330 patent/WO2002064205A2/en not_active Application Discontinuation
2002-02-13 AU AU2002240363A patent/AU2002240363A1/en not_active Abandoned
2003-10-01 US US10/605,476 patent/US20040106958A1/en not_active Abandoned
AU2002240363A1 (en) 2002-08-28
US20040106958A1 (en) 2004-06-03
US6643546B2 (en) 2003-11-04
WO2002064205A3 (en) 2003-03-20
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