Source: http://www.google.es/patents/US20050267539?dq=flatulence
Timestamp: 2016-12-02 22:30:52
Document Index: 302286246

Matched Legal Cases: ['art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'art 16', 'arts 100']

Patente US20050267539 - System and method for ventricular pacing with AV interval modulation - Google PatentesBúsqueda Imágenes Maps Play YouTube Noticias Gmail Drive Más »Iniciar sesiónPatentesA pacing protocol is provided that reduces or minimizes ventricular pacing in favor of intrinsic conduction. When operating in a mode that provides ventricular pacing, a series of conduction checks are performed to determine if intrinsic conduction has returned. These conduction checks occur according...http://www.google.es/patents/US20050267539?utm_source=gb-gplus-sharePatente US20050267539 - System and method for ventricular pacing with AV interval modulation Búsqueda avanzada de patentesTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents. Número de publicaciónUS20050267539 A1Tipo de publicaciónSolicitud Número de solicitudUS 11/115,605 Fecha de publicación1 Dic 2005 Fecha de presentación27 Abr 2005 Fecha de prioridad21 Dic 2000También publicado comoCA2605620A1, EP1901801A1, EP1901801B1, US7738955, WO2006115836A1 Número de publicación11115605, 115605, US 2005/0267539 A1, US 2005/267539 A1, US 20050267539 A1, US 20050267539A1, US 2005267539 A1, US 2005267539A1, US-A1-20050267539, US-A1-2005267539, US2005/0267539A1, US2005/267539A1, US20050267539 A1, US20050267539A1, US2005267539 A1, US2005267539A1 InventoresRobert Betzold, Michael Sweeney Cesionario originalMedtronic, Inc.Exportar citaBiBTeX, EndNote, RefManCitas de patentes (99), Citada por (35), Clasificaciones (6), Eventos legales (3) Enlaces externos: USPTO, Cesión de USPTO, EspacenetSystem and method for ventricular pacing with AV interval modulation
US 20050267539 A1 Resumen
A pacing protocol is provided that reduces or minimizes ventricular pacing in favor of intrinsic conduction. When operating in a mode that provides ventricular pacing, a series of conduction checks are performed to determine if intrinsic conduction has returned. These conduction checks occur according to a predetermined pattern that generally includes longer intervals between subsequent attempts. The AV interval provided for dual chamber based pacing is modulated and generally moves from a larger value to a nominal value as the interval between unsuccessful conduction checks increases. Imágenes(14) Reclamaciones(18)
DETAILED DESCRIPTION OF THE DRAWINGS [0021] FIG. 1 is an illustration of an implantable medical device system adapted for use in accordance with the present invention. The medical device system shown in FIG. 1 includes an implantable medical device (“IMD”) 10, such as a pacemaker that has been implanted in a patient 12. It should be appreciated that the IMD 10 may be pacemaker or may also include cardioversion and/or defibrillation capabilities such as with an implantable cardioverter/defibrillator (ICD). The IMD 10 is housed within a hermetically sealed, biologically inert outer casing, which may itself be conductive so as to serve as an indifferent electrode in a pacing/sensing circuit. One or more pacemaker leads, collectively identified with reference numeral 14 in FIG. 1 are electrically coupled to the IMD 10 in a conventional manner and extend into the patient's heart 16 via a vein 18. Disposed generally near the distal end of leads 14 are one or more exposed conductive electrodes for receiving electrical cardiac signals and/or for delivering electrical pacing stimuli to heart 16. As will be appreciated by those of ordinary skill in the art, leads 14 may be implanted with its distal end situated in the atrium and/or ventricle of heart 16. [0022] The IMD 10 is illustrated in FIG. 1 as being implanted in a “pocket” typically defined below the pectoral muscle, with leads 14 extending through the vasculature into the heart. IMD 10 may alternatively be embodied in a subcutaneously implanted device either with electrodes that are remote from the heart 16 or including lead extending to an interior or exterior portion of the heart 16. [0023] Also depicted in FIG. 1 is an external programming unit 20 for non-invasive communication with implanted device 10 via uplink and downlink communication channels, to be hereinafter described in further detail. Associated with programming unit 20 is a programming head 22, in accordance with conventional medical device programming systems, for facilitating two-way communication between IMD 10 and programmer 20. In many known implantable device systems, a programming head such as that depicted in FIG. 1 is positioned proximate the patient's body over the implant site of the device (usually within 2- to 3-inches of skin contact), such that one or more antennae within the head can send RF signals to, and receive RF signals from, an antenna disposed within the hermetic enclosure of the implanted device or disposed within the connector block of the device, in accordance with common practice in the art. Alternatively or additionally, communication with programming unit 20 occurs over a greater distance through RF transmission with the incorporation of the appropriate transceiver in the IMD 10. FIG. 2 is a perspective view of one embodiment of programming unit 20 in accordance with the presently disclosed invention. [0024] FIG. 3 is a block diagram of one embodiment of the electronic circuitry that makes up pulse generator in IMD 10. A primary stimulation control circuit 25 controls the IMD's pacing and sensing functions. For example, stimulation control circuit 25 in FIG. 3 includes sense amplifier circuitry 24, stimulating pulse output circuitry 26, a crystal clock 28, a random-access memory and read-only memory (RAM/ROM) unit 30, and a central processing unit (CPU) 32. IMD 10 also includes internal communication circuit 34 so that it is capable communicating with external programmer/control unit 20. [0025] With continued reference to FIG. 3, IMD 10 is coupled at connector block assembly 11 to one or more leads 14 which, when implanted, extend transvenously between the implant site and the patient's heart 16. Electrically, the coupling of the conductors of leads and internal electrical components of pulse generator 10 may be facilitated by means of a lead interface circuit 19 which functions, in a multiplexer-like manner, to selectively and dynamically establish necessary connections between various conductors in leads 14, including, for example, atrial tip and ring electrode conductors ATIP and ARING and ventricular tip and ring electrode conductors VTIP and VRING, and individual electrical components of IMD 10. [0026] FIG. 4 is a ladder diagram illustrating IMD operation in an ADI/R mode with a Marker Channel® Diagram. With the help of the NBG Code, one familiar with the state of the art will be able to discern that the letter in the first position (A) means that the pacemaker (or other implanted device) will pace the atrium in the absence of an atrial sensed event. The second letter (D) implies that the pacemaker will sense in dual chambers, that is, both the atrial and ventricular chambers. The third letter (I) means that, upon sensing in either chamber, pacing will be inhibited in that specific chamber. The final letter, R, implies that the device may be rate responsive, that is, altering the atrial rate in response to an artificial sensor, such as a Piezo-electrical crystal, accelerometer, minute ventilation, etc. [0027] The operation in the ADI/R mode is depicted in the ladder diagram as follows. Atrial paced (or sensed) event 1 initiates a non-programmable, auto-adjusting (e.g., 100-150 millisecond) blanking period 4, followed by auto-adjusting atrial sensitivity (not shown). Sensing circuitry (see FIG. 3) determines if and when ventricular sensed event 2 has occurred. If detected, timing circuitry (see FIG. 3) initiates VA interval 9. Other timing, blanking periods, and refractory periods serve the following purposes. A programmable ventricular blanking period 8 prevents sensing of atrial pace 1 on the ventricular channel, sometimes termed “crosstalk.” Ventricular sensed event 2 starts a 120 millisecond post ventricular atrial blanking (PVAB) period 6, followed by auto-adjusting atrial sensitivity. PVAB 6 serves the purpose of preventing sensing of the R-wave or T-wave on the atrial channel, termed “far-field R-wave sensing.” Ventricular sensed event 2 also starts 100 millisecond ventricular blanking 7 followed by auto-adjusting ventricular sensitivity. This period serves the purpose of preventing sensing of the ventricular output pulse or the ventricular depolarization itself. Repolarization, or T-wave 3, follows R-wave 2. Ventricular event 2 detected by sensing circuitry (see FIG. 3) sends signal to timing circuitry to start VA interval 9, leading to the next atrial pacing cycle. [0028] Taking into account that this mode would be used primarily with Sick Sinus patients who have full or some degree of intact AV conduction, this type of operation as depicted for the ADI/R mode is something the clinician or physician would expect to occur. In the presence of intact AV conduction, even if it is prolonged, the pacemaker will maintain the ADI/R operation/mode. Sensed ventricular events would occur in the vast majority of cardiac cycles (that is, PQRST). FIG. 5 teaches what will occur should the patient develop transient AV block for one or a few cardiac cycles. [0029] FIG. 5 is a ladder diagram of the committed DDI/R operation in the event that the patient develops transient AV block. The purpose of the committed DDI/R operation is to maintain ventricular support in the presence of AV block. Briefly stated, the implanted device mode switches from the preferred ADI/R to the committed DDI/R for one cycle. [0030] The timing of the Committed DDI/R is as follows. In the DDI/R mode (third pacing cycle, labeled DDI/R), AV interval 5 is set to a short 80 milliseconds, following the Paced P-wave due to the absence of any sensed ventricular event between the second and third atrial paced events. The purpose of this short AV interval 5 is to suppress competition between ventricular pacing pulse culminating in paced R-wave 13 and any potential intrinsic R-wave with a delayed conduction from the previous paced atrial event. Assuming the presence of such an intrinsic R-wave, the timing of the ventricular output pulse would normally result in a ventricular pacing pulse falling into the absolute refractory period of the intrinsic, conducted R-wave, resulting in a psuedo-fusion beat (not shown). This operation is intended to prevent the onset of a ventricular tachycardia, should the ventricular pacing pulse fall into the relative refractory period of the ventricle, commonly called “pacing on T” phenomenon. [0031] Continuing with the timing in FIG. 5, paced R-wave 13 starts a 120 millisecond ventricular blanking period 7, followed by auto adjusting ventricular sensitivity (not shown). Paced R-wave 13 also starts a 120 millisecond PVAB 6 followed by auto adjusting atrial sensitivity (not shown). Assuming the transient AV block self-corrects and a sensed R-wave is detected, the preferred ADI/R resumes with the next paced or sensed P-wave, as is depicted in FIG. 4. [0032] FIG. 6 is a ladder diagram that depicts the pacing operation in one embodiment in the event that the patient develops AV block that persists for more than one cycle. Note that according to the preferred embodiment of the present invention, a single missed beat (i.e., no Vs) will not by itself cause a mode switch, particularly if relatively reliable AV conduction is present. Following the one-cycle mode switch to DDI/R, VA interval 9 times out, resulting in atrial paced event 1. A very long (e.g. 400 millisecond or up to 65% of the sensor-indicated AV interval) 17 is used in an attempt to promote AV conduction. If, however, AV interval 17 is not interrupted by a sensed, intrinsic R-wave, as is depicted in the first cycle (labeled ADI/R), the pacemaker immediately switches to the DDD/R mode. In the event that a sensed, intrinsic R-wave does occur, the device would revert to the ADI/R operation (not shown). The DDD/R operation, with the programmed AV interval, will be sustained until a sensed, intrinsic R-wave is detected. Periodic attempts to force restoration of the ADI/R operation are performed (as depicted in FIG. 7). Mode switching to the DDI/R mode will occur in the event that an atrial tachycardia is detected (see FIG. 8). [0033] FIG. 7 is a ladder diagram that depicts a periodic attempt to restore the ADI/R operation during sustained DDD/R operation. As mentioned, the DDD/R mode may become the sustained mode of operation in the event that the patient develops a prolonged AV block, such as might occur with rate-dependent AV block. In such cases, the device may be programmed to revert to ADI/R 1 after a programmable number of DDD/R cycles. Then, the device looks for a ventricular sensed event, e.g., at 23 following atrial pace 1. In the event that a sensed, intrinsic R-wave is detected, the ADI/R operation is immediately resumed. In the absence of a ventricular sensed event, the device continues to operate in the DDD/R mode, as indicated in the third cycle of FIG. 7. [0034] FIG. 8 is a ladder diagram of the pacing operation in the event that the patient develops an atrial tachycardia. A sick sinus patient often has episodes of atrial tachycardia, atrial flutter, or atrial fibrillation. During these episodes, the pacing operation must be such that the ventricular pacing rate will neither be synchronized to the fast atrial rate nor so slow as to cause symptoms. [0035] In FIG. 5 it was noted that the device, while operating in the ADI/R mode, can switch to the DDI/R mode. The DDI/R mode is well suited for pacing in the presence of an atrial tachycardia because it will not allow ventricular synchronization to a fast atrial rate nor will it allow the ventricular pacing rate to go below the programmed lower rate. Therefore, when an atrial tachycardia does occur, as shown in FIG. 8, fast atrial sensed events 27 without a conducted ventricular event have no effect on ventricular timing 9. Since there is no ventricular event, the operation immediately switches to the DDI/R mode. In the presence of an atrial tachycardia, the V-V interval 9 times out so that paced R-wave 8 will occur at the faster of the programmed lower rate or sensor-indicated rate in the DDI/R mode. The operation depicted in FIG. 8 will continue so long as the atrial tachycardia persists. Upon termination of the atrial tachycardia, the preferred ADI/R will resume as shown in FIG. 4 or 7, depending on how the heart recovers from the atrial tachyarrhythmia. If the atrial tachyarrhythmia terminates abruptly, the prompt restoration of the ADI/R mode takes place (see FIG. 4). If, however, the atrial tachyarrhythmia “cools down” slowly, there may be a period of DDD/R pacing with periodic attempts to restore ADI/R pacing as shown in FIG. 7. [0036] With general reference to FIG. 9, the ventricular pacing protocols include one or more of the following aspects. A mode supervisor is included and controls a wide range of operations related to mode changes. The mode supervisor may be a hardware, software, or firmware based module. One aspect of the mode supervisor monitoring a patient's atrial-ventricular status and intervening when necessary by invoking sustained mode-switches to conventional modes of pacing (i.e. DDD/R and DDI/R). The mode supervisor, in one embodiment, defines unreliable AV conduction according to a Wenckebach pattern with definition of a critical AV conduction acceptance ratio to discriminate between tolerable (or “relatively reliable”) AV conduction states from intolerable (or “relatively unreliable”) AV conduction states. For instance, an AV conduction acceptance ratio of 4:3 allows preferred ADI/R operation to persist as long as there are at least three ventricular events for every four physiologic atrial events. Should AV conduction falter such that the ratio of A to V events falls below the pre-defined acceptance ratio, a sustained switch to conventional DDD/R pacing will occur. Atrial events classified as non-physiologic (i.e. within the ARP) are not accounted for in the calculation of the A:V ratio. Thereby, inappropriate mode-switches to DDD/R are avoided in the presence of frequent non-conducted premature atrial contractions (PAC). [0037] Upon invoking DDD/R pacing in the presence of unreliable AV conduction, the mode supervisor immediately assumes the role of striving to restore ADI/R pacing. Since it is known that AV conduction disease typically progresses gradually with brief manifestations of high degree block expected in the early stages of disease progression, the mode supervisor will attempt to restore ADI/R operation following only a brief episode of new onset DDD/R pacing. Accordingly, the first reattempt to reveal intact AV conduction and to restore ADI/R pacing will occur only after a short period of time (e.g., one minute) of DDD/R pacing. Should ADI/R restoration fail, reattempts will occur at 2, 4, 8, 16 and 32 minutes and subsequently at 1, 2, 4, 8, 12 and 16 hours. Of course, other timing sequences may be used, both periodic and aperiodic (as well as local and remote clinician- or patient-activated atrial-based pacing initiation). [0038] As indicated, the IMD 10 will periodically attempt to return to an atrial based pacing mode. Similarly, as discussed below, frequent mode switching may lead to a sustained switch to a dual chamber mode with subsequent attempts to return to the atrial based mode made at given intervals. This process of deliberately attempting to return to an atrial based mode from a dual chamber based mode will be referred to herein generally as a “conduction check” or “conduction checking.” As noted in the embodiment above, the delay between each conduction check is progressive and increasing. In the example provided, attempts are made at 2, 4, 8, 16 and 32 minutes and then at 1, 2, 4, 8, 12 and 16 hour intervals. The particular values chosen and the number of attempts made with a given interval before moving to a larger interval can be varied. For example, a pattern such as 1, 1, 2, 2, 4, 4, 8, 8, 8, etc. may be utilized. [0039] In one embodiment of the present invention, the conduction check timing interval or progression is chosen to be non-anticipatory to the patient and/or to avoid circadian repetition. In general, the occasional absence of a ventricular depolarization will be unnoticed by the patient. However, frequent skipped beats might be perceptible. In such a case, if a conduction check were performed every minute or every three minutes (e.g., a relatively short interval) and the skipped beat was perceived by the patient, then the effects either physiological or psychological on the part of the patient may result in an unsuccessful conduction check. For example, the patient may become tense or stressed in anticipation, resulting in an elevated heart rate, and under the right circumstances, this may hinder the emergence of the underlying intrinsic conduction. Thus, the pattern is staggered and set at increasing intervals such the patient does not anticipate the conduction checks. Simply for illustration, perhaps the patient perceives the conduction check at two minutes and tenses. Four minutes later, the patient could still be tense; eight or sixteen minutes later, the patient has most likely lost focus on the issue and is relaxed making for a more effective conduction check. [0040] Assuming the conduction checks fail as progressively attempted, a maximum value is reached. In the above example, this value is 16 hours. That is, a conduction check is performed once every 16 hours. This value avoids circadian repetition. This simply means that the conduction check will not occur at the same time of day on a day-to-day basis. Consider a hypothetical patient that develops transient block that lasts sufficiently long to cause the conduction check interval to reach a maximum. Subsequently, intrinsic conduction resumes (or would in the absence of pacing), but block occurs during periods of sleep. If the maximum interval were 24 hours, the conduction check could continuously be attempted when the patient is asleep and thus, will fail. Such a situation will forgo the benefits of reduced ventricular pacing during the waking hours. By utilizing a maximum value of, e.g., 16 hours, the conduction check occurs at different times of the day and avoids the above-described scenario. Of course, intervals of other than 16 hours may be chosen to accomplish this as well. However, if the chosen interval is relatively close to 24 hours (e.g., 23 hours), then the conduction check could occur during the same circadian interval (e.g., night or sleeping hours) for many consecutive days. [0041] Thus, there are several factors in determining the timing of the conduction check progression. Initially, the checks are conducted frequently and over short durations. Assuming they fail, the intervals become longer until that maximum value is reached. This maximum value should be long enough such that it is not wasteful of resources; short enough such that patient benefit may be achieved relatively quickly if intrinsic conduction returns; staggered to avoid circadian repetition; and optionally selected such that the staggering avoids prolonged repetition in circadian cycles (e.g., the 23 hour example). [0042] FIG. 10 is a flowchart illustrating a process for performing conduction checks. While operating in an atrial based pacing mode according to a ventricular pacing protocol as described, the patient has a loss (200) of intrinsic conduction. While any given protocol may take several cycles to do so, after a period of time, the device will generally operate (210) in a dual chamber-pacing mode (e.g., DDD/R). The IMD 10 initiates (220) a conduction check interval (CCI) that is a timer, count of pacing cycles, or similar mechanism used to indicate when the device should attempt a conduction check. At the expiration (230) of the CCI, the IMD 10 will perform (240) the conduction check and determine if intrinsic conduction (250) is present. If intrinsic conduction is present, then the IMD 10 will operate in the atrial based pacing mode (260). [0043] If intrinsic conduction is not found (250), then the CCI is increased by some predetermined amount (270). The CCI is evaluated (280) and if it is less than or equal to a maximum value then the process returns to the initiation of the CCI (220). This will either be at the maximum value of the CCI or at the increased value of the CCI (270). In this manner, the CCI is progressively increased until a maximum value is reached. That is, if the CCI is greater than the maximum value (280) the CCI is changed to the maximum value and the process returns to (220). The amount of any given increase will be determined by the programmed pattern. As indicated, this may be 1, 2, 4, 8, 16, and 32 minutes and then 1, 2, 4, 8 and 16 hours with 16 hours being the maximum, in one embodiment. It should be appreciated that this progression is merely exemplary and more or fewer iterations may be utilized and values may be chosen accordingly. Furthermore, step (280) may be modified to include a counter such that multiple attempts may be made at a given value before increasing that value. [0044] FIG. 11 is a schematic timing diagram indicative of conduction checks occurring on a periodic basis. Bars 300 and 320 both indicate time, with 12 hour intervals specifically indicated. Arrows 310 indicates the pattern of conduction checks occurring at maximum values. In pattern “a” conduction check are occurring every 16 hours. Referring to time bar 320 and time of day indicator 330, it is readily apparent that the first conduction check occurs 1600 hours, which is in the afternoon. The next conduction check will occur at 0800 hours, which is in the morning and the following conduction check occurs at 2400 hours (Midnight), which represents a nighttime evaluation. If a 16-hour interval is maintained, this pattern will repeat and circadian differentiation is achieved. It should be appreciated that the loss of conduction is the initiating event and the actual times of the day eventually utilized will follow from this triggering event. [0045] Though not separately illustrated, this variation may be modified slightly to achieve further circadian variability. As indicated, with a 16 hour interval, the afternoon, morning, night progression will repeat, with conduction checks occurring at generally the same time (e.g., 1600, 0800, 2400). This set of conduction checks may be labeled as a complete circadian subset; that is, at least one check occurs during each of the three main daily time periods. After one circadian subset (or some predetermined number of subsets) an offset value may be introduced. The value chosen for the offset is not critical; one, two or three hours are exemplary, but any value (positive or negative) is acceptable. Thus, after the completion of the circadian subset (or the last in a predetermined number of circadian subsets), the offset value is added to the CCI value for one iteration. Thus, in the present example, the CCI maximum is sixteen hours; after one circadian subset, an offset value of one hour is added such that the next conduction check occurs 17 hours later, rather than 16. However, the offset value is not maintained and the subsequent conduction check occurs 16 hours later. Thus, an exemplary pattern might be 16-16-16-17-16-16, etc. Stated in another way, the conduction checks may occur at 1600 hours, 0800, hours, 2400 hours, 1700 hours, 0900, etc. In this manner, the circadian differentiation is always maintained between each subsequent conduction check and over time, further variation is imparted within each daily time period. [0046] A feedback mechanism may be employed wherein successful conduction checks are noted and the offset value may be employed to cause the conduction checks to occur during periods of time shown to be successful in the past. In other words, the IMD 10 may learn patient specific parameters that increase the likelihood of a successful conduction check and tailor the progression accordingly. [0047] Returning to FIG. 11, pattern “b” illustrates conduction checks occurring at 32 hour intervals. This maintains circadian variability, but with a longer interval more time elapses between subsequent conduction check but also between repetitive checking during any given time of day. Pattern “c” represents using a 16 hour interval for a period of time, and if unsuccessful increasing the maximum to 32 hours. While the number is non-limiting, conceptually if conduction checks continue to fail over a long period of time, the likelihood of success is lowered and less frequent conduction checks may be justified. Pattern “d” illustrates conduction checks occurring at a 20-hour interval. Thus, it is apparent that there are a variety of patterns that may be employed to achieve the desired temporal relationships. [0048] In one embodiment, the algorithm used to search for intact AV conduction and restore ADI/R is defined according to one of two options. The first option is to simply withhold a ventricular pace stimulation during DDD/R operation. In the event that a ventricular sense follows the physiologic atrial event during which ventricular pacing was withheld, ADI/R pacing is resumed. Otherwise, DDD/R pacing continues with subsequent reattempts according to a schedule or by way of manual activation (as specified above). The second option searches for intact AV conduction involves extending the AV delay during DDD/R pacing to a pre-designated AV conduction [search] interval (AVCI). For instance, with an AVCI of 400 ms, the AV delay is extended to 400 ms following a physiologic atrial event (sensed or paced). In the event that the AV interval is interrupted by a ventricular sense, thereby preempting the ventricular pace in DDD/R operation, the mode supervisor reverts to ADI/R operation. Otherwise, a ventricular pace is delivered upon the expiration of the AVCI interval and DDD/R operation resumes with reaftempts according to the schedule (or with manual activation) as described above. [0049] The mode supervisor monitors for repeated failed AV conduction tests at maximal test duration in one embodiment. So for example, if seven straight tests for AV conduction fail at 16-hour intervals, the mode supervisor can suspend AV conduction testing and the device can then remain in the DDD/R mode indefinitely. Alternatively, the present invention may continue to perform the conduction checks at the maximum interval. This allows for simple programming options. That is, even with complete heart block, the protocol operates beneficially to the patient and even if unlikely, a return of intrinsic conduction can be identified. [0050] As indicated, the AVCI may be extended from a nominal value (e.g., 150 ms) to some predetermined value, e.g., the above mentioned 400 ms. The nominal value is meant to indicate the traditionally programmed parameters that are used for standard operation in a mode such as DDD or DDDR. Typically, the nominal values are in the range of about 150 ms to about 180 ms. The extended AV interval provides a longer window during which intrinsic conduction may return and permit a return to an atrial based pacing mode. As the device remains in the dual chamber based pacing mode, ventricular pacing will be provided at the end of the interval as needed. [0051] FIG. 12 is a flowchart illustrating this overall process. For illustrative purposes, the device is assumed to be in an atrial based mode (500). As previously described, the device monitors for intrinsic conduction. If present (510), the device remains in the atrial based mode (500). If intrinsic conduction fails (510), then the device determines (520) whether a change to a dual chamber based pacing mode is required. If not, then the device again remains in the atrial based pacing mode (500). [0052] If appropriate, the device will operate (530 a) in the dual chamber based pacing mode at an appropriately determined AV interval (530 b). Periodically conduction checks are performed (540), with the result (550) determining whether the device operates in the dual chamber based pacing mode or atrial based pacing mode. [0053] FIG. 13 illustrates various options for determining the AV interval while operating in the dual chamber based pacing mode. There are three general categories that will be addressed. The first is for the initial cycle or first few cycles operated in the dual chamber based pacing mode (560). The second category (600) is during the period of time periodic or progressive conduction checks are being made at less than a maximum CCI. The third category is operation in the dual chamber based pacing mode while the CCI is at a maximum (680) or alternatively, when conduction checking has been terminated. [0054] In the first category (560), operation may include the cycle or cycles immediately following a lack of ventricular depolarization. Thus, in one embodiment, this first cycle in the dual chamber mode, the AV interval may be shorter (570) than a nominal value. For example, the shortened AV interval may be set to 80 ms. Alternatively, the AV interval may be set to the preprogrammed nominal value (580). In other embodiments, this first cycle may include a prolonged (e.g., longer than nominal) AV interval, such as the AVCI. The VPP selected will determine the appropriate dual chamber based pacing protocols for the first and/or the first few cycle in this mode and separation of this category is simply meant to illustrate that the following options with respect to setting the AV interval may be optionally applied in this category (560). [0055] The second category (600) refers to operation in a dual chamber based pacing mode while conduction checks are performed. As explained above, the interval between such conduction checks, e.g., the CCI, may vary and generally becomes longer with consecutive unsuccessful attempts, until a maximum interval is reached. While in this category, the AV interval may be set to the nominal value (610). It would certainly be possible for an intrinsic event to occur during the nominal AV interval; however, with this option the VPP is relying primarily upon the conduction checks themselves to determine if intrinsic conduction has returned. [0056] In another embodiment, the AV interval is set (620) to some maximum safe prolonged value or at least a fixed value that is greater than the nominal AV interval (e.g., the AVCI). Thus, for each cardiac cycle there is an improved if not maximized opportunity for intrinsic conduction to return while still providing ventricular pacing capabilities in a dual chamber based pacing mode. [0057] In another embodiment, the AV interval is modulated (630) as the conduction checks progress. In general, this means that the AV interval will be longer initially (absent any variations occurring during the first category (560)) and shorten as conduction checks progress and consecutively fail. The variation or modulation of the AV interval may be linked with the variations in the CCI. [0058] In one embodiment, the AV interval will taper (640) at a predetermined rate over the course of the conduction checks during the second category (600). Alternatively, the AV interval may be decreased as a step-function (650) with each change of the CCI. The taper or the step function may be based on predetermined time intervals or percentage based changes. Similarly, the AV interval may be adjusted as inversely proportional (660) to the CCI. [0059] Generally, the above variations apply most directly to consecutive unsuccessful conduction checks. If conduction checks are intermittently successful, the VPP may restart this process after each successful cardiac cycles or series of cycles. This may be entirely acceptable; however, if desired the AV interval may be set to a value closer to or equal to the nominal value if these intermittent events occur; the taper rate can be increased, the change for each step may be increased, and the proportionality (inverse) may be increased to more quickly lead to a nominal AV interval. [0060] In one embodiment, the percentage of time spent in an atrial based pacing mode is compared with the percentage of time spent in a dual chamber based pacing mode. If the percentage of time in the dual chamber based pacing mode exceeds a predetermined threshold, then any of the above actions are taken to decrease the AV interval either more rapidly or to set it at the nominal value. Alternatively, mechanisms to cause the device to vary the AV interval may include the number of mode switches over a given number of cardiac cycles or within a predetermined time frame. [0061] The AV interval, in one embodiment, will progressively be reduced as unsuccessful conduction checks occur. At some point, the CCI may reach a maximum value (680). As explained, conduction checks may cease or may occur at this maximum CCI (with or without variation). In any event, the AV interval will be set (690) to the nominal value. In addition to the conduction check that may occur at the maximum CCI, the AV interval may be extended for some number of cycles prior to this conduction check in order to facilitate the return of the intrinsic conduction. Periodic extensions of the AV interval may also serve as an alternative conduction check function that can be performed on a predetermined basis. [0062] The AV interval is set to the nominal value when the CCI is at a maximum as the device is in de-facto dual chamber operation and the nominal AV interval is set according to traditional and accepted pacing programming parameters. Alternatively, even when the CCI is at a maximum, the AV interval may be modulated (700) continually or intermittently. This would also serve as variations of a conduction check that may routinely be performed while maintaining ventricular pacing without subjecting the patient to an AV interval set at a maximized value on a continuous basis. [0063] The present invention may be implemented using executable software code and/or operational parameters saved by (or downloaded to) a medical device. Such a device may be disposed in vivo and later programmed according to the invention or may be programmed prior to implantation (e.g., using firmware that may be reprogrammed or modified using telemetry techniques and the like). However, the present invention is not limited to only firmware or hardware implementations; indeed, the present invention may be implemented in a hybrid or combined in any desirable manner using device programming techniques known and used in the art. [0064] It is to be understood that the above description is intended to be illustrative and, not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. Citas de patentes Patente citada Fecha de presentación Fecha de publicación Solicitante TítuloUS3057356 *22 Jul 19609 Oct 1962Wilson Greatbatch IncMedical cardiac pacemakerUS3253596 *27 May 196331 May 1966Cordis CorpCardiac pacerUS3478746 *12 May 196518 Nov 1969Medtronic IncCardiac implantable demand pacemakerUS3595242 *26 Mar 196927 Jul 1971American Optical CorpAtrial and ventricular demand pacerUS3648707 *16 Jul 196914 Mar 1972Medtronic IncMultimode cardiac paces with p-wave and r-wave sensing meansUS3747604 *6 Dic 197124 Jul 1973American Optical CorpAtrial and ventricular demand pacer with separate atrial and ventricular beat detectorsUS4312355 *11 Feb 198026 Ene 1982Medtronic B.V.Heart pacemakerUS4386610 *27 May 19807 Jun 1983Cordis CorporationVentricular-inhibited cardiac pacerUS4428378 *19 Nov 198131 Ene 1984Medtronic, Inc.Rate adaptive pacerUS4432632 *11 Ene 198221 Feb 1984Ricoh Company, Ltd.Apparatus for holding a recording member in the form of an endless belt in a recording system using the sameUS4476868 *8 Sep 198016 Oct 1984Medtronic, Inc.Body stimulator output circuitUS4523593 *15 Jun 198318 Jun 1985Medtronic, Inc.Constant A-A interval control for DVI and DDD cardiac pacemakersUS4577633 *28 Mar 198425 Mar 1986Medtronic, Inc.Rate scanning demand pacemaker and method for treatment of tachycardiaUS4587970 *22 Ene 198513 May 1986Telectronics N.V.Tachycardia reversion pacerUS4727877 *12 Ago 19861 Mar 1988Medtronic, Inc.Method and apparatus for low energy endocardial defibrillationUS4856523 *8 Oct 198715 Ago 1989Siemens-Pacesetter, Inc.Rate-responsive pacemaker with automatic mode switching and/or variable hysteresis rateUS4856524 *29 Ago 198815 Ago 1989Intermedics, Inc.A-V responsive rate adaptive pacemakerUS4880005 *23 May 198814 Nov 1989Intermedics, Inc.Pacemaker for detecting and terminating a tachycardiaUS4890617 *25 Nov 19872 Ene 1990Medtronic, Inc.Dual chamber activity responsive pacerUS4932046 *28 Jul 19895 Jun 1990First Data Resources Inc.Telephone programming system for automated callingUS4941471 *7 Sep 198817 Jul 1990Medtronic, Inc.Rate stabilization pacemakerUS4953551 *7 Ago 19894 Sep 1990Medtronic, Inc.Method of defibrillating a heartUS5052388 *22 Dic 19891 Oct 1991Medtronic, Inc.Method and apparatus for implementing activity sensing in a pulse generatorUS5085215 *20 Mar 19904 Feb 1992Telectronics Pacing Systems, Inc.Metabolic demand driven rate-responsive pacemakerUS5097832 *9 Mar 199024 Mar 1992Siemens-Pacesetter, Inc.System and method for preventing false pacemaker pvc responseUS5117824 *14 Nov 19902 Jun 1992Medtronic, Inc.Apparatus for monitoring electrical physiologic signalsUS5133350 *31 Ene 199128 Jul 1992Medtronic, Inc.Mode switching pacemakerUS5144950 *30 Ago 19908 Sep 1992Vitatron Medical B.V.Rate controlled pacemaker system using ar interval for rate controlUS5163427 *14 Nov 199017 Nov 1992Medtronic, Inc.Apparatus for delivering single and multiple cardioversion and defibrillation pulsesUS5188105 *14 Nov 199023 Feb 1993Medtronic, Inc.Apparatus and method for treating a tachyarrhythmiaUS5188117 *25 Oct 199123 Feb 1993Telectronics Pacing Systems, Inc.Notch filter noise rejection system in a cardiac control deviceUS5228438 *8 Oct 199120 Jul 1993Siemens Pacesetter, Inc.Implantable pacemaker including means and method of terminating a pacemaker-mediated tachycardia during rate adaptive pacingUS5273035 *3 Feb 199228 Dic 1993Medtronic, Inc.Dual chamber pacemaker with safe airial pacingUS5292340 *4 Ene 19938 Mar 1994Telectronics Pacing Systems, Inc.Physiologically-calibrated rate adaptive, dual chamber pacemakerUS5318594 *24 Dic 19917 Jun 1994Ela MedicalDDD type cardiac pacemaker having automatic operating mode switchingUS5334220 *13 Nov 19922 Ago 1994Siemens Pacesetter, Inc.Dual-chamber implantable pacemaker having an adaptive AV interval that prevents ventricular fusion beats and method of operating sameUS5345362 *29 Abr 19936 Sep 1994Medtronic, Inc.Portable computer apparatus with articulating display panelUS5372607 *23 Jun 199313 Dic 1994Medtronic, Inc.Method and apparatus for monitoring pacemaker intervalsUS5388586 *23 Dic 199314 Feb 1995Ela MedicalMethods and apparatus for sensing intracardiac signals for an inplantable cardiac pacemakerUS5417714 *11 May 199323 May 1995Pacesetter, Inc.DDI pacing with PVC-protected hysteresis and automatic AV interval adjustmentUS5522859 *22 Nov 19944 Jun 1996Medtronic, Inc.Sinus preference method and apparatus for cardiac pacemakersUS5540725 *11 Jul 199530 Jul 1996Pacesetter, Inc.Upper rate response for implantable pacemaker based on atrial lock interval pacingUS5584868 *27 Jul 199417 Dic 1996Cardiac Pacemakers, Inc.Cardiac stimulating apparatus and method for heart failure therapyUS5591214 *20 Nov 19957 Ene 1997Telectronics Pacing Systems, Inc.Pacemaker with automatic blanking period functionUS5626623 *30 Abr 19966 May 1997Medtronic, Inc.Method and apparatus for optimizing pacemaker AV delayUS5643326 *7 Dic 19951 Jul 1997Weiner; Henry L.Dual chamber pacing with atrial and ventricular independenceUS5674257 *5 Mar 19967 Oct 1997Medtronic, Inc.Pacemaker adapted to prefer underlying sinus rhythm over other rate responsive indicatorUS5725561 *9 Jun 199510 Mar 1998Medtronic, Inc.Method and apparatus for variable rate cardiac stimulationUS5741308 *15 May 199521 Abr 1998Pacesetter, Inc.Dual-chamber implantable pacemaker and method of operating same for automatically setting the pacemaker's AV interval as a function of a natural measured conduction timeUS5814077 *12 May 199729 Sep 1998Pacesetter, Inc.Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular supportUS5836974 *18 Dic 199617 Nov 1998Trustees Of Boston UniversityReal-time and adaptive method and system for suppressing a pathological non-chaotic rhythmUS5861007 *26 Feb 199719 Ene 1999Medtronic, Inc.Adaptive search AV and auto PVARP adaptation to same with additional benefitUS5873895 *3 Ago 199823 Feb 1999Pacesetter, Inc.Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular supportUS5954755 *6 Jun 199721 Sep 1999Medtronic, Inc.Facilitated atrial pacing threshold testingUS6058326 *29 Ago 19972 May 2000Medtronic, Inc.Method and apparatus for cardiac pacing in accordance with multiple pacing therapy featuresUS6122546 *3 Ago 199819 Sep 2000Pacesetter, Inc.Pacemaker and method of operating same that provides functional atrial cardiac pacing with ventricular supportUS6128529 *29 Ene 19973 Oct 2000Cardiac Pacemakers, Inc.Device and method providing pacing and anti-tachyarrhythmia therapiesUS6128534 *16 Jun 19983 Oct 2000Pacesetter, Inc.Implantable cardiac stimulation device and method for varying pacing parameters to mimic circadian cyclesUS6141586 *26 May 199831 Oct 2000Mower Family Chf Treatment Irrevocable TrustMethod and apparatus to allow cyclic pacing at an average rate just above the intrinsic heart rate so as to maximize inotropic pacing effects at minimal heart ratesUS6169918 *28 Oct 19982 Ene 2001Cardiac Pacemakers, Inc.Cardiac rhythm management system with cross-chamber soft blankingUS6198968 *15 Jun 19996 Mar 2001Intermedics Inc.Implantable cardiac stimulator with safe noise modeUS6256541 *17 Abr 19983 Jul 2001Cardiac Pacemakers, Inc.Endocardial lead having defibrillation and sensing electrodes with septal anchoringUS6321115 *3 Dic 199920 Nov 2001Pacesetter, Inc.Noise detection system and method for use in an implantable medical deviceUS6397105 *26 Abr 200028 May 2002Ela Medical, S.A.Active implantable medical device having a sophisticated automatic DDD/AAI mode switchingUS6434424 *22 Dic 199913 Ago 2002Medtronic, Inc.Regularization of ventricular rate during atrial tachyarrhythmiaUS6477416 *15 May 20005 Nov 2002Pacesetter, Inc.System and method for automatically and adaptively segmenting an atrial blanking periodUS6609028 *26 Abr 200119 Ago 2003Medtronic, Inc.PVC response-triggered blanking in a cardiac pacing systemUS6654337 *7 Ago 200125 Nov 2003Sony CorporationMagneto-optical recording medium having pit pitch greater than groove pitchUS6697673 *13 Sep 200124 Feb 2004Pacesetter, Inc.Implantable stimulation device and method for detecting capture of a heart chamber using cross-chamber conducted depolarizationUS6731980 *29 Oct 20014 May 2004Pacesetter, Inc.System and method for automatically setting a pre-ventricular atrial blanking periodUS6772005 *21 Dic 20003 Ago 2004Medtronic, Inc.Preferred ADI/R: a permanent pacing mode to eliminate ventricular pacing while maintaining backup supportUS6792307 *12 Sep 200114 Sep 2004Pacesetter, Inc.Implantable cardiac stimulation system and method for measuring atrioventricular conduction and adjusting atrioventricular hysteresisUS6873875 *29 Ago 200029 Mar 2005Cardiac Pacemakers, Inc.Implantable pulse generator and method having adjustable signal blankingUS6904315 *14 Dic 20007 Jun 2005Medtronic, Inc.Atrial aware VVI: a method for atrial synchronous ventricular (VDD/R) pacing using the subcutaneous electrode array and a standard pacing leadUS6925326 *4 Ene 20022 Ago 2005Pacesetter, Inc.Implantable cardiac stimulation system and method for measuring atrioventricular conduction and adjusting atrioventricular hystersisUS7027868 *30 Oct 200111 Abr 2006Medtronic, Inc.Capture management improvementsUS7123960 *22 Dic 200317 Oct 2006Cardiac Pacemakers, Inc.Method and system for delivering cardiac resynchronization therapy with variable atrio-ventricular delayUS7130683 *17 Sep 200231 Oct 2006Medtronic, Inc.Preferred ADI/R: a permanent pacing mode to eliminate ventricular pacing while maintaining back supportUS7218965 *12 Ene 200415 May 2007Medtronic, Inc.Preferred ADI/R: a permanent pacing mode to eliminate ventricular pacing while maintaining backup supportUS7245966 *21 May 200417 Jul 2007Medtronic, Inc.Ventricular event filtering for an implantable medical deviceUS7248924 *25 Oct 200424 Jul 2007Medtronic, Inc.Self limited rate responseUS7254441 *31 Mar 20047 Ago 2007Medtronic, Inc.Fully inhibited dual chamber pacing modeUS7283872 *21 Ene 200516 Oct 2007Medtronic, Inc.Implantable medical device with ventricular pacing protocolUS20020038482 *2 Feb 20004 Abr 2002Winfried MennickeUse of liquid dyestuff preparations for dyeing woodUS20020041700 *27 Jun 200111 Abr 2002Therbaud Lawrence R.Systems and methods with identity verification by comparison & interpretation of skin patterns such as fingerprintsUS20020082646 *21 Dic 200027 Jun 2002David CasavantPreferred ADI/R: a permanent pacing mode to eliminate ventricular pacing while maintaining backup supportUS20020128687 *17 May 200212 Sep 2002Cardiac Pacemakers, Inc.Multi-site hybrid hardware-based cardiac pacemakerUS20020138417 *12 Feb 200226 Sep 2002David LawrenceRisk management clearinghouseUS20030078627 *17 Sep 200224 Abr 2003Medtronic, Inc.Preferred ADI/R: a permanent pacing mode to eliminate ventricular pacing while maintaining backup supportUS20040010292 *20 Mar 200315 Ene 2004Amel AmblardAutomatic switching of DDD/AAI mode pacing for an active implantable medical device such as pacemaker, defibrillator and/or cardiovertorUS20040024694 *19 Jun 20035 Feb 2004David LawrenceBiometric risk managementUS20040078321 *18 Jun 200322 Abr 2004David LawrenceRisk management customer registryUS20040117316 *13 Sep 200317 Jun 2004Gillum Alben JosephMethod for detecting suspicious transactionsUS20050038482 *14 Ago 200317 Feb 2005Yonce David J.EMI detection for implantable medical devicesUS20050055059 *21 May 200410 Mar 2005Betzold Robert A.Ventricular event filtering for an implantable medical deviceUS20050096708 *31 Oct 20035 May 2005Seim Gary T.Atrial antitachycardia pacing managementUS20050177197 *31 Mar 200511 Ago 2005Medtronic, Inc.System and method for ventricular pacing with progressive conduction check intervalUS20070203523 *28 Feb 200630 Ago 2007Betzold Robert AImplantable medical device with adaptive operationUS20070213777 *15 May 200713 Sep 2007Betzold Robert AVentricular Event Filtering for an Implantable Medical Device* Citada por examinador Citada por Patente citante Fecha de presentación Fecha de publicación Solicitante TítuloUS728387221 Ene 200516 Oct 2007Medtronic, Inc.Implantable medical device with ventricular pacing protocolUS750264731 Jul 200610 Mar 2009Medtronic, Inc.Rate smoothing pacing modality with increased ventricular sensingUS751595831 Jul 20067 Abr 2009Medtronic, Inc.System and method for altering pacing modalityUS7565196 *15 Jun 200621 Jul 2009Medtronic, Inc.System and method for promoting intrinsic conduction through atrial timingUS768928131 Jul 200630 Mar 2010Medtronic, Inc.Pacing mode event classification with increased ventricular sensingUS771591431 Jul 200611 May 2010Medtronic, Inc.System and method for improving ventricular sensingUS772053731 Jul 200618 May 2010Medtronic, Inc.System and method for providing improved atrial pacing based on physiological needUS773895527 Abr 200515 Jun 2010Medtronic, Inc.System and method for ventricular pacing with AV interval modulationUS778335015 Jun 200624 Ago 2010Medtronic, Inc.System and method for promoting intrinsic conduction through atrial timing modification and calculation of timing parametersUS784880828 Feb 20067 Dic 2010Medtronic, Inc.System and method for delivery of cardiac pacing in a medical device in response to ischemiaUS785626931 Jul 200621 Dic 2010Medtronic, Inc.System and method for determining phsyiologic events during pacing mode operationUS786987215 Jun 200611 Ene 2011Medtronic, Inc.System and method for determining intrinsic AV interval timingUS789489815 Jun 200622 Feb 2011Medtronic, Inc.System and method for ventricular interval smoothing following a premature ventricular contractionUS790415718 Jun 20078 Mar 2011Medtronic, Inc.Self limited rate responseUS792534420 Ene 200612 Abr 2011Medtronic, Inc.System and method of using AV conduction timingUS803221611 Ene 20114 Oct 2011Medtronic, Inc.System and method for determining intrinsic AV interval timingUS8046063 *28 Feb 200625 Oct 2011Medtronic, Inc.Implantable medical device with adaptive operationUS80602026 Oct 200915 Nov 2011Medtronic, Inc.Ventricular event filtering for an implantable medical deviceUS822955826 Feb 201024 Jul 2012Medtronic, Inc.System and method for conditional biventricular pacingUS82295601 Abr 201124 Jul 2012Medtronic, Inc.System and method of using AV conduction timingUS824435426 Feb 201014 Ago 2012Medtronic, Inc.System and method for conditional biventricular pacingUS8260420 *11 Sep 20094 Sep 2012Biotronik Crm Patent AgMethod and device for processing cardiac signalsUS826575026 Feb 201011 Sep 2012Medtronic, Inc.System and method for conditional biventricular pacingUS8396553 *26 Feb 201012 Mar 2013Medtronic, Inc.System and method for conditional biventricular pacingUS856587318 Mar 201022 Oct 2013Medtronic, Inc.System and method for providing improved atrial pacing based on physiological needUS941522725 Oct 201116 Ago 2016Medtronic, Inc.Implantable medical device with adaptive operationUS20060167509 *21 Ene 200527 Jul 2006Willem BouteImplantable medical device with ventricular pacing protocolUS20070203524 *28 Feb 200630 Ago 2007Sheldon Todd JSystem and method for delivery of cardiac pacing in a medical device in response to ischemiaUS20100087886 *11 Sep 20098 Abr 2010Ulrich BuschMethod and device for processing cardiac signalsUS20100222839 *26 Feb 20102 Sep 2010Medtronic, Inc.System and method for conditional biventricular pacingEP2060298A127 Jul 200720 May 2009Medtronic, Inc.System and method for determining physiological events during pacing mode operationWO2007101033A1 *21 Feb 20077 Sep 2007Medtronic, Inc.Implantable medical device with adaptive operationWO2008006119A2 *25 Jul 200710 Ene 2008Medtronic, Inc.System and method for promoting instrinsic conduction through atrial timing modification and calculation of timing parametersWO2008006119A3 *25 Jul 200721 Feb 2008Medtronic IncSystem and method for promoting instrinsic conduction through atrial timing modification and calculation of timing parametersWO2008057639A1 *25 Jul 200715 May 2008Medtronic, Inc.System and method for promoting intrinsic conduction through atrial timing* Citada por examinadorClasificaciones Clasificación de EE.UU.607/9 Clasificación internacionalA61N1/368, A61N1/362 Clasificación cooperativaA61N1/368, A61N1/3682 Clasificación europeaA61N1/368Eventos legales FechaCódigoEventoDescripción8 Ago 2005ASAssignmentOwner name: MEDTRONIC, INC., MINNESOTAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BETZOLD, ROBERT A.;SWEENEY, MICHAEL O.;REEL/FRAME:016884/0634;SIGNING DATES FROM 20050328 TO 20050420Owner name: MEDTRONIC, INC.,MINNESOTAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BETZOLD, ROBERT A.;SWEENEY, MICHAEL O.;SIGNING DATES FROM 20050328 TO 20050420;REEL/FRAME:016884/063414 Abr 2009ASAssignmentOwner name: MEDTRONIC, INC., MINNESOTAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CASAVANT, DAVID A.;BELK, PAUL A.;MULLEN, THOMAS J.;AND OTHERS;REEL/FRAME:022540/0581;SIGNING DATES FROM 20090402 TO 20090407Owner name: MEDTRONIC, INC.,MINNESOTAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CASAVANT, DAVID A.;BELK, PAUL A.;MULLEN, THOMAS J.;AND OTHERS;SIGNING DATES FROM 20090402 TO 20090407;REEL/FRAME:022540/058116 Dic 2013FPAYFee paymentYear of fee payment: 4GirarImagen originalPágina principal de Google - Sitemap - Descargas masivas de USPTO - Política de privacidad - Condiciones de servicio - Acerca de Google Patentes - Enviar sugerenciasDatos proporcionados por IFI CLAIMS Patent Services