Abstract: A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the return of AV conduction (absence of AV block) is performed so that the AV delay can be returned to its long value as soon as possible. In one embodiment, the pacemaker "learns" the natural conduction time (AR interval) of the patient and thereafter uses such learned natural conduction time as a reference against which subsequently measured AR intervals are compared to better distinguish conducted ventricular contractions from ectopic, pathologic, or other nonconducted ventricular contractions (e.g., PVC's).
Type:
Grant
Filed:
May 12, 1997
Date of Patent:
September 29, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Jason A. Sholder, Paul A. Levine, Joseph J. Florio, Gene A. Bornzin
Abstract: A tachycardia eliminating apparatus includes a heartbeat detector which detects heartbeats in an input heart activity signal which delivers an output heartbeat signal indicating each detected heartbeat, a tachycardia detector coupled to the output of the heartbeat detector which generates a tachycardia indication signal in response to a detected tachycardia status of a heart as reflected in the heartbeat signal, and a respiratory system stimulator coupled to the output of the tachycardia detector and generating an output respiratory system stimulation signal for stimulating a respiratory system to achieve a stimulated breathing rate, with the ratio of the detected heartbeat rate to the stimulated breathing rate corresponding to a predetermined value.
Abstract: An active medical implant has a hermetically sealable capsule formed by a first part and a second closing part, the capsule being devised to hold a battery unit, an electronics unit, conductors for electrically connecting the battery to the electronics unit, and contacts arranged on the exterior of the capsule for connection to electrodes. The first part is made, at least in part, of a rolled, multi-layer composite sheet or plate, one layer of which is made of a biocompatible material and a second layer of which is made of a diffusion-proof material which is essentially resistant to corrosive chemicals. The two layers are joined by rolling, with the layer made of biocompatible material constituting the outer wall of the capsule.
Abstract: A capacitor for an implantable cardiac defibrillator with a housing defining a chamber. A plurality of flat, stacked, charge storing layers reside within the chamber. Each of the layers includes at least a first and a second electrically conductive sheets separated by a sheet in between. The first sheet is electrically connected to the housing, and the second sheet is electrically isolated from the housing. The layers each have a periphery having at least one alignment element, with the second sheet extending to the periphery along at least a portion of the alignment element, such that the layers may be engaged at the alignment element to register the layers during assembly.
Type:
Grant
Filed:
April 23, 1997
Date of Patent:
September 29, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Timothy A. Fayram, Benjamin D. Pless, Samuel Parler, William H. Elias, Scott McCall
Abstract: A power control system is described for use in an implantable cardioverter-defibrillator (ICD) having a low-power cell and a high-power cell. The power control system includes a fuzzy logic controller for gradually varying the relative amounts of energy drawn from the low- and high-power cells based upon a selected function to be performed by the ICD and upon various operational parameters of the ICD. Example functions include cardioversion therapy, cardiac defibrillation, cardiac pacing, cardiac monitoring and capacitor reformation. Example operational parameters include the remaining capacities of the low- and high-power cells, the amount of time since implant of the ICD, the number of defibrillation shocks already delivered, and the amount of pacing energy previously utilized.
Abstract: Methods and apparatus are provided for classifying cardiac events with an implantable cardiac device. Cardiac signals are stored in a buffer. When a significant cardiac event is confirmed, a corresponding segment of the stored cardiac signals is processed to generate a set of feature values. The set of feature values is compared to various sets of reference values. Each set of reference values preferably corresponds to a separate type of cardiac event, so that the cardiac device may classify the significant cardiac event by matching its set of feature values to a set of reference values.
Type:
Grant
Filed:
December 19, 1996
Date of Patent:
September 22, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Gene A. Bornzin, Alan B. Vogel, Ali Enayat Zadeh, Jonathan A. Kleks, Raymond J. Wilson
Abstract: A device for affixing an elongate contact pin on an electrode lead for connection to a medical implant, such as a heart stimulator, contains an elongate connector part with an opening at one end into which the contact pin can be inserted. The connector part has an affixing part which, when acted on by the contact pin, can move in the connector part's longitudinal direction between a contact pin-affixing position and a contact pin-release position.
Abstract: In a cardiomyoplasty system, a rate responsive implantable device is disclosed which controls the stimulation of both the heart and a myoplasty muscle. The metabolic demand is used as a rate response parameter and one or both of the heart and the muscle stimulation are increased with metabolic demand. Under certain conditions, for example, if the muscle is tired, its stimulation is maintained constant or reduced and the cardiac stimulation is used to compensate for increased metabolic demand.
Type:
Grant
Filed:
June 27, 1997
Date of Patent:
September 15, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Tuan Bui, Stuart B. McConchie, Peter A. Crosby, Gordon Jacobs
Abstract: An improved electrolytic capacitor is provided by producing an anode foil which has areas which are not subject to stress during manufacturing being highly etched and those areas which are subject to stress during manufacturing being lightly etched or not etched at all. The process of the invention provides an etch mask to cover during the etch process those portions of the anode foil which will be subjected to stress during construction of the capacitor. The highly etched areas, which are very brittle, provide increased capacitance and thus improved energy density. For layered or stacked capacitors, a weld tab is covered with the etch mask to allow connection of the anode layers. Additionally, strong edges may be maintained thereby reducing the possibility of cracking that would normally occur during the stamping and assembly operations.
Abstract: A stylet unit which can be introduced into a narrow, hollow, flexible component, such as a hollow electrode cable for a heart stimulator, to stiffen the component and bend its distal end section, is in the form of a double stylet combination with a flexible stylet shell and an internal stylet, movably arranged inside the shell, with a pre-curved distal end section, whose radius of curvature is on a first side of the stylet. In an area before the pre-curved end section, the stylet has a pre-shaped stylet section with a pre-shaped stylet section whose radius of curvature is on the side of the stylet opposite the first side on which the end section's radius of curvature lies.
Abstract: A storm door includes a frame with opposing side rails, top and bottom rails, and a center mullion. A kick plate is mounted between the center mullion and bottom rail, and a stationary screen sash and stationary window panel are mounted within the same vertical plane between the center mullion and top rail. A window sash is slidably mounted between a pair of jamb liners on the side rails between the center mullion and top rail, and spaced inwardly of the screen sash and stationary window panel. Counterbalance assemblies are connected to the window sash and located between the jamb liners and side rails to permit retention of the window sash at any position between an upper position contacting the top rail, and the lower position contacting the center mullion.
Abstract: A multi-mode rate-responsive pacemaker provides an accurate recommended replacement time (RRT) indicator which provides for full rate response performance until RRT is indicated without any decrease in longevity due to a premature triggering of RRT during rate response. An RRT trigger signal is generated whenever the battery voltage falls below a prescribed RRT threshold voltage. In one embodiment, a sustained battery voltage (determined based, e.g., on a long-term average of the battery voltage) that is less than the RRT threshold voltage must be detected before the RRT trigger signal is generated. In another embodiment, two RRT threshold voltages are used rather than one. A normal RRT threshold voltage is used when the pacer is not operating in a rate-responsive mode, and a lower RRT threshold voltage is used when the pacer is operating in a rate-responsive mode.
Abstract: An intracardiac blood flow velocity measurement device has a catheter adapted to be inserted through a blood vessel into the heart, at least two electrodes made of two different biocompatible materials mounted on the catheter at a detecting position which is located in a selected detecting area when the catheter is inserted into the heart for detecting blood flow velocity, with at least one of the electrodes being formed as a polarizable electrode and being disposed in the detecting position, and another of the electrodes being located on the catheter at an axially spaced distance from the polarizable electrode. Variation in an over-voltage or in a galvanic voltage is detected, and is used as a blood flow velocity signal.
Abstract: A pacemaker system includes an electrode lead having a distal tip electrode for supplying stimulation pulses to cardiac tissue and a ring electrode, the electrode lead being connected to a cardiac stimulator. A detector is contained in a stimulator housing and is connected to the electrode lead for detecting electrical cardiac activity between said ring electrode and said tip electrode.
Abstract: A capacitor and a method for making the capacitor using ultrasonic welding to join the cathode layers together are provided. The capacitor includes a housing defining a chamber with a step provided at an inner portion of the housing. A plurality of capacitor layers each including a cathode foil, a separator and an anode foil, each having alignment holes therein to precisely fit with alignment elements housing, is positioned within the chamber, with the alignment holes mating with the alignment elements. The housing is electrically conductive for connection to the cathode foils. Each cathode foil includes a cathode tab which extends away from the foil. The cathode tabs are pressed together and ultrasonically welded to the housing step abutting the periphery of the interior of the housing.
Abstract: In a pacing system, the pacing controller induces the leads to deliver an impedance measurement pulse to the right ventricle of the heart at at least a 15 ms interval during a window of time following detection of the R-wave or the delivery of a pacing pulse. The window of time corresponds to a period of ventricular ejection. The two or three measured impedance values are then used to determine an impedance slope that has a strong biological correlation to the contractility of the heart. The impedance slope is then used by the controller of the pacing system to adjust the delivery of pacing pulses for purposes such as maximizing contractility for a given AV delay, PV delay and pacing rate of pacing pulses.
Type:
Grant
Filed:
December 13, 1996
Date of Patent:
September 1, 1998
Assignee:
Pacesetter, Inc.
Inventors:
Euljoon Park, Kerry Bradley, Gene A. Bornzin, Joseph J. Florio
Abstract: An electrical connector jack has at least one disk-shaped element made of an elastic, conductive material which has one or more contact surfaces arranged to come into contact with the corresponding contact surfaces on a contact pin. A layer of insulating, elastic material is provided on both sides of the electrically conductive material. The disk-shaped element is elastically deformed by the contact pin when the pin is inserted into the connector jack, so the contact surfaces of the electrically conductive material and the insulating material are pressed against the corresponding contact surfaces on the contact pin, the contact surfaces being protectively sealed by the contact surfaces of the insulating material.
Abstract: Circuitry for reducing charge injection effects in an offset voltage compensation circuit for a switched-capacitor amplifier is provided. The switched-capacitor amplifier circuitry includes an operational amplifier having inverting and noninverting inputs and an output. An initialization circuit provides the inverting input with a voltage close to the offset voltage of the operational amplifier. A feedback circuit ensures that the voltage at the inverting input attains the offset voltage. In order to attenuate the effects of disengaging the feedback circuit after the input voltage attains the offset voltage, an attenuation circuit is provided. The attenuation circuit prevents the voltage at the inverting input from being affected by charge injection effects that arise when the feedback circuit is disengaged. The offset voltage compensation circuit may be used with switched-capacitor amplifiers configured as comparators, amplifiers, or successive approximation A/D converters.
Abstract: An implantable cardiac pacemaker having a housing containing pacing circuitry, a signal generator, and an electromagnetic transducer. The transducer has an electrical input line connected to the signal generator, and an electrical output line connected to the pacing circuitry. Consequently, a forcing motion on the transducer sends an electrical signal to the pacing circuitry, and operation of the signal generator causes the transducer to vibrate. The pacemaker may also include a disablement switch connected to the signal generator, with the signal generator operating in response to activation of the switch to cause the transducer to generate an audible warning tone while the pacemaker is disabled.