Abstract: A universal cable connector includes a plurality of different sized connectors adapted to mate with the proximal connectors of different sized implantable stimulation leads. The cable connector attaches to a system analyzer and enables the system analyzer to interface with whatever implantable stimulation leads are connected to the connector block, thereby allowing the system analyzer to perform desired tests, such as threshold-determining tests, using the implanted stimulation leads. An adapter cable and clamp is also provided that allows an electrical connection of the proper polarity to be established between an implantable stimulation device, e.g., an implantable cardioverter-defibrillator (ICD), and the connector block while the implantable stimulation device is connected to a patient and is operating, thereby permitting the system analyzer to monitor the performance of the implantable stimulation device.

Abstract: An improved input protection circuit for use in a circuit for processing sensor signals from a piezoelectric patient activity sensor is provided. The input protection circuit includes a field-effect transistor to prevent the voltage at an input terminal of the processing circuit from rising beyond a first predetermined voltage or falling below a second predetermined voltage. The gate and drain terminals of the transistor are connected to a first of two input terminals of the processing circuit and the source and body terminals are connected to the second terminal. When the voltage at the first terminal rises or falls sufficiently, the transistor conducts current, thereby preventing the voltage from rising or falling further.

Abstract: A device for identifying abnormal conditions in a heart retrograde conduction and tachyarrhythmias in particular, includes a differentiating circuit electrically connected to a heart to be monitored in order to differentiate ECG signals from the heart. The differentiated signal is plotted against the ECG signal. The radius (distance from a point on the resulting curve from the origin of the plot axes) in the resulting curve is calculated in a calculator unit. The radius obtained is then compared with a threshold value in a comparator and a sequence for the progression of the radius in relation to the threshold value is obtained and compared with previously obtained sequences stored in a sequence analyzer.

Abstract: An implantable cardiac device for providing cardioversion and defibrillation therapies is provided, which forecasts time-to-therapy based on battery voltage degradation and provides an enhanced energy shock in the event a predetermined threshold time is reached. The device also monitors elapsed time-to-therapy to determine whether the predetermined threshold time is exceeded and sets the energy content of the therapeutic shock accordingly.

Abstract: In an implantable defibrillator electrode having a large surfaced electrode in the form of a netting, a spiral, or a fabric of electronically conductive material or having an intracardial electrode in the form of a coil of electronically conductive material, the electrode is completely embedded in a biocompatible, hydrophilic, electrolytically conductive polymer or is covered by such a polymer.

Abstract: An expanded screen current collector is provided with side edges coined inwardly to prevent sharp tines formed along the side edges from damaging adjacent components within the electrochemical cell. The expanded screen current collector is formed by cutting a thin flat sheet of current collector material, such as titanium or stainless steel, to have a height somewhat greater than a height required for use within the electrochemical cell. The current collector material is cut and expanded, then the side edges are coined inwardly by an amount sufficient to reduce the height of the resulting expanded screen current collector to a height appropriate for use within the electrochemical cell. An active cathode material, such as polycarbonmonoflouride, is coated onto side surfaces of the expanded screen current collector. An electrode structure employing the expanded screen current collector having the coined edges is also described.

Abstract: A periodic electrical lead integrity testing system is provided which periodically tests electrical leads used with an implantable cardiac stimulating device. The system is especially advantageous in multi-functional implantable cardiac stimulating devices. Lead integrity is evaluated by periodically comparing the impedance of the electrical leads to a reference impedance. A pass/fail algorithm is used to determine if electrical lead integrity has been compromised. The system improves the efficacy and safety of implantable cardiac stimulating devices by detecting electrical failures independent of the delivery of therapeutic shocks. The required circuitry adds only minimal complexity and cost to the implantable cardiac stimulating device.

Abstract: An implantable dual-chamber pacemaker programmed to operate primarily in an atrial tracking mode is provided, where the pacemaker includes an atrial rate smoothing filter for producing a filtered atrial rate from an intrinsic atrial rate, and where the pacemaker automatically switches its mode of operation from the atrial tracking mode to a non-atrial tracking mode in the event the filtered atrial rate exceeds a prescribed upper rate limit. The pacemaker switches from a primary set of operational parameter settings for the primary mode, to an alternate set of operational parameters for the alternate mode when the mode is switched from the primary mode to the alternate mode. The pacemaker also includes the capability of recording and storing mode switching events and data pertaining to the mode switching events.

Abstract: An improved implantable cardiac stimulating device that performs cardiac wall motion-based automatic capture verification system is provided. Pacing pulses of varying energy content are administered to a patient's heart, and the response of the patient's heart is sensed by a cardiac wall motion sensor. The cardiac wall motion sensor provides a signal which is analyzed to determine the patient's capture threshold, defined as the minimum amount of electrical stimulation required to evoke a cardiac contraction. The device then sets the amount of electrical stimulation at a level safely above the measured capture threshold. Capture verification may be performed at predetermined time intervals, on demand, or upon the occurrence of a significant cardiac event. Capture verification can also be performed on every pacing pulse delivered by the implantable cardiac stimulating device.

Abstract: A system and method for a pacemaker are provided, for using cardiac wall motion sensor signals to provide hemodynamically optimal pacing therapy to patient at rest, and for providing rate-responsive pacing therapy. The cardiac wall motion sensor signals are provided by an implantable lead that incorporates an accelerometer for measuring cardiac mechanical activity. The cardiac wall motion sensor signals are processed to derive cardiac wall velocity signals and cardiac wall displacement signals. The derived signals are further processed to derive physiologic parameters indicative of cardiac performance, including stroke volume, contractility, pre-ejection period, and ejection time. The physiological parameters, in turn, are used by the pacemaker to provide hemodynamically optimal pacing therapy at rest, and rate-responsive pacing therapy.

Abstract: A combined telemetry and magnetic field detector unit for use in a medical implant includes control logic, a magnetic field indicator, a telemetry circuit containing a number of switches, and a coil unit. The control logic is arranged to operate the switches such that switching between the telemetry function and the magnetic field detection function of the combined unit is achieved so the coil unit is utilized for transmission of telemetry signals to and from a programmer as well as for magnetic field detection. For magnetic field detection, the coil unit, which consists of multiple parts, is connected by the control logic such that the parts respectively form a primary side and a secondary side of a pulse transformer, with the magnetic field indicator connected by the control logic to the pulse transformer's secondary side.

Abstract: An implantable bipolar pacing lead having a bipolar active fixation electrode for use with a cardiac pacemaker. The bipolar active fixation electrode may include a pair of coaxial electrodes, separated by an intermediate insulator, formed into the shape of a helix. The bipolar electrode helix is preferably advanceable from a distal end of the bipolar pacing lead.

Abstract: An implantable pacing lead having a flexible insulative material injected into the passageway accommodating the electrical conductor(s) to encapsulate the conductor(s) for at least the portion of the lead body most subject to physical damage to in the lead body.

Abstract: A magnet position detector, particularly for implantable medical devices, has a resiliently supported coil, a current source delivering a current to the coil and a detecting device for detecting the movement of the coil in a magnetic field when fed with an electric current from the current source. The coil has a core with a non-linear B-H curve and the current source is a pulse source delivering current pulses with at least one positive and one negative side. The detecting device detects the movements of the coil in opposite directions respectively excited by differentiated signals respectively corresponding to the leading and trailing edges and permits the magnitudes of the respective, oppositely directed movements to be compared to each other, thereby indicating the position of a source of the magnetic field, relative to the coil, to be determined.

Abstract: Atrial lock interval pacing increases stroke volume and optimizes cardiac output by providing a modified P-wave tracking mode that tracks P-waves up to a maximum instantaneous tracking rate only for short periods of time, to provide a maximum instantaneous ventricular heart rate, yet limits the maximal mean (or average) ventricular rate over a longer period of time, to provide a safe target maximal average rate. Two main types or embodiments of modified P-wave tracking modes may be used. A first provides a sequence of timed intervals that begins upon sensing each P-wave. Such sequence may include, e.g.: (1) a PV interval; (2) a PVARP; (3) a Wenkebach interval; (4) an atrial lock interval; and (4) a P-track interval. P-waves are not tracked during the PV interval or PVARP. P-waves that occur during the Wenkebach or Atrial lock interval are tracked, but not in a conventional manner. P-waves that occur during the P-track interval are tracked in a conventional manner.

Abstract: An auxiliary body, for guiding a stylet into the stylet channel of an electrode cable in a medical electrode device whose proximal end is provided with a connector pin, has a first end provided with a cylindrical channel so the auxiliary body can be pushed onto the connector pin, a second end of the auxiliary body being provided with a cavity whose orifice is larger than the channel's opening. The cavity is connected to the channel and continuously narrows in such a way that the diameter of the channel end of the cavity is larger than the external diameter of the stylet and equal to or less than the diameter of the stylet channel.

Abstract: A pacing lead having a stylet introduced anti-inflammatory drug delivery element advanceable from the distal tip electrode. The element is preferably formed as a moldable biocompatible composite material. The element has a biocompatible matrix material which may be combined with drugs and therapeutic agents to deliver the drugs and agents by co-dissolution or diffusion to the point of either passive or active fixation. The drug delivery element may be rigid and serve to center the means, preferably a helix, for active fixation of the lead in the myocardium.

Abstract: A cardiac device that stores physiological sensor data from multiple sensors is provided. A patient may use a portable triggering device to cause the cardiac device to store the data when the patient experiences symptoms that appear to be due to an abnormal heart condition. Alternatively, the data may be stored when the cardiac device identifies an abnormal physiological condition. A physician may select which sensors are used to store the data and may also adjust the number of memory buffers in which the data is to be stored.

Abstract: A cathode material is fabricated using two binder compounds, polyethylene oxide and acrylic resin, which react during processing to achieve enhanced bonding. The cathode material is formed by dissolving acrylonitril resin within the acetonitrile solvent. Polyethylene oxide powder is added yielding a homogenous solution. A powder mix containing a carbon material, such as high surface area carbon powder, and an active cathode compound, such as polycarbon monoflouride, is added to the binder mixture to produce a slurry. In one embodiment, the slurry is heated to evaporate the solvents, yielding a thin flexible cathode material for mounting to an expanded screen current collector. In an alternative embodiment, the slurry is spread directly onto a foil current collector. The solvents thereafter evaporate from the slurry yielding excellent mechanical and electrical coupling between the active cathode compound and the current collector.

Abstract: A rate-responsive pacemaker measures a patient's level of activity and stores the results in an activity level histogram. The patient's average level of activity is maintained as a running average. Based on a prescribed base pacing rate, a prescribed maximum pacing rate, the average level of activity, and the measured levels of activity stored in the activity level histogram, the rate-responsive pacemaker automatically calculates the slope of the pacemaker transfer function. An activity deviation histogram is also maintained. Analysis of the activity deviation histogram allows the pacemaker to determine if the patient was usually inactive for an extended period of time, and to inhibit an automatic slope calculation under such conditions. If a patient desires to reach a prescribed target heart rate during exercise, the slope may be calculated using the target heart rate and a prescribed fraction of time each week that the patient devotes to exercise.