Abstract: In an implantable pacemaker or cardioversion/defibrillation device, the optimal electrodes for determining a pacing parameter are found. A test signal is sequentially switched and a response from each of the remaining electrodes is determined. From those responses an optimal electrode or electrode pair is selected and used for pacing parameter determination. If an optimal electrode (a pair) is not found, then a fall back pacing rate is used.

Abstract: An implantable cardiac device includes electrodes for sensing and pacing the heart, and optionally, defibrillation electrodes. The IECG sensed in the heart is processed to derive raw sense signals indicative of whether the sensed QRS complexes exceed a predetermined range. These signals are used to control the pacing pulses, and to detect high amplitude noise. This noise is differentiated from tachycardia.

Abstract: A surface mount component which can be mounted to a surface of a printed circuit board having a plurality of bonding pads connected to circuitry provided on the printed circuit board, which includes a puck having first and second wiring patterns, and a plurality of electrical connectors, a first set of electrical connectors being connected to the first wiring pattern, and a second set of the electrical connectors connected to the second wiring pattern. During the process of manufacturing a product which incorporates the printed circuit board, a production line worker can mount the puck to the surface of the printed circuit board in a selected one of a plurality of different possible positions, with at least selected ones of the first and second sets of electrical connectors being connected to respective ones of said bonding pads, to thereby achieve a selected one of a plurality of different selectable circuit configurations.

Abstract: The on time of a flyback converter is controlled without the need for a current-sensing resistor. Under one approach, an internal battery resistance R.sub.B is used as a substitute for the current-sensing resistor. The battery voltage V.sub.B decreases as a function of current drain from the battery due to the internal impedance. Charging control circuitry causes the on time to be terminated when the battery voltage V.sub.B falls below a predetermined reference voltage V.sub.R, where V.sub.R =V.sub.B1 -.DELTA..DELTA.V.sub.B. V.sub.B1 represents the battery voltage before charging is commenced, and .DELTA.V.sub.B represents the drop in battery voltage from V.sub.B1 when the battery current drain exceeds a predetermined maximum current. Under another approach, the charging control circuitry regulates the time out period t.sub.on1 =K/V.sub.B, where K is a predetermined constant, such that it is 10-15 percent longer than the on time t.sub.on.

Abstract: In a method and apparatus for suppressing electrode polarization components in a sensed cardiac signal, the sensed cardiac signal is added to either a differentiated or autocorrelated sensed cardiac signal and a difference is formed between the original sensed cardiac signal and the autocorrelated or differentiated signal, thereby extracting an evoked response component from the sensed cardiac signal, the evoked response component otherwise being overshadowed by the much higher-amplitude polarization component.

Abstract: An implantable cardiac stimulator has locking device for a pin-like conductor element of an electrode lead, the locking device having a helical coil which can assume a first, locking position, in which it grips the pin-like conductor element inserted into the coil to prevent longitudinal movement of pin-like conductor element, and a second, release position in which the pin-like conductor element is free to move in and out of the coil in relation to the coil's longitudinal axis. The first position is assumed when the coil is not influenced in its helix diameter increasing direction and the second position being assumed when the coil is influenced in its helix diameter increasing direction. The locking device also has a blocking component which only prevents the coil from rotating in the unwinding direction around its longitudinal axis in the locking device.

Abstract: An implantable pacemaker maintains a prescribed relationship between stimulation pulse amplitude and pulse width so as to provide an adequate safety factor above a stimulation threshold, while minimizing the current drain on the pacemaker battery. A series of stimulation pulse energies, each realized with a prescribed pulse amplitude and pulse width pair, are determined that may be used by the pacemaker as operating points. These operating points are numbered in order of increasing energy, and all adjustments of the pacing energy are made by selecting one of these operating points.

Abstract: A method and system for analyzing and displaying pacing event data of an implantable pacemaker using a programmer device comprises downloading the pacing event data from the implantable pacemaker to the programmer device and processing the pacing event data to produce an Event Record. The Event Record includes actual pacing event data obtained and stored by the implantable pacemaker over a prescribed period of time as well as various statistical information derived therefrom. Selected parametric data of the Event Record are then displayed to the physician or other user on a display screen of the programmer device in a simple and comprehensible graphical format.

Abstract: In a magnetic field detector as well as in a combined telemetry and magnetic field detector unit in a medical implant, a magnetic field sensor with a coil and a diode are employed for determining the presence of a magnetic field. For making such a determination, the coil is charged by a source of voltage for a defined period of time, the time for the discharge of the coil through the diode depending on whether a magnetic field is present. A detection signal indicating the presence of a magnetic field is generated if the discharge time is less than a defined time threshold value.

Abstract: An electrophysiology diagnostic device generating a high voltage (HV) pulse of a predetermined shape, which device is electrically connected to a patient's heart, i.e., a load resistance and which device includes a microprocessor and a load resistance measuring device, includes a variable capacitance emulation (VCE) circuit. The VCE circuit, which is capable of emulating a selected capacitance C, includes a fixed capacitor C.sub.0, and first and second branch circuits including respective resistors R.sub.1 and R.sub.2 and corresponding switching elements, connected in parallel with the load resistance R.sub.L. According to one aspect of the VCE circuit, the selected capacitance C satisfies the expression C=?(R.sub.L .parallel.R.sub.eff)*C.sub.0 !/R.sub.L, where R.sub.eff is an effective resistance value produced by pulse width modulation control of at least one of the resistors R.sub.1 and R.sub.2 using corresponding switch elements.

Abstract: A system for simulating the activity of the heart includes a computer controlled heart model for generating and displaying simulated electrogram signals. To accomplish this task, the simulation system includes various hardware components and software designed to realize a heart model and generate electrogram display data. Based on the recognition that groups of cells (tissue groups) of the heart can be selected such that the electrical characteristics of the tissue group, as a whole, resembles the simple electronic characteristics of an individual cell, the model is designed to simulate the electrical activities and interaction of multiple tissue groups. With this approach, each tissue group is associated with a software controlled state machine that changes states in response to stimulation signals from other tissue groups, internal or external sources, or timer expirations.

Abstract: A cardiomyoplastic muscle is stimulated electronically using a closed loop control system. As part of the system, a signal sensed the muscle which is characteristic of its condition. If this signal indicates an abnormal condition, then the stimulation of the muscle is modified accordingly.

Abstract: An electrode contact device for medical application as a contact device at one end of an electrically insulated conductor or electrode cable for a cardiac pacemaker, has a rotationally symmetrical main body of ceramic material with at least one contact portion of electrically conductive material being formed on the exterior of the main body, and which is in electrical communication with a conductor which can be attached to the contact device. The electrically conductive contact portions on the exterior of the ceramic main body are radially and/or axialy separated from each other and at leaest one of these contact portions is formed by a thin layer of material produced by application of electrically conductive material on a surface area of the main body.

Abstract: A cardiac electrotherapy device comprises an elongated elastic lead body having a distal electrode adapted to be connected to the heart; lead body including a sensor portion at a location adapted to undergo deformations responsive to heart muscles contractions when the lead body is connected to the heart. The lead body forms a high frequency transmission line, having two conductors which are provided with terminals at the proximal end of the lead and which are adapted to transmit high frequency signals from the terminals to the sensor portion of the lead and vice versa. The sensor portion varies its high frequency electric parameters when being subjected to said deformations.

Abstract: A lead system for use with an implantable cardioverter/defibrillator is disclosed. The lead system includes a fixation hook positioned approximately half-way between the distal tip of the lead and the tricuspid valve. The distal tip of the lead is positioned at the apex of the right ventricle and may or may not be secured there by a second fixation means such as a screw tip or tines. The fixation hook allows the defibrillation electrode to be accurately positioned by the patient's surgeon and maintained in contact with the septum wall of the patient's heart. By providing such intimate contact between the defibrillation electrode and the septum wall, defibrillation thresholds are reduced.

Abstract: In a medical therapy apparatus, such as a pacemaker, a physiological function which is to be artificially controlled by therapy administration has a natural variability associated therewith. The medical therapy apparatus generates a basic therapy which would otherwise be supplied to the subject in the absence of such natural variability. The medical therapy apparatus further includes a non-linear oscillator which emits a chaotic output, the chaotic output of the non-linear oscillator being matched to the variability of the physiological function in order to produce a variability adjustment. The basic therapy is combined with the variability adjustment and a variability-adjusted therapy is then administered to the subject.

Abstract: A rate responsive pacemaker generates an initial histogram of a rate control parameter. The histogram is then normalized to conform to preselected characteristics. For example. By linearizing a portion of the histogram. The new histogram is used to map the parameter into a corresponding pacing rate.

Abstract: A dual-chamber implantable pacemaker configured to operate in the DDD or DDDR mode automatically sets its AV (or PV) interval to an amount that is equal to the natural conduction time of a patient plus or minus a small prescribed amount, e.g., 1-100 msec. When set to a value that is less than the natural conduction time, preemptive ventricular pacing thus occurs at a time in the patient's cardiac cycle that is near when a natural ventricular contraction (an R-wave) would occur. Such ventricular pacing causes a mechanical contraction sequence of the patient's heart that differs from the natural contraction sequence following a natural depolarization, resulting in improved cardiac output. The pacemaker includes a pulse generator that generates ventricular stimulation pulses (V-pulses) at the conclusion of a pacemaker-defined AV (or PV) interval if no natural ventricular activity (an R-wave) is sensed during such AV (or PV) interval.

Abstract: A system for providing cardiac stimulation to a patient includes an implantable stimulation device with a microprocessor and a separate programmer. The stimulation device includes a memory holding substantially all the information necessary to program the device, including device specific information such as various modes of operations, the operational parameters associated with each mode, as well as patient specific information. All this information is transferred to the programmer for display and for generating a program. The program is than transferred back to the device for operating its microprocessor. In this manner, any programmer can be used to generate a program for any cardiac stimulation device without the need for providing specific programming information to the programmer for each specific device.