Abstract: A biogenerator, having a biomotor portion and a generator portion, suitable for use with, in and/or as an implantable device. A method of inducing an electromagnetic force in a coil using a biomotor.

Abstract: An implantable cardiac stimulation device provides long QT interval therapy for preventing abnormal ventricular activation-recovery time and ultimately ventricular arrhythmias. The device includes a sensing circuit that senses intracardiac activity of a heart and that generates electrical signals representing electrical activity of the heart. The device includes a physiologic sensor, such as body motion, or other diurnally varying sensor that reliably detects a diurnal state of the patient (i.e., not the QT interval itself). The device further includes a measuring circuit that measures a QT interval of the electrical signals, a control circuit that determines whether the QT interval is appropriate for the diurnal state, and a pulse generator that delivers pacing pulses to at least one chamber of the heart at a pacing rate when the QT Interval is pathologically too long.

Abstract: An implantable stimulation lead is disclosed for placement in the coronary sinus region and its associated coronary vessels overlying the left side of a patient's heart. The lead comprises at least one proximal connector; at least one tissue stimulation electrode; at least one conductor coupled between the at least one proximal connector and the at least one stimulation electrode; and a lead body including a housing of insulating material enclosing the at least one conductor, the lead body having a relatively flexible distal portion of, for example, silicone rubber, having a length corresponding to the coronary sinus region of the heart, and a stiffer proximal portion of, for example, polyurethane. A robust transition joint comprising telescoped sections of the distal and proximal portions of the lead body couples the two portions of the lead body. Also provided is a versatile lead delivery system including a stylet stop disposed within the distal portion of the lead body.

Abstract: A high voltage converter circuit for an implantable cardiac device. The circuit includes a plurality of transistors that are connected in parallel to a battery and the primary winding of a transformer. A switching element is connected to the circuit so as to periodically connect and disconnect the capacitors to the primary winding of the transformer to thereby induce the capacitors to be charged and periodically discharged across the transformer into charging capacitors. A circuit also preferably includes a disconnect circuit that will disconnect the capacitors from the battery during periods of non-use to inhibit unwanted dissipation of the battery's energy.

Abstract: A system and method for use in an implantable cardiac stimulation device permits automatic induction of a tachyarrhythmia of a heart to permit the performance of an electrophysiological test of the heart. A pulse generator repeatedly delivers a group of first and second sets of pacing pulses to a chamber of the heart. The pacing pulses are separated in time by interpulse intervals to overdrive pace a chamber of the heart. A processor, coupled to the pulse generator, varies the second set of interpulse intervals according to a predetermined protocol after each group of pacing pulses is delivered to the chamber of the heart. The successive groups of pacing pulses are delivered to the heart until the tachyarrhythmia is induced.

Abstract: An implantable cardiac stimulation device is described wherein a controller of the cardiac stimulation device controls selected functions of the device based on whether the patient is at rest and further based on whether the patient is prone to vagally-mediated arrhythmias. Functions of the device that may be controlled include, for example, a pacing base rate, an AV/PV delay, and a refractory period as well as overdrive pacing parameters and diagnostic data gathering parameters. In one example, if the patient is not prone to vagally-mediated arrhythmias, the base rate is lowered while the patient is at rest. Also, overdrive pacing parameters are set to be less aggressive. As such, the operation of the cardiac stimulation device is controlled to make it easier for the patient to rest while also reducing power consumption. However, if the patient is prone to vagally-mediated arrhythmias, the base rate is not lowered while the patient is at rest.

Abstract: An implantable medical device that includes a magnetic sensor circuit that senses the presence of an external magnetic field and provides a signal that is proportionate to the strength of the magnetic field. The implantable medical device uses the variable signal to determine whether a magnetic field is being applied that is selected to activate a preselected function. In one implementation, the preselected function is a power up sequence.

Abstract: An electrolytic capacitor with a polymeric housing in the form of a pocket defining a chamber, with an opening along a selected edge. The opening has opposed sides that are sealed together to provide a seam. A number of conductive layers are positioned within the chamber, and a feed-through conductor element has a first end electrically connected to the layers. An intermediate portion of the feed through passes through the seam, and an external portion extends from the housing. The housing may be vacuum formed high density polyethylene, with the feed-through contained in an elastomeric sleeve having a flattened cross section to be readily received in the seam, and to accommodate thermal expansion differences between the housing and the feedthrough. The device may be manufactured by inserting a stack of layers in the pocket, and thermally welding across the opening of the pocket on a single weld line.

Abstract: A congestive heart failure (CHF) mortality risk metric is automatically generated using an implantable medical device and, if it exceeds a predetermined threshold, a warning signal is issued indicating a significant risk of mortality due to CHF, perhaps necessitating more aggressive medical therapy. The CHF mortality risk metric is calculated based on a combination of estimated ventilatory response values and the slope of heart rate reserve as a function of predicted heart rates. Ventilatory response is estimated based on detected values of actual heart rate, arterial oxygen saturation, right ventricular O2, stroke volume, tidal volume, and respiration rate. Heart rate reserve values are derived from the actual heart rate along with patient age and rest heart rate. The predicted heart rates, which represent the heart rates the patient would achieve if healthy, are derived from activity sensor signals.

Abstract: A system is provided for backing up and synchronizing data stored within a set of programmers used for programming implantable cardiac stimulation devices such as pacemakers or implantable cardioverter defibrillators (ICDs). The data from the programmers that is backed up and synchronized includes programmer software, set up and configuration data, programming parameters, patient personal data, implantable device diagnostic data, and patient diagnostic data received from implanted devices. The implanted devices are classified into one or more groups and the programmer backup system merges and synchronizes data received from all programmers within a particular group. In other words, the backup system operates to ensure that each programmer within a particular group shares the same set up and configuration data, programmer software, patient contact data, and device diagnostic information.

Abstract: A system and method for use in an implantable cardiac stimulation device permits automatic induction of a tachyarrhythmia of a heart to permit the performance of an electrophysiological test of the heart. A pulse generator repeatedly delivers a group of first and second sets of pacing pulses to a chamber of the heart. The pacing pulses are separated in time by interpulse intervals to overdrive pace a chamber of the heart. A processor, coupled to the pulse generator, varies the second set of interpulse intervals according to a predetermined protocol after each group of pacing pulses is delivered to the chamber of the heart. The successive groups of pacing pulses are delivered to the heart until the tachyarrhythmia is induced.

Abstract: Increased myocardial voltage is achieved by configuring a shocking circuit of an ICD to generate a defibrillation pulse waveform having a positive phase with three distinct voltage peaks. The shocking circuit employs three capacitors along with switching circuitry for selectively discharging the capacitors so as to generate the defibrillation pulse waveform. More specifically, the switching circuitry generates a first step of the pulse waveform by discharging the capacitors while connected in parallel, then generates a second step of the pulse waveform by discharging the capacitors while the two of the three capacitors are connected in parallel and the third is connected in series, and finally generates a third step of the pulse waveform by discharging the capacitors while connected in series.

Abstract: Techniques are provided for programming a rate-responsive pacemaker or other implantable cardiac stimulation device capable of rate-responsive pacing. In one embodiment, an external programmer is configured to allow a physician to program the pacemaker with a smooth curvilinear rate-responsive pacing function having whatever shape the physician deems optimal for the patient, rather than being limited to generating a linear or bi-linear rate-responsive pacing functions as with many conventional techniques. The rate-responsive pacing function may specify, for example, pacing rates as a function of orthostatic sensor values, activity sensor values, minute ventilation sensor values, vasovagal syncope sensor values or paced depolarization integral sensor values. If several sensors are provided in the pacemaker, smooth rate-responsive pacing functions may be separately generated for use with each sensor.

Abstract: Byte-based and page-based techniques for performing error detection and correction in an implantable medical device with minimal overhead are provided. With the byte-based technique, single bit upset errors are detected by hardware during a read cycle. A software-based error correction system corrects single bit errors and detects multi-bit errors. By providing error detection in hardware and error correction in software, single bit errors can be immediately detected during read cycles such that a microcontroller of the implantable device is not at risk of receiving erroneous data. Yet the total error detection and correction overhead is kept low so that the size, cost, and longevity of the implantable device are not significantly and adversely affected. With the page-based technique, single bit upset errors are detected and corrected by software between therapy delivery cycles, such as between successive pacing cycles.

Abstract: An implantable cardiac stimulation device is equipped to differentiate fusion beats, intrinsic activity, and evoked responses. The device optionally responds to improve cardiac activity.

Abstract: To track significant changes in a hemodynamic variable of a living body regardless of measurement noise induced by cyclical functions of the body, the hemodynamic variable is measured at substantially the same instant during several cycles and the measured values compared to identify any statistically significant changes. The measurements may be discrete or continuous. The heart may be stimulated by a cardiac device during some of the cycles and parameters of the device such as the A-V delay of a pacemaker may be adjusted in accordance with the measured change in the hemodynamic variable, which may be, among others, blood pressure or blood volume.

Abstract: An implantable cardiac stimulation system capable of automatic capture verification is provided with an associated method for performing automatic testing functions using programmable, or automatically determined, AV delays. Automatic threshold testing and evoked response sensitivity testing performed at a user-specified AV delay setting, rather than a preset setting, allows assessment of automatic capture verification based on an AV delay relevant to daily system function. Further features of the present invention are an adjustable frequency with which automatic threshold tests are performed and an adjustable frequency with which threshold test results are stored in memory in a threshold record for better monitoring of lead stability or impending clinical problems. The frequency of performing threshold tests and the frequency of storing threshold test results may be varied according to the threshold stability.

Abstract: A method for monitoring the progression of the hemodynamic status of a patient by tracking autonomic tone. For example, the method may be applied to patients suffering from heart failure, diabetic neuropathy, cardiac ischemia, sleep apnea and hypertension. An implantable or other ambulatory monitor senses a pulse amplitude signal such as a vascular plethysmography signal. Variations of the signal amplitude on a scale greater than the heartbeat to heartbeat scale are indicative of variations in autonomic tone. A significant reduction in pulse amplitude and pulse amplitude variability are indicative of a heart failure exacerbation or other disease state change. This information may be used to warn the patient or healthcare providers of changes in the patient's condition warranting attention.

Abstract: A stylet unit for implanting a removable lead system for a cardiac stimulation device includes an elongated main body having an enlarged feature at the distal end of the main body with a rounded blunt tip end, a width greater than the width of the distal end of the main body, and a length greater than the width. A finger grip is provided at a proximal extremity of the elongated main body for manipulating the stylet unit. Lead system includes an elongated tubular lead body containing an elongated coil conductor with a plurality of coil windings defining a passageway extending the length of the coil conductor and having inner surfaces facing toward the passageway. The enlarged feature of the stylet is sufficiently long to assure that it advances along the passageway in slidable engagement with the inner surfaces of the coil conductor but without thrusting between adjoining coils.

Abstract: An implantable cardiac stimulation device controls dynamic atrial overdrive pacing based, in part, on sensor indicated rate. In one example, the stimulation device adjusts an overdrive pacing rate based on the sensor indicated rate by periodically decreasing the overdrive pacing rate by a programmed rate decrement whenever a difference between the current overdrive pacing rate and the sensor indicated rate falls outside predetermined acceptable range while the sensor indicated rate is decreasing. The overdrive pacing rate is decreased in this manner until a) the overdrive pacing rate falls below the base rate, rest rate or the sensor indicated rate or until b) an event triggers an increase in the overdrive pacing rate, such as the appearance of intrinsic breakthrough heart beats. The overdrive pacing rate is not decreased if the sensor indicated rate is increasing or stable.