Abstract: Multi-chamber cardiac pacing systems for providing multi-site pacing to at least one of the right and left atria and then synchronously to the right and left ventricles in a triggered pacing sequence while providing for recharge of the output capacitors of each output amplifier in the shortest time. The recharge operations of the present invention come into play when bi-chamber pacing is invoked to deliver right and left heart chamber pacing pulses that are separated by a triggered pacing delay that overlaps, i.e., is shorter than, the recharge time period. In a truncated recharge mode, the first pacing pulse is delivered through the first pacing path, and the recharging of the first pacing path is commenced for the duration of the triggered pacing delay. Then, the second pacing pulse is delivered, and the second pacing path is recharged for a second recharge period. The recharging of the first pacing path is conducted simultaneously with or after completion of the second recharge period.

Abstract: Power consumption in medical devices is reduced through the operation of circuits at clock speeds of lower levels to adequately complete desired functions during predetermined time periods (e.g., blanking interval, upper rate interval, etc.) just-in-time prior to subsequent required functional processes; by providing supply voltages tailored for various circuits of an integrated circuit; by operating two or more circuits of an integrated circuit at different clock frequencies; by changing the supply voltage level “on the fly” as required by specific circuit timing functions required for various circuitry based on clock frequencies used to control operation of such circuitry; and/or by tailoring back gate bias or adjusting back gate bias “on the fly” for circuits based on the supply voltage level applied to the circuits.

Abstract: The lead configuration enhances the sensing characteristics of the lead and provides for stable location of the electrodes in the coronary sinus. The J-shaped bend in the distal portion of the lead body spaces the distal tip of the lead body less than about 0.9 inches laterally from the portion of the lead body that is proximal to the bend. The tip of the lead body is provided with a pacing/sensing electrode and the curved portion of the J-shaped bend carries an elongated coil electrode that serves as an indifferent electrode for pacing and sensing. For left atrial pacing, the lead tip electrode is located adjacent the wall of the coronary sinus closest to the left atrium, and the indifferent electrode is located adjacent the opposite wall of the coronary sinus, closer to the left ventricle.

Abstract: An implantable medical device (IMD) coupled with leads extending to body tissue providing storage of lead related data, monitoring of lead functional status, and indication of lead integrity to the clinician. A lead status monitor (LSM) processes lead related data in a system self test mode and provides a lead status report that identifies and declares conductor/connector issues, insulation issues, and electrode/tissue interface issues indicative of suspected lead related condition mechanisms for each lead employed in the IMD. The LSM operates employing a set of LSM rules that process measured lead impedance values and loss of capture (LOC) values. In a pacing system, particular LSM rules are defined that process periodically determined, pacing pulse characteristic at LOC and bipolar and unipolar lead impedance values that are measured periodically. The lead impedance values are compared to upper and lower limits or trip points of a normal impedance range.

Abstract: A pacemaker and a method of employing a pacemaker to pace a patient's heart. The method of operation of the pacemaker includes defining a post ventricular atrial refractory period having a first duration responsive to ventricular events, during which period the pacemaker does not initiate timing of an AV delay responsive to detected atrial depolarizations and in response to events which a may disrupt AV synchrony, such as PVC's, mode changes and the like, defining a post ventricular atrial refractory period having a second duration less than the first duration. The shortened post ventricular atrial refractory period remains in effect only temporarily, for example for one cardiac cycle, and may be initiated on a ventricular event which is the disrupting event or immediately follows the disrupting event, or may be initiated following a later ventricular event.

Abstract: An introducer or guide catheter for directing an implantable medical device such as a lead or catheter to a desired location within a patient's body. In one embodiment of the invention, the introducer comprises a two-lumen tube. A first lumen is configured to receive the implantable medical device that is to be introduced. A second lumen is provided to receive an insertable, elongated guiding member such as a stylet, which may be shapable in various orientations, and which may be used to alter the configuration of the introducer. The second lumen may be provided with an internal coil or other tubular reinforcement member to prevent perforation of this lumen by the guiding member when the introducer is in the patient's body. In order to facilitate removal of the introducer over an implantable medical device having a connector or fitting that is larger than the internal diameter of the first lumen, the introducer may be adapted to be slit or split along its length.

Abstract: An implantable antiarrhythmia device which detects and classifies arrhythmias of the human heart, and delivers appropriate therapy. The device employs a method of arrhythmia classification based on a set of prioritized rules, each of the rules defining a plurality of criteria based upon characteristics of sensed depolarizations of heart tissue, each rule being met when the criteria associated with the rule are met. Some rules, when met, trigger delivery of antiarrhythmia therapy. Other rules, when met, inhibit delivery of antiarrhythmia therapy. The rules may be met simultaneously, and if so, the highest priority rule governs the behavior of the device.

Abstract: A system and method is provided to view an anatomical structure such as a blood vessel in high contrast with its surrounding tissue. The system and method may be used to produce an image of an anatomical structure using reflected electromagnetic radiation singularly scattered from target tissue. The system and method may also provide same-side illumination and detection of reflected electromagnetic radiation in a convenient integral imaging device. The system and method may also provide helmet mounted imaging technology in a single integral helmet which allows the wearer to view an anatomical structure located within a patient such that the image is continuously oriented according to the orientation of the helmet wearer's head. The system and method may also be used in the performance of venipuncture. The system and method may provide for improved contrast between any anatomical structure and its surrounding tissue for use in any imaging system.

Abstract: An implantable medical device for delivering a medical therapy or for monitoring physiologic parameters. The device is provided with a hermetic housing containing a transceiver coupled to an antenna located outside the housing by means of a feedthrough, mounted to the housing and coupled to the transceiver. The antenna takes the form of a length of conductor, coupled to the feedthrough. In some embodiments the antenna is an insulated stranded conductor coupled to the feedthrough by means of a metallic loading tab. In other embodiments the antenna includes a length of conductor encased in a dielectric, extending from the feedthrough, and a coaxial shield coupled to the housing and extending along only a portion of the length of conductor.

Abstract: A signal processor operates on a microprocessor or state machine based system to ensure that the central processing unit (CPU) and pulse generator (PG) have finished their instructions before allowing a new transition on the system master clock. The CPU and PG contain circuitry which allows them to indicate when they are busy. These signals are fed to the signal processor to indicate when the CPU and PG are ready to start another instruction. The signal processor functions to prevent a noise glitch on the system clock from causing another operation to start before the one in process has finished. The output of the signal processor becomes the master clock signal used by the system.

Abstract: An implantable medical device (IMD) capable of monitoring physiologic data, distinguishing relatively noisy and noise free physiologic data, and recording noisy and relatively noise free segments of physiologic data in separate memory registers of a limited memory for retrieval and analysis at a later time. Preferably the physiologic data comprises the sampled EGM of the heart detected from sense electrode pairs that are implanted in the patient at sites where extraneous electrical noise, e.g., electromyographic signals, are also capable of being detected. The sense electrode pairs can constitute one or both sense electrodes located on or adjacent to the atrial and/or ventricular heart chambers and coupled to the IMD by a lead body or sense electrode pairs that are located remotely from the heart, e.g. at a subcutaneous implantation site of the IMD.

Abstract: An atrial lead system and a method of employing it to provide single electrode bi-atrial pacing. The system includes an atrial pacing lead having electrode located on a distal portion thereof and a guide catheter having a longitudinal lumen and a lateral aperture open to the longitudinal lumen of the catheter proximal to a distal end of the catheter through which the distal portion of the lead may be advanced. The electrode is preferably an active fixation electrode or is associated with an active fixation device. The system is employed by first advancing the guide catheter to the ostium of a patient's coronary sinus and inserting the distal end of the guide catheter into the coronary sinus such that the lateral aperture of the catheter is located in the patient's right atrium. The atrial pacing lead is then advanced through the lumen of the guide catheter such that the electrode exits the lateral aperture of the guide catheter and the electrode is affixed to the tissue of the atrial septum.

Abstract: An introducer of the type employing an elongated introducer sleeve for receiving a catheter or lead body and an associated hemostasis clamp including a clamping member configured to engage the outer circumference of the introducer sleeve. The clamp is provided with a mechanism for maintaining the clamping member in engagement with said outer circumference of the sleeve to compress the outer circumference of the sleeve around a catheter or lead body inserted therethrough. In some embodiments the clamp takes the form of a hinged clamp provided with two jaws each having a recess adapted to engage a portion of the other circumference of the introducer sleeve. In other embodiments the clamp takes the form of interacting ramped members. The clamp is maintained in engagement with the sleeve either resiliently or by means of a latch.

Abstract: A cardiac pacing lead for pacing the atria and a method of its use. The lead is provided with a mechanism for maintaining an atrial pacing electrode adjacent stimulable tissue in a patient's superior vena cava and an additional electrode locatable in the right ventricle or elsewhere when the atrial electrode is so located One such mechanism for maintaing the atrial electrode's position may be a lead body displaying pre-formed laterally extending curves sized to span a patient's superior vena cava, with the atrial electrode located thereon.

Abstract: A method and apparatus for determining the occurrence of a mis-location of an atrial electrode in a cardiac stimulation device having an atrial pulse generator coupled with the atrial electrode and a ventricular sense amplifier coupled to a ventricular electrode. The device paces the atrium in a first pacing mode employing atrial pacing pulses at a first energy level and in a test mode employs higher energy atrial pacing pulses. In the test mode the device measures PR intervals between atrial pacing pulses following sensed ventricular depolarizations and determines that the atrial electrode is mis-located responsive to occurrence of a threshold number of short PR intervals or that the atrial electrode is appropriately located responsive to occurrence of a threshold number of long PR intervals. Operation of the device in the test mode may be pre-conditioned on an absence of atrial tachyarrhythmia.

Abstract: A guidewire placed lead employing a seal at its distal end in order to prevent entry of body fluid into the lead. The seal is particularly designed to allow radial expansion of the outer circumference of the seal due to passage of the guidewire through the seal, reducing the force required to pass the guidewire through the seal, while retaining a good sealing characteristics. The seal may extend a distance distally from the tip electrode, and include a hollow, resilient, cup-shaped seal member, configured so that the seal can readily expand radially as the guidewire passes through it. Alternatively, the seal may be located within the body of the electrode and the electrode configured so that it may be radially or laterally expanded, also allowing radial expansion of the seal during passage of the guidewire. In this case, the electrode may be rendered expandable by means of one or more slits arranged along the electrode body, extending from a point proximal to the guidewire seal.

Abstract: A high energy density capacitor comprising an organic polymeric dielectric material having a dielectric constant of at least about 7; wherein the organic polymeric dielectric material comprises polymerized alkyl (alpha-substituted)acrylate monomers having at least one dipole group; wherein when the monomers are polymerized, the dipole group is attached to the main polymeric chain through a heteroatom-containing linking group.

Abstract: A cardiac pacemaker and a method of its use. The pacemaker paces a patient's heart in a tachyarrhythmia prevention pacing mode for an extended time period, defines a metric of success of the tachyarrhythmia prevention pacing mode, monitors the metric over the extended time period and, responsive to the monitored metric, adjusts the tachyarrhythmia prevention pacing mode. Adjustment of the tachyarrhythmia prevention pacing mode may take the form of pacing the patient's heart with a different set of electrodes, pacing the patient's heart with a different tachyarrhythmia prevention pacing mode and/or terminating operation of the tachyarrhythmia prevention pacing mode.

Abstract: An arrangement for introducing and implanting the electrode(s) of an endocardial implantable cardiac lead at a cardiac implantation site within a heart chamber or vessel. An elongated guide body formed of flexible material and extending between a guide body proximal end and a guide body distal end is advanced transvenously to position the guide body distal end in relation to the cardiac implantation site. A guide body tracking mechanism is coupled with the lead distal end for receiving and slidingly engaging the guide body to allow the cardiac lead to be advanced along the guide body until the electrode is positioned at the cardiac implantation site. A pusher mechanism formed of an elongated pusher body of flexible material extends between a pusher body proximal end and a pusher body distal end and has a cardiac lead engaging mechanism for engaging the cardiac lead at or adjacent the distal lead end.

Abstract: A lead and a lead system for dispersion of a cardioversion/defibrillation electrode formed of one or more small diameter defibrillation electrodes in a heart chamber and for attaching a pace/sense electrode in contact with the heart. The small diameter defibrillation electrode or electrodes extend distally from the distal end of the lead body. If multiple electrodes are employed, they are preferably biased to spread apart when unrestrained and have a cross-section size small enough to be inserted into interstices of trabeculae in the ventricular chamber. The distal ends of the defibrillation electrodes may be free of attachment to the lead body or may be attached by a weak bond to the distal portion of the lead.