Abstract: The present invention is a pectorally implantable defibrillation system for delivering at least one electrical cardioversion/defibrillation countershock. The system has a housing designed to be implanted in a human patient, wherein the housing has an outer shell and an inner cavity. Pulse generating circuitry is positioned within the cavity for generating the at least one countershock. Circuitry is also positioned within the cavity to control delivery of the at least one countershock. A slew rate limiting circuit is connected between the pulse generating circuitry and one of a plurality of implantable electrodes so as to reduce a slew rate of the electrical countershock. Preferably, one of the implantable electrodes is the housing.

Abstract: A high voltage array switching system utilizes an array of low voltage charge storage devices to generate a relatively high energy, high voltage output required by battery powered devices such as implantable cardioverter defibrillators. The system includes a low voltage battery system having a supply voltage connection and a ground connection. N low voltage charge storage devices are provided, with each charge storage device having one of an anode and a cathode electrically connected to the supply voltage and having the other of the anode and the cathode electrically connected to the ground connection. M configuration switches are electrically connected between the charge storage devices and the battery system.

Abstract: A system for passively anchoring mid-lead electrodes on an endocardial catheter lead includes at least one fibrosis-anchoring opening positioned along the exterior surface of the catheter lead body proximal or distal to the mid-lead electrodes for passively securing the catheter lead against the interior wall of the heart. Within the fibrosis-anchoring openings a suitable material is provided for anchoring the catheter lead body to the heart wall by fibrosis. Preferably, the fibrosis-anchoring openings comprise at least a pair of openings positioned only partially around the exterior of the catheter lead body at locations both proximal and distal to the mid-lead electrodes, with the catheter lead body between the fibrosis-anchoring openings being preformed to bias the mid-lead electrodes against the heart wall.

Abstract: A silicone paint brush artist's tool includes a handle and a novel painting tip. The painting tip is made of a resilient silicone. In one embodiment, the painting tip has a series of longitudinal slits defined in the tip. In another embodiment, the painting tip has a durometer hardness value of between 20 Shore A to 70 Shore A. In a further embodiment, the painting tip has a generally three-dimensional working surface that includes a concave surface. In still another embodiment, the painting tip has a peripheral, sharp edge for removal of paint. In a still further embodiment, the painting tip has a concave surface for manipulation of paint. The tip is preferably attached to the handle using a ferrule and expansively locking the tip into a cavity of the ferrule by insertion of an insert. The insert may be a common screw or a barbed, fluted extension of the handle. The tips may include an insert cavity and have various shapes and hardnesses and may be optionally color coded.

Abstract: The invention relates to an ablation catheter which controls the temperature and reduces the coagulation of biological fluids on a tip of a catheter, prevents the impedance rise of tissue in contact with the catheter tip, and maximizes the potential energy transfer to the tissue, thereby allowing an increase in the lesion size produced by the ablation. The ablation catheter includes a catheter body. The ablation catheter also includes a tip for monitoring electrical potentials, and applying electrical energy to a biological tissue. A fluid source is positioned at one end of the catheter for supplying a fluid flow through the catheter to the tip means. Passages are positioned within the tip in a variety of manners for directing the fluid flow through the tip means to the exterior surface of the tip to control the temperature and form a protective fluid layer around the tip. Monitoring structure is also positioned within the tip structure for measurement of the electrical potentials in a biological tissue.

Abstract: A magnetic sensing circuit is arranged in cooperative relation to a flyback transformer in a capacitor charging circuit for directly sensing the state of the transformer magnetic field for controlling the switching of power to the primary winding of the flyback transformer. A first threshold is sensed when the flyback transformer is nearly saturated with magnetic energy storage. A second threshold is sensed when all of the magnetic energy stored in the flyback transformer has been transferred to the capacitor. The sensed thresholds are used to optimally control the switching of power to the primary winding to maximize the efficiency and minimize the charging time of the capacitor charging circuit. A capacitor charging circuit which utilizes the present invention can be part of an implantable cardioverter defibrillator.

Abstract: A capacitor-discharge implantable cardioverter defibrillator (ICD) has a relatively smaller mass of less than about 120 grams. The smaller mass of the ICD is achieved by selecting and arranging the internal components of the ICD to deliver a maximum defibrillation countershock optimized in terms of a minimum physiologically effective current (I.sub.pe), rather than a minimum defibrillation threshold energy (DFT). As a result of the optimization in terms of a minimum effective current I.sub.pe, there is a significant decrease in the maximum electrical charge energy (E.sub.c) that must be stored by the capacitor of the ICD to less than about 30 Joules, even though a higher safety margin is provided for by the device. Due to this decrease in the maximum E.sub.

Abstract: An intraoperative defibrillation test system for establishing defibrillation thresholds for an implantable cardioverter defibrillator (ICD) uses the actual ICD housing electrode, rather than a test housing electrode, as part of the test system. The intraoperative defibrillation test system includes the ICD, an external test station, and a test cable interconnecting the ICD with the test station. In one embodiment, the test cable is only connected to the ICD housing electrode and other test cables are used to connect to other implanted electrodes. In another embodiment, the test cable includes multiple conductors for connecting to all of the electrodes associated with the ICD, including the ICD housing electrode. In a further embodiment, the test cable includes a distal connector block that serves as a three-way T-between at least one port in a header of the ICD and an electrode lead.

Abstract: An implantable cardioverter defibrillator optimized for prophylactic use. An improved power system uses multiple, single use, short duration, battery cells for countershocks.

Abstract: A method and apparatus for generating biphasic waveforms uses an implantable cardioverter defibrillator (ICD) system having a phase transition enhancing capacitor system in addition to the capacitor system(s) which deliver the first and second phase of the biphasic countershock. Preferably, the ICD system has at least three capacitor systems and a capacitor switching network. The three capacitor systems include two primary capacitor systems and a third high voltage phase transition enhancing capacitor system having a time constant shorter than the time constant of the two primary capacitor systems. A first phase of the biphasic waveform preferably is produced by configuring the two primary capacitor systems to selectively discharge first in a parallel combination, and then in a series combination. The second phase of the biphasic waveform preferably is produced by reconfiguring the two primary capacitor systems to discharge in a parallel combination with reversed polarity.

Abstract: A tiered therapy cardiac detection system is provided for a medical device that senses cardiac signals representative of beat-to-beat intervals and delivers at least one therapy in response to a detected cardiac dysrhythmia corresponding to one of a plurality of programmed zones of heart rates. The detection system includes a global counter that counts at least all beat-to-beat intervals indicating a rate greater than a programmed threshold value representative of a minimum heart rate for delivering any therapy once an initial threshold condition is met. A plurality of window memories and parameter memories are provided in the device. Each window memory corresponds to a given one of the zones and stores an indication of whether each of a last N cardiac signals are within that zone. Each parameter memory corresponds to a given one of the zones and stores a programmed trigger value of the global counter required in order for a therapy in that zone to be delivered.

Abstract: A device and method for performing automatic battery maintenance as particularly applied in an implantable cardioverter defibrillator (ICD). The battery is maintained at a predetermined state-of-charge to enable charging a capacitor in the ICD to discharge high voltage pulse into a human patient via electrodes implanted in the patient.

Abstract: An automatic capacitor maintenance system for an implantable cardioverter defibrillator (ICD) reforms the capacitor system of the ICD based on measurements relating a current leakage and a charge time of the capacitor system as determined at a stable low voltage state. Preferably, differential changes in current leakage across the capacitor system are monitored and the capacitor system is reformed based on a pre-set estimated charge time. The automatic capacitor maintenance system produces significant savings in the amount of battery energy consumed to reform the capacitor system of an ICD, while maintaining the capacitor system at an optimum charging efficiency so as to insure high reliability of both the capacitor system and the ICD.

Abstract: A method and apparatus for generating biphasic waveforms for an implantable defibrillator uses two disparate capacitor systems. A first phase of the biphasic waveform is generated from the charge stored in a first capacitor system, and a second phase of less energy than the first phase is generated from the charge stored in a second capacitor system. By using a second capacitor system for the second phase of the biphasic waveform that stores less energy than the first capacitor system, the overall size and power requirements of the implantable device can be reduced. In a preferred embodiment, the disparate capacitor systems have different effective capacitances, with the second capacitor system preferably having a higher effective capacitance, but a lower charging voltage, than the first capacitor system.

Abstract: An implantable cardioverter defibrillator (ICD) in which capacitor systems are automatically reformed using a software-implemented computer system. The charge history and performance of the capacitor system are measured to perform intelligent calculations and to set the automatic capacitor reforming cycle. Individual capacitors among a group of many are isolatively charged as needed. Moreover, a sub optimal charge is used to automatically reform the capacitors to efficiently use battery energy. Further, excess charge is directed from one capacitor to another to thereby conserve energy. Specifically, the disclosure relates to an autonomous capacitor charging system which enhances ICD reliability to sustain real time provision of high current pulses.

Abstract: A method and apparatus for generating biphasic waveforms uses an implantable cardioverter defibrillator having two capacitor systems and a switching network. A first phase of the biphasic waveform is produced by configuring the two capacitor systems to selectively discharge first in a parallel combination, and then in a series combination. The second phase of the biphasic waveform is produced by reconfiguring the two capacitor systems in a parallel combination. By reverting to a parallel configuration for the second phase of the biphasic waveform, the output characteristics of the second phase of a biphasic waveform of the present invention more closely match a new model for understanding the effectiveness of the biphasic.

Abstract: A system and method for reducing the perceived pain by a patient occurring during cardioversion/defibrillation countershocks to the heart. The system comprises an electrode subsystem for positioning at least one electrode in contact with a patient, a pain reducing stimulation subsystem for providing pain reducing electromagnetic stimulation to the electrode subsystem, a cardioversion/defibrillation countershock subsystem for treatment of cardiac fibrillation, and a control subsystem. The control subsystem provides synchronization of the pain reducing stimulation subsystem with the cardioversion/defibrillation countershock subsystem so that delivery of pain reducing stimulation to the patient begins prior to a cardioversion/defibrillation countershock.

Abstract: A system for passively anchoring mid-lead electrodes on an endocardial catheter lead includes at least one fibrosis-anchoring opening positioned along the exterior surface of the catheter lead body proximal or distal to the mid-lead electrodes for passively securing the catheter lead against the interior wall of the heart. Within the fibrosis-anchoring openings a suitable material is provided for anchoring the catheter lead body to the heart wall by fibrosis. Preferably, the fibrosis-anchoring openings comprise at least a pair of openings positioned only partially around the exterior of the catheter lead body at locations both proximal and distal to the mid-lead electrodes, with the catheter lead body between the fibrosis-anchoring openings being pre-formed to bias the mid-lead electrodes against the heart wall.

Abstract: A photovoltaic device has micro-embossed optical enhancing structures formed on an inner surface of a transparent polymer film material which is laminated to the light incident surface of a photovoltaic cell. Preferably, the micro-embossed structures are in the form of an array of holographic pyramid structures which are interconnected by a series of light channels that are also embossed on the inner surface of transparent film material. In another embodiment, the photovoltaic device is comprised of a layer of flexible transparent polymer material, such as polyester, and a layer of flexible base substrate, preferably of a polymer film, between which are disposed at least one layer of amorphous silicon and at least one layer of metalization forming a photovoltaic cell. By utilizing a pair of flexible sheets of polymer material as the outer layers of the photovoltaic device, the device is deformable in at least one orientation other than a plane defining the sheets of polymer film material.

Abstract: A high voltage output system for use with an implantable cardioverter defibrillator (ICD) system provides for switched discharge pathways utilized to achieve a windshield wiper-like output. The high voltage output system includes at least two output capacitors each having at least a separately electrically accessible one of the cathode and anode of the capacitor system. A switching control system selectively discharges the at least two capacitor systems in a repeated alternating sequence such that the one of the cathode and anode of the capacitor systems is discharged through a common electrode and the other of the cathode and anode is electrically connected for at least a portion of the discharge to a second and third defibrillation electrode, respectively.