Abstract: A highly efficacious defibrillation lead system and method of use in the middle cardiac vein. The lead system includes a catheter shaft having a plurality of electrode channels and a venous electrode within each channel. A lead wire is electrically interconnected to each venous electrode and extends through the associated electrode channel to the distal end of the shaft. The lead system can be efficiently implanted in the middle cardiac vein when the electrodes are in retracted positions within the channels. After the lead system is implanted, the electrodes are moved to branched deployed positions beyond a distal end of the shaft and into a plurality of tributaries of the middle cardiac vein. The branched electrode distribution in the middle cardiac vein is achieved with relatively little trauma during deployment and enables successful defibrillation with reduced defibrillation threshold energy to enhance the overall defibrillation procedure.

Abstract: A staged energy storage system provides electrical energy to an implantable biomedical device by using the combination of a first stage energy source and a second stage energy concentration system. The second stage energy concentration system allows a lower density and/or lower voltage energy source to be used as the first stage energy source, thereby decreasing the battery cost, size and weight. In one embodiment, the second stage energy concentration system comprises a rechargeable battery. In another embodiment, the second stage energy capacitor system comprises a high energy density capacitor system. The staged energy storage system is ideal for internally charging a pulse-generating capacitor system within an implantable cardioverter defibrillator. In this embodiment, a high voltage transformer has a secondary side that is electrically connected to the pulse-generating capacitor system.

Abstract: A radio frequency (RF) ablation catheter system utilizes a flexible, tubular electrode that is selectively extendable from a distal end of a catheter body. The flexible, tubular electrode creates a continuous linear lesion when a longitudinal side of the electrode is arcuately positioned against an interior wall of the human body and the electrode is energized while a cooling fluid passes through the electrode. The catheter system also includes mechanisms for remotely manipulating and extending the electrode. Preferably, the catheter body include a catheter shaft and a flexible tip section such that the distal end of the catheter is steerable. The invention also includes a method of operating the RF catheter ablation system so as to create arcuate linear lesions.

Abstract: An implantable cardioverter defibrillator (ICD) apparatus produces a capacitive-discharge cardioversion/defibrillation countershock to be delivered through defibrillation electrodes adapted to be implanted in a human patient. The ICD apparatus is a self-contained human implantable device including a pulse-generating capacitor system, a battery system, a sensing system, and a control system. In response to a detected cardiac dysrhythmia, the ICD apparatus selectively charges and discharges the capacitor system through the defibrillation electrodes to generate the capacitive-discharge cardioversion/defibrillation countershock. Circuitry is added to the ICD apparatus to deliver a back-charging pretreatment pulse to the defibrillation electrodes immediately prior to delivery of the cardioversion/defibrillation countershock. The back-charging pretreatment pulse is a low-energy pulse having a polarity opposite from an initial polarity of the cardioversion/defibrillation countershock.

Abstract: A staged energy storage system provides electrical energy to an implantable biomedical device by using the combination of a first stage energy source and a second stage energy concentration system. The second stage energy concentration system allows a lower density and/or lower voltage energy source to be used as the first stage energy source, thereby decreasing the battery cost, size and weight. In one embodiment, the second stage energy concentration system comprises a rechargeable battery. In another embodiment, the second stage energy capacitor system comprises a high energy density capacitor system. The staged energy storage system is ideal for internally charging a pulse-generating capacitor system within an implantable cardioverter defibrillator. In this embodiment, a high voltage transformer has a secondary side that is electrically connected to the pulse-generating capacitor system.

Abstract: The present invention is an implantable cardioverter defibrillator (ICD) system that is electrically connected to two or more implantable discharge electrodes for implantation into a human patient for treating cardiac dysrhythmias. The ICD system has a battery system and a stepup transformer for charging a capacitive storage system in response to a cardiac dysrhythmia detected by a sensing system. A plurality of electrodes are provided which are adapted to be implanted into a human patient. A primary capacitive energy storage system is provided and is corrected to the stepup transformer for storing and delivering a high voltage output of at least 1500 volts. A stepdown transformer is also provided which is connected between the primary capacitive energy storage system and the electrodes for reducing the high voltage output of the primary capacitive energy system to a safe level for the heart.

Abstract: A low profile defibrillation catheter is disclosed which is much thinner than existing devices. The thin structure is provided by using the current conductor coil as a first electrode coil and the same materials as the conductor for the second electrode. The second electrode coil is bonded to the second conductor coil and wound in the same direction. The thin design is motivated by an electrical field analysis which reveals that the length of the catheter is the important determinant of defibrillation efficacy, and that the large radius and surface area of prior art devices were less beneficial.

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. At least one surface of the outer shell is electrically conductive to form an electrode for the system. Because of the close proximity between the housing electrode and the circuitry positioned within the housing, the circuitry is susceptible to undesired capacitive coupling effects. To reduce the capacitive coupling effects, a slew rate limiting circuit is connected between the pulse generating circuitry and the electrode formed on the housing.

Abstract: The model that is developed in the present invention is based upon the pioneering neurophysiological models of Lapicque and Weiss. The present model determines mathematically the optimum pulse duration, d.sub.p, for a truncated capacitor-discharge waveform employed for defibrillation. The model comprehends the system time constant, RC, where R is tissue resistance and C is the value of the capacitor being discharged, and also the chronaxie time, d.sub.c, defined by Lapicque, which is a characteristic time associated with the heart. The present model and analysis find the optimum pulse duration to be d.sub.p =(0.58)(RC+d.sub.c). Taking the best estimate of the chronaxie value from the literature to be 2.7 ms, permits one to rewrite the optimum pulse duration as d.sub.p =(0.58)RC+1.6 ms.

Abstract: A main energy delivery electrical circuit for use in an implantable cardioverter defibrillator device comprises a low power output primary defibrillator battery, a high power output intermediate power intensifying capacitor system, a switch for permitting the intermediate power intensifying capacitor system to rapidly charge a main energy delivery capacitor, and a main energy delivery capacitor. The main energy delivery capacitor is configured for discharging, in a first pulse, an electrical charge derived from the primary battery, and for discharging certain subsequent pulses of electrical charge derived from the intermediate power intensifying capacitor system. The circuit permits the implantable cardioverter defibrillator device to deliver multiple closely spaced defibrillation pulses to a heart.

Abstract: A method and apparatus for treating ventricular tachycardia arrhythmias using an ICD system delivers a series of stepped cardioversion pulses that include at least a first and second cardioversion countershock of low energy values that are less than about 5 joules. The energy values of each cardioversion countershocks increase in stepped progressions such that the low energy value of the first cardioversion countershock is less than the second and all subsequent cardioversion countershocks. The use of a series of stepped cardioversion pulses minimizes the possibility of "overstimulating" heart cells in any reentrant loop that are causing the ventricular tachycardia. As a result, the possibility of inducing fibrillation by the cardioversion therapy is significantly decreased. The leading edge of each of the series of stepped cardioversion pulses is sufficient to just stimulate any heart cells that are in phase 4, but is not strong enough to stimulate heart cells that are in phase 3.

Abstract: The present invention is a physician's interface expert system that allows a physician not well versed in ICD parameters to program at least one parameter into an ICD using the physician's existing knowledge of the patient's medical history. The programmable ICD system is composed of an implantable portion and a programming device external from the patient's body. The implantable portion has pulse generating circuitry, control circuitry including parameter storage, a receiver and at least one electrical lead for placement in the patient's heart. The programming device contains an operator interface device that receives a first set of values from the operator. A translator is provided in the programming device for translating the first set of values into a second set of values formatted in accordance with the programmable parameter settings of the implanted device. Finally, a transmitter is provided in the programming device to transmit the second set of values to the receiver of the implanted device.

Abstract: A defibrillator for pectoral implant in a patient wherein the metal housing or case of the defibrillator is utilized as an electrode and is operative to supply electrical pulses. The housing is coated with an oxidation resistant material to optimize electrode function.