Abstract: A method for defibrillating a patient's heart with an implantable defibrillator having defibrillation synchronized to the fibrillation waveform is disclosed. The defibrillator is used to detect fibrillation in a patient's heart, monitor at least two far-field fibrillation voltages across at least three spaced-apart electrodes while the high voltage capacitors are charging, then deliver a high energy shock during a period of ventricular fibrillation when the absolute values of the peak and trough voltages exceed a threshold based on a desired percentage greater than a running average of the absolute values of the peaks and troughs of the fibrillation voltages monitored during and after capacitor charging. The shock is then delivered synchronous with the next significant cardiac complex. The defibrillator also includes a safety timer so that if the threshold is not reached within a specified safe time limit, the high energy shock will be delivered without further delay.

Abstract: A method for electrically attaching electrode wire to a conductor in a defibrillation lead is disclosed. The method comprises melting the end of the wire with a hydrogen torch to form a ball of metal, then crimping or welding the ball to the conductor or to a joining piece attached to the conductor. Also, a hydrogen torch (water welder) may be used to join two or more electrode wires to each other.

Abstract: A lead sealing device that resides within the connector cavity of a pacemaker or defibrillator intended to prevent fluid intrusion by automatically sealing the lead lumen when the lead connector is inserted. The sealing mechanism may be in the form of a silicone disk located at the base of the space defined by the connector cavity in which the lead is inserted to make electrical and physical contact. It may be fixedly located at the bottom of the connector cavity, or may be a movable plug located within the connector cavity at a location other than the bottom of the cavity, such as adjacent to the connector block. In that case, the pin will make contact with the movable plug immediately after passing through the connector block, and will remain in contact with and seal the lead lumen while the pin and plug are further advanced to bring the pin into its final location to make electrical contact with the connector contact.

Abstract: An implantable lead for use with an implantable pacemaker/cardioverter/defibrillator. Since irradiation from a radioisotope source is capable of inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which is incorporated into the lead can be used to decrease the rate of fibrotic growth. The radioisotope may be located inside the lead, alloyed into the metal from which the lead electrode or conductor is made, molded into rubber portions of the lead, or coated onto the conductor or electrode's surface. Beta emitting radioisotopes would be best suited as a radioactive material because of their comparatively short range of action within human tissue.

Abstract: An implantable suture sleeve for use with an implantable lead with a pacemaker/cardioverter/defibrillator lead. Since irradiation from a radioisotope source is capable of inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which is incorporated into the lead can be used to decrease the rate of fibrotic growth. The radioisotope may be located inside the suture sleeve, alloyed into or coated onto the metal from which a wire or coil within the suture sleeve is made, or molded into the rubber of the suture sleeve. Beta emitting radioisotopes having a half-life between 1 and 100 days would be best suited as the radioactive material due to their comparatively short range of action within human tissue, and because of their comparatively short half-life.

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: An implantable medical apparatus operable in conjunction with an attachable lead, and having a housing containing an electronic component, with a header connected to the housing and defining a cavity. A connector element is positioned within the cavity and is operably connected to the electronic component. A lens is connected to the header, such that the connector element may be viewed through the lens to facilitate confirmation of proper connection of a lead to the connector. The header may be transparent, and the lens either formed as part of the header, or detachable therefrom.

Abstract: A lead system for use with an implantable pacemaker/cardioverter/defibrillator. The lead system includes a securable pace/sense electrode positioned 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 securable pace/sense electrode allows the defibrillation electrode to be accurately positioned by the patient's surgeon and maintained in intimate contact with the septum wall of the patient's heart, thereby reducing defibrillation thresholds; it provides a sense signal from the region of the His bundle or AV node, which can be used with other electrodes to distinguish between various arrhythmias; and it provides more physiologic pacing leading to greater cardiac output.

Abstract: The present invention is directed toward providing a composite lead body design for pacing and defibrillation leads. This lead body design improves the lead crush resistance in the lead segment that is implanted in the patient's clavicular region, while maintaining good fatigue resistance in the lead segment implanted in the heart. The clavicular segment has a generally flat profile. By flattening the clavicular segment proximal to the venous entry site, the lead will have a lower profile. Also, by substantially co-aligning the conductors within the clavicular segment, the crush resistance of the lead is significantly improved.

Abstract: A lead sealing device that resides within the connector cavity of a pacemaker or defibrillator intended to prevent fluid intrusion by automatically sealing the lead lumen when the lead connector is inserted. The sealing mechanism may be in the form of a silicone disk located at the base of the space defined by the connector cavity in which the lead is inserted to make electrical and physical contact. It may be fixedly located at the bottom of the connector cavity, or may be a movable plug located within the connector cavity at a location other than the bottom of the cavity, such as adjacent to the connector block. In that case, the pin will make contact with the movable plug immediately after passing through the connector block, and will remain in contact with and seal the lead lumen while the pin and plug are further advanced to bring the pin into its final location to make electrical contact with the connector contact.

Abstract: A defibrillator having a housing for enclosing and containing defibrillation pulse generator circuitry, particularly adapted to allow for ease of manufacture and use. At least one surface of the housing is electrically conductive and may be connected to the defibrillation pulse generator circuitry for delivering defibrillating energy to the heart. The defibrillator is provided with two case-activating setscrew blocks isolated from two contacts. By tightening the first setscrew onto its contact, the can is activated and is positive for defibrillation. By tightening the second setscrew instead, the can is activated and is negative for defibrillation. Tightening neither setscrew maintains the inactive status of the can. By using this system, various electrode configurations can be used as required to provide the optimum system for a given patient. The defibrillator generator housing is preferably implanted in the left pectoral region proximate the heart with the conductive surface facing the heart.

Abstract: A defibrillation insulating device prevents current from directly shunting through the blood pool from the right ventricular defibrillation electrode to a superior vena cava electrode and vice versa. This forces current to flow through the heart muscle, thus increasing the current density throughout the heart, to depolarize the majority of the cardiac tissue with a minimum of energy.

Abstract: Intracardiac lead for compliant fixation of a distal end of the lead to cardiac tissue. A fixation helix is disposed at the distal end of the lead. The fixation helix has a first end rigidly attached to the compliant fixation device and a second end that is sharpened to facilitate insertion of the fixation helix into cardiac tissue. The fixation helix can be designed to provide for either electrically active or inactive fixation. Once the lead is implanted in the cardiac tissue, the compliant fixation device, connecting the lead with the fixation helix, reduces the amount of lead movement that is transferred to the patient's tissue at the site of implantation of the fixation helix and reduces those forces from lead movement that could cause dislodgment of the fixation helix.

Abstract: A method for the automated manufacture of defibrillation lead electrodes is disclosed. A metallic defibrillation electrode coil is first embedded in silicone rubber. The location of the coil is mapped using a machine vision system and then a CO.sub.2 laser is used to ablate the silicone overlying the coil to expose a controlled portion of the coil while leaving the remainder securely embedded in the silicone. The power density of the laser is below that which would affect the surface or bulk properties of the coil.

Abstract: An implantable medical apparatus operable in conjunction with an attachable lead, and having a housing containing an electronic component, with a header connected to the housing and defining a cavity. A connector element is positioned within the cavity and is operably connected to the electronic component. A lens is connected to the header, such that the connector element may be viewed through the lens to facilitate confirmation of proper connection of a lead to the connector. The header may be transparent, and the lens either formed as part of the header, or detachable therefrom.

Abstract: A pulse generator having a housing for enclosing and containing pulse generator defibrillation circuitry, particularly adapted to allow for ease of manufacture and use, is disclosed. At least one surface of the housing is electrically conductive and connected to the pulse generator circuitry for delivering defibrillating energy to the heart. The defibrillator is provided with a case activating lead connector cavity having two connector blocks. By plugging in a lead with a pin long enough to contact the only first connector block, the lead becomes active. Using a plug with a longer pin to contact both blocks activates the can. To use neither a lead in the case activating port, nor an active can, a plug with a short or nonconductive pin may be used to plug the cavity without activating the can. By using this system, various electrode configurations can be used as required to provide the optimum system for a given patient.

Abstract: A suture sleeve having an elongated body defining a bore and having a relief aperture at a first intermediate position on the body and communicating with the bore. The sleeve includes a pair of actuator tabs connected to a second intermediate position on the body and extending therefrom, and at least a portion of the relief aperture is positioned between the tabs such that actuation of the tabs causes enlargement of the aperture. The sleeve may be movable between a tighter state in which a lead passing through the bore does not readily slide longitudinally within the bore, and a looser state, in which the lead may slide readily through the bore.

Abstract: A method for the automated manufacture of defibrillation lead electrodes is disclosed. A metallic defibrillation electrode coil is first embedded in silicone rubber. The location of the coil is mapped using a machine vision system and then a CO.sub.2 laser is used to ablate the silicone overlying the coil to expose a controlled portion of the coil while leaving the remainder securely embedded in the silicone. The power density of the laser is below that which would affect the surface or bulk properties of the coil.

Abstract: A lead having a defibrillation electrode that is deployed for defibrillation using artificial muscle. In an undeployed position, the defibrillation electrode is small in diameter so as to be easily implanted pervenously and nonobstructive to cardiac contraction and blood flow. In a deployed position the defibrillation electrode is larger in diameter for defibrillation shock delivery. Thus, the electrode forces an increased amount of current to flow through the heart muscle during shock delivery to depolarize the majority of the cardiac tissue with a minimum of energy, while not obstructing blood flow at other times when not used for energy delivery.

Abstract: A pulse generator circuit and method for using a defibrillation lead positioned close to the right ventricular apex to optimize energy delivery and sensing. This method includes operating a defibrillator-pacemaker system in a true bipolar sensing mode as long as high voltage therapy is not required. When required, the defibrillator-pacemaker system delivers a first high voltage therapy via an RV defibrillation electrode, and, using true bipolar sensing, determines whether the first high voltage therapy was successful. If the first high voltage therapy is deemed to be successful, then true bipolar sensing is resumed. Otherwise, the defibrillator-pacemaker system causes a ring electrode to be electrically connected to the RV defibrillation electrode, delivers a second high voltage therapy, and, using integrated bipolar sensing determines whether the second high voltage therapy was successful. In this way, because no new circuit elements are added within the lead, the lead size and complexity are not increased.