Abstract: Heart lead removal apparatus for removing an implanted cardiac pacemaker lead from the wall of a heart through a blood vessel leading to the heart. The lead removal apparatus comprises an outer tube sized for insertion into the coiled structure passageway of the pacemaker lead; an anchoring projection positioned proximate the distal end of the outer tube; and a stylet positioned through the passageway of the outer tube for urging the anchoring projection between relaxed and hooked positions. In the hooked position, the projection extends outwardly from the outer tube and when also positioned in the coiled structure passageway, hooks into the coiled structure for facilitating removal of the lead from the heart. In the relaxed position, the anchoring projection is insertable into the coiled structure passageway. The apparatus preferably includes a laterally flexible member constituted by a folded back portion of the stylet.

Abstract: A device (10) for removing from a patient (12) a previously implanted elongated structure (14), such as a catheter, sheath, defibrillator lead, pacemaker lead (15) or the like. The device (10) includes a snare (24) which encircles and reversibly grasps either the proximal end (16) or the distal end (20) of the elongated structure (14), as well as a sheath member (22) for delivering the snare (24) to the particular end (16 or 20) of the structure (14) to be grasped.

Abstract: Heart lead removal apparatus for removing an implanted cardiac pacemaker lead from the wall of a heart through a blood vessel leading to the heart. The lead removal apparatus comprises an outer tube sized for insertion into the coiled structure passageway of the pacemaker lead; an anchoring projection positioned proximate the distal end of the outer tube; and a stylet positioned through the passageway of the outer tube for urging the anchoring projection between relaxed and hooked positions. In the hooked position, the projection extends outwardly from the outer tube and when also positioned in the coiled structure passageway, hooks into the coiled structure for facilitating removal of the lead from the heart. In the relaxed position, the anchoring projection is insertable into the coiled structure passageway.

Abstract: A noninvasive, perforate, self-centering locator (10) facilitates engagement of a needle or cannula with a vascular access device (44) of the type having a subcutaneously implanted infusion port (46) and an infusion chamber (48) contained in the infusion port (46), the infusion chamber (48) being covered by a septum (52). The locator (10) is exemplified by a port stabilizer ring (12) having a central opening (18) with an interior diameter greater than the diameter of the septum (52) but less than the greatest diameter of the infusion port (46). The stabilizer ring (12) or other embodiment of the locator (10) is pressed on the skin (45) over the site of the infusion port (46), and simultaneously visually locates the septum (52) for the user while stabilizing the infusion port (46) with respect to the skin (45) and underlying tissues, permitting ready penetration of the skin (45) and septum (52) by a needle or cannula (58).

Abstract: A pulsed Doppler probe 10 for monitoring blood flow within a blood vessel 12 includes a sheath 17 and a plurality of electrically conductive wires 26 extending through the sheath 17. The wires 26 have distal ends 28 to which an ultrasonic transducer 18 is operatively connected. The transducer 18 has an operative surface 20, and the probe 10 also includes a means 22 for fixing the orientation of the operative surface 20 with respect to at least one of a longitudinal axis 38 of the sheath 17, and the orientation fixing means 22, or with respect to the distal ends 28 of the electrically conductive wires 26. The orientation fixing means 22 includes an epoxy material 24 encasing the ultrasonic transducer 18, shaped to include a cylindrically concave surface 30. The probe 10 further includes a mesh band 44 of at least one of an absorbable material and an inert material adapted to encircle the blood vessel 12.

Abstract: A reversible snare (10) for grasping and retrieving an article (15) such as a cardiac lead from within a human or veterinary patient (20) includes a sheath member (25) adapted for introduction into the patient (20), and a retractable closed loop (30) carried by the sheath member (25). The closed loop (30) is composed of a shape memory material and defines a hook (35) adapted to partly encircle the article (15). The snare further includes a threader (45) also carried by the sheath member (25), the threader (45) being reversibly extendable through the closed loop (30) (like a thread through a needle's eye) so that the hook (35) and threader (45) can fully encircle the article (15). Retraction of the closed loop (30) causes the hook (35) and threader (45) to close around the article (15) and permit its withdrawal into the sheath member (25). Independent retraction of the threader (45) allows the hook (35) to disengage from the article (15).

Abstract: A locally flexible dilator sheath (10) for separating encapsulating tissue from an implanted cardiac electrical lead. The dilator sheath includes an elongated tubular member (11) of a rigid stainless steel material, which is sized for placement of the tubular member over a cardiac lead that is implanted in the vascular system of a patient. The distal end (13) of the rigid tubular member is beveled to ease the separation of extremely tough tissue that encapsulates an implanted cardiac lead. To ease insertion around curves in the vascular system of the patient, the elongated tubular member includes a relieved portion (14). The relieved portion includes a relief pattern (15) of apertures (16,17,19,23) in the elongated tubular member. The relief apertures preferably include diametrically opposed slots (24,25) that extend perpendicularly into the tubular member. Adjacent pairs (44,45) of slots are circumferentially offset a 90.degree. angle (26) to add further lateral flexibility to the relieved portion.

Abstract: A closed-end catheter having a flat-surfaced valve positioned in a recess about the distal portion of the catheter for preventing retrograde flow of blood therethrough when positioned in a blood vessel of a patient. The valve catheter comprises a flexible material, cylindrical tube having a semi-circular cross-sectional wall extending longitudinally about the distal portion thereof. The laterally facing valve is formed in a planar surface of a flexible material layer attached to the wall in the distal portion of the cylindrical tube. One or more passages extend through the cylindrical tube in which medicaments or fluids can be simultaneously injected or aspirated. The valve is formed by inserting one or more flat-surfaced rods in the passages of the tube to stretch the surrounding wall. A flat-surfaced layer of flexible material is applied over the flat-surfaced rod to the stretched wall.

Abstract: A surgical clip having first and second separate pieces for ligating a vessel therebetween, an applicator for applying the clip to the vessel, and a method of use thereof. The surgical clip comprises a first tube having a longitudinal slot formed through the outer wall thereof and communicating with a passage extending therethrough for receiving a second tube into the passage of the first tube and circumferentially ligating a vessel positioned in a second channel transverse to and communicating with the first passage. Tangs or projections extend from the outer wall of the first tube about the longitudinal slot thereof and into the passage of the first tube for engaging the walls about a slot in the second tube and securably positioning the second tube in the passage of the first tube. An applicator includes a main housing having a vessel channel for positioning the first tube therein.

Abstract: A closed-end catheter having a flat-surfaced valve positioned in a recess about the distal portion of the catheter for preventing retrograde flow of blood therethrough when positioned in a blood vessel of a patient. The valve catheter comprises a flexible material, cylindrical tube having a U-shaped outer wall extending longitudinally about the distal portion thereof. A flat-surfaced valve is positioned in the recess along the U-shaped distal portion and attached to the outer wall. The valve is formed by inserting a flat-surfaced rod in the U-shaped portion of the tube to stretch the outer wall. A flat-surfaced layer of flexible material is applied over the flat-surfaced rod to the stretched outer wall. The flexible material layer is cured and a longitudinal fluid aperture formed therein with the rod remaining in the passage of the U-shaped portion. The rod is then removed and a plug inserted into the passage to close the distal end of the catheter.

Abstract: A synchronous telemetry receiver and receiving method for reception from an implantable medical device of a PPM signal including a plurality of bits each having a sync pulse and at least one data pulse of equal amplitude. Capability is provided for restoring correct phase in the event that a sync pulse is missing or incorrectly received for any reason. A high-frequency clock and counter are provided for counting clock pulses during the time interval between each data pulse and its respective sync pulse in order to obtain a measurement of the time interval.

Abstract: Heart lead removal apparatus and method are disclosed for removing a heart lead from the wall of a heart through a blood vessel leading to the heart. The apparatus comprises a flexible stylet wire with an expandable wire coil attached to the distal end for engaging the coiled structure of the heart lead. The wire coil includes first, second, and third pluralities of turns. The first plurality of turns is positioned around and about the distal end of the stylet wire for radially expanding when in the passageway of the lead to secure the stylet wire to the lead. The second plurality of turns extends proximally from the first plurality of turns and laterally from the stylet wire for engaging the lead and radially expanding the first plurality of turns. The third plurality of turns extends distally from the first plurality of turns and is attached around and about the distal end of the stylet wire for cooperating in the radial expansion of the first plurality of turns when in the passageway of the lead.

Abstract: A synchronous telemetry system and method for multiplexed telemetry of analog and digital information from a pacemaker or other implantable medical device. Telemetry sync pulses are generated at a 1 kHz rate, and pulse-position modulation is employed for generating an analog data pulse and a digital data pulse relative to the same sync pulse and displaced therefrom by different intervals respectively corresponding to the instantaneous value of an analog input signal and the instantaneous state of a digital input signal. In addition to multiplexing of analog and digital information in a composite bit, multiplexing is provided for dual-channel analog operation.

Abstract: A low-power A/D converter for an implantable medical device. The converter includes a high-frequency oscillator capable of generating clock pulses at a frequency substantially higher than the main clock frequency of the implantable device, and an oscillator-gating circuit for enabling the oscillator for a voltage-dependent variable time interval. The gating circuit includes a voltage-controlled monostable multivibrator for generating a gate control pulse having a pulse width corresponding to the value of an analog signal representative of a physiological parameter sensed by the implantable device. A timing controller, which operates at a low frequency under control of a crystal-controlled clock, supplies a trigger pulse to the voltage-controlled monostable at a predetermined first point in the variable time interval and generates an enable pulse at a predetermined second point in the variable time interval.

Abstract: Heart lead removal apparatus and method are disclosed for removing a pacemaker lead from a heart through a blood vessel leading thereto. The apparatus comprises a flexible stylet wire with an expandable wire coil attached to the distal end for engaging the coiled structure of the pacemaker lead. A lockable mechanism grasps the proximal end of the lead, and a wire guide is inserted in the passageway of the lead to determine its size and clear any blockage therein. The stylet wire is inserted in the longitudinal passageway of the coiled structure to the distal end of the pacemaker lead. The stylet wire is rotated in a direction to unwind and expand the wire coil and engage the coiled structure, thereby securing the stylet wire to the pacemaker lead. A tie secures the insulating material to the coiled structure of the lead at the proximal end thereof to limit motion and to apply a uniform extraction force to the entire lead.

Abstract: Heart lead removal apparatus and method are disclosed for removing a heart lead from the wall of a heart through a blood vessel leading to the heart. The apparatus comprises a flexible stylet wire with an expandable wire coil attached to the distal end for engaging the coiled structure of the heart lead. A lockable mechanism grasps the proximal end of the lead, and a wire guide is inserted in the passageway of the lead to determine its size and any blockage therein. The stylet wire is inserted in the longitudinal passageway of the coiled structure to the distal end of the heart lead where the tip is typically secured to the heart wall with a number of tines formed from the insulating material surrounding the coiled structure. A tie secures the insulating material to the coiled structure of the lead at the proximal end thereof to limit motion and apply uniform extraction force to the entire lead.

Abstract: Heart lead removal apparatus is disclosed for removing a heart lead from the wall of a heart through a blood vessel leading to the heart. The apparatus comprises a flexible stylet wire with an expandable wire coil attached to the distal end for engaging the coiled structure of the heart lead. The stylet wire is inserted in the longitudinal passageway of the coiled structure to the distal end of the heart lead where the tip is typically secured to the heart wall with a number of tines formed from the insulating material surrounding the coiled structure. When inserted, the stylet wire is rotated in a direction to unwind and expand the wire coil and engage the heart lead coiled structure, thereby securing the stylet wire to the heart lead. A separator tube is inserted over the proximal end of the stylet wire and the heart lead and moved along the entire length of the heart lead to first separate the restricted heart lead from the blood vessel leading to the heart cavity.

Abstract: A pacemaker is disclosed with a pacing rate that is restricted within a range defined by variable upper and lower rate limits that change as a function of the patient's detected level of activity. An indication such as the nonambient temperature of blood is sensed in the right ventricle of the heart to indicate detected activity level. Other activity indications, such as blood oxygen concentration and body motion, either singly or in combination are also disclosed. A control circuit of the pacemaker varies the upper and lower rate limits according to the patient's detected level of activity. The control circuit also varies the atrial and ventricular refractory periods along with the AV delay period in response to detected activity level changes.

Abstract: Heart lead removal apparatus and method are disclosed for removing a heart lead from the wall of a heart through a blood vessel leading to the heart. The apparatus comprises a flexible stylet wire with an expandable wire coil attached to the distal end for securing the distal end of the stylet wire to the heat lead. A catch wire extends from the proximal end of the wire coil. The free end of the catch wire has a segment folded back on itself for engaging the coiled structure of the lead and expanding the wire coil when the stylet wire and wire coil are rotated in the passageway of the lead. The stylet wire is inserted in the longitudinal passageway of the coiled structure to the distal end of the heart lead. When inserted in the passageway, the stylet wire and wire coil are rotated in a direction to engage the catch wire with the coiled structure. The wire coil then expands engages the heart lead coiled structure, thereby securing the stylet wire to the heat lead.

Abstract: Method and appartaus are disclosed for stimulating the heart with a pacemaker in response to a nonambient temperature of a body, which is sensed, for example, in the right ventricle of the heart. The pacemaker stimulates the heart at one of at least three different nominal rates which have been selected by the physician for the various activity levels of the patient. When the heart is stimulated at an interim rate for mild or brief exercise conditions, the activity level of the patient is sensed using a motion sensor. A control circuit terminates a predetermined time period selected for the pacemaker to stimulate at the interim rate when the sensed level is less than a predetermined activity level.