Abstract: A drug delivery catheter and storage bladder adapted for use in an implantable drug delivery system. The catheter and bladder are provided with piezoelectric layers adapted to be responsively coupled to a source of ultrasonic electrical signals. When so coupled, vibration of the piezoelectric layer dislodges any accumulation of crystallized drugs within the catheter and bladder.

Abstract: A body implantable lead for the delivery of stimulation energy to a desired body site including a drug dispenser carried by the lead which retains a drug to be dispensed while allowing the dispensing of that drug at least adjacent the desired body stimulation site. The drug may be one which is intended to counter thrombus formation, fibrosis, inflammation or arrhythmias, or any combination thereof, or to accomplish any other localized purpose. The drug is retained in a cavity within the lead, with an agency controlling dispensing of the drug. In a preferred embodiment, the drug is compounded into a solid material which is retained within a tip electrode while being exposed to body fluids through a porous elution path. The drug may also be retained on and diffused from a porous surface of the electrode, adjacent to the elution path. Preferably, the drug is compounded within a polymer carrier, mounted within the cavity in the electrode.

Abstract: A pacing system analyzer is constructed to provide verification that an implantable cardiac pacer operating in a demand mode will not itself produce tachycardia in a patient because of abnormally long patient retrograde conduction time. The analyzer when performing the retrograde conduction test provides an intercardiac electrogram, changes the ventricular sense amplifier to asynchronous and samples to determine the maximum amplitude signals over a sampling period to select an amplifier gain factor. After the gain factor is set additional signal samples are collected, peak-to-peak amplitude is measured and interpolation between data is made to provide waveform "segments" and the best waveform segment to employ for testing for retrograde conduction is selected. The time periods from pacing to these segments are measured and utilized to determine if retrograde conduction is present.

Abstract: A pacing system analyzer as connected to an implantable cardiac pacer and if an atrial pacing pulse is detected only, the analyzer sends a simulated P-wave to the pacer and determines the response of the simulated P-wave to determine if the pacing mode is AAI, AAT, or AOO. In the event a ventricular output pulse only is detected by the analyzer, a simulated R-wave is sent to the pacer and if the pacer responds either by a triggered ventricular pulse or by not changing its response, the analyzer determines that the pacer is in a VVT or VOO mode. On the other hand, if the pacer is inhibited a subsequent simulated P-wave is sent to it and the response of this P-wave determines whether or not the pacer is in a VVI or VDD mode. In the event that both atrial and ventricular pacing pulses are detected by the analyzer, the simulated R-wave is first sent to the pacer and an unchanged response determines that the pacer is in a DOO mode.

Abstract: A low-polarization electrode for use in medical stimulation leads. The electrode is provided with grooving and is coated with platinum black.

Abstract: A transvenous cardioversion lead for use in standby cardioversion in patients who have a high risk of ventricular tachycardia or fibrillation, adapted for use with presently available external defibrillation units. The lead is provided with energy-reducing or energy-limiting circuitry to prevent the inappropriately high energy levels which may be generated by external defibrillation units from causing injury to the patient while preserving the beneficial waveform of the defibrillation pulse. The lead is further provided with at least three electrodes, two for location in the ventricle, at least one for location in the superior vena cava. The lead is so constructed that the superior vena cava electrode and one of the ventricular electrodes may be used for cardioversion, while the two ventricular electrodes may be used for cardiac pacing and sensing.

Abstract: A transvenous pacing lead having a stylet including a longitudinal stylet wire, a handle affixed to the proximal end of the stylet wire, a taper of a predetermined length formed adjacent to or on the distal end of the stylet wire, and a ball affixed to the end of the stylet wire where the ball has a diameter substantially equal to the diameter of the stylet wire. The taper at the distal end of the stylet provides strain relief, least rigidity of the stylet wire and complies with the curvature bends of the transvenous pacing lead. The tapered end of the stylet wire can also be referred to as a soft tip stylet wire.

Abstract: A method and apparatus embodied in a pacemaker for attenuating polarization currents or voltages at the output terminals of the pulse generator. A heart pacemaker typically possesses a source of supply voltage, an output capacitor, an output terminal adapted to be coupled to heart tissue. A voltage source is coupled to the output capacitor during a first time interval for charging the output capacitor to a certain voltage. The output capacitor is coupled to the output terminals during a second time interval to discharge its voltage into the heart tissue. A resistor is coupled across the output terminals for providing a current path for the discharging and recharging of the effective capacitance of the stimulated heart tissue. The resistor may be coupled across the output terminals only during the first time interval and not during the discharge of the output capacitor.

Abstract: A pacer subsystem for detecting the existence of tachyarrhythmia including means for measuring the average time interval between successive heart beats and for comparing a sample beat with both a percentage of this average, and with a preset time interval. If the sample beat period is less than both criteria, it is classified as a tachy beat. If the sample beat is longer than either time interval it is classified as a non-tachy beat. Sequences of tachy beats are used to initiate an appropriate therapeutic stimulation regime.

Abstract: An ultrasound imaging system particularly adapted for detecting structure which reflects ultrasound at a variety of angles. There is a plurality of ultrasound transducers, which may be a linear array or a two-dimension array with the various horizontal rows of the array offset from one another, but having zero horizontal space or overlapping between adjacent vertical transducers. A sequencer causes one transducer to fire and then listen for an echo; if no echo is heard, the same transducer fires again and an adjacent transducer listens; if there is still no echo, the transducer fires and the next adjacent transducer listens; and so on until a predetermined listening sequence is concluded.

Abstract: A body implantable lead which may be provided with a desired predetermined curve. A memory coil is inserted into the lead while straightened by a stylet. After removal of the stylet, the memory coil imparts the desired curve to the lead.

Abstract: Pressure and motion transducer, and cooperating circuitry for an implantable medical device is disclosed. The system includes a clock for the pulse excitation of a dynamic motion transducer and further includes circuitry for recovering the modulated signal from the transducer.

Abstract: A combination ion sensing and reference electrode and a method for producing it. The electrode is formed of bi-lumen plastic tubing using one lumen as sensing chamber and the other as a reference chamber. A portion of the sensing chamber extends distally relative to the reference chamber, and is permeated with an ion selective material by soaking that portion in a solution containing the ion selective material. The method of manufacture is thereby simplified and sealing of the chambers is improved.

Abstract: A single pass atrial-ventricular endocardial lead for transvenous insertion. A ventricular electrode is mounted at the distal end of a ventricular lead sheath and an atrial electrode is mounted at the distal end of an atrial lead sheath which is slideably mounted around the ventricular lead sheath. A connector assembly is mounted at the proximal end of the atrial lead sheath. An adjustment device is provided to allow axial adjustment of the ventricular lead sheath relative to the atrial lead sheath without modification to or adjustment of the connector assembly prior to attachment to an implantable pulse generator.

Abstract: An implantable dispenser for infusing a desired drug into the blood stream. The dispenser is adapted to be spliced into a blood vessel so that blood flows freely through it. Within the dispenser is a replaceable biomass cartridge containing a colony of microorganisms which produce the drug.

Abstract: An ultrasound scanning system particularly adapted for imaging skeletal structure, such as the spinal column. An ultrasound scanning head for generating ultrasound waves and for receiving reflected ultrasound signals is mounted on a transporter for moving it linearily along the spine between a cervical reference point and a sacral reference point. A position transducer monitors the position of the transducer along the spine and a counter measures the time between the ultrasound pulse and its echo to determine the distance from the transducer face to the tissue interface responsible for generating the echo. The distance and range data is smoothed and analyzed in a digital computer using algorithms that distinguish between the echoes received from bone and other tissue such as lung tissue. The bone data is further processed via computer to produce a visual representation of the spine and rib structure sufficient for the diagnosis of spinal misalignment characteristic of scoliosis.

Abstract: An implantable pacer having an effective stimulation rate which varies in response to a measured physiological parameter. Changes in the parameter to be measured must be related to physiologically required changes in heart rate. The level of oxygen within intracardiac or pulmonary artery venous blood is the preferred parameter. This parameter is measured by an oxygen sensor located on a transvenously implanted lead. As with normal demand pacers, a sensing electrode, also located on the lead, provides the pacer with an indication of whether a pacing pulse must be generated. The measured physiological parameter determines the escape interval for demand pacing. As such, a given minimum rate is determined for a given level of molecular oxygen in the intracardiac or pulmonary artery venous blood. The technique is readily employed in both ventricular and atrial-ventricular sequential modes.

Abstract: A tool having a handle portion and a curved tongue extending from the handle. The curve of the tongue is sufficient that, when the distal end of the tongue is placed substantially parallel to the spinal cord within the epidural space, the proximal portion of the curve extends substantially parallel to the plane passing between spinal vertebrae. The tongue is formed of a pliant material having sufficient rigidity to separate epidural fat to form a pocket in the epidural space, but sufficiently pliant to prevent trauma to the dura and the spine upon contact. A circular disc, having a thickness and width substantially equal to the thickness and width of the electrode to be placed in the pocket, is formed in the distal end of the tongue to shape the pocket to the size of the electrode.

Abstract: A lead connector is disclosed for connecting cardiac pacing leads to a pulse generator through a cable. The lead connector is capable of receiving either in-line or bifurcated leads. The electrodes of the leads need not be of the same diameter due to the construction of a clamping assembly which clamps the lead electrodes to the connector electrodes. The clamping assembly includes a threaded shaft which receives a threaded nut that is retained in a clamping block. The clamping block is constructed so that it may rock relative to the shaft on a domed outer surface of the nut, thereby allowing clamping arms on the clamping block to press against the lead electrodes even if they are of different diameters. A second version of the connector has two clamping blocks and is capable of receiving either a bifurcated lead or an in-line lead, or alternately, both ventricular and atrial leads of either type at the same time.

Abstract: A biomedical stimulation lead for implanting in a living body having non-woven strands of fibrotic-inducing material attached to the distal tip of the lead for anchoring the lead in the body. The strands are sufficiently pliant to pull out of the fibrotic material along the path defined by the position of the strand within the fibrotic material, whereby the lead may be removed from the body with relatively minor trauma to body tissues.