Cordis Corporation

Telectronics N.v.

Cordis Leads, Inc.

Edward A Schroeppel

Gerrit Koning

Peter P Tarjan

Peter J Pohndorf

Stanley H Saulson

Frank J Callaghan

Van E Mumford

Louis Sasmor

A system is provided for cardiac pacing, in which the output levels of the electrical stimulus pulses are responsive to the detection or non-detection of cardiac pacer evoked potentials. A pulse generator is provided for emitting electrical stimulus pulses at variable output levels. A pulse to pulse interval and an evoked response sensing period are provided. At the beginning of the pulse to pulse interval, an electrical stimulus having a first output level is emitted. If no evoked response is sensed during the sensing period, then an electrical stimulus at a selected maximum output level is emitted and, thereafter, the next electrical stimulus pulse is emitted at a second output level that is greater than the first output level. If a predetermined number of evoked responses are sensed during the sensing periods following the emission of stimulation pulses at other than the maximum output level, then the output level of the next electrical stimulus is decreased, but not to below a selected minimum output level.

System for cardiac pacing

Automatic detection of cardiac pacer evoked potentials may be obtained through a cardiac pacer lead positioned in a heart chamber. An electrical stimulus is emitted in unipolar mode from a first electrode to stimulate muscular contraction. The cardiac electrical activity evoked by the stimulus is then detected in unipolar mode by a second electrode which is spaced from the first electrode and free of electrical connection thereto. Accordingly, signal interference caused by residual polarization of the first electrode is suppressed. The natural cardiac electrical activity is sensed in a bipolar mode, and the pulse is inhibited if a heartbeat is detected within an alert period.

Detection of cardiac evoked potentials

A method for cardiac pacing and sensing is disclosed. A cardiac pacing lead is inserted into a heart chamber. The lead carries a plurality of separate electrodes positioned at the distal tip of the lead and transversely spaced from and electrically isolated from each other. A separate electrical conductor is provided for each electrode. A plurality of the electrodes are combined via electrical conductors to provide a relatively large electrode area for sensing cardiac activity. One of the electrodes is used for providing pacing pulses to the heart chamber. The pacing electrode has a relatively smaller surface area than the relatively large surface area used for sensing.

Method for cardiac pacing and sensing using combination of electrodes

The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output while the person is exercising, comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. a microprocessor) therein, a pacing lead adapted to be implanted in a heart and having a distal electrode adapted to engage and supply pacing pulses to a right ventricle of a heart, and a pO.sub.2 sensor for sensing pO.sub.2 of the blood in the heart. An algorithm or routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to relate pO.sub.2 and/or .DELTA.pO.sub.2 with the required heart rate or change in heart rate, .DELTA.R, needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.

Apparatus and method for adjusting heart/pacer rate relative to cardiac

The apparatus is used for sensing opening and closing of a tricuspid valve in a heart, for using those sensings to determine stroke volume, and for controlling pacing of a heart relative to changes in stroke volume. The apparatus comprises a pacer, a pacing lead coupled to the pacer and having a lead body, a pressure sensor mounted in the lead body and a pacing electrode, circuit means in the pacer coupled to the sensor for sensing the opening of the tricuspid valve during each heart cycle and for sensing the closing of the tricuspid valve during each heart cycle; means for calculating ejection time from the openings and closings of the tricuspid valve; means for calculating the change in ejection time, .DELTA.ET, from calculations of ejection time; means for calculating changes in stroke volume, .DELTA.SV, means for determining the required change in heart rate, .DELTA.R, relative to the change in stroke volume, .DELTA.SV; and means for adjusting the pacing rate of said pacer relative to the required change in heart rate, .DELTA.R.

Apparatus for controlling pacing of a heart in response to changes in

The apparatus paces a heart in accordance with the heart/pacer rate needed to produce a required cardiac output while a person is exercising or undergoes emotional stress in response to changes in venous blood vessel diameter. The apparatus includes a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry, which may be realized by a microprocessor, therein; a pacing lead adapted to be implanted in a heart having a tip electrode adapted to engage and supply pacing pulses to a right ventricle of a heart; a piezoelectric sensor for determining changes in diameter of a vein in the human body; and computing circuitry including the control circuitry, for relating the changes in venous blood vessel diameter with the required pacing rate needed to supply a desired cardiac output and for causing the pacer to pace the heart at the required rate when the heart is not naturally paced.

Apparatus and method for adjusting heart/pacer relative to changes in

A cardiac pacer is provided which includes a pulse generator for providing pacing pulses and an electrical lead for connection to a chamber of the heart. A pair of separate sensing amplifiers sense selected activity of the heart chamber. One of the sensing amplifiers has a slightly lower threshold and thus a slightly higher sensitivity level than the other sensing amplifier. The thresholds of the respective sensing amplifiers are automatically adjusted so that the first sensing amplifier will sense the selected activity of the heart chamber and the other sensing amplifier will not sense the selected activity.

Automatic sensitivity control for cardiac pacer

The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output while the person is exercising, comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. including a microprocessor) therein, a pacing lead adapted to be implanted in a right ventricle in a heart and having a distal electrode adapted to engage and supply pacing pulses to the apex of the right ventricle and a pressure sensor or impedance sensing electrode mounted in or on the lead. An algorithm and routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to (a) relate right ventricular pressure to duration of contraction to determine ejection time and changes in ejection time or (b) to relate impedance and changes in impedance to blood volume or changes in volume, to relate blood volume and changes in blood volume to opening and closing of the pulmonary valve and to determine each time period between each opening and closing to determine ejection time and changes in ejection time and to correlate ejection time or changes in ejection time with the required heart rate needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.

Apparatus and method for adjusting heart/pacer rate relative to ejection

The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output relative to the partial pressure of carbon dioxide in the blood, pCO.sub.2, while the person is exercising comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. including a microprocessor) therein, a pacing lead adapted to be implanted in a heart and having a distal electrode adapted to engage and supply pacing pulses to a right ventricle of a heart and a pCO.sub.2 sensor for sensing pCO.sub.2 of the blood in the heart. An algorithm and routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to relate pCO.sub.2 with the required heart rate or change in rate, .DELTA.R, needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.

A method for sensing opening and closing of a tricuspid valve in a heart, for using those sensings to determine stroke volume, and for controlling pacing of a heart relative to changes in stroke volume, utilizing a pacing lead having a lead body and a pressure sensor mounted in the lead body, said method comprising the steps of: sensing the opening of the tricuspid valve during each heart cycle; sensing the closing of the tricuspid valve during each heart cycle; determining ejection time from the openings and closings of the tricuspid valve; calculating the change in ejection time, .DELTA.ET, from determinations of ejection time; calculating changes, in stroke volume, .DELTA.SV,; determining the required change in heart rate, .DELTA.R, relative to the change in stroke volume, .DELTA.SV,; and adjustng the pacing rate of a pacer relative to the required change in heart rate, .DELTA.R.

Method for controlling pacing of a heart in response to changes in

The pacing lead includes a catheter distal end portion which has a piezoelectric device therein and which is adapted to be inserted into a human heart. The device can be a ceramic bimorph or can be made of polyvinylidene fluoride film for generation of electrical energy upon contraction of the heart. The piezoelectric device is designed to generate electrical energy in response to movement of the implanted pacing lead and in the preferred embodiment is incorporated into the wall of the catheter of the lead as a longitudinal or spiral configured strip of film having piezoelectric properties.

Pacing lead with piezoelectric power generating means

The apparatus and method are utilized in controlling an implanted device, such as a cardiac pacer, by use of acoustic vibrations generated by a tuning fork. These vibrations are applied externally to the skin overlying the implanted device and are sensed by a transducer within the implanted device. The transducer generates an electrical signal of a frequency correlated to the tuning fork frequency. An amplifier and tuned filter are utilized to detect predetermined frequencies within the electrical signals produced by the transducer and to direct the processed signals to a programmable electronic device for control of the implanted device.

Implant and control apparatus and method employing at least one tuning

An electronic electrode switching/selection circuit minimizes the number of feedthroughs from a pacer case to a pacer neck needed to connect with pacing lead electrodes that will be actively used during operation of a pacer. These feedthroughs can be electronically connected with the desired electrode by the physician either at the time of initial implantation or at any time subsequent thereto as may be required. The electronic connection to a feedthrough may be dedicated to a single feedthrough/electrode or electrode pair or the electrodes may be electronically sampled by circuitry in the pacer. The electrode switching/selection circuit may be located in the pacer neck, in an adapter between the pacer neck and a multielectrode lead, or in a multielectrode lead. Preferably, zener protection diodes are also provided which are connected ahead of the pacing circuitry before or after the electrode switching/selection circuit. These zener protection diodes may be located in the pacer neck, in the adapter, or in the multielectrode lead, according to the location of the electrode switching/selection circuit.

Method and means of electrode selection for pacemaker with

The pacing lead with sensor is adapted to be inserted into a human heart and includes a piezoelectric device, such as a bimorph, for sensing the occurrence of a phenomenon in the heart. The piezoelectric device can be positioned in the heart while the signal it generates is carried outside the heart, where it can be utilized. The piezoelectric device of the present invention is designed to indicate a phenomenon occurring, and can measure the absolute and/or relative value of the phenomenon such as pressure. As a result, the piezoelectric device utilized is easy to construct and manufacture, and may be used without complicated equipment.

Pacing lead with sensor

A fully implantable programmable cardiac pacer includes two main pacing channels driven by a crystal oscillator circuit. For each channel, amplitude and pulse width are programmed in paired combinations corresponding to monotonically increasing charge density. Selectively combinable constant current sources are shared by each channel. A low battery indicator system samples battery voltage relative to two threshold levels. In magnet rate, if the main battery voltage is above the first threshold, the fixed pacer output will be 70 beats per minute. If the battery voltage is between the first and second threshold levels, the fixed pacer output will be 62.5 beats per minute. An emergency RC oscillator continuously produces an output at 52.5 beats per minute and one millisecond pulse width. The emergency output is switched directly to the output of channel 2 when either the low battery voltage falls below the second threshold or the crystal oscillator frequency changes when tested by a frequency checking circuit using the output of the RC oscillator as a reference clock. An emergency battery is coupled to the main battery via a diode steering circuit which allows the remaining capacity to be combined with that of the emergency battery.

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Miramar, FL, United States of America

Edward A Schroeppel