Siemens Aktiengesellschaft

Pacesetter Ab

Siemens-pacesetter, Inc.

Roland Heinze

Karl Stangl

Hans D Liess

Hans-Dieter Liess

Anders Lekholm

Alexander Wiertzfeld

Alexander Wirtzfeld

Hakan Elmqvist

Arrangement, particularly a heart pacemarker, for acquiring a

An electrode arrangement for a cardiac defibrillator includes one or more physiological sensors disposed in an electrode carrier for planar application against the exterior of the heart. The sensor contained in the electrode carrier is connected to a housing, containing a defibrillation power source and signal processing circuitry, via a sensor line, and the electrical signals obtained from the sensor are used for controlling operation of the defibrillator.

Electrode arrangement for a defibrillator

Method for adapting the stimulation frequency of a heart pacemaker to

A rate-responsive pacing method and system senses the minimum blood oxygen saturation in the right atrium of a patient's heart and uses such minimum blood oxygen saturation as a control parameter for indicating the muscular activity of a patient. Because the oxygen content of the venous blood in the right atrium varies significantly as venous blood from all parts of the body is introduced therein, evidencing differing levels of oxygen demand throughout the patient's body, the minimum oxygen content of the venous blood provides an accurate and reliable measure of those portions of the patient's body experiencing the greatest oxygen demand, i.e., experiencing muscular activity. A rate-responsive pacing system includes means for sensing the minimum oxygen content in the right atrium over a prescribed time interval, and using such minimum oxygen content as a control parameter for adjusting the rate of the pacemaker.

Rate-responsive pacing method and system employing minimum blood oxygen

A catheter of the type suitable for implantation in a human heart has a catheter tip and a preset curvature spaced along the catheter a distance from the tip. The catheter includes an integrated measuring probe with a measurement window, the measuring probe and window being disposed between the tip and the preset curvature at respective distances from each so that, given the aforementioned location of the catheter tip, it is insured that the measurement window of the probe will not lie against a wall of the heart, which would degrade the operation of the measuring probe, and moreover insures that the measuring probe and measurement window will be disposed at an optimum location for undertaking the desired measurement.

Catheter for implantation in the heart, having an integrated measuring

A sensor arrangement for controlling an implantable device, such as a heart pacemaker, has a number of individual sensors connected to an evaluation circuit through a catheter having at least two leads. The sensors are respectively activated in chronological succession by a shared control circuit, with both the sensors and the control circuit being arranged in the catheter. The corresponding measured signals are transmitted via the same leads, and also being offset chronologically. The arrangement permits a number of sensors to be connected to a catheter while maintaining only two lines in the catheter, so that the flexibility and reliability of the catheter, which are best with the fewest possible leads, remain unimpaired.

Sensor arrangement for the control of implantable devices

An implantable arrangement for operating a body-assist device, the body-assist device including circuitry for generating electrical signals and also being implanted in a patient, includes circuitry for controlling the generation of the electric signals, a measuring probe in the patient for obtaining signals to be used by the control circuitry, a single current conductor electrically connecting the control circuitry and the measuring probe and forming a first current path therebetween, and spaced electrodes connected to the measuring probe and the control circuitry disposed in the patient with body tissue therebetween such that a second current path is formed in the body tissue.

Measuring arrangement for controlling an implantable body-assist device

A follower control matches the stimulation frequency of a heart pacemaker to patient load condition by obtaining measurement values S.sub.02 corresponding to the central venous blood oxygen saturation in the heart according to the principle of reflection oximetry, by forming control values B.sub.S1 according to the quotient .DELTA.S.sub.02 /.DELTA.S.sub.02max where the numerator is the difference between the current measurement value and a stored reference value (e.g. S.sub.02max or S.sub.02min) and the denominator serves to standardize the control value based on the maximum change of the measurement value over a relatively long time interval, and by changing the stimulation frequency by an amount dependent on the magnitude of the control value. Preferably, the stimulation frequency f.sub.p is set directly as a function of the control value B.sub.S1 and most preferably according to the function ##EQU1## where f.sub.min is a prescribed minimum frequency, .DELTA.f.sub.max is the maximum frequency difference, c.sub.w is a programmable constant and .DELTA.f.sub.opt is a frequency change introduced by a concurrently operating optimizing control. Artifacts are avoided by obtaining measurement values at sampling intervals distributed in the time span between heart beats and varying in phase during each measurement cycle, and then selecting the minimum measurement value occurring in each measurement cycle.

System and method for controlling the stimulation frequency of heart

A measuring instrument for obtaining an intracardial signal indicative of blood oxygen saturation, which may be used to control the stimulation frequency of a heart pacemaker, has a measuring probe which contains a light transmitter and a light receiver. The light receiver receives light from the light transmitter reflected by the blood. The light transmitter and the light receiver are connected in parallel to an evaluation circuit via two leads. A constant current source is connected in series with the light transmitter. The current generated by the light receiver, indicative of blood oxygen saturation, can be identified by forming the difference between current flowing in the measuring probe and the constant current. A reference measurement to compensate for factors in the total current resulting from the lead resistances and the measuring probe temperature is not necessary.

Measuring instrument for intracardial acquisition of blood oxygen

An apparatus for impedance measurement of body tissue has a signal source which impresses an electrical signal in body tissue, circuitry for acquiring an impedance signal from the body tissue dependent on the impressed electrical signal, and an evaluation stage for evaluating the impedance signal by filtering higher frequency components and low frequency components from the impedance signal which correspond to the conductance of the tissue. A correction stage corrects the high frequency signal components with the low frequency signal components by eliminating the higher frequency signal components of influences due to changes in the tissue conductance. The corrected signal is supplied at an output of the correction stage.

Apparatus and method for impedance measurement of body tissues

A measuring instrument for the intracardial acquistion of the blood oxygen saturation of a patient for use in controlling a heart pacemaker implanted in the patient has a measuring probe with a measuring current path which includes a light transmitter and a light receiver which receives light emitted by the light transmitter and reflected by the blood. The measuring probe is connected to an evaluation circuit via two lines. A useful signal measurement and a reference measurement, independent of the blood reflection, are made and the blood oxygen saturation is identified by comparing the two signals. A separate evaluation of the useful signal measurement and the reference signal measurement is enabled by making the useful signal measurement chronologically offset with respect to the reference measurement in one embodiment, or by using the amplitude of the current from the light receiver to make one measurement, and using the voltage amplitude to make the other measurement in another embodiment.

Measuring instrument for intracardial acquisition of the blood oxygen

An apparatus for measuring the impedance of body tissue has a signal source connected to the tissue to be measured which supplies an electrical signal to the tissue, a unit for acquiring an impedance signal from the body tissue dependent on the electrical signal, and an evaluation stage for the impedance signal. The evaluation stage filters out low frequency signal components corresponding to the conductance of the tissue, and has a signal output to which the signal components which were filtered out are supplied.

Apparatus for measuring impedance of body tissue

The stimulation frequency of a heart pacemaker is controlled dependent on a signal representative of the blood oxygen content of the patient. The blood oxygen dependent signal is generated by a blood oxygen sensor. A temperature sensor generates a separate signal dependent on blood temperature. The blood oxygen and blood temperature signals are combined such that the blood oxygen signal is lowered, i.e., the value thereof is reduced, in ranges of higher physical load indicated by an increase in the temperature dependent signal. The combined signal is used to control the stimulation frequency of a heart pacemaker so that the stimulation frequency is increased, if blood oxygen saturation is decreasing and/or blood temperature is increasing.

Frequency-controlled heart pacemaker

A measurement device for frequency control of a heart pacemaker based on the level of blood oxygen saturation contains a measuring probe which includes a light transmitter and a light receiver. The light receiver receives the light emitted by the light transmitter and reflected by the blood. The light transmitter and the light receiver are connected in parallel to an evaluation circuit via two common lines, this evaluation circuit charging the measuring probe with a constant current or with a constant voltage. A resistor is arranged in series with the light receiver. A transistor is arranged parallel to this series circuit, the base thereof being connected to the junction of the resistor and the light receiver. By means of this arrangement, the measurement sensitivity given deposits on the probe is maintained at a higher level. In an alternative embodiment, this can also be achieved using a resistor in series with the light transmitter with a transistor controlled by the light receiver connected in parallel therewith.

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Munich, Germany

Roland Heinze