Implantable cardiac pacemaker
First Claim
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1. A heart pacemaker implantable in a patient, said pacemaker comprising:
- impedance responsive means constructed to be operatively associated with the patient for detecting impedance variations in the patient'"'"'s body which are at least in part dependent on the act of respiration and for deriving an impedance signal corresponding in value to such impedance variations;
signal extraction means connected to said impedance responsive means for deriving from the impedance signal a respiration dependent signal which undergoes a variation in value each time the value of the impedance signal exceeds a selected threshold value, whereby the respiration dependent signal is a periodic signal synchronized with respiration acts of the patient;
programmable signal generating means connected to said signal extraction means for deriving from the respiration dependent signal a stimulation control signal which is linearly proportional to the respiratory rate of the patient, between selected upper and lower limits;
heart stimulation means connected to said signal generating means for supplying stimulation signals to the patient'"'"'s heart at a rate controlled by the stimulation control signal; and
programming means operatively associated with said signal extraction means for adjusting the selected threshold value under control of programming signals delivered from outside the patient'"'"'s body.
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Abstract
An implantable cardiac pacemaker in which the stimulation rate is determined through a suitable programmable algorithm by the patient'"'"'s ventilation rate which is taken by measuring the impedance variations throughout a distance within the human body; preferably a distance within the thoracic region that goes between the pacemaker box and the lead which is placed subcutaneously. The pacemaker is constructed to detect variations, even rapid ones, of the corporeal impedance and to discriminate substantial variations attributable in all probability to a respiratory act, as well as to limit the drain of electrical energy.
265 Citations
27 Claims
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1. A heart pacemaker implantable in a patient, said pacemaker comprising:
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impedance responsive means constructed to be operatively associated with the patient for detecting impedance variations in the patient'"'"'s body which are at least in part dependent on the act of respiration and for deriving an impedance signal corresponding in value to such impedance variations; signal extraction means connected to said impedance responsive means for deriving from the impedance signal a respiration dependent signal which undergoes a variation in value each time the value of the impedance signal exceeds a selected threshold value, whereby the respiration dependent signal is a periodic signal synchronized with respiration acts of the patient; programmable signal generating means connected to said signal extraction means for deriving from the respiration dependent signal a stimulation control signal which is linearly proportional to the respiratory rate of the patient, between selected upper and lower limits; heart stimulation means connected to said signal generating means for supplying stimulation signals to the patient'"'"'s heart at a rate controlled by the stimulation control signal; and programming means operatively associated with said signal extraction means for adjusting the selected threshold value under control of programming signals delivered from outside the patient'"'"'s body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. In a heart pacemaker implantable in a patient, the pacemaker comprising:
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impedance responsive means constructed to be operatively associated with the patient for detecting impedance variations in the patient'"'"'s body which are at least in part dependent on the act of respiration and for deriving an impedance signal corresponding in value to such impedance variations, and heart stimulation means connected to the impedance responsive means for supplying stimulation signals to the patient'"'"'s heart at a rate controlled by the impedance signal, the improvement wherein said impedance responsive means are operative for monitoring the impedance between two selected points of the patient'"'"'s body in response to application of an electrical signal having a selected intensity between those points, and said impedance responsive means comprise;
two measuring electrodes installable at the selected points; and
means connected to apply between said electrodes a succession of pulses of the electrical signal having the selected intensity, the pulses being of short duration and the succession of pulses having a high ratio of pulse repetition period to pulse duration, whereby the impedance is monitored at regular intervals with low energy consumption. - View Dependent Claims (24, 25, 26)
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27. In a heart pacemaker implantable in a patient, the pacemaker comprising:
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detecting means constructed to be operatively associated with the patient for detecting variations in a parameter of the patient'"'"'s body and for deriving a signal corresponding in value to such variations, and heart stimulation means connected to the detecting means for supplying stimulation signals to the patient'"'"'s heart at a rate controlled by the signal, the improvement wherein said detecting means are operative for monitoring the parameter between two selected points of the patient'"'"'s body in response to application of an electrical signal having a selected intensity between those points, and said detecting means comprise;
two measuring electrodes installable at the selected points; and
means connected to apply between said electrodes a succession of pulses of the electrical signal having the selected intensity, the pulses being of short duration and the succession of pulses having a high ratio of pulse repetition period to pulse duration, whereby the parameter is monitored at regular intervals with low energy consumption.
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Specification