Minute ventilation dependent rate responsive pacer
First Claim
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1. An implantable rate responsive pacer arranged to be implanted in a patient and comprising:
- pacer control means for producing control pulses for controlling cardiac activity at a rate which is variable between selected upper and lower limits as a function of the metabolic demand of the patient;
means connected to said pacer control means for producing heart stimulation pulses in response to the control pulses; and
measurement circuit means responsive to respiratory activity of the patient for producing a signal representative of the change in volume of air in the patient'"'"'s lungs, corresponding to pulmonary minute ventilation, that is the quantity of air inhaled by the patient in unit time, said measurement circuit means being connected to said pacer control means for controlling the rate of the control pulses on the basis of the signal.
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Abstract
An electronic circuit included in a pacer detects the impedance between two electrodes connected to it and made up by the conducting part of the pacer case (B) and by an auxiliary subcutaneous lead placed in the chest or by an electrode placed on the insulating part (C) of the case itself. The changing geometry of the chest, due to pulmonary ventilation, determines the impedance variations. The electronic circuit, by processing the impedance signal is able to automatically adjust the stimulation rate of the ventricle and/or of the atrium between minimum and maximum preset values according to the activity levels of the patient.
129 Citations
17 Claims
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1. An implantable rate responsive pacer arranged to be implanted in a patient and comprising:
- pacer control means for producing control pulses for controlling cardiac activity at a rate which is variable between selected upper and lower limits as a function of the metabolic demand of the patient;
means connected to said pacer control means for producing heart stimulation pulses in response to the control pulses; and
measurement circuit means responsive to respiratory activity of the patient for producing a signal representative of the change in volume of air in the patient'"'"'s lungs, corresponding to pulmonary minute ventilation, that is the quantity of air inhaled by the patient in unit time, said measurement circuit means being connected to said pacer control means for controlling the rate of the control pulses on the basis of the signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- pacer control means for producing control pulses for controlling cardiac activity at a rate which is variable between selected upper and lower limits as a function of the metabolic demand of the patient;
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10. A control circuit for an active device implantable in a patient, the active device being operable at a controllable rate, and said control circuit producing an output signal which controls the operating rate of the active device, said control circuit comprising:
- means for detecting variations with respect to time in the geometry of at least part of the chest of the patient due to pulmonary ventilation and for producing a first signal representative of such variations; and
circuit means connected to said means for detecting variations, and responsive to the first signal, for producing a second signal which is representative of the change in volume of air in the patient'"'"'s lungs, corresponding to the patient'"'"'s minute ventilation and which constitutes the output signal from said control circuit. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
- means for detecting variations with respect to time in the geometry of at least part of the chest of the patient due to pulmonary ventilation and for producing a first signal representative of such variations; and
Specification