Cardiac and pulmonary physiological analysis via intracardiac measurements with a single sensor

Electronic medical instrumentation for determining a plurality of physiological parameters related to a patient's heart activity, comprising in combination,

• detection means comprising measuring element means adapted to be located within a patient's heart with accompanying measuring means for producing a variable electrical signal containing one or more physiological parameters within the patient's heart varying with blood characteristics to include signal information responsive to both the intrathoracic pressure fluctuations acting on the heart from the patient's breathing and the internal heart activity,
• and separate signal processing channels including separation means for deriving from said variable electrical signal two subsignals respectively representative of the patient's breathing and internal heart activity for use in monitoring the patient's condition.

In a cardiac heartbeat pacing system, the improvement comprising in combination,

• electronic heart stimulating means for inducing pacing pulses, a bipolar electrode adatpted to be implanted within the heart of a patient to receive the pacing pulses for pacing a heart,
• measuring means for measuring a variable wholly within the heart representative of at least one physiological factor of the patient detected at said electrode in response to periodic pulmonary activity of the patient and deriving a signal of a frequency and amplitude that represents breathing rate and tidal volume and which does not interfere with pulses at the bipolar electrode for pacing the heart of the patient, and
• means for modulating the signal from the pacing pulses frequency as a function of the pulmonary activity measured by the measuring means.

In a cardiac pacing method for stimulating a heartbeat with an electronic stimulation signal induced in a stimulation electrode implanted in the heart of a patient, the improvement comprising in combination the steps of, deriving a variable signal representative of a parameter exhibited wholly within the heart from said electrode with which the stimulation signal does not interfere, establishing a control signal from a restricted range of lower frequency components of said variable signal excluding higher frequency heartbeat components for the patient being monitored representive of a physiological respiratory parameter of the patient critical to pacing, and controlling the stimulation signal as a function of the control signal.

The method of control of a heartbeat pacing system having a bipolar electrode implanted in a patient's heart and means for producing periodic electronic stimulation signals thereto to induce heartbeats, comprising the steps of:

• measuring the impedance at a position wholly within the heart by means of the implanted bipolar electrode to produce a variable intracardiac impedance signal indicative of dynamic instantateous physiological functioning of the lungs and heart, and
• modulating the periodic stimulation signals with a pulmonary function derived from the variable impedance signal.

The method of monitoring physiological functioning of the lungs and the heart during variations of workload exercise in a patient, comprising the steps of:

• developing characteristics of blood detected at an in-situ electrode within the heart in response to a variable signal having two periodic signal components respectively signifying the cardiac activity and the pulmonary activity of the patient, and
• separating the two periodic signal components for processing in separate channels responsive respectively to a lower frequency pulmonary activity and a higher frequency cardiac activity with said channels having a bandwith sufficient to identify modulations of rate and amplitude of the respective lower and higher frequency signal components for monitoring respectively pulmonary and cardiac activity.

The method of monitoring a patient's cardiac activity comprising the steps of detecting at only two separated positions within the heart of a patient a single variable impedance signal carrying separable signal components of two differing periodic frequency ranges respectively in a higher heartbeat rate range and a lower respiratory rate range, and monitoring respective signal components to obtain information pertaining to pulmonary and cardiac activity from frequency and amplitude variations of the respective two impedance signal components.

The method of monitoring cardiac conditions comprising the steps of determinig ventilatory parameters of a patient from an analysis of the influence of periodic intrathoracic pressure fluctuations in a signal detected by a detector electrode structure implanted wholly within the heart by a substep of isolating signal components in a restricted frequency range including the pulmonary rate and excluding the heartbeat rate with low pass filter means to derive a signal representative of said ventilatory parameters.

The method of operating a stimulus electrode with bipolar electrode structure implanted wholly within the heart to control a heartbeat pulse rate comprising the steps of operating the electrode structure in a concurrent mode as a detector of intracardiac impedance of a pulmonary parameter wholly within the heart that is critical to the heartbeat pulse rate, and controlling heartbeat pulse rate by stimulus to the electrode as a function of the pulmonary parameter.

A heart pacemaker system including pulse generator means for generating heart pacing pulses, comprising in combination, blood flow sensing means adapted to be located wholly within the heart coupled with means for deriving from a patient a signal modulated with a multiplicity of physiological functional parameters relating to the patient's condition, detection means responsive to said signal to provide sub-signal components representative of said physiological parameters for cardiovascular activity, and control means for changing the rate of the pacing pulses in response to the detected cardiovascular activity sub-signal components.