System for and method of therapeutic stimulation of a patient's heart

A method of therapeutic stimulation of a patient's heart comprising:

• sensing mean pressure at a site in circulatory system of said patient during a current period and a baseline period of respective given duration;
• comparing mean pressure at the site as determined over said baseline period of given duration with mean pressure at the site as determined over said current period of given duration, said current period of given duration being less than the duration of the baseline of given duration, to find if the determined means pressures at the site differ by at least a predetermined amount;
• sensing at least one physiological variable of the patient;
• and
• controlling escape interval or rate of a pacing system alternatively based on the at least one physiological variable whenever the determined mean pressures at the site differ by less than the predetermined amount and based, on pressure at the site whenever the mean pressures differ by at least the predetermined amount.

In a system for therapeutic stimulation of a patient's heart and which includes means for varying escape interval or rate of a means for producing pacing pulses, an improvement comprising means for sensing pressure at a site in circulatory system of a patient, means responsive to output from the sensing means for developing a variable first signal representative of mean pressure at the site over a period of predetermined duration, means responsive to output from the sensing means for developing a variable second signal representative of mean pressure at the site over a period of given duration less than the period of predetermined duration, means responsive to the first variable signal and to the second variable signal for developing a stored first signal upon the first variable signal and the second variable signal differing by at least a predetermined amount, means responsive to the stored first variable signal and to the second variable signal for developing a first control signal whenever the first variable signal and the second variable signal differ by at least a given amount, means responsive to a signal dependent on at least one physiological variable for developing a second control signal, and means for alternatively supplying the first control signal and the second control signal to the means for varying the escape interval or rate of the means for producing pacing pulses, the second control signal being supplied in absence of the first control signal and the first control signal being supplied, when present, to exclusion of the second control signal, whereby the escape interval or rate may be determined alternatively by the at least one physiological variable and the hemodynamic pressure at a site in said circulatory system.

A method of therapeutic stimulation of a patient's heart comprising:

• sensing pressure at a site in circulatory system of a patient;
• comparing means pressure at the site as determined over a period of predetermined duration with mean pressure at the site as determined over a current period of given duration less than the duration of the period of predetermined duration to find if the determined mean pressures at the site differ by at least a predetermined amount;
• storing a representation of the mean sensed pressure at the site as determined over a period of predetermined duration at the time the sensed means pressure differed by at least the predetermined amount;
• comparing the stored representation of the sensed mean pressure with mean sensed pressure at the site as determined over a current period of the given duration to determine if current mean pressure at the site differs from the stored representation by at least a given amount;
• sensing at least one physiological variable of the patient;
• and
• controlling escape interval or rate of a pacing system alternatively based on said at least one physiological variable upon determine that mean pressures at the site differ by less than the given amount and based upon current mean pressure at the site differing from the stored representation of the mean pressure by at least the given amount.