Stroke volume controlled pacer

• US 4,535,774 A
• Filed: 06/30/1983
• Issued: 08/20/1985
• Est. Priority Date: 06/30/1983
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Olson, Walter H.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Shein, Mitchell J.
• Application Number:
  US06/509,573
• Time in Patent Office: 782 Days
• Field of Search: 128/419 P, 128/419 PG, 128/713
• US Class Current: 607/24
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance

Abstract

A rate responsive pacer which paces the heart at a rate dependent on detected variations in the stroke volume of the heart.

Claims

1. A cardiac pacer for the therapeutic stimulation of a heart comprising:

lead system means for coupling said pacer to the patient'"'"'s heart;

measuring means coupled to said lead for inferring the stroke volume of said heart from the measurement of a physiologic parameter and for producing a measurement indicative of stroke volume;

computation and control means coupled to said measuring means for determining a heart rate value in response to said stroke volume measurements wherein said heart rate is defined as the V--V interval;

means for comparing the value of said stroke volume measurement with the value of a stroke volume set point for producing a stroke volume difference value;

means for determining a heart rate difference value, wherein said heart rate value is defined as the V--V interval, from said stroke volume difference value;

means for adding said heart rate difference value to the previous heart rate value yielding a current, heart rate value; and

pulse generator means coupled to said lead system and said computational and control means for providing stimulation pulses to said heart at a frequency which is a function of said heart rate value.

4. The cardiac pacer of claim 1 or claim 2 or claim 3 wherein said computation and control means further includes:

means for determining said stroke volume set point value from said heart rate value.

2. A cardiac pacer for the therapeutic stimulation of a heart comprising:

measuring means for periodically inferring the stroke volume of said heart and for roducing a sequence of stroke volume measurements;

pulse generator means for providing stimulation pulses to said heart at a frequency proportional to a heart rate value wherein said heart rate value is defined as the V--V interval;

means coupled to said measuring means and coupled to said pulse generator means for determining said heart rate value in response to stroke volume measurement;

means for comparing the value of said stroke volume measurement with the value of a stroke volume set point for producing a stroke volume difference value;

means for determining a heart rate difference value, wherein said heart rate value is defined as the V--V interval, from said stroke volume difference value; and

means for adding said heart rate difference value to the previous heart rate value yielding a current, heart rate value.

3. A cardiac pacer for the therapeutic stimulation of a heart comprising:

measuring means for measuring the ventricular volume of said heart at end diastole and at end systole and for inferring a stroke volume measurement from said end systolic and end diastolic measurements;

pulse generator means for providing stimulation pulses to said heart at a frequency proportional to a heart rate value wherein said heart rate value is defined as the V--V interval;

computational control means coupled to said measuring means and coupled to said pulse generator means for determining said heart rate value in response to the stroke volume measurement;

means for comparing the value of said stroke volume measurement with the value of a stroke volume set point for producing a stroke volume difference value;

means for determining a heart rate difference value, wherein said heart rate value is defined as the V--V interval, from said stroke volume difference value; and

means for adding said heart rate difference value to the previous heart rate value yielding a current, heart rate value.

5. A method of controlling the escape rate of a pacer comprising the steps of:

(a) measuring the cardiac stroke volume;

(b) comparing the measured stroke volume with a stroke volume set point value yielding a stroke volume variation value;

(c) calculating a heart rate variation value from said stroke volume variation value;

(d) adding said heart rate variation value to an existing value of heart rate yielding a heart rate summation value;

(e) calculating an updated heart rate value from said heart rate summation value; and

(f) setting said escape rate in response to said updated heart rate value.

6. A method of controlling the escape rate of a pacer comprising the steps of:

(a) measuring the cardiac stroke volume;

(b) comparing the measured stroke volume with a stroke volume set point value yielding a stroke volume variation value;

(c) calculating a heart rate variation value from said stroke volume variation value;

(d) adding said heart rate variation value to an existing value of heart rate yielding a heart rate, summation value;

(e) calculating an updated heart rate value from said heart rate summation value;

(f) setting said escape rate in response to said updated heart rate value; and

(g) calculating a stroke volume set point value from said heart rate value.