Apparatus and method for determining a plurality of hemodynamic variables from a single, chroniclaly implanted absolute pressure sensor

• US 5,368,040 A
• Filed: 08/02/1993
• Issued: 11/29/1994
• Est. Priority Date: 08/02/1993
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Carney, James K.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/100,881
• Time in Patent Office: 484 Days
• Field of Search: 128/670, 128/672, 128/673, 128/700
• US Class Current: 600/513
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36564 controlled by blood pressure

Abstract

A method and apparatus for monitoring and measuring the hemodynamic status of a patient'"'"'s pulmonary pressure and right atrial pressure. The aforementioned is achieved by using an implanted absolute pressure sensor located in the right ventricle, coupled to an implantable monitoring device, which records pressure values in response to a combination of sensed electrical depolarizations of the atrium and ventricle and occurrence of first and second derivatives of the pressure signal having values less than zero.

Claims

1. A method of pressure monitoring employing an absolute pressure sensor, which provides an output signal having an amplitude which varies according to pressure, comprising:

implanting said absolute pressure sensor in said right ventricle of said patient;

deriving a first derivative of said output signal;

deriving a second derivative of said output signal;

providing said output signal to first, second and third holding means for storing signal amplitudes;

enabling said first holding means and said second holding means in response to occurrence of an R-wave;

thereafter storing a first output signal amplitude in said first holding means in response to said first derivative being less than zero, wherein said first stored output signal amplitude is equal to said patient'"'"'s pulmonary artery systolic pressure and, storing a second output signal amplitude in said second holding means in response to said second derivative being less than zero, wherein said second stored output value is equal to said patient'"'"'s pulmonary artery diastolic pressure;

enabling said third holding means in response to occurrence of a P-wave;

thereafter storing a third output signal amplitude in said third holding means in response to said first derivative being less than zero, wherein said third stored output signal amplitude is equal to said patient'"'"'s right atrial systolic pressure;

delaying said output signal; and

storing an amplitude of said delayed output signal in a fourth holding means for storing signal amplitudes in response to occurrence of said P-wave, wherein said stored amplitude of said delayed output signal is equal to said patient'"'"'s right atrial diastolic pressure.

2. A method of pressure monitoring employing an absolute pressure sensor, which provides an output signal having an amplitude which varies according to pressure, comprising:

implanting said absolute pressure sensor in said right ventricle of said patient;

deriving a first derivative of said output signal;

deriving a second derivative of said output signal;

providing said output signal to first and second holding means for storing signal amplitudes;

enabling said first and second holding means in response to occurrence of an R-wave; and

thereafter storing a first output signal amplitude in said first holding means in response to said first derivative being less than zero, wherein said first stored output signal amplitude is equal to said patient'"'"'s pulmonary artery systolic pressure and storing a second output signal amplitude in said second holding means in response to said second derivative being less than zero, wherein said second stored output value is equal to said patient'"'"'s pulmonary artery diastolic pressure.

3. A method of pressure monitoring employing an absolute pressure sensor, which provides an output signal having an amplitude which varies according to pressure, comprising:

implanting said absolute pressure sensor in said right ventricle of said patient;

deriving a first derivative of said output signal;

providing said output signal to a first holding means for storing signal amplitudes;

enabling said first holding means in response to occurrence of a P-wave;

thereafter storing a first output signal amplitude value in said first holding means in response to said first derivative value being less than zero, wherein said first stored output signal amplitude is equal to said patient'"'"'s right atrial systolic pressure;

delaying said output signal; and

storing an amplitude of said delayed output signal in a second holding means for storing signal amplitudes in response to said P-wave, wherein said second stored output signal amplitude is equal to said patient'"'"'s right atrial diastolic pressure.

4. A pressure monitoring system, comprising:

an absolute pressure sensor means for providing an output signal having an amplitude which varies according to pressure, adapted to be implanted in a patient'"'"'s right ventricle;

means for detecting R-waves;

means for detecting P-waves;

means for deriving a first derivative of said output signal;

means for deriving a second derivative of said output signal;

first holding means coupled to said pressure sensor, enabled in response to detection of an R-wave, for thereafter storing a first output signal amplitude in response to said first derivative being less than zero;

second holding means coupled to said pressure sensor, enabled in response to detection of an R-wave, for thereafter storing a second output signal amplitude in response to said second derivative being less than zero;

third holding means coupled to said pressure sensor, enabled in response to detection of an P-wave, for thereafter storing a third output signal amplitude in response to said first derivative being less than zero;

delay means coupled to said pressure sensor for providing a delayed output signal; and

fourth holding means coupled to delay means, for storing an amplitude of said delayed output signal in response to detection of a P-wave.

5. A pressure monitoring system, comprising:

an absolute pressure sensor means for providing an output signal having an amplitude which varies according to pressure, adapted to be implanted in a patient'"'"'s right ventricle;

means for detecting R-waves;

means for deriving a first derivative of said output signal;

means for deriving a second derivative of said output signal;

first holding means coupled to said pressure sensor, enabled, in response to detection of an R-wave, for thereafter storing a first output signal amplitude in response to said first derivative being less than zero; and

second holding means coupled to said pressure sensor, enabled in response to detection of an R-wave, for thereafter storing a second output signal amplitude in response to said second derivative being less than zero.

6. A pressure monitoring system, comprising:

an absolute pressure sensor means for providing an output signal having an amplitude which varies according to pressure, adapted to be implanted in a patient'"'"'s right ventricle;

means for detecting P-waves;

means for deriving a first derivative of said output signal;

first holding means coupled to said pressure sensor, enabled in response to detection of an P-wave, for thereafter storing a first output signal amplitude in response to said first derivative being less than zero;

delay means coupled to said pressure sensor for providing a delayed output signal; and

second holding means coupled to delay means, for storing an amplitude of said delayed output signal in response to detection of a P-wave.