CARDIAC OUTPUT ESTIMATION USING PULMONARY ARTERY PRESSURE

• US 20100056931A1
• Filed: 08/18/2009
• Published: 03/04/2010
• Est. Priority Date: 08/26/2008
• Status: Abandoned Application

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Soffer, Leah, Sachanandani, Haresh G., Zhang, Yunlong, Mi, Bin
• Application Number:
  US12/543,227
• Publication Number:
  US 20100056931A1
• Time in Patent Office: Days
• US Class Current: 600/486
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

A system and method sense a pressure signal in a pulmonary artery and compute a stroke volume and cardiac output. A pressure signal is received from an implantable pressure sensor disposed in a pulmonary artery. The pressure signal includes a systolic period and a diastolic period for determining a heart rate (HR) and a heart cycle. An iteratively-updating model can relate pressure signal and HR to a stroke volume (SV) and a cardiac output (CO). The model extracts a mean pulse pressure (MPP) from the PAP signal and receives a patient-specific vascular resistance model parameter and a patient-specific arterial compliance model parameter. CO can be calculated using the HR, the PAP signal, and the model. The vascular resistance model parameter and the arterial compliance model parameter are iteratively updated using the output of the model.

Claims

1. An apparatus comprising:

an input receiving a pressure sensor signal from an implantable pressure sensor;

an output providing an output signal used to calculate a cardiac output;

a memory configured to store a patient-specific vascular resistance model parameter and a patient-specific arterial compliance model parameter; and

a processor coupled to the input, the output and the memory, wherein the processor is configured to;

receive the pressure sensor signal, the pressure sensor signal including a systolic period and a diastolic period;

determine a heart rate (HR) of a heart cycle;

provide an iteratively-updating model that relates the pressure sensor signal and HR to at least one of a stroke volume (SV) and a cardiac output (CO), and that extracts a measure of a pulse pressure derived from the pressure sensor signal, the model using a patient-specific vascular resistance model parameter and a patient-specific arterial compliance model parameter;

calculate the CO using the HR, the pressure sensor signal, and the model;

iteratively update the patient-specific vascular resistance model parameter using the output signal from the model; and

iteratively update the patient-specific arterial compliance model parameter using the output signal from the model.

2. The apparatus of claim 1, wherein the implantable pressure sensor includes a pulmonary artery pressure (PAP) sensor disposed in a pulmonary artery of a patient and configured to generate the pressure sensor signal.

3. The apparatus of claim 1, wherein the processor receives a patient-specific vascular impedance model parameter stored in the memory.

4. The apparatus of claim 1, wherein the processor is configured to determine a pulmonary blood flow profile over the heart cycle using the pressure sensor signal, the vascular resistance model parameter and the arterial compliance model parameter that are stored in the memory.

5. The apparatus of claim 1, wherein the processor is configured to determine the stroke volume by integrating the pulmonary blood flow profile over the heart cycle.

6. The apparatus of claim 1, wherein the processor is configured to determine a second arterial compliance model parameter using the pressure sensor signal.

7. The apparatus of claim 6, wherein the processor is configured to determine the second arterial compliance model parameter using the stroke volume and a pulse pressure extracted from the pressure sensor signal.

8. The apparatus of claim 4, wherein the processor is configured to determine a second vascular resistance model parameter using the pressure sensor signal.

9. The apparatus of claim 8, wherein the processor is configured to determine a second vascular resistance model parameter using a central tendency of the pressure sensor signal and a central tendency of the pulmonary blood flow profile over the heart cycle.

10. The apparatus of claim 8, wherein the processor is configured to replace the vascular resistance model parameter with the second vascular resistance model parameter.

11. The apparatus of claim 6, wherein the processor is configured to replace the arterial compliance model parameter with the second arterial compliance model parameter.

12. The apparatus of claim 2 configured to filter and down-sample the pressure sensor signal and generate a pulmonary blood flow profile.

13. The apparatus of claim 1, wherein the processor is configured to determine the heart rate and the heart cycle by identifying the systolic period and the diastolic period in the pressure sensor signal.

14. The apparatus of claim 13, wherein the processor is configured to identify the systolic period and the diastolic period by identifying a dicroctic notch in the pressure sensor signal during the heart cycle.

15. The apparatus of claim 14, wherein the processor identifies the dicrotic notch using peak detection.

16. The apparatus of claim 14, wherein the processor identifies the dicrotic notch using a physiological signal generated from a second physiological sensor.

17. The apparatus of claim 16, wherein the second physiological sensor includes at least one of a heart sound sensor or an ECG monitor.

18. The apparatus of claim 1, wherein the processor is configured to determine a central tendency of the CO over a specified number of heart cycles.

19. The apparatus of claim 1, comprising a posture sensor as an input to normalize cardiac output calculations.

20. The apparatus of claim 1, comprising attenuating a respiration effect of the patient from the calculated CO.

21. The apparatus of claim 1, wherein the processor is disposed in an implanted device capable of being communicatively coupled to the implantable pressure sensor

22. The apparatus of claim 21, wherein the implantable medical device is configured to communicate with an external device.

23. The apparatus of claim 1, wherein the processor is disposed in an external device capable of being communicatively coupled to the implantable pressure sensor.

24. A system comprising:

means for receiving a pulmonary artery pressure (PAP) signal from a pulmonary artery pressure sensor disposed in a pulmonary artery of a patient, the PAP signal including a systolic period and a diastolic period;

means for determining a heart rate (HR) of a heat cycle;

means for providing an iteratively-updating model that relates PAP and HR to at least one of a stroke volume (SV) and a cardiac output (CO), and that extracts a measure of central tendency of pulse pressure (MPP) from the PAP, the model using a patient-specific vascular resistance model parameter and a patient-specific arterial compliance model parameter;

means for calculating the CO using the HR, the PAP signal, and the model;

means for iteratively updating the patient-specific vascular resistance model parameter using the model outputs; and

means for iteratively updating the patient-specific arterial compliance model parameter using the model outputs.

25. The system of claim 24, wherein the means for receiving a pulmonary artery pressure includes an external device.