METHOD FOR ESTIMATING CARDIAC PRESSURE USING PARAMETERS DERIVED FROM IMPEDANCE SIGNALS DETECTED BY AN IMPLANTABLE MEDICAL DEVICE

• US 20080039821A1
• Filed: 08/20/2007
• Published: 02/14/2008
• Est. Priority Date: 01/11/2000
• Status: Active Grant

• Current Assignee: Brian Mann, James Whiting, Neal L. Eigler
• Original Assignee: Brian Mann, James Whiting, Neal L. Eigler
• Inventors: Whiting, James, Eigler, Neal, Mann, Brian
• Granted Patent: US 8,068,907 B2
• Time in Patent Office: Days
• US Class Current: 604/891.1
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/02156 Calibration means
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/7267 involving training the classification device
• CPC Class Codes: A61B 8/04 Measuring blood pressure
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36564 controlled by blood pressure

Abstract

A method of monitoring pressure within a medical patient, includes measuring an actual pressure in a medical patient in a first time period; measuring an indicator of the actual pressure in the first time period, wherein the indicator is derived from an electrical signal of the patient'"'"'s heart; determining a correlative relationship between the actual pressure and the indicator, wherein both the actual pressure and the indicator are obtained in the first time period; measuring the indicator in a second time period; and determining the actual pressure in the second time period based on the correlative relationship obtained in the first time period and the indicator obtained in the second time period.

Claims

1. A method for estimating cardiac pressure within a patient using an implantable medical device, the method comprising:

applying an electrical field to tissues of the patient including cardiac tissues;

measuring a parameter influenced by the electrical field, the parameter being affected by cardiac pressure; and

estimating cardiac pressure within the patient by applying predetermined conversion factors to the measured parameter.

2. The method of claim 1 wherein applying an electrical field to tissues of the patient includes applying an electrical impedance detection pulse from which electrical impedance can be measured.

3. The method of claim 2 wherein measuring the parameter includes:

detecting an electrical impedance (Z) signal within the patient along a sensing vector wherein impedance is affected by cardiac pressure; and

deriving the parameter from the electrical impedance (Z) signal.

4. The method of claim 1 further including controlling therapy based on estimated cardiac pressure.

5. The method of claim 1 wherein the implantable device is equipped with an implantable drug pump and wherein drug therapy is controlled based on estimated cardiac pressure.

6. The method of claim 1 further including detecting heart failure based on estimated cardiac pressure.

7. The method of claim 6 wherein the implantable device is equipped with an implantable warning device and wherein a warning is generated upon detection of heart failure.

8. The method of claim 6 wherein the implantable device is equipped to transmit signals to an external display device and wherein the warning is transmitted to the external device.

9. The method of claim 1 wherein the implantable device is equipped to transmit signals to an external display device and wherein estimated cardiac pressure values are transmitted to the external device.