Extravascular hemodynamic monitor

• US 6,409,675 B1
• Filed: 11/10/1999
• Issued: 06/25/2002
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Turcott, Robert
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/438,017
• Time in Patent Office: 958 Days
• Field of Search: 600/480, 600/481, 600/486, 600/504, 600/586, 600/489, 600/508, 600/526-528
• US Class Current: 600/508
• 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 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6817 Ear canal
• CPC Class Codes: A61B 7/00 Instruments for auscultation

Abstract

A method and apparatus for monitoring the hemodynamic status of a patient is provided. It comprises an implantable monitor with one or a plurality of sensors configured for extravascular placement, electronic circuitry that is coupled to the sensors and processes their output, a transmitter/receiver for conveying information between the monitor and an external unit, and a patient alert which notifies the patient if medical attention should be sought. The extravascular sensors include vascular plethysmography, heart and lung sounds, thoracic impedance, and ECG. In the preferred embodiment, the radio frequency transmitter/receiver provides for the automatic telemetry of data, without requiring the active participation of the patient or clinician. Thus data can be conveyed routinely and automatically, allowing more computationally demanding analysis to be done by an external device, or allowing human review at a central location. The monitor is particularly applicable to patients with heart failure.

Claims

1. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

a lung sound sensor for extravascular implantation; and

electronic circuitry coupled to said sensor for processing an output of said sensor and for providing an indication of hemodynamic status of said patient;

wherein said lung sound sensor and said electronic circuit detect pulmonary rales.

2. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

a physiologic sensor for extravascular implantation, said sensor being capable of sensing a non-electrical parameter of said patient; and

electronic circuitry coupled to said sensor for processing an output of said sensor and for providing an indication of hemodynamic status of said patient;

wherein said electronic circuitry is adapted to process the output of one or more sensors to provide an indication of the patient'"'"'s physiologic state.

3. The device of claim 2 wherein said physiologic state is a predetermined phase of sleep.

4. The device of claim 2 wherein said physiologic state is the patient walking.

5. The device of claim 2, said electronic circuitry further including:

a transmitter for telemetering data from said electronic circuitry to a receiver outside said patient'"'"'s body;

a memory for storing an output form said electronic circuitry for later analysis or telemetry by said transmitter; and

wherein said electronic circuitry provides an output which is an indication of said patient'"'"'s hemodynamic status.

6. The device of claim 5 wherein said electronic circuit stores in said memory the unprocessed output of said sensor, whereby said output can be later transmitted using said transmitter for analysis and interpretation outside said patient'"'"'s body.

7. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

a physiologic sensor for extravascular implantation, said sensor being capable of sensing a non-electrical parameter of said patient; and

electronic circuitry coupled to said sensor for processing an output of said sensor and for providing an indication of hemodynamic status of said patient;

wherein said processing by said electronic circuitry quantifies the patient'"'"'s sympathetic/parasympathetic balance, whereby hemodynamic status can be assessed.

8. The device of claim 7 further including a receiver connected to said electronic circuitry whereby instructions can be conveyed to said device from outside the body of said patient.

9. A method for chronically and acutely monitoring the medical status of a patient comprising:

(a) providing an implantable, extravascular monitoring device having a physiologic sensor and electronic circuit for processing an output of said sensor; and

(b) monitoring hemodynamic status using said sensor and said electronic circuit to monitor vascular volume.

10. An implantable hemodynamic monitor for monitoring the chronic hemodynamic status of a heart failure patient comprising:

at least one extravascular physiologic sensor for sensing a hemodynamic parameter indicative of heart function;

electronic circuitry coupled to an output of said physiologic sensor for chronically monitoring changes in the patient'"'"'s hemodynamic status indicative of heart failure exacerbation; and

means coupled to said electronic circuitry for warning the patient or a healthcare provider of an indicated exacerbation.

11. The monitor of claim 10 wherein said at least one extravascular physiologic sensor is selected from among a vascular plethysmography sensor, an arterial hemoglobin saturation sensor, a heart and lung sound sensor, a thoracic impedance plethysmography sensor and an electrocardiogram sensor.

12. The monitor of claim 10 and further including a telemetry circuit for telemetrically transmitting information to an external unit.

13. The monitor of claim 12 wherein said telemetry circuit periodically operates automatically to telemeter information to said external unit.

14. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

a physiologic sensor for extravascular implantation, said sensor being capable of sensing heart sounds of said patient;

electronic circuitry coupled to said sensor for processing an output of said sensor including detecting cardiac gallops and changes in heart sound energy and for providing an indication of hemodynamic status of said patient.

15. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

a physiologic sensor for extravascular implantation, said sensor being capable of sensing a physiologic parameter indicative of vascular volume of said patient; and

electronic circuitry coupled to said sensor for processing an output of said sensor and for providing an indication of hemodynamic status of said patient.

16. The device of claim 15 and further including an electrocardiogram (ECG) sensor wherein said electronic circuit calculates a measure of variability of cardiac electrical activity from an output of said ECG sensor.

17. The device of claim 15 and further including:

a light source positioned to radiate light energy toward vascularized tissue of said patient'"'"'s body; and

a light detector positioned to detect light radiated by said light source and reflected from said tissue and provide an output signal to said electronic circuitry;

wherein said electronic circuitry measures vascular volume by recording changes in detected light.

18. The device of claim 15 wherein said sensor comprises a mechanical transducer that detects changes in cardiac pulse amplitude.

19. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

a physiologic sensor for extravascular implantation for measuring metabolic chemicals within a patient'"'"'s tissues; and

electronic circuitry coupled to said sensor for processing an output of said sensor and for providing an indication of hemodynamic status of said patient.

20. The device of claim 19 wherein said sensor measures tissue pH.

21. The device of claim 19 wherein said sensor measures tissue O₂.

22. The device of claim 19 wherein said sensor measures tissue CO₂.

23. An implantable medical device for monitoring the hemodynamic status of a patient comprising:

an intrathoracic pressure sensor for extravascular implantation; and

electronic circuitry coupled to said sensor for processing an output of said sensor and for providing an indication of hemodynamic status of said patient.

24. A method for chronically and acutely monitoring the medical status of a patient comprising:

(a) providing an implantable, extravascular monitoring device having a physiologic sensor and electronic circuit for processing an output of said sensor; and

(b) monitoring hemodynamic status using said sensor and said electronic circuit to monitor metabolic chemicals within tissue of the patient.

25. A method for chronically and acutely monitoring the medical status of a patient comprising:

(a) providing an implantable, extravascular monitoring device having a physiologic sensor and electronic circuit for processing an output of said sensor;

(b) monitoring hemodynarnic status using said sensor and said electronic circuit;

(c) determining with said electronic circuitry if the patient'"'"'s hemodynamic status is progressively worsening; and

(d) if the patient'"'"'s hemodynamic status is progressively worsening the device providing a warning of said worsening status.

26. An implantable hemodynamic monitor for monitoring the chronic hemodynamic status of a heart failure patient comprising:

at least one extravascular physiologic sensor for sensing a hemodynamic parameter indicative of heart function;

electronic circuitry coupled to an output of said physiologic sensor for chronically monitoring changes in the patient'"'"'s hemodynamic status indicative of heart failure exacerbation; and

a telemetry circuit for telemetrically transmitting information to an external unit;

wherein said telemetry circuit periodically operates automatically to telemeter information to said external unit.

27. An implantable hemodynamic monitor for monitoring the chronic hemodynamic status of a heart failure patient comprising:

at least one physiologic sensor for sensing a hemodynamic parameter indicative of heart function;

electronic circuitry coupled to an output of said physiologic sensor for chronically monitoring changes in the patient'"'"'s hemodynamic status indicative of heart failure exacerbation; and

a telemetry circuit for telemetrically transmitting information to an external unit;

wherein said telemetry circuit periodically operates automatically to telemeter information to said external unit.