Implantable cardiac monitor

1. An implantable cardiac monitor (ICM) configured to be deployed subcutaneous, submuscular, or substernal at a position that enables the ICM to detect cardiac activity of a patient's heart but the ICM is not configured to provide therapy to the patient's heart, the ICM comprising:

a first electrode;

a second electrode spaced from the first electrode;

a third electrode spaced from the first electrode and the second electrode;

a housing that is configured for subcutaneous, submuscular or substernal deployment and to support the first electrode, the second electrode and the third electrode, the housing comprising:

a body portion having a first end and a second end;

a tail portion extending from the body portion to a tail end;

the first electrode disposed adjacent the first end of the body portion;

the second electrode disposed adjacent the second end of the body portion;

the third electrode disposed adjacent the tail end of the tail portion;

a controller disposed within the housing and operably coupled to the first electrode, the second electrode and the third electrode;

the controller configured to select a pair of the first electrode, the second electrode and the third electrode to use for sensing P-waves resulting from an atrial contraction; and

the controller configured to communicate via wireless communication an atrial contraction timing fiducial based on a sensed P-wave to a second medical device that receives and uses the communicated atrial contraction timing fiducial to deliver a therapy to the patient's heart.

2. The ICM of claim 1 , wherein the tail portion is more flexible than the body portion.

3. The ICM of claim 2 , wherein the body portion comprises a hermitically sealed metallic enclosure that houses the controller, and the tail portion comprises a polymeric body carrying the third electrode.

4. The ICM of claim 3 , further comprises an antenna wherein the antenna is embedded in the polymeric body of the tail portion.

5. The ICM of claim 3 , wherein the polymeric body of the tail portion comprises a biocompatible polyurethane and/or a biocompatible polyethylene.

6. The ICM of claim 3 , wherein the polymeric body is secured relative to the hermitically sealed metallic enclosure.

7. The ICM of claim 2 , further comprises an antenna wherein the antenna is carried by the tail portion.

8. The ICM of claim 7 , wherein the antenna is operatively coupled to the controller and is used to communicate with an external programmer.

9. The ICM of claim 1 , wherein the second medical device is a subcutaneous implantable cardioverter-defibrillator (SICD), and the controller is configured to communicate information about the sensed P-waves to the SICD via conducted communication using two of the first electrode, the second electrode and the third electrode.

10. The ICM of claim 9 , wherein the controller is configured to select which two of the first electrode, the second electrode and the third electrode to use for conducted communication with the SICD.

11. The ICM of claim 1 , wherein

the second medical device is a leadless cardiac pacemaker (LCP), and the controller is configured to communicate information about the sensed P-waves to the LCP via conducted communication using a pair of the first electrode, the second electrode and the third electrode.

12. The ICM of claim 11 , wherein the controller is configured to select which two of the first electrode, the second electrode and the third electrode to use for conducted communication with the LCP.

13. The ICM of claim 1 , further comprising an accelerometer disposed within the housing, wherein the controller is configured to communicate accelerometer information.

14. The ICM of claim 1 , further comprising a heart sound sensor, wherein the controller is configured to communicate heart sound information.

15. An implantable cardiac monitor (ICM) configured to be deployed subcutaneous, submuscular or substernal at a position that enables the ICM to detect signs of cardiac activity, the ICM comprising:

a housing having a first major housing side extending substantially parallel with an opposing second major housing side and a minor side wall extending therebetween;

a first electrode secured relative to the housing, the first electrode having a first electrode portion on the first major housing side and a second electrode portion spaced from the first electrode portion of the first electrode and on the opposing second major housing side;

a second electrode secured relative to the housing and spaced from the first electrode, the second electrode having a first electrode portion on the first major housing side and a second electrode portion spaced from the first electrode portion of the second electrode and on the opposing second major housing side;

a third electrode secured relative to the housing and spaced from the first electrode and the second electrode, the third electrode having a first electrode portion on the first major housing side and a second electrode portion spaced from the first electrode portion of the third electrode and on the opposing second major housing side;

a controller disposed within the housing and operably coupled to the first electrode, the second electrode and the third electrode;

the controller configured to select a pair of the first electrode, the second electrode and the third electrode for sensing cardiac electrical activity; and

the controller configured to select a pair of the first electrode, the second electrode and the third electrode for communication with a second medical device;

wherein the first electrode, the second electrode and the third electrode permit testing of a possible location for deployment of the ICM before inverting the ICM into its desired deployment orientation.

16. The ICM of claim 15 , wherein the pair of the first electrode, the second electrode and the third electrode selected for sensing cardiac electrical activity is the same as the pair of the first electrode, the second electrode and the third electrode selected for communication with the second medical device.

17. The ICM of claim 15 , wherein the controller is configured to detect an atrial contraction using the pair of electrodes selected for sensing cardiac electrical activity, and is further configured to communicate an atrial contraction timing fiducial based on a detected atrial contraction to the second medical device using the pair of electrodes selected for communication with the second medical device.

18. The ICM of claim 15 , wherein the controller is configured to select a different pair of electrodes for sensing cardiac electrical activity than for communication with the second medical device.

19. An implantable cardiac monitor (ICM) configured to be deployed subcutaneous, submuscular, or substernal at a position that enables the ICM to detect cardiac activity, the ICM comprising:

a first electrode;

a second electrode spaced from the first electrode;

a controller operably coupled to the first electrode and the second electrode;

a housing that is configured for subcutaneous, submuscular or substernal deployment, the housing having a first major housing side extending substantially parallel with an opposing second major housing side and a minor side wall extending therebetween;

the first electrode including a first electrode portion disposed on the first major housing side and a second electrode portion disposed on the opposing second major housing side;

the second electrode including a first electrode portion disposed on the first major housing side and a second electrode portion disposed on the opposing second major housing side;

the controller configured to selectively electrically couple to either the first electrode portion of the first electrode or the second electrode portion of the first electrode and to selectively electrically couple to either the first electrode portion of the second electrode or the second electrode portion of the second electrode; and

the controller configured to communicate information about the cardiac activity to a second medical device.