Cardiac signal recording using dynamically generated detection thresholds

A method, comprising:

• (a) setting an initial detection threshold Th1 and an occurrence threshold X, where X is a positive integer;
• (b) sensing cardiac signals from a patient;
• (c) recording cardiac signals up to X times in response to sensing cardiac signals that meet or exceed the initial detection threshold Th1;
• (d) automatically generating an additional detection threshold Th2 in response to sensing X cardiac signals that meet or exceed the initial detection threshold Th1;
• (e) in response to sensing up to Y cardiac signals that meet or exceed the additional detection threshold Th2:
• (i) recording cardiac signals that meet or exceed the additional detection threshold Th2 up to Y times;
• and
• (ii) automatically generating another additional detection threshold Th3;
• and
• (f) for each of the respective detection thresholds Th1, Th2, and Th3, counting each occurrence of a cardiac signal that meets or exceeds each respective detection threshold, Th1, Th2, and Th3.

A medical device, comprising:

• a housing configured for implantation within a body of a patient;
• detection circuitry disposed in the housing and coupled to an electrode arrangement, the detection circuitry configured to sense cardiac signals from the patient;
• and
• a processor coupled to the detection circuitry, the processor configured to compare the cardiac signals to an initial detection threshold, automatically generate an additional detection threshold in response to a predetermined number of the cardiac signals meeting or exceeding:
• the initial detection threshold or a previously generated detection threshold, concurrently count each occurrence of a cardiac signal meeting or exceeding each of the respective detection thresholds, and record cardiac signal data only for a cardiac signal of the sensed cardiac signals that meets or exceeds the highest of the detection thresholds.