T-wave alternans train spotter

A method of determining an indication of T-wave alternans using an implantable medical device, comprising:

• using said device to detect values of T-wave signals;
• storing said detected time values in a queue within said device;
• operating on n of said stored time values using a transform program within said device including pattern factors in the form of alternating positive and negative factors by multiplying said stored time values by said positive and negative pattern factors to produce a value indicative of a degree of T-wave alternans;
• detecting the occurrence of T-wave alternans responsive to said indicative value exceeding a defined threshold value;
• storing a record of said occurrence of T-wave alternans within said device, and
• transmitting said record to an device external device.

A method of detecting and responding to T-wave alternans using an implantable heart stimulator, comprising:

• using said stimulator to detect values of T-wave signals;
• storing said detected time values in a queue within said stimulator;
• operating on n of said stored time values using a transform program within said stimulator including pattern factors in the form of alternating positive and negative factors by multiplying said stored time values by said positive and negative pattern factors to produce a value indicative of a degree of T-wave alternans;
• detecting the occurrence of T-wave alternans responsive to said indicative value exceeding a defined threshold value;
• and
• responsive to said detected occurrence of T-wave alternans, modifying an operating parameter of said stimulator.