Alternans and pharmacological agents

A system comprising:

• sensors configured to measure electrical activity of heart beats;
• an amplifier configured to amplify the electrical activity;
• an analog to digital converter configured to convert the electrical activity to cardiac signal data;
• a user input control configured to enable a user to indicate a change relating to an administration of a pharmacological agent;
• and
• a processor configured to:
• generate first cardiac signal data when the user input control is not used to indicate the change relating to the administration of the pharmacological agent, and
• generate second cardiac signal data when the user input control is used to indicate the change relating to the administration of the pharmacological agent, wherein the second cardiac signal data is associated with an indication of the occurrence of the change relating to the administration of the pharmacological agent.

A computer-readable medium encoded with a computer program comprising instructions that, when executed, operate to cause a computer to perform operations comprising:

• segmenting, into first cardiac signal data segments, cardiac signal data generated from measured heart beats of a subject, each first cardiac signal data segment including cardiac signal data of sequential heart beats;
• determining, for each segment of the first cardiac signal data segments, characteristics of alternans occurring in the segment;
• segmenting, into second cardiac signal data segments, cardiac signal data generated from measured heart beats of the subject after a change relating to an administration of a pharmacological agent, each second cardiac signal data segment including cardiac signal data of sequential heart beats;
• determining, for each segment of the second cardiac signal data segments, characteristics of alternans occurring in the segment;
• and
• comparing the characteristics of alternans occurring in the first cardiac signal data segments with the characteristics of alternans occurring in the second cardiac signal data segments.

A method comprising:

• receiving a cardiac signal data generated from measured heart beats of the subject after a change relating to an administration of a pharmacological agent;
• determining characteristics of alternans occurring in the received cardiac signal data;
• and
• comparing the characteristics of alternans occurring in the received cardiac signal data with the characteristics of alternans expected to be present prior to administration of the pharmacological agent.