Heartbeat - Another 2nd factor for authentication (Biometrics)

Wondering if this might be useful in a kidnap situation. Can there be a signature mismatch if the victim is tense.

(The article also has a youtube video)

From the article:

The Nymi Band offers a way to use  your heartbeat as a secure payment method and unlocking technique.  The band uses a biometric authentication technology called Heart ID that allows the band to confirm its user’s identity by monitoring the unique signature of his or her heartbeat.


For more information:
http://www.eedesignit.com/ditch-the-credit-cards-and-fingerprints-pay-with-your-heartbeat-instead/