Patent ID: 8024039

Claim:
An implantable subcutaneous device, comprising: a housing configured for subcutaneous non-intrathoracic placement; detection circuitry provided in the housing and configured to produce a cardiac electrophysiologic signal; energy delivery circuitry provided in the housing; at least one electrode configured for subcutaneous non-intrathoracic placement and coupled to the detection and energy delivery circuitry; an implantable blood sensor configured to produce a blood sensor signal; and a processor provided in the housing and coupled to the blood sensor, the detection circuitry, and the energy delivery circuitry, the processor using the blood sensor signal to verify that the cardiac electrophysiologic signal comprises a cardiac signal having a QRS complex, the processor configured to discriminate between a tachyarrhythmia condition that requires cardioversion or defibrillation therapy and a condition that does not require cardioversion or defibrillation therapy using the cardiac electrophysiologic signal verified to have a QRS complex and the blood sensor signal, the processor configured to withhold delivery of cardioversion or defibrillation therapy in response to determining, using the blood sensor signal, that the condition does not require cardioversion or defibrillation therapy.