This post market clinical follow-up study is a multi-center, non-randomized, unblinded, observational registry of the performance of the FRx Automated external defibrillator (AED) used in conjunction with electrodes with or without use of the infant/child key. The registry is focused only on on post-event data collection and does not prescribe any device usage. This registry has several safeguards in place to prevent against selections bias, including enrollment of all participants who have pads placed. This registry will evaluate the safety and verify the clinical performance of the device in relation to its claims, when used in accordance with the Device Manual.

Inclusion Criteria:

• Subjects accepted into the study must: have been suspected of a circulatory arrest for any cause
• Have had HeartStart FRx AED with electrodes: HeartStart SMART PADS II applied to their body and powered up, regardless of whether a defibrillation shock was delivered

Exclusion Criteria:

• AED or pad use other than the HeartStart FRx AED with electrodes : HeartStart SMART PADS II
• AED used for training purposes.

Use of the HeartStart FRx AED is intended for the following populations in addition to adults: newborns, neonates, infant, children, and adolescents. It may also be used on pregnant women. Devices are located in public access spaces and with first responders around the world.