Cardiac arrest, also known as sudden cardiac arrest, is when the heart suddenly and unexpectedly stops beating. As a result, blood cannot properly circulate around the body and there is diminished blood flow to the brain and other organs. When the brain does not receive enough blood, this can cause a person to lose consciousness. Coma and persistent vegetative state may result from cardiac arrest. Cardiac arrest is also identified by a lack of central pulses and abnormal or absent breathing.

पूर्णहृदरोध, हृदय द्वारा प्रभावी ढंग से सिकुड़ने में विफलता की वजह से रक्त के सामान्य संचरण का ठहराव है। चिकित्सा कर्मी एक अप्रत्याशित पूर्णहृदरोध को सडेन कार्डियक अरेस्ट या SCA सन्दर्भित कर सकते हैं।