Definition
An irregular rhythm of the heartbeat, in which the heart beats too fast, too slow, or in an uneven pattern. In an aviation context, cardiac arrhythmia is one of the medical effects associated with exposure to elevated carbon dioxide levels, such as those produced by sublimating dry ice in an enclosed cabin.
Plain English
An abnormal heartbeat — beating too fast, too slow, or in an irregular pattern instead of a steady rhythm.
Context Anchor
Seen in aeromedical and safety discussions, including the hazards of carrying dry ice in an aircraft, because dry ice gives off carbon dioxide gas.
Derivation
From Greek 'kardia' (heart) and 'arrhythmia' (lack of rhythm) — literally 'no rhythm of the heart.' The 'a-' prefix means 'without,' and 'rhythmos' means 'measured flow.' The word itself names the problem: the heart has lost its steady beat.
Why Pilots Care
Elevated CO2 from dry ice can trigger cardiac arrhythmia, leading to sudden incapacitation in flight.
Grounding Statement
If a pilot begins feeling unwell while carrying dry ice, an abnormal heartbeat is a serious warning sign, not a minor discomfort to ignore.
Intuition Check
A cardiac arrhythmia is not the same thing as a heart attack. It means the heart’s rhythm is abnormal, whether or not there is a blocked blood vessel.
Example Sentence 1
Carrying too much dry ice in a small cabin can raise carbon dioxide levels enough to cause headaches, shortness of breath, or even cardiac arrhythmia.
Example Sentence 2
Any history of cardiac arrhythmia must be evaluated before a pilot can return to flying duties.