Tachy is a Greek prefix meaning ‘fast’. In medical terminology, it is used to describe conditions characterised by an abnormally fast rate, most commonly in relation to heart rhythms or breathing.
The most common cardiac uses of the prefix include tachycardia (abnormally fast heart rate, above 100 beats per minute in adults), ventricular tachycardia (a fast rhythm originating in the ventricles), and supraventricular tachycardia (fast rhythms originating above the ventricles). Tachyarrhythmia is a broader term for any fast abnormal heart rhythm. Tachypnoea refers to an abnormally fast breathing rate.
Tachycardia may be physiological (a normal response to exercise, emotion, fever, or pain) or pathological (caused by a specific arrhythmia). The clinical significance depends on the cause and the rate: a sinus tachycardia at 110 bpm in a febrile patient is of little concern, while ventricular tachycardia at 200 bpm in a patient with structural heart disease is a medical emergency.
For cardiac arrest survivors, awareness of their own pulse rate can be helpful in identifying symptoms. Palpitations or awareness of a rapid heart rate, particularly if accompanied by dizziness, breathlessness, or near-blackout, should be reported to the cardiac team promptly.
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