Table 2: Definitions of Syncope, Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia and Vasovagal Syncope.

Syncope	A transient loss of consciousness, associated with inability to maintain postural tone, rapid and spontaneous recovery and the absence of clinical features specific for another form of transient loss of consciousness such as epileptic seizures.
Postural Tachycardia Syndrome	A clinical syndrome that is usually characterised by: 1) frequent symptoms that occur with standing such as lightheadedness, palpitations, tremulousness, generalised weakness, blurred vision, exercise intolerance and fatigue; 2) an increase in heart rate of ≥30 beats within 10 minutes of going from lying down to standing (or ≥40 beats in those 12 to 19 years of age) and 3) the absence of orthostatic hypotension (>20 mmHg drop in systolic BP).
Inappropriate Sinus Tachycardia	A daytime sinus heart rate >100 bpm at rest, with a mean 24-hour heart rate >90 bpm not due to primary causes, and associated with distressing symptoms of palpitations.
Vasovagal Syncope	A syncope syndrome that usually 1) occurs with upright posture greater than 30 seconds, or with exposure to emotional stress, pain, or medical settings; 2) features diaphoresis, warmth, nausea, and pallor; 3) where known, is associated with hypotension and relative bradycardia and 4) is followed by fatigue.

BP = blood pressure. Based on the 2015 Heart Rhythm Society Expert Statement.[1]