Table 3.

The characteristics of the patterns associated with the tilt test.

Disorder/syndrome	HR		BP		CBFv		ETCO2		Comments
	Supine	Tilt	Supine	Tilt	Supine	Tilt	Supine	Tilt
Orthostatic hypotension (OH), compensated, with stable orthostatic CBFv	↔	↕	↕	↓∗	↔	↔	↔	↔	OH with stable orthostatic CBFv indicating preserved cerebral autoregulation. OH can have any pattern: early, late, sustained, intermittent, progressive, stable. Patients are typically not dizzy during the tilting
OH, uncompensated, with reduced orthostatic CBFv	↔	↕	↕	↓∗	↔	↓	↔	↔	OH with reduced orthostatic CBFv indicating either autoregulatory failure or BP below the autoregulatory range. Patients are typically dizzy during the tilting
Orthostatic cerebral hypoperfusion syndrome (OCHOs)	↔	↔	↕	↔	↔	↓∗	↔	↔	Orthostatic CBFv is low without OH or arrhythmia. Patients are typically dizzy during the tilting
Orthostatic hypertension syndrome (OHTN)	↔	↔	↕	↑∗	↔	↔↑	↔	↔	If HR increases ≥30 BPM during the tilt then it is POTS. If HR increases <30 BPM and CBFv decreases during the tilt then it is OCHOs
Postural tachycardia syndrome (POTS)	↔	↑∗	↔↓	↔↑	↔	↔↓	↔	↔ or HV	HR increase during the tilt is usually sustained. HR ≥ 120 BPM during the tilt is also required. If maximal HR < 120 BPM during the tilt then it is called “mild orthostatic intolerance”
Inappropriate sinus tachycardia (IST)	↑∗	↑∗	↔↑	↔↑	↔	↔	↔	↔	HR during the supine may fluctuate but mean HR > 100 BPM during supine. HR is increased during the tilt and the increase is usually fluctuating
Paroxysmal sinus tachycardia (PST)	↔↑	↑∗	↕	↔↑	↔	↔↑	↔ or HV	↔ or HV	HR increase which may happen during both supine and the tilt is usually intermittent and associated with anxiety and may respond to reassurance
Syncope, cardiovagal	↔	↓	↔	↓∗	↔	↓	↔	↕	HR < 40 BPM
Syncope, vasodepressor	↔	↔↑	↔	↓∗	↔	↓	↔	↕	Minimal HR slowing (<10%)
Syncope, mixed	↔	↓	↔	↓∗	↔	↓	↔	↕	Both HR and BP decrease
Primary cerebral autoregulatory failure (pCAF)	↔	↔	↔↑	↔	↓∗	↔↓	↔	↔	Hyperventilation should be ruled out
Psychogenic pseudosyncope	↕	↕	↕	↕	↔∗	↔∗	↕	↕	Pseudosyncope can occur in both supine and upright position

Comments: CBFv = cerebral blood flow velocity; ET_CO2 = end tidal CO₂; HR = heart rate; BP = blood pressure; BPM = beats per minute; supine = absolute values of respective variables in supine position; tilt = absolute values of respective variables during the tilt (upright position); HV = hyperventilation defined as ET_CO2 < 35 mmHg in supine position and < 30 mmHg during the tilt; CAF = cerebral autoregulatory failure; ↑ = increased; ↓ = decreased; ↕ = any; ↔ normal; ↔↑ = normal or increased; ↔↓ = normal or decreased. ∗ indicates the primary abnormality.