Table 1.
Criteria for the orthostatic syndromes.
| Disorder/syndrome | Criteria | Comments |
|---|---|---|
| Normal response to tilt | QASAT [1]—bradycardia supine = 0 AND QASAT [3]—increased heart rate response to tilt = 0 QASAT [7]—orthostatic hypotension during the tilt = 0 AND QASAT [10]—orthostatic hypertension during the tilt = 0 AND QASAT [15]—cerebral blood flow response to tilt = 0 |
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| Orthostatic hypotension (OH), compensated, with stable orthostatic CBFv | QASAT [7]—orthostatic hypotension during the tilt > 0 AND QASAT [15]—cerebral blood flow response to tilt = 0 |
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| OH, uncompensated, with reduced orthostatic CBFv | QASAT [7]—orthostatic hypotension during the tilt > 0 AND QASAT [15]—cerebral blood flow response to tilt > 0 |
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| Orthostatic cerebral hypoperfusion syndrome (OCHOs) | QASAT [7]—orthostatic hypotension during the tilt = 0 AND QASAT [15]—cerebral blood flow response to tilt > 1 AND QASAT [3]—increased heart rate response to tilt = 0 |
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| Orthostatic hypertension syndrome (OHTN) | QASAT [7]—orthostatic hypotension during the tilt = 0 AND QASAT [10]—orthostatic hypertension during the tilt = 1 AND QASAT [15]—cerebral blood flow response to tilt = 0 AND QASAT [3]—increased heart rate response to tilt = 0 |
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| Postural tachycardia syndrome (POTS) | QASAT [7]—orthostatic hypotension during the tilt = 0 AND average supine heart rate before the tilt < 100 BMP AND maximal heart rate increment during the tilt ≥ 30 BMP AND the duration of the increment ≥ 3 minutes AND the maximal absolute heart rate during the increment ≥ 120 BPM |
If the maximal heart rate does not cross 120 BMP, it is called mild orthostatic intolerance |
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| Inappropriate sinus tachycardia (IST) | QASAT [7]—orthostatic hypotension during the tilt = 0 AND average supine heart rate before the tilt ≥ 100 BMP AND heart rate increment during the tilt ≥ 30 BMP |
Grading is based on maximal heart rate |
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| Paroxysmal sinus tachycardia (PST) | QASAT [7]—orthostatic hypotension during the tilt = 0 AND average supine heart rate before the tilt < 100 BMP AND maximal heart rate increment during the tilt ≥ 30 BMP AND the duration of the increment < 3 minutes AND the maximal absolute heart rate during the increment ≥ 120 BPM |
PST usually affects the first 2 minutes of the tilt but not always. If, for example, the tachycardia with the 30 BPM increment occurs at minutes 9 and 10 of the tilt (the tachycardia duration = 2 minutes), then it is recommended to continue the tilt to clarify the diagnosis. If the tachycardia continues it is the POTS; if not it is PST |
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| Syncope, cardiovagal | HR < 40 BPM AND systolic BP < 60 mmHg AND diastolic CBFv < 5 cm/sec |
All variables are obtained during the syncope |
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| Syncope, vasodepressor | HR ≥ before syncope AND systolic BP < 60 mmHg AND diastolic CBFv < 5 cm/sec |
All variables are obtained during the syncope |
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| Syncope, mixed | HR > 40 BPM AND HR < before syncope AND systolic BP < 60 mmHg AND diastolic CBFv < 5 cm/sec |
All variables are obtained during the syncope |
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| Primary cerebral autoregulatory failure | QASAT [13]—supine cerebral low flow = 1 AND QASAT [6]—supine hypotension = 0 |
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| Psychogenic pseudosyncope | QASAT [15]—cerebral blood flow response to tilt = 0 AND physical examination indicative of apparent loss of consciousness |
Typically patient is unresponsive, atonic, although bizarre posturing can be observed, without abnormal movement that can be seen in seizures |
Comments: QASAT = Quantitative Scale for Grading of Cardiovascular Autonomic Reflex Tests and Small Fibers from Skin Biopsies, details of calculations can be found in Novak, 2015 [6]. HR = heart rate; BP = blood pressure; CBFv = cerebral blood flow velocity.