Cerebral Blood Flow, Heart Rate, and Blood Pressure Patterns during the Tilt Test in Common Orthostatic Syndromes
Table 1
Criteria for the orthostatic syndromes.
Disorder/syndrome
Criteria
Comments
Normal response to tilt
QASAT —bradycardia supine = 0 AND QASAT —increased heart rate response to tilt = 0 QASAT —orthostatic hypotension during the tilt = 0 AND QASAT —orthostatic hypertension during the tilt = 0 AND QASAT —cerebral blood flow response to tilt = 0
Orthostatic hypotension (OH), compensated, with stable orthostatic CBFv
QASAT —orthostatic hypotension during the tilt > 0 AND QASAT —cerebral blood flow response to tilt = 0
OH, uncompensated, with reduced orthostatic CBFv
QASAT —orthostatic hypotension during the tilt > 0 AND QASAT —cerebral blood flow response to tilt > 0
QASAT —orthostatic hypotension during the tilt = 0 AND QASAT —cerebral blood flow response to tilt > 1 AND QASAT —increased heart rate response to tilt = 0
Orthostatic hypertension syndrome (OHTN)
QASAT —orthostatic hypotension during the tilt = 0 AND QASAT —orthostatic hypertension during the tilt = 1 AND QASAT —cerebral blood flow response to tilt = 0 AND QASAT —increased heart rate response to tilt = 0
Postural tachycardia syndrome (POTS)
QASAT —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
Inappropriate sinus tachycardia (IST)
QASAT —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
Paroxysmal sinus tachycardia (PST)
QASAT —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
Syncope, cardiovagal
HR < 40 BPM AND systolic BP < 60 mmHg AND diastolic CBFv < 5 cm/sec
All variables are obtained during the syncope
Syncope, vasodepressor
HR ≥ before syncope AND systolic BP < 60 mmHg AND diastolic CBFv < 5 cm/sec
All variables are obtained during the syncope
Syncope, mixed
HR > 40 BPM AND HR < before syncope AND systolic BP < 60 mmHg AND diastolic CBFv < 5 cm/sec
QASAT —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.