In children, vasovagal syncope and postural tachycardia syndrome constitute the major types of orthostatic intolerance. The clinical characteristics of postural tachycardia syndrome and vasovagal syncope are similar but their treatments differ. Therefore, their differential diagnosis is important to guide the correct treatment. Children suffering from vasovagal syncope or postural tachycardia syndrome might be treated using water, β-blockers, salt, or midodrine. However, the effificacy of the drugs varies. Biomarkers or certain hemodynamic parameters that can predict the treatment effects of individualized treatment for POTS or VVS have been used.
Cut-Off | Sensitivity | Specificity | Year | |
---|---|---|---|---|
Plasma H2S level | 98 μmol/L | 90% | 80% | 2012 |
Serum iron level | 11.8 μmol/L, | 92.50% | 64.70% | 2013 |
AI and 30/15 | AI: 28.180; 30/15: 1.025 |
95.80% | 80.80% | 2018 |
dULF | 36.2 ms2 | 71.40% | 75.00% | 2019 |
Diagnosis |
Treatment |
Biological Markers or Predictors |
Cut-off |
Sensitivity |
Specificity |
Year |
|
POTS |
non-pharmacotherapy |
Qtcd [27] |
43.0 msec |
90% |
60% |
2016 |
|
|
|
Salivary cortisol levels [28] |
4.1 ng/mL |
83.30% |
68.70% |
2017 |
|
|
ORS |
24-h urinary sodium [29] |
124 mmol/24 h |
76.90% |
93% |
2012 |
|
|
|
Changes in heart rate during HUTT [30] |
pre-treatment increase in HR = 41 beats/min maximum upright HR in 10 min = 123 beats/min |
84% |
56% |
2015 |
|
|
|
BMI [31] |
18.02 |
92% |
82.80% |
2016 |
|
|
|
BRS [32] |
17.01 ms/mmHg |
85.70% |
87.50% |
2016 |
|
|
|
MCHC [33] |
347.5 g/L |
68.80% |
63.20% |
2017 |
|
|
midodrine hydrochloride |
MR-proADM [34] |
61.5 pg/mL |
100% |
71.60% |
2012 |
|
|
|
FMD [35] |
9.85% |
1-month |
76.9% |
93% |
2013 |
3-month |
71.6% |
80% |
|||||
|
|
H2S in erythrocyte [36] |
27.1 nmol/min/108 |
78.90% |
77.80% |
2013 |
|
|
|
Blood pressure changes in the upright position [37] |
SBP ≤ 0 mmHg; DBP ≤ 6.5 mmHg |
72% |
88% |
2014 |
|
|
|
AVP/Plasma copeptin [38] |
10.482 pmol/L |
81.30% |
76.50% |
2014 |
|
|
metoprolol |
Orthostatic plasma norepinephrine [39] |
3.59 pg/mL |
76.90% |
91.70% |
2014 |
|
|
|
AVP/Plasma copeptin [40] |
10.225 pmol/L |
90.50% |
78.60% |
2014 |
|
|
|
CNP [41] |
32.55 pg/mL |
95.80% |
70% |
2015 |
|
|
|
HRV [42] |
TR index ≤ 33.7; SDNN index ≤ 79.0ms |
85.3%, |
81.80% |
2019 |
|
|
|
HR and HR Difference [43] |
HR 5 ≥ 110 beats/min |
82.50% |
69.23% |
2020 |
|
|
|
HR 10 ≥ 112 beats/min |
84.62% |
69.70% |
|||
|
|
HR difference 5 ≥ 34 beats/min |
85.29% |
89.47% |
|||
|
|
HR difference 10 ≥ 37 beats/min |
97.56% |
64.86% |
|||
VVS |
orthostatic training |
AI [44] |
26.77 |
85.00% |
69.20% |
2019 |
|
|
midodrine hydrochloride |
FMD [45] |
8.85% |
90% |
80% |
2012 |
|
|
metoprolol |
HR [46] |
increase of 30 beats/min |
81% |
80% |
2007 |
|
|
|
LVEF and LVFS [47] |
two month |
LVEF > 70.5% |
80.00% |
100.00% |
2018 |
|
|
|
LVFS > 38.5% |
90.00% |
90.00% |
||
|
|
six month |
LVEF > 70.5% |
81.30% |
88.90% |
||
|
|
|
LVFS > 37.5% |
93.80% |
66.70% |
||
|
|
BRS [48] |
10 ms/mmHg |
82% |
83% |
2019 |
|
|
|
24 h urine NE [49] |
34.84 μg/24h |
70% |
100% |
2019 |