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Decreased upright cerebral blood flow and cerebral autoregulation in normocapnic postural tachycardia syndrome.
Am J Physiol Heart Circ Physiol. 2009 Aug; 297(2):H664-73.AJ

Abstract

Postural tachycardia syndrome (POTS), a chronic form of orthostatic intolerance, has signs and symptoms of lightheadedness, loss of vision, headache, fatigue, and neurocognitive deficits consistent with reductions in cerebrovascular perfusion. We hypothesized that young, normocapnic POTS patients exhibit abnormal cerebral autoregulation (CA) that results in decreased static and dynamic cerebral blood flow (CBF) autoregulation. All subjects had continuous recordings of mean arterial pressure (MAP) and CBF velocity (CBFV) using transcranial Doppler sonography in both the supine supine position and during a 70 degrees head-up tilt. During tilt, POTS patients (n = 9) demonstrated a higher heart rate than controls (n = 7) (109 +/- 6 vs. 80 +/- 2 beats/min, P < 0.05), whereas controls demonstrated a higher MAP than POTS (87 +/- 2 vs. 77 +/- 3 mmHg, P < 0.05). Also during tilt, mean CBFV decreased 19.5 +/- 2.6% in POTS patients versus 10.3 +/- 2.0% in controls (P < 0.05). We then used a transfer function analysis of MAP and CFBV in the frequency domain to quantify these changes. The low-frequency (LF; 0.04-0.15 Hz) component of CBFV variability increased during tilt in POTS patients (supine: 3 +/- 0.9 vs. tilt: 9 +/- 2, P < 0.02). In POTS patients, there was an increase in LF and high-frequency coherence between MAP and CBFV, an increase in LF gain, and a lack of significant change in phase. Static CA may be less effective in POTS patients compared with controls, since immediately after tilt CBFV decreased more in POTS patients and was highly oscillatory and autoregulation did not restore CBFV to baseline values until the subjects became supine. Dynamic CA may be less effective in POTS patients because MAP and CBFV during tilt became almost perfectly synchronous. We conclude that dynamic and static autoregulation of CBF are less effective in POTS patients compared with control subjects during orthostatic challenge.

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Authors+Show Affiliations

Ocon AJ
Department of Physiology, The Center for Hypotension, New York Medical College, Valhalla, New York 10532, USA.
Medow MS
No affiliation info available
Taneja I
No affiliation info available
Clarke D
No affiliation info available
Stewart JM
No affiliation info available

MeSH

AdolescentAdultBlood PressureCarbon DioxideCerebrovascular CirculationFemaleHeart RateHomeostasisHumansMalePostural Orthostatic Tachycardia SyndromeRespiratory MechanicsSupine PositionTilt-Table TestUltrasonography, Doppler, TranscranialYoung Adult

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19502561

Clinical Trial Links

Hypercapnia and Orthostatic Tolerance in Postural Orthostatic Tachycardia Syndrome

Citation

Ocon, Anthony J., et al. "Decreased Upright Cerebral Blood Flow and Cerebral Autoregulation in Normocapnic Postural Tachycardia Syndrome." American Journal of Physiology. Heart and Circulatory Physiology, vol. 297, no. 2, 2009, pp. H664-73.
Ocon AJ, Medow MS, Taneja I, et al. Decreased upright cerebral blood flow and cerebral autoregulation in normocapnic postural tachycardia syndrome. Am J Physiol Heart Circ Physiol. 2009;297(2):H664-73.
Ocon, A. J., Medow, M. S., Taneja, I., Clarke, D., & Stewart, J. M. (2009). Decreased upright cerebral blood flow and cerebral autoregulation in normocapnic postural tachycardia syndrome. American Journal of Physiology. Heart and Circulatory Physiology, 297(2), H664-73. https://doi.org/10.1152/ajpheart.00138.2009
Ocon AJ, et al. Decreased Upright Cerebral Blood Flow and Cerebral Autoregulation in Normocapnic Postural Tachycardia Syndrome. Am J Physiol Heart Circ Physiol. 2009;297(2):H664-73. PubMed PMID: 19502561.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Decreased upright cerebral blood flow and cerebral autoregulation in normocapnic postural tachycardia syndrome. AU - Ocon,Anthony J, AU - Medow,Marvin S, AU - Taneja,Indu, AU - Clarke,Debbie, AU - Stewart,Julian M, Y1 - 2009/06/05/ PY - 2009/6/9/entrez PY - 2009/6/9/pubmed PY - 2009/9/2/medline SP - H664 EP - 73 JF - American journal of physiology. Heart and circulatory physiology JO - Am J Physiol Heart Circ Physiol VL - 297 IS - 2 N2 - Postural tachycardia syndrome (POTS), a chronic form of orthostatic intolerance, has signs and symptoms of lightheadedness, loss of vision, headache, fatigue, and neurocognitive deficits consistent with reductions in cerebrovascular perfusion. We hypothesized that young, normocapnic POTS patients exhibit abnormal cerebral autoregulation (CA) that results in decreased static and dynamic cerebral blood flow (CBF) autoregulation. All subjects had continuous recordings of mean arterial pressure (MAP) and CBF velocity (CBFV) using transcranial Doppler sonography in both the supine supine position and during a 70 degrees head-up tilt. During tilt, POTS patients (n = 9) demonstrated a higher heart rate than controls (n = 7) (109 +/- 6 vs. 80 +/- 2 beats/min, P < 0.05), whereas controls demonstrated a higher MAP than POTS (87 +/- 2 vs. 77 +/- 3 mmHg, P < 0.05). Also during tilt, mean CBFV decreased 19.5 +/- 2.6% in POTS patients versus 10.3 +/- 2.0% in controls (P < 0.05). We then used a transfer function analysis of MAP and CFBV in the frequency domain to quantify these changes. The low-frequency (LF; 0.04-0.15 Hz) component of CBFV variability increased during tilt in POTS patients (supine: 3 +/- 0.9 vs. tilt: 9 +/- 2, P < 0.02). In POTS patients, there was an increase in LF and high-frequency coherence between MAP and CBFV, an increase in LF gain, and a lack of significant change in phase. Static CA may be less effective in POTS patients compared with controls, since immediately after tilt CBFV decreased more in POTS patients and was highly oscillatory and autoregulation did not restore CBFV to baseline values until the subjects became supine. Dynamic CA may be less effective in POTS patients because MAP and CBFV during tilt became almost perfectly synchronous. We conclude that dynamic and static autoregulation of CBF are less effective in POTS patients compared with control subjects during orthostatic challenge. SN - 1522-1539 UR - https://www.unboundmedicine.com/medline/citation/19502561/Decreased_upright_cerebral_blood_flow_and_cerebral_autoregulation_in_normocapnic_postural_tachycardia_syndrome_ L2 - https://journals.physiology.org/doi/10.1152/ajpheart.00138.2009?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -