Sympatho-vagal responses in patients with sleep and typical vasovagal syncope. Clinical science (London, England : 1979) [Clin Sci (Lond)] Journal article | | Title | Sympatho-vagal responses in patients with sleep and typical vasovagal syncope. | | Author(s) | Jardine D, Krediet C, Cortelli P, Frampton C, Wieling W | | Source | Clin Sci (Lond) 2009 Mar 12. | | Abstract | Sleep syncope is a recently-described form of vasovagal syncope which interrupts sleep. The pathophysiology of this condition is uncertain but a "central" non-baroreflex mediated trigger has been suggested. We tested the hypothesis that patients with sleep syncope, have abnormal sympatho-vagal responses to non-baroreflex, but normal responses to baroreflex stimuli. We collected historical data from patients with a history of vasovagal syncope with (SS, n=16) and without sleep syncope (NSS, n=35), including demography, triggers and symptoms during syncope. We compared mean blood pressure (MBP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) in SS patients to NSS patients and matched controls (n=16) during hand grip (HG), cold pressor tests (CPT), head-up tilt (HUT) and tilt-induced presyncope. Patients and controls were of similar age and sex distribution. SS patients: mean age 46.0+/-4 yrs, (69% female); NSS patients: 47.3 yrs+/-4, (63%); controls 43.7+/-5 yrs, (69%). Compared to NSS, the SS patients reported more fainting episodes: (a) triggered by phobias, (69 v 9%, p=0.001); (b) while in the horizontal position (56 v 6%, p=0.001); and (c) associated with abdominal symptoms (69 v 9%, p=0.001). Compared to controls, MBP response to HG was attenuated in SS patients (p=0.016) and MSNA (burst frequency and incidence) responses to CPT were attenuated in both syncope groups (SS p=0.011, 0.003, NSS p=0.021, 0.049). MSNA responses to HUT did not differ. For both non-baroreflex and baroreflex responses, there were no differences in any of the MSNA indices between syncope groups. Patients with vasovagal syncope, with or without sleep syncope, have very similar sympatho-vagal responses to both non-baroreflex and baroreflex stimuli. This is consistent with sleep syncope being a sub-form of vasovagal syncope. Attenuation of sympathetic responses to non-baroreflex pathways may be important in the mechanism of vasovagal syncope. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19281451 |
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