Influence of respiratory instability during neurocardiogenic presyncope on cerebrovascular and cardiovascular dynamics
| Autor: | Gaia Casucci, Andrea Rinaldi, Cesare Porta, Stefano Castoldi, Luciano Bernardi |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Adult
Male Supine position Blood Pressure Cardiovascular System Syncope Oxygen Consumption Hypocapnia Tilt-Table Test medicine.artery medicine Syncope Vasovagal Humans Mean Blood Flow Velocity Retrospective Studies Presyncope business.industry Hemodynamics Carbon Dioxide medicine.disease Blood pressure Anesthesia Cerebrovascular Circulation Middle cerebral artery Breathing Female Cardiology and Cardiovascular Medicine business Respiratory minute volume |
| Zdroj: | Heart (British Cardiac Society). 94(11) |
| ISSN: | 1468-201X |
| Popis: | To analyse the influence of breathing activity on cerebrovascular dynamics during presyncope.Retrospective study.University hospital.38 subjects developing neurocardiogenic syncope (syncope group), and 61 age-matched control subjects with negative tilt.Middle cerebral artery mean blood flow velocity (MCFV), continuous non-invasive blood pressure (BP), end-tidal CO(2) (CO(2)-et) and minute ventilation were measured before and during 45' 60 degrees tilting.Respiratory and cerebrovascular variability, cerebrovascular resistance (CVR)-absolute and corrected for CO(2)-et at 40 mm Hg (CVR-40)-and dynamic cerebrovascular regulation (CVR-dyn: transfer function phase analysis between MCFV and BP), obtained during supine rest (baseline), first 5 minutes of tilt (early tilt), early- and late presyncope (first and second half, respectively, of 4 minutes preceding syncope in syncope group, and equivalent time in controls).Tilting induced a mean (SE) CVR decrease in controls (baseline 1.20 (0.04); late presyncope 1.12 (0.06) mm Hg x s/cm, p0.05) but not in the syncope group (baseline 1.09 (0.04); late presyncope 1.09 (0.06) mm Hg x s/cm, p = NS). However, CVR-40 showed similar reduction in both groups (controls: from 1.15 (0.04) to 0.96 (0.04) mm Hg x s/cm; syncope group: from 1.01 (0.04) to 0.83 (0.04) mm Hg x s/cm, p = NS). CVR-dyn of the two groups was also similar (p = NS). Respiratory variability increased in the syncope group, from early tilt to late presyncope (p0.05 or better), preceding hyperventilation and being significantly correlated with an increase in MCFV and BP variability (p0.01).During presyncope, the development of respiratory instability and hypocapnia impairs MCFV, thus facilitating the onset of syncope despite preserved cerebrovascular regulation. |
| Databáze: | OpenAIRE |
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