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Microvascular blood flow fluctuations during tilt table induced syncope.
F Censi1, S Strano, S Festinese
1Department of Computer and Systems Science, "La Sapienza" University of Rome, Italy. censi@dis.uniroma1.it
Computers in Cardiology
|December 16, 2003
Summary
Neurally mediated syncope is linked to altered microvasculature blood flow (BF) oscillations. In patients experiencing syncope, blood flow in the skin and sternum showed changes in frequency and amplitude near symptom onset.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Function
- Microvascular Research
Background:
- Neurally mediated syncope (NMS) is a common cause of recurrent fainting, often triggered by autonomic nervous system dysfunction.
- Understanding microvascular blood flow (BF) dynamics is crucial for elucidating the pathophysiology of cardiovascular regulation during syncope.
- Previous research has primarily focused on macrohemodynamic changes, with less attention paid to peripheral microvascular alterations in NMS.
Purpose of the Study:
- To investigate alterations in the frequency domain of microvasculature blood flow (BF) during neurally mediated syncope.
- To compare peripheral BF oscillations between patients with recurrent syncope and healthy controls during a head-up tilt test.
- To identify specific BF changes preceding symptom development in individuals susceptible to syncope.
Main Methods:
- Studied 20 patients with recurrent syncope and 10 healthy controls.
- Measured peripheral blood flow (PBF) and sternal blood flow (SBF) using laser Doppler technique.
- Simultaneously recorded electrocardiogram (ECG), respiration activity (RA), and blood pressure (BP) at rest and during a 70-degree head-up tilt test.
Main Results:
- SBF and PBF exhibited distinct oscillations around 0.16 Hz, independent of other cardiovascular variability signals.
- Mean BF did not significantly change in tilt-negative, control, or tilt-positive groups during the tilt test.
- In tilt-positive patients, a decrease in mean PBF and SBF, along with an increased oscillation frequency, occurred near symptom onset.
Conclusions:
- Peripheral microvasculature exhibits unique oscillatory patterns that may be disrupted in neurally mediated syncope.
- Specific changes in peripheral blood flow dynamics, including frequency shifts, precede the development of syncope symptoms.
- These findings highlight the role of microvascular dysregulation in the pathophysiology of NMS and suggest potential targets for future research.