Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.21 (CPT)
 4,580 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An easy and low-cost method for identification of subjects prone to orthostatic vasovagal syncope would be of clinical benefit. An orthostatic test with 60 degrees head-up tilt and progressive lower-body negative pressure was performed on 79 patients with histories of unexplained syncope and 26 control subjects. The test was stopped at the onset of presyncope and time to presyncope was taken as a measure of orthostatic tolerance. Spectral and cross-spectral analysis was performed on the supine time series of the R-R interval (ECG) and systolic pressure (Finapres) recorded before the beginning of the test. According to reference values, 38 patients and 11 controls were classified as having poor orthostatic tolerance (PPT and CPT respectively), whereas 41 patients and 15 controls displayed normal orthostatic tolerance (PNT and CNT respectively). The central frequency of the low-frequency (LF approximately equal to 0.1 Hz.) oscillations in PNT and CNT was significantly higher than that in PPT and CPT. In addition, it was significantly linearly correlated with the time of presyncope. Using our test of orthostatic tolerance as a comparison, the LF central frequency allows the classification of subjects with poor or normal tolerance with 80% sensitivity and 82% specificity. These results suggest that the LF central frequency in the supine position may provide a useful index in the diagnosis of orthostatic intolerance.
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PMID:Cross-spectral analysis of cardiovascular parameters whilst supine may identify subjects with poor orthostatic tolerance. 1267 Feb 99

Sleep syncope is a recently described form of vasovagal syncope that interrupts sleep. The pathophysiology of this condition is uncertain but a 'central' non-baroreflex-mediated trigger has been suggested. In the present study, 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 SS patients (patients with vasovagal syncope with sleep syncope; n=16) and NSS patients (patients with vasovagal syncope without sleep syncope; n=35), including demography, and triggers and symptoms during syncope. MBP (mean blood pressure), HR (heart rate) and MSNA (muscle sympathetic nerve activity) in SS patients were compared with NSS patients and matched controls (n=16) during HG (handgrip), CPTs (cold pressor tests), HUT (head-up tilting) and tilt-induced pre-syncope. Patients and controls were of similar age and gender distribution [SS patients, age 46.0+/-4 years (69% female); NSS patients, 47.3+/-4 years (63% female); controls, 43.7+/-5 years (69% female)]. Compared with NSS patients, SS patients reported more fainting episodes: (i) triggered by phobias (75 compared with 37%; P=0.001); (ii) while in the horizontal position (44 compared with 6%; P=0.001); and (iii) associated with abdominal symptoms (69 compared with 9%; P=0.001). Compared with controls, the 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 and 0.003 respectively; NSS, P=0.021 and 0.049 respectively). 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 the 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 subform of vasovagal syncope. Attenuation of sympathetic responses to non-baroreflex pathways may be important in the mechanism of vasovagal syncope.
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PMID:Sympatho-vagal responses in patients with sleep and typical vasovagal syncope. 1928 51