The middle cerebral artery flow velocities during head-up tilt testing in diabetic patients with autonomic nervous system dysfunction.
BACKGROUND
The goal of this study was to examine the effects of diabetes mellitus on the trend of mean arterial velocity (v(m)) in both middle cerebral arteries during head-up tilt (HUT).


METHODS
The study was performed in 20 patients, 9 females and 11 males (mean age 51 +/- 12 years) with an average 17-year history of insulin-dependent diabetes mellitus type I or II and a dysfunction of the autonomic nervous system confirmed by cardiocirculatory tests [Valsalva maneuver, deep breathing test, handgrip test, orthostatic test and spectral analysis of heart rate (HR) variability], and 19 age-matched healthy volunteers, 9 females and 10 males (mean age 48 +/- 6.8 years). v(m) was measured by a transcranial Doppler monitoring system during a 5-min baseline period, followed by a 5-min HUT in the upright position (90 degrees ). Mean arterial blood pressure (MAP), HR and end-tidal CO(2) (Et-CO(2)) were monitored concomitantly.


RESULTS
In healthy volunteers, v(m) decreased stepwise during the first minute of HUT, reaching a minimum during the last 2 min of the test (v(m): basal 63.0 +/- 11.7 cm/s, 1st min 57.6 +/- 12.2 cm/s, 2nd min 55.9 +/- 12.6 cm/s, 3rd min 53.4 +/- 12.6 cm/s, 4th min 52.1 +/- 12.7 cm/s, 5th min 51.3 +/- 13.5 cm/s). In the supine position, v(m) recovered and reached the resting v(m) values. It declined gradually during HUT and less steeply in diabetic (v(m): basal 54.4 +/- 10.1 cm/s, 1st min 51.96 +/- 9.3 cm/s, 2nd min 50.7 +/- 11.6 cm/s, 3rd min 50.5 +/- 11.4 cm/s, 4th min 49.5 +/- 10.7 cm/s, 5th min 48.8 +/- 11.5 cm/s) than in healthy subjects. v(m) differed significantly (p = 0.00) between rest and HUT in both groups. The differences in MAP, HR and Et-CO(2) during rest and HUT between the groups were not statistically significant (p DeltaMAP = 0.36, p DeltaHR = 0.86, p DeltaEt-CO(2) = 0.97). The results of the analysis of variance of v(m) for repeated measurements between the two groups of subjects were highly significant (p = 0.00). The model of linear regression analysis was significant (p = 0.007). Diabetes was significant in the model (p = 0.00), while DeltaMAP, DeltaHR and DeltaEt-CO(2) were not.


CONCLUSIONS
These findings may indicate that vasomotor responses during HUT testing are decreased in diabetic patients.
Zvan
Bojana
B
University Medical Center Ljubljana, Department of Neurology, Laboratory of Neurosonology, Ljubljana, Slovenia. bojana.zvan@guest.arnes.si
Zaletel
Marjan
M
Pretnar Oblak
Janja
J
Pogacnik
Tomaz
T
Kiauta
Tomaz
T
D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018667:Tilt-Table Test; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial; D014666:Vasomotor System / Q000000981:diagnostic imaging / Q000503:physiopathology