Reference normal values for FMD were ��5%.14,15 After a rest period of 15 minutes, baseline measurements (diameter and flow velocity) of the brachial artery were repeated, and the endothelium-independent vasodilatation was evaluated by sublingual administration of 300 ?g of nitroglycerine (Natispray); thereafter, the diameter of the brachial artery was measured every 30 seconds until each patient recovered the basal values; the changes in brachial artery diameter were reported as percentage of basal values. Reference normal values for nitrate-mediated dilation (NMD) were ��10%.15,16 Investigations were in accordance with the Declaration of Helsinki. selleckchem
Data are expressed as mean �� standard deviation if not otherwise stated. Obtained variables were tested for normal distribution by the Kolmogorov-Smirnov test. The values obtained in each group and the differences between measurements were analyzed by paired or unpaired Student t test or by analysis of variance for repeated measurements, followed by the Bonferroni test; the Wilcoxon test was used when otherwise appropriate. Linear regression analysis with Pearson correlation coefficient was used to investigate the relationship between variables of interest. Results were considered statistically significant Luminespib
if P < 0.05; differences between fainting subjects and controls were calculated with the unpaired t test; differences within each group, in different conditions, were calculated with paired t test. In all tests, statistical http://www.selleckchem.com/
significance was defined as P < 0.05. The NMS, induced by tilt test, in our 15 patients, was classified as cardioinhibitory (CI) in 7 cases (VASIS-2A in 4 and VASIS-2B in 3), VD in 8 (VASIS-3), and mixed in 2 cases (VASIS-1); all but 1 of the subjects with VD syncope were women and were significantly younger than CI patients, (21.9 �� 4.6 vs 49.7 �� 11.8 years, P < 0.05). Compared to the controls, patients showed lower basal values of systolic blood pressure (113.2 �� 14.8 vs 125.7 �� 7.3 mm Hg, P < 0.05), diastolic blood pressure (60.0 �� 8.8 vs 78.7 �� 3.2 mm Hg, P < 0.05), with similar heart rate values (66.4 �� 9.2 vs 68.2 �� 9.8 bpm, P = ns). The drug-free tilt test phase induced the syncope in 6 subjects, at 19.5 �� 7.3 minutes of passive standing (CI in 3 cases and VD in 3); the other 11 patients developed syncope during the nitroglycerine-potentiated phase, at 11.6 �� 3.6 minutes after drug administration, classified as VD in 5 cases, CI in 4, and mixed in 2. The ultrasound assessment of the endothelial function showed resting values of brachial artery diameter lower in syncope patients than in controls (3.4 �� 0.6 vs 4.0 �� 0.8 mm, P < 0.05); lower values of the brachial artery diameter were recorded in VD than in CI (3.0 �� 0.4 vs 3.8 �� 0.6 mm, P < 0.01) and mixed syncope (3.0 �� 0.