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Background: The neurally mediated syncope (NMS) is sustained by complex cardiac and vascular reflexes, acting on and amplified by central autonomic loops, resulting in bradycardia and hypotension. Hypothesis: Our aim was to assess whether the pathophysiology of NMS is also related to an abnormal peripheral vasoreactivity. Methods: We evaluated by ultrasound the flow-mediated vasodilation (FMD) and the nitrate-mediated dilation (NMD) in 17 patients with NMS, induced by drug-free tilt test in 6 subjects and by nitrate-potentiated tilt test in the other 11 cases; the syncope was classified as vasodepressive (VD) in 8 cases, cardioinhibitory (CI) in 7, and mixed in 2. Results: The FMD was not different from controls (10.2 ± 4.5 vs 11.4 ± 3.9, P = ns), with normal recovery times; the NMD was greater in fainting subjects than in controls (26.7 ± 7.3 vs 19.0 ± 3.6, P < 0.05), with higher values in VD than in CI syncope (31.1 ± 7.0 vs 23.1 ± 5.0, P = ns); compared to controls, subjects with NMS showed normal recovery times after FMD but longer recovery times after nitrate administration (13.0 ± 5.6 vs 6.3 ± 0.7 minutes, P < 0.05). Conclusions:The evaluation of endothelial function supports evidence that NMS is characterized by a marked and sustained endothelial-independent vasodilation, in the presence of a normal FMD; vascular hyperreactivity in response to nitrate administration is particularly overt in vasodepressive syncope and can explain the high rate of responses to nitrate administration during tilt test.

Background: Angioedema (AE) is a potentially life-threatening condition with hereditary (HAE), acquired (AAE), or iatrogenic causes. A careful workup allows for the identification of the etiology of attacks and the appropriate management. In this cohort study, based on a clinical practice setting, we aimed at investigating clinical and laboratory findings concerning different features of patients with recurrent AE who were referred to a single, tertiary-level center for HAE. Methods: Clinical and laboratory data of patients fulfilling the criteria for C1-inhibitor-deficient HAE (C1-INH-HAE), C1-INH-AAE, angiotensin-converting enzyme inhibitor-related AE (ACEI-RA), and idiopathic AAE (I-AAE) were evaluated. Descriptive statistics were analyzed by means of the Mann-Whitney U test. The Fisher exact test was used for group comparisons. Results: Patients were diagnosed with type 1 HAE (n = 14), type 2 HAE (n = 1), C1-INH-AAE (n = 8), ACEI-RA (n = 16), or I-AAE (n = 26). We included only patients with concomitant autoimmune diseases from the I-AAE group (n = 8, aut-I-AAE). Age at disease onset and at diagnosis was younger in type 1 HAE than in all the other groups. The diagnostic delay was longer in type 1 HAE than in ACEI-RA. C4 and C1q levels were lower in C1-INH-AAE than in type 1 HAE, ACEI-RA, and aut-I-AAE. Both HAE and C1-INH-AAE showed lower C1-INH antigen and function compared to the other groups. Peripheral attacks were more frequent in type 1 HAE, while airway, abdominal, and oral attacks were prevalent in C1-INH-AAE. Conclusion: Investigating the clinical and laboratory features of recurrent AE without wheals represents a major topic for facilitating early diagnosis and improving treatment strategies for this heterogeneous and misdiagnosed condition.

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