Symptoms such as stridor, persistent cough, wheezing, recurrent respiratory infections, vomiting and dysphagia usually lead to diagnosis and surgical treatment in early

childhood. Indeed, 5-months is the median age of presentation.8, 9, 10 and 11 However, because of only a few published reports, the real prevalence of vascular rings in adults is unknown.2 Dysphagia is the prevalent presenting symptom, but also a clinical history of chronic cough and/or dyspnea is quite frequent; moreover, some asymptomatic cases can be incidentally diagnosed.12, 13, 14 and 15 Pediatricians and cardiologists are usually aware of this clinical condition, but this is not always true for pulmonologists HDAC activation and gastroenterologists managing adult patients. A delay in diagnosis and treatment can be responsible for several late complications, such as tracheomalacia or aortoesophageal fistula.16 and 17 With regard to the present report, the typical spirometric pattern of a central

airway obstruction led to the diagnosis of DAA. Similarly, available literature includes several cases of patients misdiagnosed as asthmatics until the execution of pulmonary function tests.5, 6 and 7 Vascular rings may determine either a plateau on the expiratory limb of the flow-volume curve, indicative of a variable intrathoracic airway obstruction, or a flattening of both the expiratory and inspiratory arms of the curve, consistent with a fixed intrathoracic airway obstruction. This condition does not usually lead to a decrease in FEV1 and/or VC, but PEF can be severely impaired, thus producing a ratio check details of FEV1 divided by PEF greater than 8 mL/L/min.18

Poor initial effort can also affect this ratio; therefore, it is of paramount importance to obtain the optimal patient collaboration during spirometry performance. Efforts must be maximal and repeatable in order to accurately evaluate flow-volume curve morphology, but of course it is particularly difficult to achieve this goal in the pediatric population. Current guidelines recommend that spirometry should be performed also in preschool children but, as Ketotifen reported in the present case, its execution is often delayed.19 Therefore, we strongly suggest to perform spirometry as soon as possible in all cases of unexplained respiratory symptoms, refractory to pharmacologic treatments. Persistent cough, stridor, wheezing, dyspnea, noisy breathing and recurrent respiratory infections can be related to abnormalities involving central airways, not always detectable by chest X ray. DAA may be suspected if a frontal chest radiograph shows the presence of either an aortic knob projecting over the right side of sternal manubrium, or a narrowing/deviation/indentation of tracheal shadow. However, as observed in our patient, chest radiogram can also be normal.