Fernex et al. Journal of Medical Case Reports 2012, 6:241 http://www.jmedicalcasereports.com/content/6/1/241 Page 3 of 5 Table 2 Head-up tilt test Time (minute) Systolic blood pressure (mmHg) Diastolic blood pressure (mmHg) Mean blood pressure (mmHg) Heart rate (beats/min) 0 (supine) 118 85 94 69 94 93 83 82 80 2 4 6 8 10 118 124 119 121 123 pain). The diagnostic criteria include the presence of orthostatic symptoms associated with a heart rate in- crease of 30 beats/min or greater within five minutes of standing or head-up tilt, without orthostatic hypotension. Typically, the heart rate increases to 120 beats/min [1]. The etiology of POTS is probably heterogeneous and the pathophysiology remains unclear. Three main groups have been identified: neuropathic, hyperadrenergic and POTS related to deconditioning [1]. In the neuropathic form, a restricted autonomic neuropathy with partial sympathetic denervation is present and predominates in the lower limbs [6], with an inability of the peripheral vasculature to constrict in response to orthostatic stress. The hyperadrenergic form of POTS is characterized by increased sympathetic activity of unknown origin, with orthostatic plasma norepinephrine values above 600pg/ mL and a higher blood pressure on standing [7]. POTS related to deconditioning affects patients with a severe illness or any event impeding physical activity. It is due to excessive venous pooling in the legs and hypovolemia while standing [1]. Infection, surgery and traumas are frequent precipitating events. Secondary forms of POTS occur in association with other disorders, most commonly diabetes mellitus. Other conditions include amyloidosis, sarcoidosis, al- coholism, systemic lupus erythematosus, Sjögren’s syn- drome, heavy-metal intoxication, joint hypermobility syndrome, pure autonomic failure, multiple-system at- rophy and paraneoplastic syndrome [7]. Therapy and prognosis are determined by the underlying causative disorder. Recently, Kanjwal et al. published a series of nine patients diagnosed with multiple sclerosis and POTS [8]. POTS after a traumatic brain injury, Lyme disease, atrioventricular nodal reentrant tachycardia ablation and electrical injury has also been described [9-12]. Our patient presented several risk factors for POTS. First, prolonged bed rest following coarctation repair may have been an initiating event for his physical decon- ditioning. Second, the antihypertensive drugs (amlodi- pine and valsartan) prescribed after surgery for residual hypertension, known to worsen orthostatic intolerance, 99 102 97 94 94 87 99 93 93 99 may also have contributed to his condition. This could partly explain the improvement observed after discon- tinuation of these pharmacologic agents. Our patient developed symptoms of POTS after the surgical correction of aortic coarctation. Beekman et al. described in 1983 an altered baroreceptor function with diminished baroreceptor sensitivity in a group of chil- dren with repaired aortic coarctation [13]. Functional changes of the aortic arch and carotid baroreceptors seem to be related to structural modifications of the pre- coarctation aorta, the wall of which contains more colla- gen and fewer muscular fibers, resulting in decreased compliance. In a more recent paper, other authors stud- ied 45 patients with aortic coarctation repair and found frequent abnormal hemodynamic responses to ortho- static tests. Nine patients had a blood pressure decrease of more than 20mmHg, while two patients had a blood pressure increase of more than 50mmHg. Mean vari- ation of heart rate in upright position was +12 beats per minute (standard deviation 20) but no functional symp- toms were noted after standing up. Altered blood pres- sure circadian rhythm was also observed, the whole results suggesting an alteration of the autonomic ner- vous regulation of blood pressure [14]. The hormonal response to exercise was studied by Guenthard et al. in a group of 36 patients after coarctation repair. They observed a higher increase of plasma adrenaline after ex- ercise in hypertensive patients. Thus, enhanced sympa- thetic nerve activity was proposed as a factor contributing to late hypertension after coarctation repair [15]. How- ever, since no report of POTS following coarctation re- pair has been published yet to our knowledge, it is unclear if the results of these studies can be applied to our patient. Whether a state of augmented sympathetic activity and autonomic dysfunction related to aortic co- arctation surgery could contribute to the development of POTS should be further evaluated. UARS is a form of sleep-related breathing disorder belonging to the obstructive sleep-apnea and hypopnea syndromes (OSAHS). It is characterized by increased airflow resistance within the upper airways that leads to repetitive abnormal respiratory effort-related arousal. The consecutive sleep fragmentation gives rise to a