Resistant arterial hypertension (RAH) is a complex and multifactorial syndrome, with hyperactivity of the sympathetic nervous system (SNS) and reduction of vagal activity being considered some of the main causes of refractoriness to treatment. Seen from the outside, it resembles a complicated (see lat. Cum plicate) or complex disease (see lat. Cum plexus), Chaotic with the participation of several open systems. For example, in recent years some relationships have been demonstrated between the autonomic nervous systems, synaptic mediators, hormones, inflammatory and immune responses. However, these findings have not been investigated together and systematically. In the present project, we intend to establish and compare, in an integrated way, the clinical alterations present in RAH (resistant and refractory), hemodynamic variables, autonomous activity (sympathetic and baroreflex) and interactions with the neuroimmune-endocrine systems. To this end, we will test the hypothesis that resistant patients have greater damage to the autonomic nervous system (ANS) associated with exacerbated systemic and hormonal inflammatory profile, including SNA mediators (noradrenaline and acetylcholinesterase). This is also intended to determine the behavior (deterministic or chaotic) of the systems evaluated (mentioned above) in volunteers with RAH. Sample and methods: The sample space (calculated) will consist of 72 individuals, being: - 18 refractory hypertensive (HRT); II- 18 resistant hypertensive patients (HRfT); III- 18 controlled hypertensive (1-2 drugs) (CAH); and IV- 18 healthy normotensive individuals. This is a prospective, double-blind study (patient and professional-technician), paired (1 X 4), in which the 72 volunteers will be evaluated by the methods set out below. We will also have the chance to observe whether resistant and refractory hypertension share the same pathophysiological bases and clinical manifestations (deterministic-isolated or cardiovascular chaos) by analyzing the patterns of cardiovascular variability (MAPA and Holter) (SpaceLabs, USA; DynaMap, Brazil), inflammatory and hormonal mediators (ELISA) in the resistant hypertension - RHT and refratary hypertension - HfRT groups. Central pressure (CP) and arterial stiffness (pulse wave velocity, VOP) (Sphymocor, ATCor, USA) will also be assessed. Healthy normotensive (NT) and controlled hypertension (CAH) will be evaluated in an identical way to control the other groups. Perspectives: The findings will improve the clinical knowledge based on pathophysiology about Resistant Hypertension and, mainly, the bases of pharmacological treatment and with implantable devices (stimulation of baroreceptors and sympathetic denervation) used in this condition.