Pathogenesis and treatment of resistant hypertension.

Current prevalence estimates suggest that approximately 25% of the world's population has arterial hypertension making this one of the most common conditions for which individuals seek health care. Currently, hypertension is considered resistant if blood pressure (BP) cannot be reduced to <140/90 mmHg with an appropriate triple-drug regimen, including an oral diuretic with all agents administered at or near maximal dosages. This definition has evolved with the development of new therapies and evidence-based data supporting treatment to lower BP goals. With current poor hypertension control rates worldwide, more individuals are being referred for resistant or refractory hypertension. Causes for refractory hypertension are multi-factorial and a systematic approach to evaluation can be most beneficial in identifying the causative factors. This review focuses initially on those causes of resistance to treatment that can be evaluated cost-effectively in the outpatient setting. These include a search for nonadherence, assessing the adequacy of the treatment regimen, ruling out drug interactions and associated conditions. Pseudoresistance and evidence of volume expansion can also often be identified in the office setting. In the absence of the above factors, assessment for secondary causes of hypertension, not yet identified, is appropriate, and further hemodynamic and/or neurohumoral assessment may be indicated to facilitate more targeted and individualized therapy. This careful step-wise evaluation is not only cost-effective and office-based, but also largely noninvasive, and capable of identifying the causative factors in the vast majority of patients with apparently resistant hypertension.