How to Investigate the Vascular Changes in Resistant Hypertension

The pathophysiological mechanism of resistant hypertension (RH) is related to increased vascular smooth muscle tone and blood volume, exacerbation of the activity of the sympathetic system and hyperactivity of the renin-angiotensin-aldosterone system (RAAS), all of which are important regulatory mechanisms of blood pressure. Hypertension is associated with reduced endothelial homeostasis, and thus the best treatment would not only reduce blood pressure but also reverse endothelial injury. RH is associated with more serious vascular dysfunction, assessed by endothelium-dependent vasodilation and the presence of serum biomarkers. Arterial stiffness also constitutes an important independent factor that can determine risk of cardiovascular events in patients with RH; it is an important indicator of vascular changes, and is associated with cardiovascular mortality. Arterial stiffness can be assessed by 3 measures: central blood pressure, augmentation index (AIx) and pulse wave velocity (PWV). PWV is a recognized as main marker of the severity of vascular injury. The increase in central blood pressure caused by backward (reflected) waves can be evaluated as an index derived from an analysis of the central aortic blood pressure curve known as the AIx, and depends on the magnitude and time of the reflected waves and indirectly on heart frequency and arterial stiffness. The evaluation of patients with RH is focused on the identification of causes of hypertension guided by the clinical features of hypertension and metabolic, vascular, endocrine and family history.