Effect of Renal Sympathetic Denervation on Resistant Hypertension and Cardiovascular Hemodynamic in Comparison to Intensive Medical Therapy Utilizing Impedance Cardiography

Hypertension is the most common cardiovascular disease, affecting approximately 1 billion1 people worldwide. Hypertension is a major public health concern, because of its complications (coronary artery disease, heart failure, renal disease, stroke). Early blood pressure control in hypertensive patients guarantees the best prevention of cardiovascular events on the long term (2007 ESH-ESC Guidelines on the Management of Hypertension; VALUE study). However, in spite of education efforts and antihypertensive drugs, blood pressure control rates remain low. The most common cause of uncontrolled BP is inadequate pharmacological treatment, because the selection of antihypertensive agents is often done independently of the hemodynamic status of the patient (volemic status, peripheral resistance, cardiac inotropy).

The sympatho-renal axis describes the dual role of the kidney as originator of some central nervous system afferent signals and recipient of efferent sympathetic signals. Both the contribution of the kidney to central sympathetic drive and the consequences of sympathetic efferent drive to the kidney contribute to the development and sustenance of hypertension. Poly-pharmacy strategies for the treatment of elevated blood pressure have identified populations of patients with treatment resistant hypertension.

Treatment Resistant Hypertension(TRH) is a blood pressure that remains above goal in spite of the concomitant use of antihypertensive medications from more than 3 drug classes. Patients who require more than 4 drug classes to have their blood pressure controlled are also considered to have resistant hypertension. Preferably, the regimen should include a diuretic and all doses should be optimal2 .The true prevalence of treatment resistant hypertension is unknown. In clinical trials from 20 to 40% of randomized patients did not reach blood pressure targets3. In the National Health and Nutrition Examination Survey in USA (2003-2008), non-pregnant adults with hypertension were classified as resistant if their blood pressure was 140/90 mmHg or higher and if they reported using antihypertensive medications from 3 different drug classes or drugs from 4 antihypertensive drug classes regardless of blood pressure. The prevalence was 12.8% of the drug-treated hypertensive population. Risk factors for treatment-resistant hypertension include older age and obesity .

Treatment-resistant patients are more likely to have albuminuria, reduced renal function, and a history of diabetes mellitus, coronary heart disease, stroke or heart failure. They are at increased risk of cardiovascular complications although the true incidence of death and morbidity remains currently unknown.

In the Spanish Ambulatory Blood Pressure Monitoring Registry5, 8295 of 68045 treated patients (12.2%) had treatment resistant hypertension, defined as an office blood pressure equal to or exceeding 140 mm Hg systolic and/or 90 mm Hg diastolic.