A 52-year-old man with hypertension for the past decade presented with poorly controlled blood pressure despite increasing doses of 4 antihypertensive medications including a diuretic, angiotensin-converting enzyme inhibitor, β-blocker, and calcium channel blocker. Office-based blood pressure measurements remained in the 160 to 180/100 to 110 mm Hg range despite escalation of medical therapy over a several-month period. Serum and urine testing revealed no evidence of hyperaldosteronism or pheochromocytoma. Renal artery ultrasonography demonstrated moderately elevated systolic flow velocities (295 cm/s) near the ostium of the left renal artery with an elevated renal resistive index; however, renal artery angiography was normal (Figure 38-1). What other treatment options might be considered for this patient with resistant hypertension?
Renal angiography of the (A) right and (B) left renal arteries demonstrating the absence of stenosis.
OVERVIEW OF RESISTANT HYPERTENSION
In the United States, based on the most recent results of the National Health and Nutrition Examination Survey (NHANES), 29.1% of adults (>70 million individuals) have hypertension.1 Among them, 12.2% are estimated to have resistant hypertension defined as office blood pressure ≥140 mm Hg systolic and/or ≥90 mm Hg diastolic while being treated with ≥3 antihypertensive drugs, including a diuretic.2 Progression of previously controlled hypertension despite treatment is also common, with an incidence of resistant hypertension of 1.9% within a median of 1.5 years from initial treatment.3 When resistant, hypertension is associated with a substantially increased likelihood of cardiovascular events and worse prognosis (Figure 38-2).4 Renal denervation (RDN) and endovascular carotid baroreceptor modulation are novel strategies to improve blood pressure control in this challenging population and are currently being evaluated in clinical studies. The principles of these techniques and clinical experience to date will be reviewed in this chapter.
Cumulative event rates (all-cause mortality, myocardial infarction, or stroke) among 17,190 patients with coronary artery disease and resistant, uncontrolled, or controlled hypertension (HTN) enrolled in the International Verapamil SR-Trandolapril (INVEST) Study. (Reproduced, with permission, from Smith SM, Gong Y, Handberg E, et al. Predictors and outcomes of resistant hypertension among patients with coronary artery disease and hypertension. Journal of hypertension 2014;32:635-643.)
THE SYMPATHETIC NERVOUS SYSTEM AND HYPERTENSION
The sympathetic nervous system plays a fundamental role in blood pressure control and is primarily responsible for acute changes in blood pressure via (1) extensive innervation of capacitance vessels, which alter arterial resistance in response to norepinephrine release from nerve endings; and (2) adrenal medullary stimulation, leading to increased epinephrine production and release, resulting in increased cardiac contractility, and increased heart rate and cardiac output (Figure 38-3). Chronic increases in blood pressure related to augmentation of ...