Renal denervation (RDN) is being studied in different clinical conditions associated with an overactive sympathetic nervous system such as: hypertension, diabetes, obesity, apnea, and heart failure in EU, AU, South America and, Asia. Renal denervation is a minimally invasive catheter based endovascular procedure to ablate the renal nerves and disrupt the crosstalk (sympathetic signals) between kidney and brain. There are multiple products in development focusing on RDN.
Renal denervation is currently only approved for patients with resistant hypertension in Europe and Australia. In the USA, FDA has approved RDN for investigational clinical studies in the treatment of resistant hypertension.
The American Heart Association (AHA) defines resistant hypertension as blood pressure (BP) that remains above goal (>140/90 for all patients, >130/80 for diabetes and chronic renal insufficiency patients) despite the use of maximum tolerated doses of 3 antihypertensive drugs (from different classes, one of which should be a diuretic/water pill) and compliance to the AHA lifestyle measures.1 High blood pressure that is under control but requires more than 4 antihypertensive drugs is also considered resistant hypertension. It is thought that 30% of people with high blood pressure have uncontrolled blood pressure (per the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure Guidelines). National Health and Nutrition Examination Survey (NHANES) estimated that 8.9% of all adults with hypertension and 12.8% of all drug-treated hypertensive adults in the US2 have resistant HTN.
Race (non-hispanic black) , obesity and age are all risk factors for resistant hypertension.2 Patients with resistant HTN are more likely to have albuminuria, reduced renal function, and self-reported histories of coronary heart disease, heart failure, stroke, and diabetes mellitus (P<0.001).2
Importance of reducing your blood pressure
So far there is no data that actually addresses the prognosis of resistant HTN/high blood pressure; however the risks of myocardial infarction, stroke, heart failure, and renal failure are directly related to the level of BP.3 There is a direct relationship with blood pressure level and cardiovascular mortality. Every 20/10 mm Hg increase in blood pressure is associated with more than a twofold difference in the death rate of stroke from ischemic heart disease and other vascular causes.3
Small reductions in your blood pressure can be extremely beneficial. For example, a middle aged (between ages 40 and 69) person with a blood pressure reading of 175/105 mm Hg is 8X (absolute risk increase of 800%) more likely to die of cardiovascular disease in the next 10 years in comparison to a patient of the same age/ethnicity/sex with a BP reading of 115/75 mmHg.3
In a meta-analysis of 61 prospective, observational studies evaluating data of 1 million adults between the ages of 40-89 from multiple different countries and ethnicities showed that just reducing mean systolic blood pressure by 2 mm Hg had a 7% relative risk reduction of cardiovascular mortality and 10% relative risk reduction of stroke mortality.3
What you can do to ensure proper diagnosis of resistant hypertension
You may not have true resistant hypertension, but you might continuously lack adequate blood pressure control, a condition known as “pseudo-resistance”. You should be aware of the following factors if you have been diagnosed with resistant hypertension and prior to considering the treatment with RDN.
- Take your medicine on time and as prescribed
- Discontinuation rate of antihypertensive drug is about 50% within 1 year
- Be aware of the importance of achieving blood pressure control
- Every 20/10 mm Hg increase in BP is associated with more than a twofold difference in the stroke death rate
- Know the side effects of your medications
- Alcohol consumption:
- Large amounts of alcohol intake (3 or more drinks/day) have a dose-related effect on blood pressure and it should be limited to no more than 2 drinks/day for men and 1 drink)/day women.
- Cut out excess dietary salt
- Average sodium intake of resistant HTN exceeds 10 g/day.
- Dietary sodium for a hypertensive person should be
- Exercise and live an active lifestyle
- A 20 minute walk in the morning will help keep your blood pressure in check
- Ensure you are using proper blood pressure measuring techniques
- Sit quietly for at least 5 minutes prior to measuring your blood pressure
- Take a mean reading of at least 3 blood pressure measurements
- Ensure the cuff fits your arm or finger properly
- No smoking at least 3 hours prior to BP reading
- When measuring your blood pressure, ensure your arm is at heart level
- Understand and know the White-Coat effect
- Sometimes you can have higher office readings than at home or in ambulatory BP readings (readings taken throughout the day)
- 25% of patients referred for resistant hypertension achieve goal blood pressure under treatment when ambulatory measurements are performed
- Understand and know the secondary causes of Hypertension
- Renal parenchymal disease
- Obstructive sleep apnea
- Primary aldosteronism
- Renal artery stenosis
- Cushing’s syndrome
- Coarctation of aorta
- Calhoun DA, et al. Resistant hypertension: diagnosis, evaluation, and treatment: a scientific statement from the American Heart
Association Professional Education Committee of the Council for High Blood Pressure Research. Circulation. 2008;117:e510-e526.
- Persell SD. Prevalence of resistant hypertension in United States, 2003-2008. Hypertension. 2011;57:1076-1080
- Lewington S, Clarke R, Qizilbash N, Peto R, Collins R. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet. 2002;360: 1903-1913.
- SingerGM, Izhar M, Black HR. Goal-oriented hypertension management: translating clinical trials to practice. Hypertension. 2002;40:464-469.
- Sarafidis P, Bakris G. Resistant hypertension: an overview of evaluation and treatment. JACC. 2008;52(22): 1749–57