- Last Updated: November 30, 2016
Hypertension, or high blood pressure, is a condition in which the blood pressure in the arteries is chronically elevated (defined as a systolic pressure ≥140 mm Hg and/or a diastolic pressure ≥80 mmHg). Hypertension is classified as either essential hypertension or secondary hypertension, with 90% of affected patients falling in the essential hypertension category. The cause of elevated pressure is unknown in essential hypertension, while secondary hypertension has a definite underlying cause, such as kidney disease, which may be permanently cured.
Hypertension is a major risk factor for coronary artery disease, stroke, heart failure, renal disease, and peripheral vascular disease. Surprisingly, hypertension rarely causes any symptoms and is usually diagnosed during routine physical exams. Some people with high blood pressure may experience headaches, light-headedness, tinnitus (buzzing in the ears), altered vision or fainting.
Data from the Framingham Heart Study indicate that 90% of people over age 55 will develop hypertension during their lifetime.
The first line of treatment for hypertension is lifestyle modification, such as weight loss, exercise, diet improvements (high in fruits, vegetables, whole grains, and nuts and low in fat and sodium), smoking cessation, and relaxation therapy.
For most patients with hypertension, medication is ultimately needed to maintain blood pressure in a range that can lower the risk of future complications. The most commonly used medications include diuretics, sympatholytics, vasodilators, and drugs that interfere with the renin-angiotensin system. Overall, these medications work to reduce strain on the heart through decreasing blood circulation volume, heart rate, and/or resistance to blood flow in the vessels.
If patients have hypertension due to renal artery stenosis (narrowing of the blood vessels going to the kidneys), then catheter directed angioplasty and stenting usually normalizes the blood pressure.
Although initial investigations utilizing catheter based RF ablation of the nerves around the renal arteries in the SYMPLICITY HTN - 1 and SYMPLICITY HTN - 2 trials were promising, the most recent SYMPLICITY HTN - 3 trial did not show a significant decrease in the systolic blood pressure in patients with resistant hypertension at 6 months.
Focused Ultrasound Treatment
Researchers at the Chongqing Medical University initially investigated the feasibility of non-invasive focused ultrasound in controlling blood pressure through renal denervation in preclinical studies. Subsequent clinical studies with US guided focused ultrasound for renal denervation show promising results. Three single-arm pilot studies sponsored by Kona Medical have been completed utilizing focused ultrasound for renal denervation in resistant hypertension. One year results of the WAVE I,II,and III studies demonstrated a 23% average reduction in systolic blood pressure, with a good safety profile1. A larger, sham controlled clinical trial is underway with the WAVE IV study.
For a full list of known hypertension clinical trials, please see here.
Schmieder RE, Ott C, Bramlage P. Non-invasive Renal Denervation: Update on External Ultrasound Approaches. Curr Hypertens Rep. 2016 Jun;18(6):48. doi: 10.1007/s11906-016-0653-6.
Rong S, Zhu H, Liu D, Qian J, Zhou K, Zhu Q, Jiang Y, Yang G, Deng C, Zhang D, Zhou Q, Lei H, He TC, Wang Z, Huang J. Noninvasive renal denervation for resistant hypertension using high-intensity focused ultrasound. Hypertension. 2015 Oct;66(4):e22-5. doi: 10.1161/HYPERTENSIONAHA.115.05754. Epub 2015 Aug 3.
Kandzari DE et al. Predictors of blood pressure response in the SYMPLICITY HTN-3 trial. Eur Heart J. 2015 Jan 21;36(4):219-27
Bakris GL et al. Impact of renal denervation on 24-hour ambulatory blood pressure: results from SYMPLICITY HTN-3. J Am Coll Cardiol. 2014 Sep 16;64(11):1071-8
Wang Q, Guo R, Rong S, Yang G, Zhu Q, Jiang Y, Deng C, Liu D, Zhou Q, Wu Q, Wang S, Qian J, Wang Q, Lei H, He TC, Wang Z, Huang J. Noninvasive renal sympathetic denervation by extracorporeal high-intensity focused ultrasound in a pre-clinical canine model. J Am Coll Cardiol. 2013 May 28;61(21):2185-92.
Tokarczyk A, Rivens I, van Bavel E, Symonds-Tayler R, ter Haar G. An experimental system for the study of ultrasound exposure of isolated blood vessels. Phys Med Biol. 2013 Apr 7;58(7):2281-304.
Symplicity HTN-1 Investigators; Krum H, Barman N, Schlaich M, et al. Catheter-based renal sympathetic denervation for resistant hypertension: durability of blood pressure reduction out to 24 months. Hypertension. 2011;57:911-917. Expanded results presented at the Transcatheter Cardiovascular Therapies annual meeting 2013.
Symplicity HTN-2 Investigators; Esler MD, Krum H, Sobotka PA, et al. Renal sympathetic denervation in patients with treatment-resistant hypertension (The Symplicity HTN-2 Trial): a randomised controlled trial. Lancet. 2010;376:1903-1909. Expanded results presented at the Transcatheter Cardiovascular Therapies annual meeting 2013.
Pathak A, Girerd X, Azizi M, Benamer H, Halimi JM, Lantelme P, Lefèvre T, Sapoval M; French Society of Hypertension. French Society of Cardiology; Working Group on Atheroma, Interventional Cardiology; French Society of Radiology. Expert consensus: renal denervation for the treatment of arterial hypertension. Arch Cardiovasc Dis. 2012 Jun-Jul;105(6-7):386-93.
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