The American Heart Association (AHA) issued a scientific statement in 2008, defining intractable hypertension as a condition in which three different antihypertensive drugs (one of which is a diuretic) with different mechanisms of action, or at least four drugs, are required to control systolic and diastolic blood pressure at target levels (< 140/90 mm Hg) after lifestyle improvement. There are no precise statistics on the prevalence of intractable hypertension, but a number of clinical studies suggest that this group accounts for 20% to 30% of patients with hypertension, which is not an uncommon disease. 2007 China Cardiovascular Disease Report states that there are at least 200 million people with hypertension in China, and according to this figure, it is estimated that there are nearly 50 million patients with intractable hypertension in China. In addition, patients with hypertension who have a combination of risk factors (smoking, diabetes, obesity, etc.) require stricter control of blood pressure (< 130/80 mm Hg), so the actual number of patients with intractable hypertension is higher than expected. The current treatment strategies for persistent hypertension include lifestyle changes, combination of antihypertensive drugs, target organ protection, and control of multiple risk factors. However, the diagnosis and treatment of hypertension is still a challenge even in developed countries. Despite the availability of a variety of safe and effective drug therapies (including fixed combinations of multiple drugs), only 6.1% of patients in China are able to achieve the target level required by treatment guidelines. Although the majority of patients' failure to achieve BP targets can be attributed to poor adherence to the principle of lifelong medication adherence in the absence of symptoms, it also suggests that there is an urgent need to develop new hypertension treatment pathways to improve patient adherence and to compensate for the lack of pharmacological therapy. Since 2007, Krum et al. have attempted to treat intractable hypertension with percutaneous catheterized renal sympathetic nerve radiofrequency ablation, and achieved satisfactory results, providing a new idea for the treatment of intractable hypertension. The following is a review of renal sympathetic nerve radiofrequency ablation treatment for recalcitrant hypertension. 1, renal sympathetic nerve and hypertension Sympathetic hyperexcitability has been considered to be the basic link in the development of hypertension. Numerous animal experiments have demonstrated the effect of the real sympathetic nervous system on blood pressure. Clinical studies have also found a positive correlation between the degree of sympathetic excitation and the blood pressure level of patients. In particular, the renal sympathetic nervous system, especially the renal sympathetic efferent and afferent nerves closest to the renal artery wall, plays a decisive role in triggering and maintaining systemic hypertension. The renal sympathetic nerves originate from the thoracic vertebrae10 and descend to the lumbar vertebrae1 , entering the kidney with the renal artery, mainly in the renal vascular epithelium. The return of normal central sympathetic excitation after bilateral nephrectomy in patients with advanced nephropathy suggests that renal sensory nerve efferent signals have a strong agonistic effect on central sympathetic nerves. The mean arterial pressure was (135 ± 11) and (166 ± 4) mm Hg in the bilateral renal denervated and sham-operated groups after 10 ng/(kg ・min) of angiotensin II injection for 10 d, suggesting that renal sympathetic nerves play an important role in angiotensin II-induced hypertension. The mean arterial pressure was (125 ± 3) and (145 ± 4) mm Hg (n = 7) in the two groups at 12 weeks of age, and the blood pressure in the sympathetic nerve removal group was significantly lower (P < 0101). Krum et al. used transgenic technology to construct a hypertension model in young pigs, and used percutaneous bilateral renal sympathetic nerve radiofrequency ablation to remove the bilateral renal sympathetic nerves, and compared with the sham-operated group, the blood pressure in the operated group decreased significantly, and the blood catecholamine concentration decreased significantly. In the above experiments, it was observed that removal of bilateral renal sympathetic nerves significantly reduced blood pressure in different hypertension models. In addition, a large number of animal experiments have also found that blocking renal sympathetic efferent nerves has a positive effect not only on blood pressure but also on organ-specific damage caused by chronic sympathetic overactivity. Based on the above theory, sympathectomy was considered as a treatment for hypertension long before the introduction of modern drug therapy. Since then, various sympathectomy procedures have been performed. Although satisfactory results were achieved in lowering patients' blood pressure, long-term follow-up revealed that:simple sympathetic ganglionectomy was associated with high mortality and postoperative morbidity with serious long-term complications, including bowel, bladder, and erectile dysfunction as well as severe postural hypotension. Therefore, sympathectomy for intractable hypertension has not been popularized in clinical practice because the disadvantages outweigh the benefits. Nevertheless, selective sympathectomy is still an interesting treatment strategy. In April 2009, Krum et al. reported a new technique of percutaneous catheter renal sympathetic nerve radiofrequency ablation for intractable hypertension. This method is used to cut the renal sympathetic nerve by radiofrequency ablation without affecting other abdominal, pelvic, or lower extremity innervation, achieving the goal of lowering blood pressure while avoiding serious complications. Patients in this study were enrolled with an in-office systolic blood pressure ≥160 mm Hg despite treatment with class 3 antihypertensive agents (including diuretics) or proven intolerance to treatment. Glomerular filtration rate ≥ 45 mL/ (min ・1173 m2 ). Exclusion criteria: secondary hypertension, type 1 diabetes mellitus, and renal vascular abnormalities. A total of 50 patients were enrolled at the beginning, but 5 patients were excluded for anatomical reasons (mainly bilateral renal arterial system), so a total of 45 patients were treated surgically. The study endpoints were perioperative and long-term safety and in-office blood pressure levels. The procedure was performed by implanting therapeutic catheters into both renal arteries, followed by intermittent ablation for 2 min each with ≤8 weeks of radiofrequency energy in 6 axially rotated segments of the renal arteries. During the ablation period, tip temperature and impedance were monitored by the catheter system, and the amount of RF emission was varied according to a predetermined formula. In 10 of the patients, norepinephrine release from the sympathetic nerves of the kidneys was measured bilaterally by isotope dilution before and 15-30 days after the RF treatment, and the results showed an average reduction of 47% in norepinephrine release after the treatment, confirming the denervation effect of RF ablation on the sympathetic efferent nerves of the kidneys. The postoperative follow-up revealed that the antihypertensive effect of the procedure was evident at month 1, more evident at month 3, and continued until subsequent multiple evaluations. blood pressure decreased by 14/10, 21/10, 22/11, 24/11, and 27/17 mm Hg at months 1, 3, 6, 9, and 12 after treatment, respectively. only one of the 45 patients had renal artery dissection (cured by renal artery stenting), and no other complications were found. This study shows that percutaneous catheter renal sympathetic nerve radiofrequency ablation is simple to perform, has few complications, and can result in significant and sustained reduction of blood pressure in patients with intractable hypertension, which is a novel, simple, and effective method for the treatment of intractable hypertension. 4, shortcomings and prospects of renal sympathetic nerve radiofrequency ablation At present, percutaneous catheter renal sympathetic nerve radiofrequency ablation for the treatment of intractable hypertension is still in the exploratory stage, and the Krum study itself has some shortcomings: ① The study focused on the report of new technology, its sample size was insufficient and no control group was established, only some patients in the study used ambulatory blood pressure as an index to judge the efficacy, and no norepinephrine and other (ii) The inclusion criteria in the study were ②The inclusion criteria in the study were too simple and did not exclude pseudohypertension, white coat hypertension, etc. (iii) Whether all patients with intractable hypertension are suitable for this procedure is unclear. Although renal sympathetic efferent and afferent nerves play a decisive role in inducing and maintaining systemic hypertension, some scholars believe that this does not apply to all hypertensive patients. ④ Long-term follow-up for safety is lacking in studies. Despite these shortcomings, the use of interventional means to selectively remove the sympathetic nerve undoubtedly provides a very good idea for the treatment of recalcitrant hypertension. A lot of research work needs to be done on the treatment of intractable hypertension with percutaneous catheterized renal sympathetic nerve radiofrequency ablation. Secondly, the screening of the indications for the procedure, whether plasma angiotensin II, cardiac natriuretic factor, cerebral natriuretic factor, aldosterone and other clinical tests can be included in the indications, in addition to recalcitrant hypertension, needs to be further investigated. Finally, the screening of its contraindications and the treatment of side effects, all of which require a large number of animal experiments and clinical trials for further research and discovery. Although this method cannot be used as the first-line treatment for intractable hypertension, it can be a useful supplement to pharmacological therapy. At present, cardiovascular interventions are very popular in China, and the majority of interventionalists have mastered radiofrequency ablation technology.