Renal sympathetic nerve radiofrequency ablation for intractable hypertension.
Medical Director: Tao Zhou, Director of Department of Cardiology, The Third Affiliated Hospital of Southern Medical University
Q: What is recalcitrant hypertension?
A: Diagnostic criteria for intractable hypertension: In 2008, the AmericanHeartAssociation (AHA) defined intractable hypertension as: taking three different antihypertensive drugs (one of which is a diuretic) with different mechanisms of action after lifestyle improvement, or requiring at least four drugs to control systolic and diastolic blood pressure at target levels (< 140/90 mmHg).
Q: What is radiofrequency ablation and what is the main treatment?
A: Cardiac radiofrequency ablation is an interventional treatment for tachyarrhythmias that has been available for more than 20 years.
A very thin catheter is inserted into the blood vessel from the neck or the root of the thigh, and after reaching the location of the disease, radiofrequency current is released to eliminate the “lesion” at one time. This method is non-invasive, minimally invasive, and has a very high success rate. It has become the first choice for the treatment of tachyarrhythmias, and has become a very effective treatment for atrial fibrillation with the advent of the 3-D scaler system.
Q: What are the advantages of radiofrequency ablation treatment?
A: ① precise efficacy, high success rate, low recurrence rate; ② can significantly improve the quality of life of patients, reduce the incidence of sudden death, heart failure and stroke; ③ small trauma, fast recovery.
Q: When was the breakthrough in the treatment of intractable hypertension? What method?
A: Starting from 2007, Krum et al. tried to treat recalcitrant hypertension with percutaneous catheter renal sympathetic nerve radiofrequency ablation, which achieved satisfactory results and became a breakthrough in the treatment of recalcitrant hypertension.
Q: What is the relationship between renal sympathetic nerve and hypertension?
A: Sympathetic hyperexcitability has been considered to be the underlying link in the development of hypertension. Numerous animal studies have demonstrated the effect of the real sympathetic nervous system on blood pressure. Clinical studies have also found that the degree of sympathetic excitation is positively correlated with 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 the induction and maintenance of systemic hypertension. The renal sympathetic nerves originate superiorly from the thoracic spine10 and descend to the lumbar spine1 and enter the kidney with the renal artery, mainly in the extravascular membrane of the kidney. Renal sympathetic nerves play an important role in angiotensin II-induced hypertension. Blood catecholamine concentrations decreased significantly after renal sympathetic nerve radiofrequency ablation. Removal of bilateral renal sympathetic nerves was observed to significantly lower blood pressure in experiments in different hypertension models, and the common mechanism may be to reduce blood catecholamine concentrations by removing renal sympathetic nerves. In addition, numerous animal studies have 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.
Q: When did the exploration of sympathetic nerve removal for hypertension begin? What are the results?
A: Based on the above theory, sympathectomy was considered as a treatment for hypertension long before modern drug therapy was introduced, and in 1941, Grimson et al. began experimenting with lumbar and abdominal sympathectomy to treat intractable hypertension with some success. A variety of sympathetic ganglionectomy procedures have been carried out since then. 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, as well as serious long-term complications, including bowel, bladder, and erectile dysfunction and severe postural hypotension. Therefore, sympathetic nerve removal for recalcitrant hypertension failed to gain clinical popularity early on because the disadvantages outweighed the benefits. Nevertheless, selective sympathectomy remains an interesting treatment strategy.
1. What is renal sympathetic nerve radiofrequency ablation?
In April 2009, Krum et al. reported a new technique of percutaneous catheter renal sympathetic nerve radiofrequency ablation for the treatment of intractable hypertension. This method achieves the goal of lowering blood pressure while avoiding serious complications by cutting the renal sympathetic nerve with radiofrequency ablation without affecting other abdominal, pelvic, or lower extremity innervation.
Inclusion criteria for patients in this study: patients with systolic blood pressure ≥ 160 mmHg despite treatment with class 3 antihypertensive drugs (including diuretics) or proven intolerance to drug therapy. Glomerular filtration rate ≥ 45 mL/(min?1173m2).
Exclusion criteria: secondary hypertension, type 1 diabetes mellitus, and renal vascular abnormalities.
The procedure was performed by implanting a therapeutic catheter into the bilateral renal arteries followed by intermittent ablation with ≤8 weeks of radiofrequency energy for 2 min each, within 6 regions of the axially rotated segmentation within the renal arteries. During ablation, tip temperature and impedance were monitored by the catheter system, and the amount of RF emission was varied according to a predetermined formula. Patients underwent isotope dilution before and 15-30 d after radiofrequency treatment to measure norepinephrine release from the sympathetic nerves of the kidneys bilaterally, and the results showed an average 47% reduction in norepinephrine release after treatment, confirming the denervation effect of radiofrequency ablation on the sympathetic efferent nerves of the kidneys. Postoperative follow-up revealed that the antihypertensive effect of the procedure was evident at month 1, more pronounced at month 3, and continued until several subsequent evaluations, with blood pressure decreases of 14/10, 21/10, 22/11, 24/11, and 27/17 mm Hg at months 1, 3, 6, 9, and 12 after treatment, respectively. no significant complications were observed at this time. 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 blood pressure reduction in patients with intractable hypertension, which is a novel, simple, and effective method for the treatment of intractable hypertension.
2.What are the shortcomings and outlook of renal sympathetic nerve radiofrequency ablation?
Medical guidance expert: Zhou Tao, Director of Department of Cardiology, Third Affiliated Hospital of Southern Medical University A: Currently, percutaneous catheter renal sympathetic nerve radiofrequency ablation for recalcitrant hypertension is still in the stage of clinical exploration, and the Krum study itself has certain shortcomings.
(1) The study focused on reporting 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 determine the efficacy, and no norepinephrine and other indexes were tested.
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. In addition to intractable hypertension, whether plasma angiotensin II, cardiac natriuretic factor, cerebral natriuretic factor, aldosterone and other clinical tests can be included in the indications needs to be further studied. 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 interventional physicians are skilled in radiofrequency ablation technology.
Q: What is the prevalence of intractable hypertension?
A: There are no precise statistics, but several clinical studies suggest that this type of patients account for 20%-30% of hypertensive patients, which is not a rare disease. 2007 China Cardiovascular Disease Report pointed out that there are at least 200 million hypertensive patients in China, and according to this data, it is estimated that there are nearly 50 million persistent hypertensive patients in China. In addition, hypertensive patients with combined risk factors (smoking, diabetes, obesity, etc.) require stricter blood pressure control (<130/80 mmHg), so the actual number of patients with recalcitrant hypertension exists more than expected.
Q: What are the principles of treatment for intractable hypertension?
A: The principles of treatment for recalcitrant hypertension mainly include: change of lifestyle habits, combination of antihypertensive drugs, protection of target organs, 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 multiple safe and effective drug therapies (including fixed combinations of multiple drugs, etc.), only 6.1% of patients in China are able to achieve the target goal levels required by treatment guidelines. Although most of the patients’ failure to achieve the target blood pressure can be attributed to poor compliance and inability to adhere to the principle of lifelong medication in the absence of symptoms, it also shows that there is an urgent need to open up new avenues of hypertension treatment to improve patient compliance and to compensate for the lack of pharmacological therapies. 10% of hypertensive patients, i.e., recalcitrant hypertension, are suitable for radiofrequency ablation of renal sympathetic nerves.
Provide new treatment medical guidance for hypertensive patients Expert: Zhou Tao, Director of Department of Cardiology, Third Affiliated Hospital of Southern Medical University Global Health Survey shows that about 7 million people die from hypertension-related diseases every year due to poor blood pressure control. According to the survey, there are 200 million hypertensive patients in China, and 10 million new hypertensive patients are added every year. The medical community has been looking for new strategies for the treatment of hypertension, hoping to treat hypertension “once and for all”, so that patients can continue to effectively lower blood pressure without long-term medication, and to reduce the target organ damage caused by the disease. Interventional surgery for hypertension is one of the new treatment strategies that the medical community is focusing on.
If you are a patient with hypertension, are you worried about taking medication every day? Are you unable to afford the expensive drugs? Are you seeking medical help because your medication is not working well?
3. A recent study may solve these problems for you.
The Lancet recently reported on a study led by Professor Henry Kramer, director of the Centre for Cardiovascular Research and Therapeutic Education at Monash University in Melbourne, Australia. The Lancet recently reported a study led by Professor Henry Kramer, director of the Centre for Cardiovascular Research and Therapeutic Education at Monash University in Melbourne, Australia. The study showed that the use of radiofrequency ablation to remove sympathetic nerves innervating the kidneys significantly reduced blood pressure in patients with intractable hypertension. Henry? Professor Kramer said the treatment would benefit 5 to 20 percent of hypertensive patients for whom drug therapy had failed. He said the experimental results confirm that the therapy is significant in treating hypertension. The researchers confirmed that the simple catheter-based therapy is safe and can lower blood pressure over time in patients with hypertension who are resistant to multiple antihypertensive drugs. Moreover, patients whose blood pressure was significantly lower at one month had a further reduction at three months, and the blood pressure reduction remained significant at one year.
This is an exciting study and is arguably the most interesting result in the treatment of hypertension in the last 20 years. The most intriguing aspect of the results is that they offer the hope of a one-time cure for a lifelong disease like hypertension. It also uses a minimally invasive interventional approach that causes minimal damage to the patient.
The procedure does not require an incision. To be precise, this treatment cannot be called surgery. It is similar to coronary intervention at the initial stage of treatment.
The treatment process lasts for a very short time, less than an hour, and does not cause much pain to the patient.
The treatment principle is not entirely innovative In fact, before modern antihypertensive drugs were available, doctors had tried to cut the sympathetic nerves in the chest, abdomen or pelvis of hypertensive patients to control blood pressure. This was a very risky procedure, with a mortality rate of up to 20%. With the introduction of several effective antihypertensive drugs, this treatment was abandoned by doctors many years ago.
Although the cause of hypertension is not fully understood, the medical community has long believed that sympathetic excitation and elevated blood pressure are closely related. In particular, sympathetic overexcitation of the kidneys can cause vasoconstriction of the kidneys, reducing renal secretion, causing water and salt to be retained in the body, and also promoting renal secretion of renin, a substance that causes an increase in angiotensin II and aldosterone in the blood, the latter two substances, which can lead to increased blood pressure. There is a class of antihypertensive drugs that work by inhibiting the production of these substances.
Nevertheless, this treatment method can be called a very great innovation.
4.Answers to questions and answers Is the procedure safe?
Interventional treatment via femoral artery puncture is a very mature technique that requires no incision and generally only local anesthesia rather than general anesthesia, thus reducing the risk. It is also minimally invasive, requiring only a puncture in the femoral artery, causing minimal trauma to the patient, and the patient is largely pain-free during treatment.
In this report from Melbourne, out of 50 patients, only one case had a pseudoaneurysm at the puncture site, and this complication is treatable.
5. Is there any damage to the kidneys?
Is there any damage to the renal artery when the energy of radiofrequency is destroying the nerve? Is there any effect on kidney function after nerve removal?
When the energy of radiofrequency destroys the nerve, it may damage the inner lining of the renal artery to a certain extent. However, the sympathetic nerve of the kidney and the renal artery are closely associated, and radiofrequency only needs to emit a smaller amount of energy to achieve the purpose of treatment, and there is less damage to the artery, and the arterial intima has a good self-repair function.
The authors of the paper noted that only one of the 50 patients treated developed renal artery entrapment. Arterial entrapment is a common complication of endovascular interventions. A wide variety of endovascular stents are now available, and arterial entrapment can be managed with vascular stents, usually without serious consequences.
With regard to the effect on kidney function, the paper states that this treatment does not impair the kidney function of the patient, and some patients with pre-existing renal insufficiency have even seen some improvement in their kidney function with the treatment. Hypertension itself can cause damage to the kidneys, and when blood pressure is controlled, it has a protective effect on the kidneys. However, the long-term effects of this treatment on kidney function need further observation before conclusions can be drawn. This aspect may not be a cause for undue concern. In patients with kidney transplants, although the sympathetic nerves are cut off, the function of the newly transplanted kidney in these patients does not seem to be significantly affected as a result.
6. Can the nerve regenerate?
If the sympathetic nerve regenerates, isn’t this surgery done for nothing?
The researcher did 12 months of observation during the treatment and did not find significant nerve regeneration. He said that in patients with kidney transplantation, after a certain period of time, the efferent nerves can regenerate to some extent, but the afferent nerves will not regenerate. The mechanism of hypotension of this treatment may include both removal of the efferent nerve and destruction of the afferent nerve. Therefore, even if the efferent nerve is partially regenerated, there may be maintenance of the hypotensive effect.
7. Prospects – There are still many limitations in the research So when will this treatment go to the clinic?
It is difficult to say. As physicians, we often rejoice at the emergence of a new treatment, but unfortunately, in most cases, what follows is disappointment. The study is still preliminary, a “proof-of-principle” or “proof-of-concept” study, and has many limitations, such as a small sample size of less than 50 cases, no control group, and uncertain long-term effects. The long-term effects are uncertain, etc. The antihypertensive effect of this treatment cannot be excluded, for example, by the placebo effect. Furthermore, it is worth pointing out that the patients who received this treatment were still taking antihypertensive drugs.
It is even possible that, over time, this treatment will develop multiple problems and be abandoned. But in any case, this spirit of discovery by Australian doctors is admirable! This method may also open up a new way of treating persistent hypertension.
Research will be conducted in China on hypertension, which is responsible for coronary heart disease and stroke, and is one of the most serious diseases affecting the Chinese. There are nearly 200 million patients with hypertension in China, but for many reasons, only 1/4 of the patients take antihypertensive drugs, and even among those who do, only 1/4 of them have their blood pressure well controlled.
It is believed that there will be many related researchers in China to verify and explore this treatment in a new way.
8, how to effectively prevent hypertension hypertensive disease is one of the most important risk factors for coronary heart disease. Prevention and treatment of hypertension is important to prevent coronary heart disease and reduce the mortality rate of coronary heart disease. Specific methods are as follows.
(1) Regular blood pressure measurement is an effective method for early detection of symptomatic hypertension. For people with a family history of hypertension, blood pressure should be checked regularly from childhood onwards.
(2) Salt restriction. Many studies have shown that salt intake is positively associated with the incidence of hypertension.
(3) Quit smoking. Smoking can make blood pressure rise, heartbeat accelerated, smoking a cigarette can sometimes make blood pressure rise 3.33 kpa. long-term heavy smoking, can make small arteries continue to contract, long arterial wall degeneration, hardening, narrowing the lumen, the formation of persistent hypertension.
(4) control weight. Overweight brings many side effects to the organism. The prevalence of hypertension in fat people is 2-6 times that of normal weight people, while reducing weight can normalize blood pressure.
(5) actively participate in physical exercise, relax tension. Lack of physical exercise is prone to fat accumulation, weight gain, and increased blood pressure.
(6) Timely control of critical hypertension. When the blood pressure is between 18.7-21.3/12-12.7kpa is called critical hypertension, critical hypertension is mostly asymptomatic, but must be paid attention to.
9, new technology is expected to safely control hypertension.
Professor Suzanne Oparil of the University of Alabama at Birmingham pointed out in the report “Radiofrequency ablation of renal sympathetic nerve for intractable hypertension and related diseases” that radiofrequency ablation of renal sympathetic nerve technology has been developed since 1940, and the therapeutic efficiency has increased significantly, and the related mortality rate is also decreasing gradually. deaths, and they were not related to surgery. The long-term safety of radiofrequency ablation of renal sympathetic nerves was analyzed by monitoring 81 patients in the trial with cardiac angiography (CTA), magnetic resonance angiography (MRA), or Doppler ultrasound (Duplex) over a 6-month period, with no vascular abnormalities and no changes in renal function. At 6 months post-procedure, subjects experienced a 32 mmHg decrease in systolic blood pressure and a 12 mmHg decrease in diastolic blood pressure, with a sustained decrease in blood pressure and stable renal function over this 6-month period. In addition, the study also found that renal sympathetic denervation significantly reduced insulin, C-reactive protein and fasting glucose levels and improved insulin resistance in patients with intractable hypertension.
According to Professor Oparil, radiofrequency ablation of renal sympathetic nerve technique is a very encouraging and important development. This is because since the introduction of angiotensin II receptor antagonists in 1994, there has been little progress in the field of pharmacological treatment of hypertension, except for direct renin inhibitors. From the available information, the prospects for the application of radiofrequency ablation of renal sympathetic nerve technique are very promising. Of course, there are still some unknown things about the technique, such as the results of a 3-year follow-up in a center in the United States, which showed that some patients had recurrence of the disease, whether this is due to the failure of the surgical operation or the natural history characteristic of hypertension, we do not know yet. Professor Oparil reminds physicians who are eager to start this technique that we need to follow patients closely and it is important to observe the long-term prognosis of these patients. In addition, more experience and data are needed to implement this technique in clinical practice, and it remains to be tested in large clinical trials to verify its efficacy and safety. The high cost of the technology may be one of the reasons limiting its implementation.