On August 9, 2013 at the China Heart Conference (CHC), the National Cardiovascular Center released the China Cardiovascular Disease Report 2012. The report points out that the number of current cardiovascular disease patients in China is 290 million, and 1 person dies of cardiovascular disease every 10 seconds; projected by the average annual increase of 3% in the prevalence of hypertension in people over 15 years old in the past, the prevalence of hypertension in China was 24% in 2012, and it is estimated that the number of hypertensive patients in the country is 266 million, that is, at least 1 out of every 5 adults suffers from hypertension.
Among them, about 26 to 78 million people have persistent hypertension. It is generally accepted that recalcitrant hypertension is highly associated with the risk of cardiovascular and cerebrovascular events. The main indications for hypertension device therapy are currently strictly among the population with intractable hypertension, especially in high-risk patients with intractable hypertension who have not reached the standard despite well-documented treatment with various antihypertensive drugs.
I. Is it true recalcitrant hypertension?
To establish a diagnosis of intractable hypertension one must first exclude pseudo-intractable hypertension by.
1) Excluding pseudo-intractable hypertension due to poor compliance;
2) Excluding in-office hypertension (white coat effect);
3) Excluding pseudo-intractable hypertension due to incorrect measurement method or mismatch between arm and cuff;
4) Excluding pseudo-intractable hypertension due to peripheral vascular sclerosis in the elderly
What are the causes of true intractable hypertension?
Once it is clear that the patient is suffering from true intractable hypertension, the possible causes of intractable hypertension need to be further defined as follows.
1) Lifestyle risk factors not well controlled: such as excessive alcohol consumption, heavy smoking, high-fat diet, high-salt diet, excessive life stress, repeatedly staying up late, etc.;
2) Metabolic syndrome: obesity, abnormal glucose metabolism or insulin resistance, severe lipid metabolism abnormalities are not well controlled;
3) Obstructive sleep apnea syndrome: an increasingly common cause of intractable hypertension, probably due to chronic hypoxia, chemoreceptor stimulation and the long-term effects of sleep elimination on vasoconstriction factors;
4) Undetected secondary hypertension: such as primary aldosteronism and renal artery stenosis, which are the most common;
5) Combined with target organ damage such as the kidney.
III. What is the current status of device treatment for intractable hypertension?
1, carotid pressure receptor stimulation: long-term electrical stimulation of carotid sinus nerve receptors through implanted devices to reduce sympathetic nerve impulses sent to reduce systolic and diastolic blood pressure in patients with intractable hypertension. The characteristics of the hypotensive effect: the higher the patient’s initial blood pressure, the more pronounced the reduction; the control effect on ambulatory blood pressure lasts for more than 53 months; there are few adverse effects, mainly some local reactions such as nerve irritation and glossopharyngeal neuralgia. However, the results of long-term observation data are limited to a limited population, and further clarification of its long-term safety and efficacy is needed. Technical improvements are currently being made in Europe to improve the ease of implantation and to extend the life of the battery. Unfortunately the US FDA has temporarily terminated its further clinical research work.
2, renal denervation therapy: mainly through the catheter ablation technology in the renal artery local selective destruction of renal sympathetic nerve fibers, to achieve the role of blocking sympathetic nerves, without affecting other abdominal or lower limb innervation, to achieve the purpose of lowering blood pressure while avoiding serious complications; studies have shown that it has a reduction in atherosclerosis, improve the left ventricular hypertrophy and diastolic domestic hypotension, renal protection, abnormal glucose metabolism, etc. additional benefits.
The characteristics of this treatment method: it leads to a significant reduction in office blood pressure, and the status of blood pressure control can be maintained for 1 year and, in a few cases, 2-3 years after treatment; limited reduction in ambulatory and home blood pressure, requiring anti-hypertensive medication; few complications, except for local hematoma and renal artery entrapment due to catheter manipulation, no serious complications or deterioration of its renal function have been reported. Therefore, this method is regarded as the most promising means of hypertension device treatment. However, long-term safety, surgical implementation and evaluation methods, specific mechanisms of action and major targets still need to be further confirmed by reasonably designed long-term comparative clinical trials and basic research.
3. Other methods: Other instrumental or surgical treatment methods for recalcitrant hypertension include renal denervation by ultrasound technology, surgical creation of arteriovenous fistula and neural tube decompression. Still in the exploratory phase, they are limited to secondary approaches for severe intractable hypertension.
In conclusion, the instrumental treatment of intractable hypertension is still in a period of clinical exploration, and even though some of the interventions are promising, the available evidence is, after all, quite limited. Therefore, the 2013 ESH/ESC guidelines for the prevention and treatment of hypertension only recommend renal denervation and carotid pressure receptor stimulation for patients with true intractable hypertension who have failed pharmacological treatment (Class IIb recommendation, Level C evidence), and patients should have blood pressure ≥160/110 mmHg (Class I recommendation, Level C evidence), and strictly limit this type of operation to experienced physicians. and requires postoperative follow-up observation by a specialized hypertension center (Class I recommendation, Level C evidence).
In addition, we must correct some misconceptions to prevent misinformation to patients and the general public. First, the role of device therapy for intractable hypertension is relatively limited, and it cannot replace medication completely, and it cannot be done once and for all; second, medication is still the mainstream treatment for hypertension and intractable hypertension, and device therapy cannot replace medication, that is, we are still quite far from the era of true hypertension device therapy. Therefore, how to improve patients’ compliance with medication, improve patients’ blood pressure compliance rate, and strengthen the overall disease management of hypertension are still long-term issues of hypertension prevention and control.