Cerebrovascular stenosis is an important cause and risk factor for ischemic cerebrovascular disease. Narrowing of cerebral blood vessels reduces the amount of blood passing through them, and brain cells die of ischemia.
There are many causes of cerebrovascular stenosis, and they are age-related. For example, the age of onset of stenosis caused by arteritis nodosa is usually between 10 and 30 years old, while those with stenosis due to atherosclerosis are often middle-aged and elderly people between 40 and 80 years old, or even older. In children, the onset of stenosis is usually due to congenital abnormalities in blood vessel development.
Treatment for cerebral artery stenosis includes medication, surgical treatment and vascular stenting. If the stenosis is less than 50%, we can take medication, mainly aspirin (A), propofol (P) and statin (S) drugs, which is called PAS therapy. If the stenosis exceeds 50% of the vessel diameter, carotid endarterectomy or stenting of the stenotic vessel to enlarge the lumen is required for treatment.
The main advantage of endovascular stenting is that it is less invasive to the patient and can treat multiple stenotic lesions at the same time, making it particularly suitable for patients who cannot tolerate or refuse surgery, whose stenosis recurs after surgery, whose stenosis is multiple and whose stenosis cannot be reached by surgery. Each of these three treatment methods has its own indications, advantages and disadvantages, and can complement each other. Intracranial stents open up new horizons
Innovation 1: Development of intracranial stents
Prof. Weijian Jiang said that, unlike white people in Europe and the United States where extracranial carotid artery stenosis is common, the distribution of atherosclerotic stenosis in the cerebral blood supply in Chinese people is mostly intracranial. In the past, coronary stents were used instead of doing intracranial artery stenosis angioplasty. The coronary arteries are relatively straight, the soft segments of the coronary stent system are short and the named pressure is high (greater than 6 atmospheres), while the intracranial vessels are tortuous and thin-walled, thus increasing the difficulty and risk of the procedure.
How could we seek for a stent with good flexibility and low naming pressure, which is more suitable for intracranial? At that time, there was no stent specifically for intracranial use at home and abroad. So, Prof. Weijian Jiang had an idea to design an independent intracranial stent. After repeated research and demonstration, Prof. Jiang Weijian designed and developed the first stent (Apollo stent) specifically for intracranial artery stenoplasty in China, and obtained a patent.
Apollo stent is a balloon-expandable type, which is characterized by long soft segment and low naming pressure (less than 6 atmospheres) without excessive damage and compression of blood vessels. The clinical study results of this domestic stent will be published in the American Journal of Neuroradiology in May 2007.
Innovation 2 proposes LMA staging
In the past, the Morri stenosis stenosis has been staged by Japanese scholars.
However, this staging method was proposed for conventional balloon angioplasty, and when it was used to guide stent interventions, the difference between the two different devices made the original staging unable to help the surgeon accurately predict the outcome of the procedure. For this reason, Prof. Jiang et al. proposed the first international location, morphology and access staging, or LMA staging, designed for intracranial stenting after a careful review of clinical practice.
This staging helps the operator to design an individualized stenting plan preoperatively, ensures the best benefit/risk ratio for patient treatment, and improves the preoperative evaluation system for intracranial stenting. The results of this study were named one of the Advances in Neurointervention 2004 by the American Journal of Stroke when it was published in 2004. So far, it has been applied more than 30 times by foreign influential journals and has been recognized by foreign colleagues.
Innovation 3: Bridging the “gap” in drug therapy
In patients with severe intracranial vascular stenosis, more than 20% of patients will have another stroke after two years of drug treatment. Therefore, there is a consensus that patients with severe intracranial artery stenosis are at high risk of stroke and are not suitable for drug treatment, thus making them “hopeless” patients. The study by Prof. Jiang et al. was the first in the world to find that successful stenting benefited ≥70% of patients with severe stenosis, providing a scientific basis for establishing the indications for intracranial stenting and giving new hope to this group of patients.
The results of this study also provide a scientific basis for the selection of target populations for future randomized controlled trials of drugs and stents. In addition, they completed a registry study of intracranial artery stenting and established a standard intracranial artery stenting registry study database.
Finally, Prof. Jiang emphasized that intracranial stenting is extremely demanding for the operator. Due to the tortuosity and slenderness of intracerebral vessels and the importance of brain tissue function, stenting carries a high surgical risk. With the improvement of stent flexibility and other properties, intracranial stenting has been applied to the treatment of intracranial artery stenosis in recent years, but stenting for intracranial artery stenosis is still in the exploratory stage internationally.
This technique requires the operator to have rich clinical experience in cerebrovascular disease and skillful interventional techniques, otherwise it is bound to increase the risk of the procedure and affect the smooth development of this new technology. In general, the surgeon should grasp two principles: First, the incidence of perioperative stroke should be controlled to less than 6% before surgery. Second, surgery should only be considered in patients with arterial stenosis greater than 70% and who have caused a cerebrovascular ischemic event.
Related links Washington Post report
A study from China shows that patients who are at risk for stroke due to narrowing of the internal cerebral arteries may benefit from stent placement at the site of the stenosis.
”There is still controversy about the value of stenting for intracranial cerebral artery stenosis because the procedure itself may lead to stroke, and the high rate of perioperative complications may offset the potential value of the treatment,” said Dr. Weijian Jiang, a neurologist at Beijing Titan Hospital, affiliated with Capital Medical University in Beijing, the study’s lead researcher.
The study included 121 patients with severe intracranial cerebral artery stenosis of more than 70 percent and 92 patients with stenosis less than 70 percent.
The results of the study, which included 121 patients with severe intracranial cerebral artery stenosis of more than 70 percent and 92 patients with stenosis of less than 70 percent, showed that patients with severe stenosis were able to benefit significantly from stentoplasty. The stroke rate was 7.2 percent at one year and 8.2 percent at two years after stenting in patients with severe cerebral artery stenosis, and 5.3 percent at one year and 8.3 percent at two years in the group with lower stenosis.
Kang said, “The findings suggest that patients with severe intracranial cerebral artery stenosis can benefit from stenting treatment, while patients with moderate stenosis may not, because our findings suggest that the degree of stenosis in intracranial cerebral arteries is not a predictor of the risk of stroke after stenting.” In other words, the potential risk of stenting in patients with milder stenosis may not warrant such a procedure.
Because of the relatively small sample size of the study, further large sample size, tightly controlled studies are needed to compare the therapeutic value of stenting with other treatments, such as drugs and surgery, in patients with severe cerebral artery stenosis.
This report from China is very encouraging,” said Professor Edgar J. Kenton, clinical professor of neurology at Thomas Jefferson University Hospital in Philadelphia and executive chairman of the American Academy of Neurology. But he added that “given other confounding factors, a double-blind controlled study will eventually be needed” to compare the value of stenting with other treatments for patients at high risk for stroke, including severe stenosis, diabetes, hypertension, and history of stroke.