Mechanical thrombectomy: stroke treatment 2.0

Each year, approximately 250,000 Germans suffer a stroke. This makes stroke the third leading cause of death after heart disease and cancer. The circulatory disorder that occurs in the brain is normally treated using systemic thrombolysis, a procedure that bears various risks. Unlike mechanical thrombectomy, which offers clear advantages by comparison.


Photo: Hans-Georg Diener

Prof. Hans-Georg Diener; © private

A stroke is caused by vascular obliteration, also called ischemic infarction or by a cerebral hemorrhage. The brain cells are subsequently not getting enough oxygen and nutrients. They literally die. Patients receive the best treatment in a stroke unit, a specialized organizational unit within a hospital or clinic.

Systemic thrombolysis not without risks

"Systemic thrombolysis with tissue plasminogen activator is being considered for a subgroup of stroke patients with circulatory disorders. Between 14 and 20 percent of all patients are suited for this type of treatment provided they are being treated within four and a half hours," explains Professor Hans-Christoph Diener, Neurology Director at the University Hospital Essen. So far, there is no other evidence-based process that’s being applied aside from this one.

In addition, this procedure is a medical treatment that has potentially 22 contraindications. "This is why patients need to be carefully selected to not cause a cerebral hemorrhage. The other big disadvantage is that in only about half of the cases the blood vessel can be opened up again when large vessels are obliterated," Diener adds.
Graphic: stent in a blood vessel

The blood clot in the brain is enclosed with a stent and removed simultaneously; © Atanasov

Revolution in stroke treatment

Things are now happening in stroke treatment with a catheter-based procedure, the mechanical thrombectomy. This method is used in addition to systemic thrombolysis.
This procedure is not new. However, the first three randomized controlled studies failed. Diener sees the reasons for this in the technical nature of the catheter systems, the treatment duration and patient selection. "The advantage of negative results is that we can learn how to do things correctly."

Almost simultaneously, five more studies were initiated that utilize novel stent retrievers. "These are special catheters where you virtually forged ahead from the groin area into the respective artery in the brain. A thin wire pushes through the blood clot, which is literally being captured in a stent so that it can be extracted along with the stent," explains Diener.

The likelihood that large blood vessels are being reopened is approximately 90 percent in this case. This is why a portion of the studies was cut short since the results were way above average.
Procedure is suited for particularly difficult cases

Mechanic thrombectomy is only suited as an additional treatment procedure in about four to five percent of all stroke cases. According to Diener, this is especially the case when the aorta (internal carotid artery) or the major artery within the brain (middle cerebral artery) are obliterated.

The advantages are obvious. "There are significantly fewer risks with this intervention because the low rate of bleeding complications tends to also lower the death rate," Diener sums up. This in turns has a positive effect on neurological symptoms. At the end of the procedure, patients who are partially hemiplegic or whose language center is defective suffer no or only minor neurological deficits.

According to Diener, whether and to what extent a comprehensive introduction of mechanical thrombectomy is feasible does not depend on the technical implementation or acquisition. The expansion of stroke units, especially in rural areas is far more important, says Diener. There is still lots to be done here to ensure adequate stroke treatment.
Foto: Melanie Günther; Copyright: B. Frommann

© B. Frommann

The article was written by Melanie Günther and translated from German by Elena O'Meara.