Endovascular treatment | Stroke treatment
It is very important that patients with ischemic stroke are hospitalized as soon as possible for treatment, preferably in a stroke unit. First, one has to determine whether a cerebral infarction or hemorrhage is causing the stroke. This requires a CT scan or an MRI scan.
Intravenous thrombolysis (administered through the vein)
Approximately half of patients with acute stroke are seen within six hours in the hospital. If the diagnosis is a stroke, the standard treatment is intravenous thrombolysis (IVT), provided that the treatment can be started within 4.5 hours after onset of symptoms. The sooner the treatment begins, the more the chance of a good outcome. The aim of thrombolysis is to restore blood flow in the affected brain area and to limit or repair the damage. By means of an infusion, a thrombolytic (clot dissolving agent) is administered, which spreads over the whole-body circulation. The most commonly used thrombolytic is recombinant tissue-type plasminogen activator (rtPA). A risk of administering thrombolytics is a cerebral hemorrhage or bleeding elsewhere in the body. The risk of symptomatic brain hemorrhage caused by IVT is between 2 and 8% (Singer et al, 2009).
An important limitation is the limited time within which IVT therapy should be applied. Many patients arrive in hospital too late to still be eligible. After IVT, only in 25% of cases the blood vessels reopen.
Patients who can not be treated with IVT or who are not better after IVT can still be treated with intra-arterial thrombolysis (IAT) and recently also with mechanical thrombectomy (MT). IAT can be performed up to 6 hours after onset of symptoms, MT up to 8 hours and until 12 hours.
Intra-arterial thrombolysis (local administration via artery)
If IVT is no longer possible or has not led to an improvement, intra-arterial trombolysis (IAT) is a possible alternative. For this treatment, a microcatheter is brought through an arterial puncture in the femoral artery (groin) at the location of a the thrombus (clot), and subsequently a thrombolytic is administered at the location of the clot. In theory, local treatment has a number of advantages. With intravenous treatment the thrombolytic I spread throughout the body and not locally. It is not clear whether the advantages outweigh the disadvantages of IAT, such as a higher risk of brain haemorrhage (Wardlaw and Mielke 2004, Singer et al, 2009).
Mechanical thrombectomy (local removal of the clot)
With the local arterial approach one can not only apply the pharmacological thrombolysis, but also mechanical thrombectomy (MT). In MT, the clot is passed with a microcatheter. Then one removes the thrombus with a special stent mounted catheter. This method has potential benefits: a thrombolytic is not necessary, which reduces the risk of bleeding, and also a clot can be removed in a shorter time with rapid recovery of blood perfusion of the brain. An additional advantage with respect to IAT and IVT is that emboli consisting of insoluble material, can also be removed. Possible drawbacks of mechanical thrombectomy are the relatively complex operation and the high material costs. According to two observational studies on mechanical thrombectomy, 42% of patients were functionally independent after mechanical thrombectomy that led to recanalization, whereas in patients without recanalization this was only 10%. (Smith WS, et al Stroke. 2005 and 2008; for Healthcare Improvement CBO. Guideline 'Diagnosis, treatment and care for stroke patients. Utrecht: Dutch Society for Neurology, 2008).
Intra-arterial treatment of acute ischemic stroke places heavy demands on the logistics within a hospital. A neuro-intervention team has to be available on a 24-hour basis, consisting of a specialist with experience in neuro-interventions, radiological technologist, neurologist (with expertise in acute stroke treatment) and anesthetist, so this procedure can only be done in university hospitals and some larger clinics. Each center at least two suitably trained intervention specialists. (CBO guideline, 2008). The Antwerp University Hospital has all conditions to perform the intra-arterial treatments.