Available treatments for stroke. Figure 5 Mechanism of t-PA action, (Genentech, 2014) Thrombolysis medication

Figure 5 Mechanism of t-PA action, (Genentech, 2014)  

Thrombolysis medication, recombinant tissue plasminogen activators(rt-PA), such as alteplase, work by binding to the fibrin rich clots via the fibronectin finger-like domain and the Kringle 2 domain. Plasminogen is the inactive precursor of plasmin and is activated by rt-PA. The protease domain in rt-PA then cleaves the Arg561 - Val562 peptide bond in plasminogen to form plasmin. Plasmin is a serine protease and can cleave the haemostatic clot, consisting

The medicines used for the treatment of ischemic stroke at the moment are alteplase, aspirin, heparin and other anticoagulants and mechanical thrombectomy.

of polymerized fibrin and platelets by proteolytic digestion. Therefore, rt-PA mediates recanalization of the congested vessels. (Figure 5) rt-PA is contraindicated in hemorrhagic stroke and older ischaemic stroke patients with mild or resolving symptoms and thrombophilia, as it increases the risk of intracranial bleeding.

Thrombectomy is the surgical removal of the blood clot, mechanically recanalising the obstructed vessels, used in patients unsuitable for rt-PA therapy or in combinations with it. It can be proximal and distal. (Figure 6) In proximal thrombectomy manual suction is performed by placing an aspiration catheter at the proximal surface of the thrombus. Then, manual aspiration is applied and the catheter is retrieved under constant negative pressure. Distal thrombectomy is more challenging technically. To deliver the device distally to the thrombus, a microcatheter is passed at the occlusion site. To avoid thromboembolic problems, a balloon guide catheter is placed in the cervical internal cerebral artery and aspiration during device retrieval is recommended for most devices. Several distal thrombectomy devices are in clinical practice, e.g. Merci, Catch, BALT. (Mordasini et al., 2012)

Figure 6 Thrombectomy illustrated. A - Catheter aspiration thrombectomy B - Mechanical thrombectomy devices C - Proximal embolic protection devices D and E - Distal embolic protection devices (Mordasini P. et al., 2012)

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