Clinical safety and efficacy of thrombolytic therapy with low-dose prolonged infusion of tissue type plasminogen activator in patients with intermediate-high risk pulmonary embolism

Successful treatment of acute device thrombosis of patent foramen ovale with slow infusion of low-dose thrombolytic therapy

Background

Percutaneous closure of patent foramen ovale (PFO) is used in selected individuals to eliminate the risk of recurrent cerebral embolism due to paradoxical embolization. Although device thrombosis is rare, it can cause serious complications. Herein, we report a 40-year-old woman who developed acute PFO closure device-associated thrombus and was subsequently treated with slow infusion of low-dose tissue plasminogen activator (t-PA) (25 mg/6 h).

Case summary

A 40-year-old woman was admitted to the hospital because of an cerebrovascular accident (CVA). Computed tomography and magnetic resonance imaging of the brain demonstrated the presence of an ischaemic lesion in the right cerebellar infarct. Since no pathological finding was detected that could cause CVA, it was considered that there might be paradoxical embolism due to PFO. Percutaneous PFO closure was decided by the heart and brain team. The occluder was implanted under transoesophageal echocardiography (TEE) and fluoroscopy guidance. Although activated clotting time was 250 s, hypermobile acute thrombus measuring 11 × 5 mm was seen on the left atrial side of the PFO device. Slow infusion of low-dose t-PA treatment was given. As soon as after a single-dose t-PA, control TEE was performed and it was seen that almost the entire thrombus was lysed. The patient did not have any complications during the treatment period.

Discussion

Acute PFO device thrombosis is a rare but important complication. If there is no contraindication for lytic treatment in acutely developing large PFO device thrombosis, slow infusion of low-dose t-PA may be useful.

Role of Fibrinolytic Enzymes in Anti-Thrombosis Therapy

Thrombosis, a major cause of deaths in this modern era responsible for 31% of all global deaths reported by WHO in 2017, is due to the aggregation of fibrin in blood vessels which leads to myocardial infarction or other cardiovascular diseases (CVDs). Classical agents such as anti-platelet, anti-coagulant drugs or other enzymes used for thrombosis treatment at present could leads to unwanted side effects including bleeding complication, hemorrhage and allergy. Furthermore, their high cost is a burden for patients, especially for those from low and middle-income countries. Hence, there is an urgent need to develop novel and low-cost drugs for thrombosis treatment. Fibrinolytic enzymes, including plasmin like proteins such as proteases, nattokinase, and lumbrokinase, as well as plasminogen activators such as urokinase plasminogen activator, and tissue-type plasminogen activator, could eliminate thrombi with high efficacy rate and do not have significant drawbacks by directly degrading the fibrin. Furthermore, they could be produced with high-yield and in a cost-effective manner from microorganisms as well as other sources. Hence, they have been considered as potential compounds for thrombosis therapy. Herein, we will discuss about natural mechanism of fibrinolysis and thrombus formation, the production of fibrinolytic enzymes from different sources and their application as drugs for thrombosis therapy.