Thrombolytic Therapy

Thrombolytics, also called clot busters, are medications that break up clots, and are used for the short-term emergency management of thrombotic conditions, such as myocardial infarction, pulmonary embolism, ischemic stroke, and thrombosis of prosthetic heart valves and stents.

Now, thrombolytics are usually derived from enzymes involved in fibrinolysis, or the gradual degradation of the fibrin mesh. These include alteplase, reteplase, and tenecteplase, which are derived from tissue plasminogen activator, or tPA, through recombinant DNA technology, and act locally at the clot site.

Thrombolytics are given intravenously. Once in the blood, they act on a protein produced by the liver called plasminogen, and convert it into its active form called plasmin. These medications directly bind to fibrin proteins in the clot and preferentially act on plasminogen trapped in the fibrin mesh, also called fibrin-bound plasminogen. The resulting plasmin then acts as a protease and cuts the fibrin into smaller pieces. This allows the trapped red blood cells and platelets to float away, dissolving the clot.

The main side effect of all thrombolytics is undue bleeding from other sites, including the injection site, gastrointestinal bleeds, and hemorrhagic stroke. In severe cases, thrombolytic-associated bleeding can be treated with medications like aminocaproic acid, which acts by binding to plasminogen and plasmin, ultimately inhibiting their action on fibrin. If aminocaproic acid fails, other transfusion products can be administered, such as platelets or coagulation factors in the form of fresh frozen plasma.

In addition, thrombolytics, when given following a myocardial infarction, can precipitate an abnormal cardiac rhythm, or a reperfusion arrhythmia, which is usually benign. Other side effects include hypersensitivity reactions like anaphylaxis, nausea, vomiting, and fever.

Due to the risk of bleeding, thrombolytics are contraindicated in clients with active internal bleeding, suspected aortic dissection, or recent trauma in the past three months, as well as those with any history of intracranial hemorrhage or ischemic stroke in the past three months, and coagulopathies or bleeding disorders. In addition, thrombolytics should be avoided before major surgeries.

Thrombolytics should be used with caution in clients older than 75 years, as well as in those with severe hypertension, pericarditis, active peptic ulcer, or diabetic retinopathy. Thrombolytics should also be used with caution in clients with hepatic disease, who can have a defective production of clotting factors and plasminogen; as well as during pregnancy and breastfeeding.

Finally, thrombolytics should be used with caution in clients taking anticoagulants like heparin and warfarin; and antiplatelet medications like aspirin and clopidogrel; which can increase the risk of bleeding.

Alright, before administering an intravenous thrombolytic to your client, be sure to perform a baseline assessment, including vital signs, and cardiac and neurological status. Then, review the client’s latest laboratory test results, including CBC, hematocrit, coagulation studies like PT, aPTT, and INR, as well as renal and hepatic function.

In addition, if your client is receiving thrombolytics for a myocardial infarction, remember to monitor your client’s cardiac enzymes. On the other hand, if your client is being treated for a pulmonary embolism, review their most recent ABGs. Be sure to ensure they have a patent IV and that continuous ECG monitoring is in place. Lastly, explain to your client that they are receiving a thrombolytic medication to help dissolve a causative clot.

Now, during administration of a thrombolytic medication, closely monitor your client for any signs and symptoms of active bleeding, like epistaxis, hematuria, petechiae; and the presence of blood in the stool. Continue to monitor vital signs, neurological and cardiac status, and coagulation studies during treatment.