What is Fibrinolytic Therapy?
Fibrinolytic therapy, also known as thrombolytic therapy, is used to lyse acute blood clots by activating plasminogen. This results in the formation of plasmin, which cleaves the fibrin cross-links causing thrombus breakdown.
Although fibrinolytic medications are not usually found in advanced cardiac life support pharmacological drug cards, their use is extremely important to reperfusion therapies.
The most common indications for the use of fibrinolytic therapy include the following:
- Acute myocardial infarction, also known as AMI.
- Acute ischemic stroke, also known as AIS.
Fibrinolytic therapy is commonly used in cases of stroke and acute coronary syndrome (ACS) and specifically in STEMI cases – ST-Elevation Myocardial Infarction (STEMI) is a very serious type of heart attack during which one of the heart’s major arteries, which supplies oxygen and nutrient-rich blood to the heart muscle, is blocked.
Patients who have suffered from an acute ischemic stroke have a time-dependent benefit for fibrinolytic therapy similar to that of patients with STEMI, but this time-dependent benefit is much shorter. It should also be noted that the critical period for the administration of IV fibrinolytic therapy begins with the onset of symptoms.
Fibrinolytic Therapy and Stroke
Fibrinolytic therapy can be a lifesaving treatment for victims of stroke and can also reduce the effects of strokes which often lead to permanent disabilities.
If the indication is related to ischemic stroke, patients may qualify if they suffer from a sudden onset of a focal neurological deficit such as:
- Slurred speech
- Facial droop
- Weakness on one side of their body
- Paralysis on one side of their body
Patients may also qualify for fibrinolytic therapy if the stroke symptoms do not seem to be self-resolving, which is what you usually see when it’s a transient ischemic attack (or TIA) and the signs and symptoms are present for up to three hours but not greater than 4.5 hours.
Fibrinolytic Therapy and ACS/AMI
In patients with acute myocardial infarction, fibrinolytic therapy would be indicated if the ST-segment elevation is consistent with myocardial infarction of greater than or equal to 1mm in two or more contiguous leads. Contiguous leads are next to one another anatomically speaking, and they view the same general area of the heart (specifically the left ventricle).
Fibrinolytic therapy may also be indicated if the signs and symptoms of a myocardial infarction last longer than 15 minutes and less than 12 hours and if PCI (percutaneous coronary intervention) is not available within 90 minutes of medical contact.
Fibrinolytic Therapy and Medications
Fibrinolytic drugs – also called thrombolytic drugs – are any medication that is capable of stimulating the dissolution of blood clots, or as they’re sometimes referred to as – thrombus. These types of drugs work by activating something referred to as fibrinolytic pathways.
Fibrinolytic medications, which prevent the formation of blood clots by suppressing the function of multiple clotting factors that are normal and present in the blood, are different from anticoagulants, which work by preventing normal clotting factors from functioning correctly, thereby inhibiting the blood from clotting.
There are numerous fibrinolytic agents on the market, each of which may produce varying mechanisms of action. And while there are similarities between these and anticoagulants, fibrinolytic drugs produce the therapeutic effect of breaking down the fibrin and fibrinogen matrix of a thrombosis (fibrinolysis), thus fragmenting the clot that is obstructing an artery and reestablishing distal blood flow.
Fibrinolytic Therapy Precautions and Contraindications
As you’ll note from the video above when using fibrinolytic drugs, several patient factors would exclude their use, which includes (but are not limited to):
- Hypertension with systolic blood pressure greater than 180 to 200mm HG
- Right arm vs. left arm blood pressure differences greater than 15mm HG
- Significant head or facial trauma within the past 3 months
- Prior intracranial hemorrhage
- A bleeding disorder or internal bleeding within the prior 2 to 4 weeks
- The use of a current anticoagulant treatment
- Pregnancy
- A serious systemic disease which would include advanced cancer or kidney disease
- Ischemic stroke greater than 3 hours or less than 3 months
However, that last contraindication would not include the current condition being considered for the current fibrinolytic treatment.