Thrombolytic Therapy

Question 1

What is the treatment for acute MI?

Answer 1

Acute:
M- morphine
O- high flow oxygen
N - nitrates - vasodilation
A - aspirin - COX1, inhibits platelet aggregation

Then:

PCI - percutaneous corollary intervention
OR
Thrombolysis

Question 2

What are the options for thrombolysis?

Answer 2

Streptokinase (derived from bacteria) or Recombinant tissue plasminogen activator (r-tPA) such as Alteplase.

They activate plasminogen which breaks down the clot (by breaking down fibrin, fibrinogen and factors 2, 5 and 8)

Question 3

What are the mechanism of action of alteplase and streptokinase?

Answer 3

• Alteplase binds to fibrin and then cleaves plasminogen to plasmin
• Only works in the presence of fibrin so is clot specific not widespread through circulation like streptokinase
• Streptokinase generates plasminogen in the general circulation and is not “clot specific”

Question 4

What are the main conditions for which thrombolytics are used?

Answer 4

• Acute myocardial infarction
• Ischaemic stroke
• Pulmonary embolism
• Major venous thrombosis

Question 5

What is inclusion criteria for thrombolysis?

Answer 5

You should offer fibrinolysis if they are eligible for reperfusion therapy and PCI cannot be offered in 2 hours.
Inclusion criteria:
• Evidence from the history and ECG of acute MI
• Less than 12 hours duration

Question 6

What is exclusion criteria/CI for thrombolytic therapy?

Answer 6

• Recent haemorrhage, trauma or surgery including dental extraction
• Active peptic ulcer
• History of cerebral haemorrhage or stroke of uncertain aetiology
• Uncontrolled hypertension
• Coagulation defects

Question 7

When can you treat PE with thrombolysis?

Answer 7

Clear diagnosis and evidence of haemodynamic compromise

Question 8

What are risks of thrombolysis?

Answer 8

• Haemorrhage

o Intracranial
• If stroke occurs must image to determine if its embolic (from the heart) of haemorrhagic

o GI tract

o Treat severe bleeding with blood transfusion or volume expanders and prevent further fibrinolysis with tranexamic acid, aprotinin, recombinant or pooled clotting factors

Question 9

What are the ADRs of streptokinase?

Answer 9

• Is antigenic (since it is a bacterial protein) and as such can cause allergic reactions.
o Stop and use a non-antigen treatment
o If severe give adrenaline, oxygen, IV fluids, antihistamine and hydrocortisone
• It cannot be used twice as the body generates blocking antigens.
• Transient hypotension
o Slow the rate of infusion