thrombolytic therapy Flashcards
clotting vs clearing
- Both are necessary, both must be controlled
- Prevent formation and growth of clots
–> warfarin, ASA, NOACs
- Breakdown already formed clots
–> plasmin (native agent) is the direct lytic
–> thrombolytics are not lytics per se; activated plasmin
describe Streptokinase
- Derived from Group C streptococci
- DIRECT PLASMINOGEN ACTIVOTR (activates plasmin to break up clots)
- Antigenic, generic
- Efficacy in MI time-dependent, drip dosing
Urokinase
- Human neonatal kidney cells
- DIRECT PLASMIOGEN ACTIVATOR
- non-antigenic
- used to clear lines, Pulmonary embolus, direct arterial infusion
- Limited use in coronary thrombosis (expense limited original studies)
Tissue Plasminogen Activator
- ALTEPLASE
- recombinant molecule
- occurs naturally in blood
- DIRECT PLASMINOGEN ACTIVATOR
- Was drug of choice for acute MI
describe the Thrombolysis goals in MI
- Disease oriented:
- Good blood flow in infarct vessel
–> TIMI risk: risk increases with number (0 = less risk)
–> TIMI flow: Flow increaes with number (0 = no blood flow)
- Reduce in infarct size measured by DECREASE markers
- patient oriented
- improved survival rates
- Reduce LV failure, ventricular dysrhythmias, direct complications of MI
Describe the effects of mortality
- HIGH RISK GROUPS
- More to gain as risk higher
- Hypotension
- diabetes
- Mortality improves across all groups
- some risk/reward balance
- younger patients have decreased acute mortality (may not benefit as much)
- Older patients may have more head bleeds
describe complications of thrombolytics
- Bleeding (lytics don’t know what to lyse)
–> intercranial bleeds (higher risk if you less than 70kg, over age of 65 or have poorly controled hypertension
- allergic reactions (rare) with SK and congeners
describe the Acute MI protocols
- Less than 120 mins from FIRST CONTACT: go to cath lab
- aspirin, nitro, morphine/fentanyl
- maybe oxygen
- local choice: anticoagulants (hemaprin, enoxaparin, ticagrelor)
- more than 120 mins: thrombolysis
- TNKase recommended by AHA
- aspirin, nitro, morphine/fentanyl
- Heparin or enoxaparin
describe Acute MI, late presentation
- 4 to 12 hours
–> consider using lytics (steptokinase-maybe lower risk of intercranial bleeds)
- lytic therapy >12 hours after onset
–> maybe with ongoing symtpoms/necrosis (must have low stroke risk)
–> use only with large MI (AW), low CVA risk
Points to ponder
- Thrombolytics are not anticoagulants (thrombolytics are tx only!!! not prevention)
- thrombolytics activate a natural process (plasmin breaks up fibrin clots)
- thrombolytics use the benefit and risk; they usually go bi-directionally (patients with most at risk benefit the most so may tolerate harm)
- Most newer lytics have no great patient-level benefit
- Administering lytics in acute MI when PCI is delayed will save lives
