Acute pulmonary embolism is a vascular emergency.Massive pulmonary embolism needs immediate thrombolysis or embolectomy. Success rate of thrombolysis appears good . But , the symptom improvement is slower .
Sterptokinase is the commonly used drug to dissolve the pulmonary thrombus . (Except in USA , where they prefer the much costlier TPA )
The sterptokinase adminstered with the following protocol
- 2.5 lakh Unit bolus over 30 minutes
- Follow with 1lakh unit /per hour for the next 48 hours (Up to 72 h)
When to start Heparin infusion ?
For TPA , there is no confusion .Heparin must be started immediately after the completion of TPA infusion (100mg in 2 hours)
Cardiology community is divided for heparin protocol with streptokinase. Because , streptokinase is administered over 48hours it is thought heparin is not required during this period.But in reality , it implies , we deny a role for this powerful anti thrombin in the critical hours of ongoing intra vascular clotting . Hence logic demands to start heparin along with streptokinase.
There is further concern that, the dissolved thrombus generate pro coagulant debri , that will negate the benefits of thrombolysis. Oral anticoagulants are supposed to be started as soon as the diagnosis of pulmonary embolism is made. In that case , heparin will be required much earlier as warfarin has to be overlapped with heparin.
We would argue for , a careful simultaneous infusion of heparin (May be 500units/hour ) .Strict monitoring of APTT is warranted.
What does the clinical trials say ?
There are few studies address this specific issue .I am still searching the data base. Once i get it i will post it. The readers may also try to find an answer .