- First and fore most dictum is not every prosthetic valve obstruction is thrombotic (Most cardiologists are tuned to think that way )
- Pannus, Mechanical failure and vegetations can increase the gradient across prosthetic valve.
- If the clinical presentation is acute (< 48 hours ) it is more likely to be a thrombotic event .
- History of recent discontinuation of oral anticoagulants /sub optimal INR will favor thrombosis.
A meticulous Echocardiography is vital (TEE though gives more information in an emergency TEE is suffice )
- Thrombolysis is to be considered in all .
- For right sided prosthetic obstruction thrombolysis is the initial modality of choice.
- For left sided valve thrombosis surgery is the preferred option .However a trial of thrombolysis for 24 hours may be tried .
- For a high risk mobile thrombus , thromolysis is contrandicated.
The success rate is less with Mitral than Aortic valve . Success depend upon more on the location / Freshness of thrombus than the type of the lytic agent used.
Is there a time window for prosthetic valve thrombolysis ?
Thrombus organisation takes 2 weeks at- least.Hence , it better not to attempt thrombolysis in documented late prosthetic valve thrombosis.
Thrombolysis of left-sided valves has inherent risk of stroke .
Simultaneous usage of heparin along with streptokinase or TPA is perceived as risky (No good evidence for this perception )It is logical to expect even as the thrombus lyses the clot lots of pro-coagulant debri are released . Concomitant usage of heparin will definitely help accelerate thrombus dissolution. (I am glad Joseph S Alpert also feels the same ! )
Assessing successful thrombolysis
- Can be a tough task .
- Relying purely on gradient is vested with risk of huge error.
- In a patient with shock or LV dysfunction gradients are not reliable as low flow status masks the gradient.
- A accelerated thrombolytic protocol 15lakhs streptokinsae in 60 minute may be tries in unstable patient .
- It is wiser to rapidly asses for clinical improvement in high risk subsets and refer the patient for early surgery .
Prohibitive mortality reported in many centres.
It need to be remembered no surgeon will operate on a sick patient in shock exposed to cocktail of heparin and streptokinase.
Valve replacement is required in most case. Simple valve debridement (servicing the valve ) and releasing discs from the sticky thrombus is also possible in an occasional patient.( Do not ask reference for this !)
Reference (Surprisingly most of the good papers in the topic appeared in JACC)
I have not seen a single case of acute prothetic valve thrombosis involving Starr Edwards valve in the last 20 years of of clinical cardiology practice.
Is it true . . . the new age valves with more mechanical stress points are proving more injurious to our patients. Our pursuit towards a perfect artificial valve need some introspection .
Read a related article in my site : Who killed Starr Edwards valve ?