Obstruction of a prosthetic valve by a non infective thrombus is what we mean by prosthetic valve thrombosis. Size of the thrombus is important in deciding the management.
Pathophysiology
1) Endothelial factors: Suture zone endothelisation occurs in 3-4 weeks.
2) Hemodynamic factors: localised region of turbulent flow causes endothelial trauma, and damage to blood cells, releasing ADP which promote platelet aggregation.
3) Coagulation factors
Predisposing factors
Insufficient anticoagulation, mitral / tricuspidposition, hypercoagulable state, atrial thrombus
Pannus can occur along with the thrombus as well.
Diagnosis
Clinical presentations
1) Clinically silent prosthetic valve thrombosis
2) Prosthethetic valve thrombosis wth embolic episodes like cerebral, coronary or peripheral embolism can occur in upto 25% case.
3) Hemodynamic problem with evidence of valve thrombosis
Prosthetic valve thrombosis can present with fever in the setting of infective endocarditis. Fever can occur in prosthetic valve thrombosis even without endocarditis.
High resolution sound spectrograph can detect valve thrombosis by the change in the valve sounds.
Cine fluroscopy is useful as it can detect decreased leaflet and poppet movements as well as abnormal movement of the valve cage.
Echocardiography is an important tool for evaluation of prosthetic valve thrombosis. Thrombus can be visualised by echocardiography, better with transesophageal than transthoracic echocardiography. Gradients and valve areas can be estimated. Dimensionless obstruction indexes are the ratio of subvalvular/valvular velocities and velocity time integrals.