Prosthetic valve thrombosis

Prosthetic valve thrombosis

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 endothelialization occurs in 3-4 weeks. Risk of thrombosis is higher prior to endothelialization if anticoagulation is suboptimal.
2. Hemodynamic factors: Localised region of turbulent flow causes endothelial trauma, and damage to blood cells, releasing adenosine diphosphate (ADP) which promote platelet aggregation.
3. Coagulation factors

Predisposing factors

Insufficient anticoagulation, mitral/tricuspid position, hypercoagulable state, presence of associated atrial thrombus.
Pannus can occur along with the thrombus as well.

Diagnosis

Clinical presentations

1. Clinically silent prosthetic valve thrombosis.
2. Prosthetic valve thrombosis with embolic episodes like cerebral, coronary or peripheral embolism can occur in up to 25% cases.
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. This is probably similar to suspicion of thrombosis when audible valve sound intensity decreases clinically. Patients are routinely instructed to listen for the valve sounds in a quiet room and report back if there is a decrease in intensity.

Cine fluoroscopy 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.