Prosthetic Valve Thrombus Versus Pannus

Prosthetic valve obstruction is a condition associated with significant morbidity and mortality.1 The most common causes of obstruction include valve thrombosis or pannus formation. Thrombosis is more likely to occur early after valve implantation, in the setting of inadequate anticoagulation, and is more common in mechanical prostheses.2,3 However, it can occur with bioprostheses and may develop long after implantation.4 Pannus is a more chronic process associated with ingrowth of tissue, causing obstruction.5 Distinguishing between thrombus and pannus as a cause of obstruction is important because thrombus can potentially be treated with fibrinolysis, whereas pannus requires surgical intervention to relieve the obstruction. Fibrinolysis is associated with potentially serious adverse outcomes including intracranial bleeding or embolic events, particularly when used for left-sided prosthetic valve thrombosis.6 Unsuccessful fibrinolysis may delay surgical intervention; this delay can be associated with increased mortality.3 Hence, correctly identifying the cause of prosthetic valve obstruction is critically important for management.See Article by Gunduz et al The evaluation of obstructed prosthetic valves has traditionally used both transthoracic and transesophageal echocardiography (TEE), as well as fluoroscopy.3 Transthoracic echocardiography serves well as the standard for evaluation of the hemodynamic performance of prosthetic heart valves; an increase in gradient and decrease in orifice area can signal development of obstruction. Gradual rotation of the imaging plane is required to appreciate occluder motion. However, the ability to visualize thrombus or pannus may be compromised by acoustic shadowing from the mechanical prosthesis or by limited acoustic windows because of patient size or lung disease. Fluoroscopy is good at determining whether leaflet motion is normal or abnormal, but cannot provide additional information about the presence or the absence of the thrombus.7 TEE provides a better assessment of the prosthesis, and the presence of mobile masses with …