Mechanical valve obstruction: Review of diagnostic and treatment strategies

Abstract

Prosthetic valve obstruction (PVO) is a rare but feared complication of mechanical valve replacement. Diagnostic evaluation should focus on differentiating prosthetic valve thrombosis (PVT) from pannus formation, as their treatment options differ. History of sub-optimal anti-coagulation and post-op time course to development of PVO are useful clinical characteristics in differentiating thrombus from pannus formation. Treatment of PVT is influenced by the patient's symptoms, valve location, degree of obstruction and thrombus size and may include thrombolysis or surgical intervention. Alternatively, pannus formation requires surgical intervention. The purpose of this article is to review the pathophysiology, epidemiology, diagnostic approach and treatment options for aortic and mitral valve PVO.

Complementary role of cardiac CT in the assessment of aortic valve replacement dysfunction

“…Acquired mechanical prosthetic valve obstruction (PVO) is an uncommon but serious and potentially fatal complication of valve replacement 31. A definitive diagnosis is of paramount importance due to the associated morbidity and mortality and the frequent need for appropriately timed intervention 32.…”

“…A definitive diagnosis is of paramount importance due to the associated morbidity and mortality and the frequent need for appropriately timed intervention 32. The two main mechanisms of acquired mechanical PVO are thrombosis and pannus formation, both of which restrict normal leaflet motion 31. Differentiation of these two causes is of critical importance in guiding appropriate treatment (table 1).…”

“…While both can be treated with urgent surgical revision, valve thrombosis is also potentially amenable to thrombolysis 33. Moreover accurate assessments of the degree of valve obstruction and the size of the thrombus will help to determine the urgency with which intervention is required alongside standard clinical assessments 31. CT is increasingly being used in this role to complement standard imaging and to help guide patient management, in particular when a clear aetiology has not been established 30…”

Echocardiographic evaluation of heart valve prosthetic dysfunction

“…According to various data it occurs in 0.1 -5.7% of patients per year. In addition, disorders of the prosthetic functioning may occur due to the vegetation growth, the development of ring abscess or pannus formation (7). A reverse flow (regurgitation) through the prosthetic orifice or outside the valve ring (paravalvular regurgitation) could be detected.…”

A funnel shaped pannus formation above the mitral prosthetic valve diagnosed with real time three-dimensional echocardiography

“…Prosthetic valve obstruction has an incidence ranging from 0.4% to 6% per year (1). Apart from thrombus formation, prosthetic valve obstruction can also be caused by pannus formation with variable frequency (2,3).…”