Reoperation for prosthetic aortic valve obstruction in the era of echocardiography: Trends in diagnostic testing and comparison with surgical findings

OBJECTIVES: We sought to: 1) identify trends in the diagnostic testing of patients with prosthetic aortic valve (AVR) obstruction who undergo reoperation and 2) compare diagnostic test results with pathologic findings at surgery. BACKGROUND: It is unclear whether Doppler transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) have reduced hemodynamic catheterization rates. METHODS: We reviewed 92 consecutive cases of AVR reoperation at a single center from 1989 to 1998, comparing 49 cases of mechanical AVR obstruction (group A) to 43 cases of bioprosthetic obstruction (group B). Preoperative Doppler TTE was performed in all cases. RESULTS: In group A cases, there was a marginally significant trend towards lower catheterization rates for the Gorlin AVR area, from 36% in 1989 to 1990 to 10% in 1997 to 1998 (p = 0.07), but diagnostic TEE utilization (47% of cases) did not vary. The cause of mechanical AVR obstruction was pannus in 26 cases (53%), mismatch (P-PM) in 19 (39%) and thrombosis in 4 (8%). The mechanism (pannus/thrombus vs. mismatch) was identified in 10% by TTE and 49% by TEE (p < 0.001). In group B cases, hemodynamic catheterization rates (21%) and diagnostic TEE utilization (21%) did not vary with time. Obstruction was caused by structural degeneration in 37 cases (86%), thrombosis in 3 (7%), mismatch in 2 (5%) and pannus in 1 (2%). The mechanism was correctly identified in 63% by TTE and in 81% by TEE (p = 0.18). CONCLUSIONS: Doppler TTE is the primary means to diagnose AVR obstruction; hemodynamic catheterization is not routinely needed. In unselected patients with mechanical AVR obstruction, TEE differentiation of pannus or thrombus from mismatch is challenging.