Dysfunction of bileaflet aortic prosthesis: accuracy of echocardiography versus fluoroscopy

The authors sought to investigate the accuracy of transthoracic echocardiography (TTE)-derived parameters in the identification of bileaflet aortic prosthesis dysfunction, compared with fluoroscopy (FL).

Identification of bileaflet aortic prosthesis dysfunction is challenging, because high mean pressure gradient (MPG >20 mm Hg) is not proof of prosthetic obstruction (AVPO), and may be due to prosthesis-patient mismatch (PPM). Conversely, high gradients may not be manifest in AVPO and low cardiac output.

TTE and FL were prospectively performed in 100 nonconsecutive patients with bileaflet aortic prosthesis. TTE included the estimation of MPG, indexed effective orifice area (EOAi), Doppler velocity index (DVI), intraprosthetic regurgitation, acceleration time (AT), ejection time (ET), AT/ET, and the difference (dA) between the expected prosthetic orifice area and EOA. FL allowed the calculation of opening and closing angles, and the discrimination of AVPO from normal (NL) and PPM.

On the basis of FL examination and MPG and EOAi at TTE, patients were classified as NL (42%), PPM (32%), and AVPO (26%). High MPG (>20 mm Hg) was present in 65% of the patients, with higher values in PPM (36 ± 8 mm Hg) and AVPO (43 ± 16 mm Hg) than in NL (16 ± 6 mm Hg). DVI was reduced in PPM (0.30 ± 0.05) and AVPO (0.25 ± 0.04) compared with NL (0.42 ± 0.09). In AVPO, dA (0.59 ± 0.32 cm(2)), AT (108 ± 20 ms), and AT/ET (0.35 ± 0.05) significantly differed from NL (dA = -0.12 ± 0.43 cm(2), AT = 74 ± 15 ms, AT/ET = 0.25 ± 0.05) and PPM (dA = 0.15 ± 0.24 cm(2), AT = 78 ± 13 ms, AT/ET = 0.26 ± 0.04). Moderate or severe intraprosthetic regurgitation was observed only in AVPO. All considered TTE-derived parameters were found related to obstruction, and dA (accuracy = 87%), AT (94%), and AT/ET (89%) showed the highest accuracy in discriminating normofunctioning prostheses from AVPO.

In the presence of high MPG, TTE parameters play a key role in aortic prosthesis examination. Especially time indices and dA add to the functional assessment of prosthetic aortic valves. However, the TTE discrimination between AVPO and PPM may be suboptimal, and fluoroscopy is a complementary and essential diagnostic step.