Cinefluoroscopic assessment of mechanical disc prostheses: its value as a complementary method to echocardiography

Many types of mechanical prostheses are used for heart valve replacement, but it is difficult to distinguish between them using transthoracic echocardiography. Hence, cinefluoroscopy complements the echocardiographic evaluation of cardiac prostheses. The aims of the present study were to: (i) describe the contribution of cinefluoroscopy in identifying different prostheses; (ii) compare gradients obtained by Doppler echocardiography with the opening angle of the discs assessed by cinefluoroscopy; and (iii) assess the ability of cinefluoroscopy to distinguish normal from dysfunctional prostheses.

A total of 229 mechanical disc prostheses was prospectively evaluated with cinefluoroscopy. Eight prosthetic valves (six aortic, two mitral) were excluded due to the coexistence of severe left ventricular dysfunction. Thus, the final analysis comprised 221 prosthetic valves (146 aortic, 75 mitral).

Based on the characteristics of the ring and the discs, cinefluoroscopy identified 87 single-leaflet and 134 bileaflet prostheses. Disc motion allowed distinction to be made between normal and dysfunctional prostheses (opening angle: 74 +/- 13 degrees versus 49 +/- 18 degrees). Fluoroscopy could not define disc profile or the ring in 6% of aortic valves and in 26% of mitral prostheses. The technique could be used to identify the TriTechnologies and HP-Biplus valves, but could not provide data on prosthetic function due to radiolucency of the discs. Among the 146 aortic prostheses, Doppler echocardiography helped to identify 109 normal valves and 37 dysfunctional valves. Among 75 mitral prostheses, 54 normal and 21 dysfunctional prosthetic valves were identified. When both methods were correlated, the sensitivity, specificity and positive and negative predictive values of fluoroscopy to distinguish normal from malfunctioning prostheses were 83%, 80%, 89%, and 71%, respectively.

Each prosthesis type has radioscopic characteristics that allow its identification. Fluoroscopy permitted rapid and easy evaluation of mechanical prosthetic valve function, and in most cases allowed a distinction to be made between normal and dysfunctional prostheses. The presence of high gradients by Doppler echocardiography, with normal opening angles by fluoroscopy, and without pannus on transesophageal echocardiography, is indicative of patient-prosthesis mismatch. Fluoroscopy was superior to echocardiography in identifying disc motion, whilst Doppler study allowed the measurement of gradients and areas, and semiquantification of regurgitation. Thus, cinefluooscopy rapidly provides valuable information which is complementary to that obtained by echocardiography.