Doppler echocardiography is an established technique for the routine assessment of prosthetic heart valve function; its accuracy in the estimation of pressure valve gradients has been demonstrated in comparative studies with invasive data.<sup>1Wilkins G.T., Gillam L.D., Kritzer G.L., Levine R.A., Palacios I.F., Weyman A.E. Validation of continuous-wave Doppler echocardiographic measurements of mitral and tricuspid prosthetic valve gradients: a simultaneous Doppler-catheter study Circulation 1986 ;  74 : 786-795 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti,2Burstow D.J., Nishimura R.A., Bailey K.R., Reeder G.S., Holmes D.R., Seward J.B., Tajik A.J. Continuous-wave Doppler echocardiographic measurements of prosthetic valve gradients—a simultaneous Doppler-catheter corrdatjve study Circulation 1989 ;  80 : 504-514 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Ultrasound examination therefore is an important aid in the clinical follow-up of these patients. Nevertheless, the variability of normal values for transprosthetic Doppler gradients is relatively wide, depending basically on the model and size of the valve.<sup>3Goldrath N., Zimes R., Vered Z. Analysis of Doppler-obtained velocity curves in functional evaluation of mechanical prosthetic valves in the mitral and aortic positions J Am Soc Echo 1988 ;  1 : 211-225

Cliccare qui per andare alla sezione Riferimenti,4Nihoyannopoulos P., Karnbouroglou D., Athanassopoulos G., Nadazdin A., Smith P., Oakley C.M. Doppler haemodynamic profiles of clinically and echocardiographically normal mitral and aortic valve prostheses Eur Hean J 1992 ;  13 : 348-355

Cliccare qui per andare alla sezione Riferimenti</sup> For this reason, the availability of reference values for different valve sizes of a particular model is necessary for a correct assessment of the prosthetic function in every patient. This study reports the normal range of Doppler gradients in a large series of patients with clinically normal-functioning Monostrut Björk-Shiley valves<sup>5Arís A., Padró J.M., Cámara M.L., Lapiedra O., Caralps J.M., Borrás X., Carreras F., Pons-Lladó G. The Monostrut Björk-Shiley valve J Thorac Cardiovasc Surg 1992 ;  103 : 1074-1082

Cliccare qui per andare alla sezione Riferimenti</sup> (Shiley, Inc., Irvine, California) in the aortic or mitral position, obtained either postoperatively or over a long-term follow-up.