To evaluate the narrowing of the left ventricular outflow tract (LVOT) during systole caused by a rigid mitral prosthesis, the geometric relationship between the prosthesis (or the mitral annulus) and the left ventricular base (LVB) was studied in five patients with mechanical mitral valve prostheses and eight normal subjects. The images of the mitral valve annulus (MVA) and the LVOT Orifice reconstructed in three dimensions were projected on the plane of the I.V base. Colculating the areas of these projected images (i.e., those for MVA [5ml LVOT orifice [So], the LVB [Sb; Sb = Sm + So], the MVALVB ratio (Sm/Sb) was determined. In the normal subject, the MVA-LVB ratio was nearly constant during systole (59 ± 5% at 0 msec and 62 ± 7% at 300 msec, respectively), whereas in the patients with prostheses, the ratio increased from 61 ± 4% (0 msec) to 69 ± 4% (300 msec). The increase in MVALVB ratio reduces the proportionate share of LVOT orifice in relation to the total LVB. The ideal mitral valve prosthesis should be flexible at the annulus to attain good performance in LVB dynamics. ASAIO Journal 1997; 43:M392-M395.
© Lippincott-Raven Publishers.