Abstract
The hemodynamic performance of a prosthetic valve after aortic valve replacement (AVR) is influenced by valve design and the prosthesis-specific sizing strategy. The design determines the actual opening area of the prosthesis in relation to its outer diameter while sizing determines the actual size of the implanted prosthesis. Currently, the hemodynamic outcome after AVR is assessed by calculating the pressure gradient (Bernoulli equation) and/or the effective orifice area (EOA). The EOA is calculated by means of the continuity equation using flow velocities and the left ventricular outflow tract area (LVOTA) and represents a virtual opening of the valve area for the individual patient; however, it does not necessarily represent the maximal opening area of the implanted valve. Irrespective of this recognition, the question whether a prosthesis size is adequate for a patient is addressed by relating the EOA to body surface area as the EOA indexed (EOAi). Accordingly, a valve is considered too small if moderate (EOAi between 0.65 and 0.85 cm(2)/m(2) body surface area) or severe (EOAi <= 0.65 cm(2)/m(2)) patient-prosthesis mismatch (PPM) is present. Currently, approximately one half of the publications on this topic refute an effect of PPM on long-term survival; however, it is quite possible that the cause for this discrepancy is due to the way PPM is assessed. This article describes the current standards for hemodynamic evaluation after aortic valve replacement and points out major problems in the assessment of PPM. Also presented is the prosthesis annulus relation (PAR-I) trial which includes a new approach to assessing and predicting hemodynamic results as well as PPM.