Simultaneous Determination of Aortic Valve Are by the Gorlin Formul and by Transesophageal Echocardiography Under Different Transvalvular Flow Conditions: Evidence That Anatomic Aortic Valve Are Does Not Change With Variations in Flow in Aortic Stenosis

Objectives. The purpose of this study was to determine the impact of changes in flow on aortic valve are (AVA) as measured by the Gorlin formul and transesophageal echocardiographic (TEE) planimetry. Background. The meaning of flow-related changes in AV calculations using the Gorlin formul in patients with aortic stenosis remains controversial. It has been suggested that flow dependence of the calculated are could be due to true widening of the orifice as flow increases or to disproportionate flow dependence of the formul itself. Alternatively, anatomic AV can be measured by direct planimetry of the valve orifice with TEE. Methods. Simultaneous measurement of the planimetered and Gorlin valve are was performed intraoperatively under different hemodynamic conditions in 11 patients. Left ventricular and ascending aortic pressures were measured simultaneously after transventricular and aortic punctures. Changes in flow were induced by dobutamine infusion. Using multiplane TEE, AV was planimetered at the level of the leaflet tips in the short-axis view. Results. Overall, cardiac output, stroke volume and transvalvular volume flow rate ranged from 2.5 to 7.3 liters/min, from 43 to 86 ml and from 102 to 306 ml/min, respectively. During dobutamine infusion, cardiac output increased by 42% and mean aortic valve gradient by 54%. When minimal flow was compared with maximal flow, the Gorlin are varied from (mean ± SD) 0.44 ± 0.12 to 0.60 ± 0.14 cm2 (p < 0.005). The mean change in Gorlin are under different flow rates was 36 ± 32%. Despite these changes, there was no significant change in the planimetered are when minimal flow was compared with maximal flow. The mean difference in planimetered are under different flow rates was 0.002 ± 0.01 cm2 (p = 0.86). Conclusions. By simultaneous determination of Gorlin formul and TEE planimetry valve areas, we showed that acute changes in transvalvular volume flow substantially altered valve are calculated by the Gorlin formul but did not result in significant alterations of the anatomic valve are in aortic stenosis. These results suggest that the flow-related variation in the Gorlin AV is due to disproportionate flow dependence of the formul itself and not true change in valve area.