Transaortic gradient is pressure-dependent in a pulsatile model of the circulation

Background and aim of the study: Although the transvalvular gradient is des cribed as flow-dependent, pressure-dependence of the gradient, irrespective of flow, has not been demonstrated. Methods: The Sheffield pulse duplicator equipped with a X-Cell 21 porcine v alve mounted in the aortic position was used. Transaortic gradient was meas ured at a constant rate of 80 beats/min, while now was kept at 2, 5 or 8 l/ min, and systemic pressure was increased up to 200 mmHg by adjusting periph eral resistance manually. Valve area was computed with the Gorlin formula. A total of 87 measurements was carried out. Results: For each flow, transvalvular gradient increased linearly with pres sure, and computed area decreased. The slope of the pressure-gradient relat ionship was independent of flow. Conclusion: Transaortic gradient depends not only on flow, but also shows p ressure-dependency that should be taken into account when evaluating aortic stenosis especially in hypertensive and hypotensive states.