Transaortic gradient is pressure-dependent in a pulsatile model of the circulation
Razzolini, R.; Gerosa, G.; Leoni, L.; Casarotto, D.; Chioin, R.; Dalla-Volta, S.
Journal of Heart Valve Disease 8(3): 279-283
1999
ISSN/ISBN: 0966-8519 PMID: 10399661 Document Number: 499718
Although the transvalvular gradient is described as flow-dependent, pressure-dependence of the gradient, irrespective of flow, has not been demonstrated. The Sheffield pulse duplicator equipped with a X-Cell 21 porcine valve mounted in the aortic position was used. Transaortic gradient was measured at a constant rate of 80 beats/min, while flow was kept at 2, 5 or 8 l/min, and systemic pressure was increased up to 200 mmHg by adjusting peripheral resistance manually. Valve area was computed with the Gorlin formula. A total of 87 measurements was carried out. For each flow, transvalvular gradient increased linearly with pressure, and computed area decreased. The slope of the pressure-gradient relationship was independent of flow. Transaortic gradient depends not only on flow, but also shows pressure-dependency that should be taken into account when evaluating aortic stenosis, especially in hypertensive and hypotensive states.