Transaortic gradient is pressure-dependent in a pulsatile model of the circulation.
OBJECTIVE
Although the transvalvular gradient is described 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 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.


RESULTS
For each flow, transvalvular gradient increased linearly with pressure, and computed area decreased. The slope of the pressure-gradient relationship was independent of flow.


CONCLUSIONS
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.
Department of Cardiology and Hemodynamics, University of Padova, Italy.
R
R
Razzolini
G
G
Gerosa
L
L
Leoni
D
D
Casarotto
R
R
Chioin
S
S
Dalla-Volta
D001021:Aortic Valve / Q000502:physiology*; D001024:Aortic Valve Stenosis / Q000503:physiopathology; D003326:Coronary Circulation / Q000502:physiology; D006801:Humans; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D014655:Vascular Resistance