Range gated echo-Dopplervelocity and turbulence mapping in patients with valvular aortic stenosis

Flow beyond a stenotic aortic valve (AS) is dynamically complex. Numerous hydraulic studies have demonstrated that at least four well-known major flow areas occur distal to a stenotic valve. These include a jet, an area alongside the jet (the parajet), an area of flow disturbance, and an area in which disturbed flow again becomes laminar downstream. Of these, only the flow disturbance area has markedly turbulent flow, although some turbulence can be at times detected in the area beside the jet. The purpose of this investigation was to test a technique of patient examination that might allow a range-gated pulsed Doppler to detect each of these known areas in the aorta (Ao) of valvular AS patients. A method for mapping flow in the lumen of the Ao root and ascending Ao is detailed. The transverse Ao arch was studied in the standard manner. With this mapping method, 14 patients with AS were studied. We were able to identify the jet in 13 of 14 as a high velocity, narrow-width signal in the Ao root. The parajet area was characterized by no detectable or low flow in 12 of 14, but two patients had late systolic flow disturbance in the parajet area. All patients ahd a strong flow disturbance detected; 3 of 14 were first detected in the Ao root and the remainder were first detected higher in the ascending Ao. The area of relaminarization was not addressed in this study. This investigation demonstrates that a proper interpretation of range-gated pulsed Doppler recordings from areas distal to AS requires knowledge of flow dynamics beyond an obstruction and a methodical range-gated pulsed Doppler examination technique.