Application of the Continuity Equation and Valve Resistance to the Evaluation of St. Jude Medical Prosthetic Aortic Valve Dysfunction

Hemodynamic performance evaluation of TTK Chitra heart valve prosthesis in the aortic position using Doppler echocardiography

“…However, even within each valve size there was a wide range in VR, suggesting this parameter as flow dependent. The maximum recorded value of VR in our study was 206.4 dynes s cm − 5 in a 19 mm valve, which was comparable to the upper value of 170 mm Hg for normal controls in the study by Saad et al [6]. The flow dependency of VR is consistent with many published studies [8][9][10][11], which contradicted the initial concept that VR is less flow dependent.…”

“…VR, as measured by Doppler echocardiography in normal Carbomedics and St. Jude Medical bileaflet valves has been reported as 102 ± 32 and 85 ± 38 dynes s cm − 5 respectively [6,8]. In our study, VR of CHVP averaged 88.6 ± 44.4 dynes s cm − 5 .…”

“…The following parameters were assessed to evaluate the prosthetic valve in the aortic position as described earlier [4][5][6]; peak velocity, peak gradient, mean gradient, Doppler velocity index (DVI), effective orifice area (EOA) and valve resistance (VR).…”

Recommendations for Evaluation of Prosthetic Valves With Echocardiography and Doppler Ultrasound

“…In a group of patients with severe stenosis of St Jude Medical aortic valves requiring reoperation, the mean DVI was 0.19 6 0.05 (range, 0.12-0.27) and significantly lower compared with matched controls with normal prosthetic valve function (mean DVI, 0.39; range, 0.28-0.55). 22,125 Similar to EOA, DVI is not affected by high flow conditions through the valve, including AR, whereas blood velocity and gradient across the valve are. 125 3.…”

“…22,125 Similar to EOA, DVI is not affected by high flow conditions through the valve, including AR, whereas blood velocity and gradient across the valve are. 125 3. Diagnosis of Prosthetic Aortic Valve Stenosis.…”