TY - JOUR
T1 - Doppler echocardiographic assessment with the continuity equation of St. Jude medical mechanical prostheses in the mitral valve position
AU - Bitar, Jamil N.
AU - Lechin, Marcel E.
AU - Salazar, Gabriel
AU - Zoghbi, William A.
N1 - Funding Information:
From the Section of Cardiology, Department of Medicine, Baylor College of Medicine, The Methodist Hospital, Echocardiography lube ratory, Houston, Texas. Computational assistance was provided by the CLINFO Project funded by Grant RR00350 from the Division of Research Resources, National Institutes of Health, Bethesda, Mary land. Manuscript received March 31, 1995; revised manuscript received and accepted May 22, 1995. Address for reprints: William A. Zoghbi, MD, Echocardiography Research, Baylor College of Medicine, 6.550 Fannin, SM 677, Houston, Texas 77030.
PY - 1995/8/1
Y1 - 1995/8/1
N2 - Evaluation of the St. Jude Medical (SJM) valve in the mitral position with Doppler echocardiography has usually involved the use of gradients across the valve and the application of the pressure half-time (PHT) method to derive a mitral valve area. The purpose of this study was, first, to determine the normal values of effective orifice areas for the SJM valve in the mural position using the continuity equation, and second, to evaluate whether this parameter provides an improved assessment of valve function. Accordingly, Doppler echocardiography was performed in 40 patients within 6 weeks after valve replacement. All patients were clinically stable, without evidence of valvular dysfunction or aortic insufficiency. Valve size ranged from 23 to 33 mm and ventricular ejection fraction averaged 54 ± 13%. Effective orifice area was derived by the continuity equation using stroke volume measured in the ventricular outflow tract, divided by the time-velocity integral of the SJM valve jet, and by PHT. Doppler-derived SJM valve mean gradient averaged 4 ± 2 mm Hg. Effective area by the continuity equation averaged 1.82 ± 0.36 cm2 (range 1.03 cm2 for a 23 mm valve to 2.63 cm2 for a 31 mm valve) and was smaller than by PHT (mean 3.10 ± 0.65 cm2, p = 0.0001; range 1.38 to 4.78 cm2). Areas by both methods were smaller than the actual valve orifice area provided b the manufacturer (4.53 ± 0.80 cm2, p = 0.0001). With use of analysis of variance, effective SJM valve area by the continuity equation differentiated various valve sizes (p = 0.0002) better than did mean gradient (p = 0.013) or PHT (p = NS). Effective area by the continuity equation also correlated better with actual valve orifice area (r = 0.68, p <0.0001) than the area derived by PHT (r = 0.31, p = 0.06). Derivation of effective orifice area of SJM valves in the mitral position with the continuity equation allows better differentiation among valve sizes than mean gradients and PHT, and provides an additional index for assessing prosthetic mitral valve function.
AB - Evaluation of the St. Jude Medical (SJM) valve in the mitral position with Doppler echocardiography has usually involved the use of gradients across the valve and the application of the pressure half-time (PHT) method to derive a mitral valve area. The purpose of this study was, first, to determine the normal values of effective orifice areas for the SJM valve in the mural position using the continuity equation, and second, to evaluate whether this parameter provides an improved assessment of valve function. Accordingly, Doppler echocardiography was performed in 40 patients within 6 weeks after valve replacement. All patients were clinically stable, without evidence of valvular dysfunction or aortic insufficiency. Valve size ranged from 23 to 33 mm and ventricular ejection fraction averaged 54 ± 13%. Effective orifice area was derived by the continuity equation using stroke volume measured in the ventricular outflow tract, divided by the time-velocity integral of the SJM valve jet, and by PHT. Doppler-derived SJM valve mean gradient averaged 4 ± 2 mm Hg. Effective area by the continuity equation averaged 1.82 ± 0.36 cm2 (range 1.03 cm2 for a 23 mm valve to 2.63 cm2 for a 31 mm valve) and was smaller than by PHT (mean 3.10 ± 0.65 cm2, p = 0.0001; range 1.38 to 4.78 cm2). Areas by both methods were smaller than the actual valve orifice area provided b the manufacturer (4.53 ± 0.80 cm2, p = 0.0001). With use of analysis of variance, effective SJM valve area by the continuity equation differentiated various valve sizes (p = 0.0002) better than did mean gradient (p = 0.013) or PHT (p = NS). Effective area by the continuity equation also correlated better with actual valve orifice area (r = 0.68, p <0.0001) than the area derived by PHT (r = 0.31, p = 0.06). Derivation of effective orifice area of SJM valves in the mitral position with the continuity equation allows better differentiation among valve sizes than mean gradients and PHT, and provides an additional index for assessing prosthetic mitral valve function.
UR - http://www.scopus.com/inward/record.url?scp=0029115783&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029115783&partnerID=8YFLogxK
U2 - 10.1016/S0002-9149(99)80083-6
DO - 10.1016/S0002-9149(99)80083-6
M3 - Article
C2 - 7618626
AN - SCOPUS:0029115783
SN - 0002-9149
VL - 76
SP - 287
EP - 293
JO - The American Journal of Cardiology
JF - The American Journal of Cardiology
IS - 4
ER -