TY - JOUR
T1 - The dependence of pressure half-time on initial and mean pressure gradients
T2 - Exercise Doppler in patients with St. Jude valves
AU - Rosamond, T.
AU - Vered, Z.
AU - Perez, J. E.
PY - 1990
Y1 - 1990
N2 - To assess the hemodynamic factors that influence the Doppler-derived mitral pressure half-time, we studied 11 patients with St. Jude valves in place, with constant effective mitral orifice area. Mitral pressure half-time, heart rate, time velocity integral, peak and mean pressure gradients were measured at rest and immediately after exercise. Despite in vitro stable effective orifice area in St. Jude valves, the pressure half-time decreased with exercise (95.0 ± 6.6 ms (SE) to 62.3 ± 4.7 ms; p < 0.01) as heart rate increased (73.8 ± 2.2 to 99.2 ± 3.2 beats/min; p < 0.01). Peak (early diastolic) and mean pressure gradients increased (6.3 ± 0.7 to 9.8 ± 0.9 mmHg and 2.5 ± 0.2 to 3.9 ± 0.3 mmHg, respectively; p < 0.05 for both). Mean transmitral time velocity integral did not change (26.6 ± 1.0 and 27.1 ± 1.8 cm; p = NS). Thus, under conditions of fixed effective orifice area, the mitral pressure half-time varies inversely with the peak and mean pressure gradients. This study suggests that the initial pressure gradient and volume flow should be considered when interpreting changes in Doppler pressure half-time as indicative of changes in mitral valve area.
AB - To assess the hemodynamic factors that influence the Doppler-derived mitral pressure half-time, we studied 11 patients with St. Jude valves in place, with constant effective mitral orifice area. Mitral pressure half-time, heart rate, time velocity integral, peak and mean pressure gradients were measured at rest and immediately after exercise. Despite in vitro stable effective orifice area in St. Jude valves, the pressure half-time decreased with exercise (95.0 ± 6.6 ms (SE) to 62.3 ± 4.7 ms; p < 0.01) as heart rate increased (73.8 ± 2.2 to 99.2 ± 3.2 beats/min; p < 0.01). Peak (early diastolic) and mean pressure gradients increased (6.3 ± 0.7 to 9.8 ± 0.9 mmHg and 2.5 ± 0.2 to 3.9 ± 0.3 mmHg, respectively; p < 0.05 for both). Mean transmitral time velocity integral did not change (26.6 ± 1.0 and 27.1 ± 1.8 cm; p = NS). Thus, under conditions of fixed effective orifice area, the mitral pressure half-time varies inversely with the peak and mean pressure gradients. This study suggests that the initial pressure gradient and volume flow should be considered when interpreting changes in Doppler pressure half-time as indicative of changes in mitral valve area.
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AN - SCOPUS:0025542165
SN - 1043-4356
VL - 9
SP - 227
EP - 234
JO - Journal of Cardiovascular Technology
JF - Journal of Cardiovascular Technology
IS - 3
ER -