Isovolumic relaxation flow propagation velocity: a promising load-independent relaxation parameter in hemodialysis patients.
ABSTRACT The aim of this study is to evaluate whether isovolumic relaxation flow propagation velocity (IRFPV), a newly proposed relaxation parameter, is independent of load alterations. Thirty-nine uremic patients (21 men; age 62 +/- 10 y) who underwent echocardiography 1 h before and 1 h after hemodialysis (HD) were included. After HD, body weight, systolic blood pressure, early transmitral filling wave velocity (E), early diastolic mitral annular velocity (Ea) and early diastolic inflow propagation velocity (EPV) decreased significantly (p <or= 0.007), while IRFPV kept constant (p = 0.550). A subgroup analysis showed that in patients with body weight reduction <2.5 kg, E (p = 0.005) decreased significantly, but Ea (p = 0.078), EPV (p = 0.155) and IRFPV (p = 0.324) did not change after HD. In patients with body weight reduction >or=2.5 kg, E (p < 0.001), Ea (p = 0.001) and EPV (p = 0.001) decreased significantly but IRFPV (p = 0.715) was still constant after HD. In conclusion, IRFPV may be a load-independent parameter in assessing left ventricular diastolic function. However, Ea and EPV are load-independent only at minor load alterations. In evaluating left ventricular diastolic function in HD patients whose loading conditions frequently vary with time, IRFPV seems to be more adequate than Ea and EPV.
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ABSTRACT: Transmitral E wave velocity was reported to be positively related to left ventricular (LV) filling pressure and negatively related to LV relaxation constant, and isovolumic relaxation flow propagation velocity (IRFPV) was proven recently to be negatively related to LV relaxation constant and independent of preload alterations. Therefore, the combination index, E/IRFPV, may eliminate the influence of LV relaxation and bring the LV filling pressure into focus. However, it is unknown whether E/IRFPV is a useful index in prediction of LV filling pressure. The aim of this study is to evaluate the correlation between E/IRFPV and LV end-diastolic pressure (LVEDP). Forty-three patients with suspected coronary artery disease who underwent a Doppler echocardiographic study and cardiac catheterization were included. LVEDP was determined by a micromanometer-tipped catheter. In a univariate analysis, LVEDP had a positive correlation with left atrial dimension, LV end-diastolic dimension, LV end-systolic dimension, the ratio of E to E wave propagation velocity (EPV) (r = 0.408, p = 0.007), the ratio of E to early diastolic mitral annular velocity (Ea) (r = 0.439, p = 0.003) and E/IRFPV (r = 0.686, p < 0.001). It had a negative correlation with diastolic blood pressure, E wave deceleration time, LV ejection fraction, EPV, Ea and IRFPV. After stepwise multiple linear regression analysis, only the E/IRFPV was the independent predictor of LVEDP (beta = 0.667, p < 0.001). In conclusion, E/IRFPV is a useful parameter in prediction of LVEDP.Ultrasound in medicine & biology 07/2008; 34(11):1752-7. · 2.46 Impact Factor
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ABSTRACT: Satellite communication and remote sensing systems need reflector antennas for communication. An efficient system could be constructed with offset reflector and an appropriate corrugated horn to generate low cross polarization, high efficiency, low VSWR and low side lobe level. An offset reflector antenna has been designed and an appropriate corrugated horn in X-band satellite communication with near perfect Gaussian beam was constructed to achieve the required specifications.Antennas, Propagation and EM Theory, 2003. Proceedings. 2003 6th International SYmposium on; 01/2003