Associations of coenzyme Q10 with endothelial function in hemodialysis patients.

BACKGROUND: Endothelial dysfunction is common in patients undergoing hemodialysis (HD). However, little is known about the relationship between endothelial dysfunction and coenzyme Q10 (CoQ10) levels in HD patients. METHODS: Eligible HD patients were enrolled in this study according to prespecified inclusion and exclusion criteria. Endothelial function was assessed by brachial artery flow-mediated dilation (FMD). Plasma CoQ10, serum malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) levels were measured. The potential confounders identified by univariate analyses (P < 0.15) were selected in a stepwise multiple regression model. RESULTS: In total, 111 HD patients were enrolled in this study. The mean CoQ10 level was 633.53 ± 168.66 ng/mL, and endothelial dysfunction was prevalent (91.0%) using a cut-off value of 10% FMD. A significant correlation was observed between FMD and plasma CoQ10 level (r = 0.727, P < 0.001). After adjusting for potential parameters, a stepwise multivariate linear regression analysis revealed that CoQ10 level was an independent predictor of FMD (ß = 0.018, P < 0.001). When CoQ10 was dichotomized using the median value (639.74 ng/mL), the conclusion remained unchanged (ß = 0.584, P < 0.001). Pearson's correlation analyses revealed that plasma CoQ10 level was negatively correlated with MDA (r = -0.48, P < 0.001) and 8-OHdG (r = -0.43, P < 0.001) levels. CONCLUSION: Our data demonstrate that impaired brachial artery FMD was common in HD patients. CoQ10 level was independently associated with FMD, and oxidative stress may constitute a link between CoQ10 level and endothelial dysfunction in these patients.

Effects of respiration on pulmonary venous flow and its clinical applications by Doppler echocardiography.

OBJECTIVES: This study was aimed to explore respiratory variations of pulmonary venous flow and its clinical applications and the potential mechanism. METHODS: Pulsed-wave Doppler waveforms of right-upper pulmonary vein were recorded with Siemens Sequoia 512 in 20 healthy young subjects. Electrocardiogram and respiratory tracing were recorded simultaneously. The inspiratory and expiratory pulmonary venous peak flow velocities of S- and D-waves and their velocity-time integrals (VTIs) were acquired and averaged for five consecutive respiratory cycles, respectively. The ratios of velocities and the VTIs of S- to D-waves (S/D, VTIs/VTId) during inspiration and expiration were calculated. RESULTS: The velocity and VTI of S-wave did not vary significantly between inspiration and expiration (58.31 cm/sec +/- 9.22 cm/sec, 58.96 cm/sec +/- 7.79 cm/sec, P = 0.221; 16.29 cm +/- 2.59 cm, 16.54 cm +/- 2.18 cm, P = 0.090), while the velocity and VTI of D-wave increased significantly from inspiration to expiration (48.23 cm/sec +/- 8.32 cm/sec, 51.82 cm/sec +/- 8.72 cm/sec, P < 0.0001; 10.84 cm +/- 1.65 cm, 11.66 cm +/- 1.53 cm, P < 0.0001), resulting in significantly decreased ratios of the velocity and the VTI of S- to D-waves from inspiration to expiration (1.23 +/- 0.22, 1.17 +/- 0.27, P < 0.0001; 1.53 +/- 0.31, 1.43 +/- 0.22, P < 0.0001). CONCLUSIONS: Respiration has significant influence on pulmonary venous flow, which should be taken into account in evaluating left ventricular diastolic function when adopting pulmonary venous flow waveform, especially in diseased settings. The different anatomical positions of left and right heart relative to the thoracic cavity may account for the respiratory variations of pulmonary venous flow.

The characteristics of the spectra of superior venae cavae in patients with right heart failure.

BACKGROUND: Aimed to elucidate the characteristics of the spectra of superior venae cavae (SVC) in respiratory cycles in patients with right heart failure. METHODS: The spectra of SVC of 30 patients with right heart failure and 30 paired healthy subjects were recorded through right supraclavicular fossa view. The profiles of spectra of superior venae cavae were observed, and peak velocity and velocity time integral (VTI) of every wave of SVC under spontaneous respiration were measured for statistical analysis. RESULTS: In healthy subjects, the peak velocities and VTI of S wave and D wave increased in inspiratory phase and diminished in expiratory phase, and which of S wave were larger than which of D wave in whole respiratory cycle. In patients with right heart failure, spectral variations of SVC could be classified into three patterns: Pattern I: peak velocities and VTI of S wave were larger than that of D wave in early inspiratory phase, but peak velocities and VTI of D wave were larger than those of S wave in late inspiratory phase and early expiratory phase [Pattern I-1], even in whole respiratory cycle [Pattern I-2]; Pattern II: the S wave disappeared and was substituted by inverse wave with low amplitude in whole respiratory cycle. Pattern III: the profiles of the spectra of SVC in patients were similar to those of healthy subjects. In the whole, the respiratory variation ratios of peak velocities and VTI of S wave and D wave were diminished in patients compared with those in healthy subjects. CONCLUSION: The spectra of superior venae cavae in patients with right heart failure were abnormal, and these characteristics could be used as signs in evaluating right heart failure.