Background-We previously demonstrated that power loss (PL) through the total cavopulmonary connection (TCPC) in single-ventricle patients undergoing Fontan can be calculated by computational fluid dynamic analysis using 3-dimensional MRI anatomic reconstructions. PL through the TCPC may play a role in single-ventricle physiology and is a function of cardiac output. We hypothesized that PL through the TCPC increases significantly under exercise flow conditions. Methods and Results-MRI data of 10 patients with a TCPC were analyzed to obtain 3-dimensional geometry and flow rates through the superior vena cava, inferior vena cava, left pulmonary artery, and right pulmonary artery. Steady computational fluid dynamic simulations were performed at baseline conditions using MRI-derived flows. Simulated exercise conditions of twice (2ϫ) and three times (3ϫ) baseline flow were performed by increasing inferior vena cava flow. PL, head loss, and effective resistance through the TCPC were calculated for each condition. Each condition was repeated at left pulmonary artery/right pulmonary artery ratios of 30/70 and 70/30 to determine the effects of pulmonary flow splits on exercise PL. For each patient, PL increases dramatically in a nonlinear fashion with increasing cardiac output, even when normalized to calculate head loss or resistance. Flow splits had a significant effect on PL at exercise, with most geometries favoring right pulmonary artery flow. Conclusions-The relationship between cardiac output and PL is nonlinear and highly dependent on TCPC geometry and pulmonary flow splits. This study demonstrates the importance of studying the TCPC under exercise conditions, because baseline conditions may not adequately characterize TCPC efficiency.
Non-destructive examination of human brain tissues and several kinds of brain tumours using near-infrared (1064 om) excited Fourier transform (NIR-FT) Raman spectroscopy is reported. The spectra from normal but oedematous grey and white matter were similar to those of normal rat grey and white matter reported previously. The brain tumours investigated (glioma grade I1 and 111, two acoustic neurinomas and central neurocytoma) gave Raman spectra essentially the same as to that of grey matter. Histological examination of glioma grade I11 revealed extracellular PAS-positive materials, which have a band at 856 cm-' due to polysaccharides. One of the neurinoma contained a carotenoid which exhibited two resonance Raman peaks at 1157 and 1524 cm-'; another neurinoma did not contain the carotenoid. The appearance of a strong Raman peak at 960 cm-' suggested that the central neurocytoma of choroid plexus was calcified.
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