Although low systemic vascular resistance occurs during normothermic and hypothermic cardiopulmonary bypass, the determinants of depressed systemic vascular resistance and its effect on outcomes are ...unknown. To assess the predictors and clinical effects of low systemic vascular resistance, 555 patients undergoing isolated coronary artery bypass grafting were evaluated prospectively. The extent of low systemic vascular resistance during bypass was estimated by the amount of the vasoconstrictor phenylephrine administered: group 1, 0 to 160 μg; group 2, 161 to 800 μg; group 3, more than 800 μg. Multivariate analysis identified bypass temperature, bypass time, and ventricular function as determinants of low systemic vascular resistance. Patients on normothermic bypass accounted for 65% of the patients in group 3 and only 34% of the patients in group 1 (
p < 0.0001). The bypass time was longer in the patients in group 3 (97 ± 28 minutes) than in the patients in group 1 (89 ± 24 minutes;
p < 0.006). Patients with a preoperative left ventricular ejection fraction of 0.40 or less required less phenylephrine during cardiopulmonary bypass (498 ± 68 μg) than did patients with a fraction exceeding 0.40 (1.087 ± 88 μg;
p < 0.001). By multivariate analysis, advanced age and the presence of peripheral vascular disease were found to decrease the likelihood of low systemic vascular resistance during normothermic bypass. Diabetes, the left ventricular ejection fraction, the bypass time, and the total cardioplegia infused were found to influence the likelihood of low systemic vascular resistance during hypothermic bypass. Patients in group 3 had a higher cardiac index and lower mean arterial pressure and systemic vascular resistance postoperatively. In those patients who received a left internal mammary artery graft, the incidences of the low-output syndrome (group 1, 4.9%; group 3, 2.7%;
p = not significant) and myocardial infarction (group 1, 1.4%; group 3, 1.8%;
p = not significant) were not influenced by the amount of phenylephrine infused during cardiopulmonary bypass. In those patients who were at high risk of suffering a stroke preoperatively, the hypotension induced by the low systemic vascular resistance and its treatment with phenylephrine was not associated with an increased incidence of stroke (group 1, 5.8%; group 3, 2.8%;
p = not significant).
Cardiac surgeons are using more bioprosthetic valves due to the ageing population as well as to improvements that have been made to these implants. We sought to compare the 1-year hemodynamics of two ...commercially available valves by echocardiographic parameters.
Retrospective review of our institutional database revealed 69 patients who received either Perimount Magna (n = 33) or St Jude Epic (n = 36) valves in the aortic position with no other valve surgery between June 2004 and March 2006. All patients received transthoracic echocardiography at 1 year. Comparisons between groups were made at baseline and at 1-year follow-up. In addition, a pairwise comparison was performed in each patient to determine the change in echocardiographic parameters between baseline and follow-up.
Mean implanted valve size was similar (Magna 24.3 ±2.0 mm vs. Epic 24.1 ±2.2 mm). Pre- and intraoperative patient variables were similar between the two groups. There were lower peak and mean pressure gradients in the Magna group, both at discharge and one year after surgery. This correlated with a larger indexed effective orifice area (Magna 0.8 ±0.2 cm(2)/m(2) vs. Epic 0.67 ±0.2 cm(2)/m(2), p = 0.02). In spite of these findings, left ventricular mass regression was not different.
These findings suggest that in a series with relatively low indexed effective orifice areas, the peak and mean gradients obtained were acceptable. More clinical follow-up of these patients is required to assess the true impact of prosthesis patient mismatch.
This paper describes the integration of perceptual guidelines from human vision with an Al-based mixed-initiative search strategy. The result is a visualization assistant called ViA, a system that ...collaborates with its users to identify perceptually salient visualizations for large multidimensional data sets. ViA applies the knowledge of low-level human vision to 1) evaluate the effectiveness of a particular visualization for a given data set and analysis tasks and 2) rapidly direct its search toward new visualizations that are most likely to offer improvements over those seen to date. Context, domain expertise, and a high-level understanding of a data set are critical to identifying effective visualizations. We apply a mixed-initiative strategy that allows ViA and its users to share their different strengths and continually improve ViA's understanding of a user's preferences. We visualize historical weather conditions to compare ViA's search strategy to exhaustive analysis, simulated annealing, and reactive tabu search and to measure the improvement provided by mixed-initiative interaction. We also visualize intelligent agents competing in a simulated online auction to evaluate ViA's perceptual guidelines. Results from each study are positive, suggesting that ViA can construct high-quality visualizations for a range of real-world data sets.
Background: This study examined the impact of mitral valve repair (MVRe) on survival of patients with moderate or severe (≥2+) MR and ischemic cardiomyopathy randomized to coronary artery bypass ...grafting (CABG) versus CABG+surgical ventricular reconstruction (SVR) in the STICH trial.
Methods: Among patients with moderate or severe MR and ischemic cardiomyopathy undergoing CABG or CABG+SVR, the impact of MVRe on mortality between the two treatment arms was compared.
Results: Among 867 patients with assessment of baseline MR severity, 211 had moderate or severe MR. After excluding 7 patients who underwent mitral valve replacement, 50, 44, 62, and 48 patients underwent CABG, CABG+MVRe, CABG+SVR, and CABG+SVR+MVRe, respectively. Four-year mortality rates were lower following CABG+MVRe than CABG alone (16% vs. 55%; adjusted hazard ratio HR 0.30; 95% CI 0.13-0.71). In contrast, the CABG+SVR+MVRe and CABG+SVR groups had similar 4-year mortality of 39% vs. 39% (adjusted HR 0.88; 95% CI 0.46-1.70). MVRe had a more favorable effect on survival in patients undergoing CABG alone compared to CABG+SVR (p = 0.013). Baseline MR severity was similar between patients that received CABG+MVRe and those that underwent CABG+SVR+MVRe. A larger proportion of patients demonstrated a reduction in MR between 4 and 24 months after CABG+MVRe compared to CABG+SVR+MVRe (50.0% versus 25.0%, p = 0.023).
Conclusion: In patients with moderate or severe MR and ischemic cardiomyopathy undergoing CABG, MVRe appears to have a favorable effect on survival. The addition of SVR to CABG may attenuate the anticipated benefits of MVRe by limiting the long-term reduction of MR with MVRe.
Little is known about host-parasite inter-relationship in the lymphatic filarial parasites. There is no information available about the ability of these parasites to acquire cholesterol, though it is ...known that in general, nematodes lack the ability to synthesise cholesterolde novo. In this study, we have shown that the filarial parasites also lack the ability to incorporate labelled acetate into cholesterol, indicating the absence of the machinery for cholesterol biosynthesis. We have further shown that they elaborate a 43 kDa surface receptor for acquiring LDL-bound cholesterol. We have shown by polymerase chain reaction the presence of a 860 bp fragment indicating the presence of the gene for LDL-related protein (LRP) in the human filarial parasiteWuchereria bancrofti in the genomic DNA. We have also shown that it is expressed as seen in the cDNA clones identified from an expression library.
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