Biomedical subjects

Vijay Natarajan

Publications and source records attributed to Vijay Natarajan.

4 recordsLinked to original sources

PubMed2002

Clinical outcomes of on-pump coronary bypass using heparin-bonded circuits and reduced anti-coagulation compare favorably with off-pump approach.

Coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB), or off pump, has gained popularity by avoiding the postoperative morbidity related to the use of CPB. Previously, we have demonstrated that CABG done on pump using heparin-bonded cardiopulmonary bypass circuits (HBC) with a lower anti-coagulation protocol (LAP) attenuates these effects, reduces homologous blood product requirement, and improves clinical outcome when compared with conventional CPB circuits. Our purpose in this study was to compare off-pump CABG clinical outcomes to on-pump CABG using HBC with LAP. We retrospectively analysed preoperative and postoperative variables of all primary CABG (n=1214) performed at this institution from 1 January 1997 to 28 July 2000. These patients were divided into the on-pump (n=1152) and off-pump groups (n=62). HBC with LAP were used in all on-pump CABG cases. There was no statistical difference in preoperative comorbid risk factors except percentage of females (on pump, 30% vs. off pump, 44%; p=0.02) and body surface area (on pump, 1.94 +/- 0.25 ml vs. off pump, 1.85 +/- 0.22 ml; p=0.02). There was no difference in intraoperative and postoperative complications, risk-adjusted mortality, total blood product usage, or length of stay. The mean number of distal anastomoses performed was significantly different (on pump, 3.5 +/- 0.82 vs. off pump 1.8 +/- 0.82; p < 0.001). Despite similar preoperative risk factors, clinical outcomes and homologous blood requirements were not statistically different between the off-pump and on-pump groups. These endpoints should not be the only criteria to justify performing off-pump CABG.

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PubMedDate not supplied

Simplification of three-dimensional density maps.

We consider scientific data sets that describe density functions over three-dimensional geometric domains. Such data sets are often large and coarsened representations are needed for visualization and analysis. Assuming a tetrahedral mesh representation, we construct such representations with a simplification algorithm that combines three goals: the approximation of the function, the preservation of the mesh topology, and the improvement of the mesh quality. The third goal is achieved with a novel extension of the well-known quadric error metric. We perform a number of computational experiments to understand the effect of mesh quality improvement on the density map approximation. In addition, we study the effect of geometric simplification on the topological features of the function by monitoring its critical points.

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PubMedDate not supplied

A topological approach to simplification of three-dimensional scalar functions.

This paper describes an efficient combinatorial method for simplification of topological features in a 3D scalar function. The Morse-Smale complex, which provides a succinct representation of a function's associated gradient flow field, is used to identify topological features and their significance. The simplification process, guided by the Morse-Smale complex, proceeds by repeatedly applying two atomic operations that each remove a pair of critical points from the complex. Efficient storage of the complex results in execution of these atomic operations at interactive rates. Visualization of the simplified complex shows that the simplification preserves significant topological features while removing small features and noise.

Algorithms↗

PubMedDate not supplied

Off-pump versus on-pump reoperative CABG via a left thoracotomy for circumflex coronary artery revascularization.

OBJECTIVE: Reoperative CABG via a left thoracotomy (RCLT) has become a useful approach for revascularization of the circumflex coronary territory for patients who are at high risk for conventional approach. This study compares the results of RCLT using cardiopulmonary bypass (CPB) with those of a beating heart technique (OPCAB). METHODS: Thirty-two patients who underwent RCLT over the past 10 years were included. Fourteen patients undergoing on-pump RCLT (CPB) were compared to 18 patients undergoing off-pump RCLT (OPCAB). Baseline characteristics of the study groups were similar. Follow-up was 100% complete. A single graft was performed in all patients except one who had two grafts. RESULTS: There were no deaths or perioperative myocardial infarctions in either group. The incidence of atrial fibrillation (CPB: 29% vs. OPCAB: 11%) and the percentage of patients requiring ventilator support longer than 24 hours (21% vs. 6%) was not significantly different between the groups. However, allogeneic blood product utilization (0.9 +/- 1.2 vs. 0.3 +/- 0.7 units, p = 0.04), ICU stay (65 +/- 79 vs. 28 +/- 16 hours, p = 0.04) and total hospital length of stay (8 +/- 4 vs. 5 +/- 1 days, p = 0.001) were significantly lower in the OPCAB group. Average follow-up for the entire cohort was 33 +/- 9.8 months (range 2-102 months). Three-year survival was 74 +/- 9% with 9 deaths (28%) during the follow-up, but only 3 (9%) were cardiac related. Reinterventions were indicated in 6 patients (19%) (PTCA; 5, CABG: 1). Follow-up was longer for the CPB group (51 +/- 33 vs. 19.5 +/- 14 months, p = 0.001). Three-year survival (CPB 69 +/- 13%, OPCAB: 82 +/- 12%, p = 0.47) and reintervention rates (CPB: 3 [21%], OPCAB: 3 [17%], p = 0.33) were similar between the groups. CONCLUSIONS: RCLT is an effective and safe approach for circumflex artery revascularization with excellent short- and mid-term results using either technique. The OPCAB technique is associated with reduced blood product utilization and shorter ICU and hospital length of stay and, therefore, is more cost-effective.

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