On the use of computational models for the quantitative assessment of surgery in congenital heart disease.
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The surgical repair of congenital heart disease often involves significant modifications to the circulatory tree. Resections, reconstructions, graft insertions and the deployment of implants and biomedical devices have an impact on local and systemic haemodynamics, which may be difficult to foresee or to assess quantitatively by clinical investigation alone. Mathematical models can be employed to visualise, estimate or predict events and physical quantities that are difficult to observe or measure, and can be successfully applied to the study of the pre- and post-operative physiology of cardiovascular malformations. This paper analyses the potentialities of computation fluid dynamics in this respect, outlining the method, its requirements and its limitations. Examples are given of lumped parameter models, axi-symmetric models, three-dimensional models, fluid-structure interaction simulations and multiscale computing applied to total cavo-pulmonary connection, aortic coarctation and aortic arch reconstruction. (+info)
Minute distance obtained from pulmonary venous flow velocity using transesophageal pulsed Doppler echocardiography is related to cardiac output during cardiovascular surgery.
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PURPOSE: We studied the relationship between minute distance calculated from pulmonary venous flow (PVF) velocity tracing and cardiac output (CO) measured with thermodilution method in patients undergoing cardiovascular surgery. METHODS: In 32 patients undergoing cardiovascular surgery, simultaneous measurements of hemodynamics including CO and transesophageal pulsed Doppler signals of PVF velocity were performed before and after surgical repair. Minute distance was calculated as the product of the heart rate and the sum of time-velocity integrals of PVF. RESULTS: The minute distance after surgical intervention increased from 1121 +/- 347 cm x sec(-1) to 1764 +/- 538 cm x sec(-1) (p < 0.001; mean +/- SD), while CO increased after surgical intervention from 3.5 +/- 0.9 L x min(-1) to 5.3 +/- 1.1 L x min(-1). Simple linear regression analysis showed that minute distance was related with CO before and after surgical intervention (r = 0.81 and r = 0.76, respectively). The changes in minute distance were also related with those in CO (r = 0.80). CONCLUSION: The present study demonstrated that minute distance obtained from the pulsed Doppler tracings of PVF velocity was related with CO during cardiovascular surgery in adults. These results suggest that the changes in CO could be estimated from minute distance in pulmonary vein. (+info)
The occurrence of acute postoperative confusion in patients after cardiac surgery.
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This study quantified the occurrence of acute confusion in cardiac surgery patients at three German hospitals. A total of 867 patients, 22-91 years old, were examined each nursing shift postoperatively for 5 days for the presence of acute confusion using a modified version of the Glasgow Coma Scale and Confusion Rating Scale. The night shifts and the third postoperative day showed the most frequent periods of occurrence. Confusional state was noted in patients ranging from 10.5% for patients aged <70, to 40.7% for patients >80 years of age. Those found at increased risk were patients of increasing age and coexisting disease. Targeted nursing interventions for patients at increased risk of acute confusion may decrease this complication. (+info)
Troponin: the biomarker of choice for the detection of cardiac injury.
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It has been known for 50 years that transaminase activity increases in patients with acute myocardial infarction. With the development of creatine kinase (CK), biomarkers of cardiac injury began to take a major role in the diagnosis and management of patients with acute cardiovascular disease. In 2000 the European Society of Cardiology and the American College of Cardiology recognized the pivotal role of biomarkers and made elevations in their levels the "cornerstone" of diagnosis of acute myocardial infarction. At that time, they also acknowledged that cardiac troponin I and T had supplanted CK-MB as the analytes of choice for diagnosis. In this review, we discuss the science underlying the use of troponin biomarkers, how to interpret troponin values properly and how to apply these measurements to patients who present with possible cardiovascular disease. (+info)
Surfactant application during extracorporeal membrane oxygenation improves lung volume and pulmonary mechanics in children with respiratory failure.
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INTRODUCTION: This study was performed to determine whether surfactant application during extracorporeal membrane oxygenation (ECMO) improves lung volume, pulmonary mechanics, and chest radiographic findings in children with respiratory failure or after cardiac surgery. METHODS: This was a retrospective chart review study in a pediatric intensive care unit (PICU). Seven patients received surfactant before weaning from ECMO was started (group S). They were compared to six patients treated with ECMO who did not receive surfactant (group C). These control patients were matched based on age, weight, and underlying diagnosis. Demographic data, ventilator settings, tidal volume, compliance of respiratory system (calculated from tidal volume/(peak inspiratory pressure - positive end-expiratory pressure), and ECMO flow were extracted. Chest radiographs were scored by two blinded and independent radiologists. Changes over time were compared between groups by repeated-measures analysis of variance (time*group interaction). Values are given as percentages of baseline values. RESULTS: The groups did not differ with regard to demographic data, duration of ECMO, ventilator settings, PICU and hospital days. After application of surfactant, mean tidal volume almost doubled in group S (from 100% before to 186.2%; p = 0.0053). No change was found in group C (100% versus 98.7%). Mean compliance increased significantly (p = 0.0067) in group S (from 100% to 176.1%) compared to group C (100% versus 97.6%). Radiographic scores tended to decrease in group S within 48 h following surfactant application. ECMO flow tended to decrease in group S within 10 h following surfactant application but not in group C. Mortality was not affected by treatment. CONCLUSION: Surfactant application may be of benefit in children with respiratory failure treated with ECMO, but these findings need confirmation from prospective studies. (+info)
Effect of fluid loading with saline or colloids on pulmonary permeability, oedema and lung injury score after cardiac and major vascular surgery.
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BACKGROUND: The optimal type of fluid for treating hypovolaemia without evoking pulmonary oedema is still unclear, particularly in the presence of pulmonary vascular injury, as may occur after cardiac and major vascular surgery. METHODS: In a single-centre, prospective, single-blinded clinical trial 67 mechanically ventilated patients were randomly assigned to receive saline, gelatin 4%, HES 6% or albumin 5%, according to a 90 min fluid loading protocol with target central venous pressure of 13 and pulmonary capillary wedge pressure of 15 mm Hg, within 3 h after cardiac or major vascular surgery. Before and after the protocol, we recorded haemodynamics and ventilatory variables and took chest radiographs. The pulmonary vascular injury was evaluated using the 67Ga-transferrin pulmonary leak index (PLI) and extravascular lung water (EVLW). Plasma colloid osmotic pressure (COP) was determined and the lung injury score (LIS) was calculated. RESULTS: More saline was infused than colloid solutions (P<0.005). The COP increased in the colloid groups and decreased in patients receiving saline. Cardiac output increased more in the colloid groups. At baseline, PLI and EVLW were above normal in 60 and 30% of the patients, with no changes after fluid loading, except for a greater PLI decrease in HES than in gelatin-loaded patients. The oxygenation ratio improved in all groups. In the colloid groups, the LIS increased, because of a decrease in total respiratory compliance, probably associated with an increase in intrathoracic plasma volume. CONCLUSIONS: Provided that fluid overloading is prevented, the type of fluid used for volume loading does not affect pulmonary permeability and oedema, in patients with acute lung injury after cardiac or major vascular surgery, except for HES that may ameliorate increased permeability. During fluid loading, changes in LIS (and respiratory compliance) do not represent changes in pulmonary permeability or oedema. (+info)
New paradigms in cardiovascular medicine: emerging technologies and practices: perioperative genomics.
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Considerable progress has been made in understanding the pathophysiology of perioperative stress responses and their impact on the cardiovascular system; however, researchers are just beginning to unravel genetic and molecular determinants that predispose to increased risk for postoperative cardiovascular adverse events. A new field, coined perioperative genomics, aims to apply functional genomic approaches to uncover the biological reasons why similar patients can have dramatically different clinical outcomes after surgery. For the perioperative physician, such findings may soon translate into prospective risk assessment incorporating genomic profiling of markers important in inflammatory, thrombotic, vascular, and neurologic responses to perioperative stress, with implications ranging from individualized additional pre-operative testing and physiological optimization, to perioperative decision-making, choice of monitoring strategies, and critical care resource utilization. We review current knowledge regarding genomic technologies in perioperative cardiovascular disease characterization and outcome prediction, as well as discuss future trends/challenges for translating integrated "omic" information into daily clinical management of the surgical patient. (+info)
Impact of hospital volume on racial disparities in cardiovascular procedure mortality.
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OBJECTIVES: We assessed use of low-volume hospitals by race and ethnicity for major cardiovascular procedures and determined whether hospital volume is an important factor explaining racial and ethnic differences in post-procedure mortality. BACKGROUND: Low hospital volume predicts mortality for cardiovascular procedures and could be a mediator of racial and ethnic differences in procedure outcomes. METHODS: We analyzed data from 719,679 hospitalizations for cardiac artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty (PTCA), abdominal aortic aneurysm (AAA) repair, and carotid endarterectomy (CEA) from 1998 to 2001 using the Nationwide Inpatient Sample. We used multivariate logistic regression to assess whether race predicts use of low-volume hospitals and the relative contribution of hospital volume to racial disparity in post-procedure in-hospital mortality. RESULTS: Black and Hispanic patients were more likely than white patients to receive cardiovascular procedures in low-volume hospitals. Black patients had greater risk-adjusted mortality than white patients after elective AAA repair (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.20 to 2.84), CABG (OR, 1.19; 95% CI, 1.06 to 1.33), and CEA (OR, 1.56; 95% CI, 1.07 to 2.27), but not PTCA. Hispanic patients did not have higher risk-adjusted mortality than white patients. Adjusting for hospital volume did not substantially reduce the relative risk of death for black patients compared with white patients. CONCLUSIONS: Black and Hispanic patients were more likely to receive cardiovascular procedures in low-volume hospitals, but hospital volume did not explain a large proportion of racial differences in post-procedure mortality. Additional research is needed to determine why black patients have increased mortality after cardiovascular procedures and how these mortality rates can be reduced. (+info)