Thanos Athanasiou

Pulse wave velocity and neutrophil gelatinase-associated lipocalin as predictors of acute kidney injury following aortic valve replacement

BackgroundAccurate prediction, early detection and treatment of acute kidney injury (AKI) are essential for improving post-operative outcomes. This study aimed to examine the role of aortic stiffness and neutrophil gelatinase-associated lipocalin (NGAL) as predictors of AKI or need for early medical renal intervention following aortic valve replacement (AVR).MethodsAortic pulse wave velocity and plasma NGAL were measured pre-operatively in recruited patients undergoing AVR for aortic stenosis (AS). Plasma NGAL was also measured at 3 and 18–24 hours after cardiopulmonary bypass (CPB). AKI was defined using RIFLE criteria. Early medical renal intervention included diuretics or dopamine infusion exclusively for renal causes.ResultsFifty-three patients aged 71u2009±u20099xa0years were included. Sixteen (30%) developed AKI (AKI-Yes) and 24 patients (45%) received early medical intervention (Intervention-Yes). There was no significant difference in the demographic, clinical or operative characteristics between the two groups for either outcome. PWV did not significantly correlate with AKI (ru2009=u20090.12, Pu2009=u20090.13) or early intervention (ru2009=u20090.18, Pu2009=u20090.18). At 3xa0h post-CPB, plasma NGAL was a much stronger predictor of both AKI and the need for early medical intervention than conventional markers such as creatinine (AKI: AUC 83%, 95%u2009CI 0.70–0.95 vs. AUC 65%, 95%u2009CI 0.47- 0.82; Medical intervention: AUC 84%, 95%u2009CI 0.72–0.96 vs. AUC 56%, 95%u2009CI 0.38–0.73). Post-CPB (3xa0hr) plasma NGAL was also significantly associated with AKI (ru2009=u20090.68, Pu2009<u20090.001) at levels above 150xa0ng/ml; and significantly associated with early intervention (ru2009=u20090.64, Pu2009<u20090.001) above 136xa0ng/ml. Simple linear regression showed no relationship between PWV and NGAL levels.ConclusionAortic PWV does not correlate significantly with post-operative AKI or plasma NGAL levels in surgical AS patients. Post-operative NGAL is however an early and powerful predictive biomarker of both post-operative AKI and the need for early medical renal intervention and should consequently be considered in prediction models for AKI after cardiac surgery.

Aortic stiffness is an indicator of cognitive dysfunction before and after aortic valve replacement for aortic stenosis

OBJECTIVESnPost-cardiac surgical cognitive dysfunction occurs more commonly following valvular procedures. Cognitive function has been related to vascular health status; however, the relation between pre-existent arterial stiffness and perioperative cognitive dysfunction is yet to be defined. The objective of this study was to assess whether aortic stiffness is related to cognitive dysfunction in surgical aortic stenosis (AS) pre- and postoperatively.nnnMETHODSnBetween June 2010 and August 2012, patients undergoing aortic valve replacement (AVR) for AS were recruited for inclusion in this prospective observational study. Aortic pulse wave velocity (PWV) was used as a measure of aortic stiffness and cognitive function was assessed using the computerized Cambridge Neuropsychological Test Automated Battery (CANTAB) preoperatively and (409 ± 159 days) post-AVR.nnnRESULTSnFifty-six patients (age 71 ± 8.4 years) were recruited. Of the total, 50 (89%) completed postoperative follow-up. Pre- and postoperatively, patients with normal PWV (PWV-norm) had significantly superior delayed memory, sustained visual attention and executive function compared with those with high PWV (PWV-high). Immediate memory and decision-making were similar between groups. Postoperatively, improvement in cognitive function was more marked in PWV-high compared with PWV-norm patients. In two models of multiple regression analysis, PWV as a continuous variable was independently related to all preoperative main cognitive components as well as postoperative executive function. PWV as a dichotomous variable was independently related to all pre- and postoperative main cognitive function components.nnnCONCLUSIONSnAVR may not be associated with an independent or homogeneous effect on cognitive decline. Aortic PWV might be useful as an additional indicator for cognitive dysfunction before and after surgical intervention for AS.

Evidence Synthesis: Evolving Methodologies to Optimise Patient Care and Enhance Policy Decisions

Evidence synthesis is a term applied to a group of assessment techniques that integrate the data from variable evidence sources. These techniques are used to provide best evidence in healthcare. Evidence synthesis has several advantages when compared to single studies and traditional data integration through meta-analysis. The complexities of combining heterogeneous data sources such as the amalgamation of both qualitative and quantitative data sources can be successfully overcome by applying these techniques. Evidence synthesis can summarise data by classifying each individual source according to its quality whilst it can also quantify the degree of uncertainty in synthesis results. In this chapter, we discuss current evidence synthesis methods and consider their application for medical practitioners, scientists and policymakers. We identify the future trends and increased importance of utilising evidence synthesis for evidence-based medicine. The versatility of evidence synthesis renders it a powerful tool in attaining the ultimate goal of improved health outcomes, innovation and enhanced quality of patient care.

Modification of the Cabrol as a bailout procedure in complicated bicuspid valve aortopathy

The Cabrol technique is reserved where the conventional button or Bentall techniques fail to maintain a tension-free anastomosis between the coronary arteries and aortic conduit. However, the side-to-side anastomosis of the interposition graft that connects the coronary ostia with the aorta in the Cabrol, may lead to kinking or tension, and subsequent occlusion. We present a case of successful Cabrol modification in a patient with bicuspid aortopathy where the graft to the right coronary artery was anastomosed directly onto the valved conduit and the graft to the left main stem onto the previous right aortocoronary graft in a T-fashion.

Influence of body mass index on outcomes after minimal-access aortic valve replacement through a J-shaped partial upper sternotomy

BackgroundMinimal-access aortic valve replacement (MAAVR) may reduce post-operative blood loss and transfusion requirements, decrease post-operative pain, shorten length stay and enhance cosmesis. This may be particularly advantageous in overweight/obese patients, who are at increased risk of post-operative complications. Obese patients are however often denied MAAVR due to the perceived technical procedural difficulty. This retrospective analysis sought to determine the effect of BMI on post-operative outcomes in patients undergoing MAAVR.MethodsNinety isolated elective MAAVR procedures performed between May 2006–October 2013 were included. Intra- and post-operative data were prospectively collected. Ordinary least squares univariate linear regression analysis was performed to determine the effect of BMI as a continuous variable on post-operative outcomes. One-way ANOVA and Chi-squared testing was used to assess differences in outcomes between patients with BMI <25 (nu2009=u200936) and BMI ≥25 (nu2009=u200954) as appropriate.ResultsThere was no peri-operative mortality, myocardial infarction or stroke. Univariate regression demonstrated longer cross-clamp times (pu2009=u20090.0218) and a trend towards increased bypass times (pu2009=u20090.0615) in patients with higher BMI. BMI ≥25 was associated with an increased incidence of hospital-acquired pneumonia (pu2009=u20090.020) and new-onset atrial fibrillation (pu2009=u20090.036) compared to BMI <25. However, raised BMI did not extend ICU (pu2009=u20090.3310) or overall hospital stay (pu2009=u20090.2614). Similar rates of sternal wound complications, inotrope requirements and renal dysfunction were observed in both normal- and overweight/obese-BMI groups. Furthermore, increasing BMI correlated with reduced mechanical ventilation time (pu2009=u20090.039) and early post-operative blood loss (pu2009=u20090.004).ConclusionsOur results demonstrate that within the range of this study, MAAVR is a safe, reproducible and effective procedure, affording equivalent clinical outcomes in both overweight/obese and normal-weight patients considered for an isolated first-time AVR, with low post-operative morbidity and mortality. MAAVR should therefore be considered as an alternative surgical strategy to reduce obesity-related complications in patients requiring aortic valve replacement.

An Introduction to Decision Analysis

Clinicians learn to balance the intended benefits of alternative treatments against the risk of complications. Unfortunately, such implicit risk-benefit analysis is highly vulnerable to bias.

Diagnostic Meta-Analysis: Case Study in Surgery

Surgery and surgical research are continually expanding fields that derive from the increasing global volume of surgical patients and pathology combined with the growth of surgical capability and novel technological innovations. As a result, there are associated diagnostic requirements due to the expansive nature of available surgical techniques, tools, and surgical evidence. Diagnostic accuracy meta-analysis can help clarify diagnostic decisions in all elements of the surgical patient pathway including the quantitative synthesis of evidence for (1) specific elements to the pre-, peri-, and postoperative period, (2) surgical and medical pathology, (3) advances in disease imaging and tissue guidance, and (4) awareness of new devices ranging from operative monitoring/diagnostic devices, stapling instruments, and robots. The process and methodology of diagnosis meta-analysis in surgery is described with contemporary surgical cases. Techniques of data presentation and analysis are reviewed for surgical procedures and pathologies. Barriers and typical problems in surgical diagnostic meta-analysis are also considered and discussed. Diagnostic meta-analytical techniques can offer a prime solution through which to process the ever-increasing volume of surgical outcome data into meaningful information for enhancing clinical outcomes, supporting safety, and developing the next generation of cutting-edge surgical technology.

NR2 antibody is associated with quality of life in aortic valve replacement.

Background The relationship between the potential brain injury biomarker N-methyl-D-aspartate receptor antibody and quality of life has never been assessed. Methods We measured serum N-methyl-D-aspartate receptor antibody levels preoperatively in patients undergoing aortic valve replacement. Quality of life was scored using the Short Form-36 and European Quality of Life 5-Dimensions questionnaires pre- and postoperatively. We analyzed the antibody levels as a continuous variable and as a dichotomous variable with 1.8u2009ngu2009mL−1 as the cutoff. Results Fifty-two patients (15 females) with a mean age of 71u2009±u20098.4 years were recruited for this study. Forty-eight (92%) patients attended the follow-up visit (405u2009±u2009161 days). No mortality or severe neurological event was recorded. In both quality-of-life instruments, the low antibody level group (nu2009=u200935) had significantly better scores than the high antibody level group (nu2009=u200917) preoperatively. Postoperatively, the scores for both groups improved; however, the low antibody level group continued to score significantly better in most of the physical and mental health domains (pu2009=u20090.04 to <0.001). Multiple regression analyses revealed that antibody level and the 1.8u2009ngu2009mL−1 cutoff were independently related to quality of life (pre- and postoperatively). Conclusions Higher N-methyl-D-aspartate receptor antibody levels in aortic valve replacement patients are independently related to poorer quality of life pre- and postoperatively.

Robotic Coronary Revascularisation

Minimally invasive techniques have revolutionised cardiothoracic surgery by reducing surgical trauma and consequently the length of post-operative hospital stay and subsequently cost. Surgically established and safely reproducible currently used methods for robotic coronary revascularisation include the atraumatic coronary artery bypass grafting (ACAB) and the totally endoscopic coronary artery bypass grafting (TECAB) for single-vessel and multi-vessel disease with or without the use of cardiopulmonary bypass whose surgical techniques are systematically described.

A Practical Approach to Diagnostic Meta-analysis

This chapter gives a demonstration of the practical aspects of diagnostic meta-analysis, with emphasis on data entry and manipulation, allocation of variables and code formation, and ensuring the appropriate outcome measures are produced at the end of the analysis. SAS is used to show the manipulation of data in this process. Graphical representation of data and results is shown using Review Manager.