Justin Nowell

Protective effect of epicardial adiponectin on atrial fibrillation following cardiac surgery

OBJECTIVE Inflammation has been implicated in the pathogenesis of postoperative atrial fibrillation (AF). Adipose tissue secretes both pro-inflammatory cytokines such as interleukin-6 (IL-6) and anti-inflammatory mediators such as adiponectin. We set out to examine the association of adiponectin and IL-6, both circulating and locally produced by the epicardial adipose tissue, with AF development after cardiac surgery. METHODS A total of 90 consecutive patients undergoing cardiac surgery were evaluated. Blood samples were collected before induction of anaesthesia. Epicardial fat was obtained upon commencement of cardiopulmonary bypass. IL-6 and adiponectin levels were determined in serum and supernatant of epicardial adipose tissue organ cultures with two-site enzyme-linked immunosorbent assay (ELISA). Heart rhythm was assessed with continuous tele-monitoring for 72 h postoperatively, and with 6-hourly clinical examinations and daily electrocardiograms (ECGs) thereafter. RESULTS A total of 36 patients developed postoperative AF (40%). Baseline-serum IL-6 and adiponectin were not associated with AF (p = 0.86 and 0.95, respectively). Epicardial adipose tissue IL-6 levels did not correlate with the development of the arrhythmia either (p = 0.37). However, epicardial adiponectin release was lower in patients who developed AF than in those who remained in sinus rhythm (76 (interquartile range (IQR) 35-98) vs 53 ((IQR) 35-69) ng h(-1)g(-1) of tissue cultured, p = 0.066). Following linear regression, the association of epicardial adiponectin with AF almost reached statistical significance (p = 0.066). Multivariate logistic regression analysis of identified risk factors for AF, with the inclusion of epicardial adiponectin as an independent variable, revealed increased age (odds ratio (OR) 1.09, 95% confidence interval (CI) 1.02-1.17, p = 0.013) and epicardial adiponectin levels (OR 0.98, 95% CI 0.97-1.00, p = 0.054) as independent predictors of postoperative AF. CONCLUSIONS Increased epicardial adiponectin is associated with maintenance of sinus rhythm following cardiac surgery. This reinforces the inflammatory hypothesis in the pathogenesis of postoperative AF and may represent a novel therapeutic target for its effective prevention.

Strategies in the Surgical Management of Atrial Fibrillation

Atrial fibrillation (AF) is associated with substantial morbidity, mortality, and economic burden and confers a lifetime risk of up to 25%. Current medical management involves thromboembolism prevention, rate, and rhythm control. An increased understanding of AF pathophysiology has led to enhanced pharmacological and medical therapies; however this is often limited by toxicity, variable symptom control, and inability to modulate the atrial substrate. Surgical AF ablation has been available since the original description of the Cox Maze procedure, either as a standalone or concomitant intervention. Advances in novel energy delivery systems have allowed the development of less technically demanding procedures potentially eliminating the need for median sternotomy and cardiopulmonary bypass. Variations in the definition, duration, and reporting of AF have produced methodological limitations impacting on the validity of interstudy comparisons. Standardization of these parameters may, in future, allow us to further evaluate clinical endpoints and establish the efficacy of these techniques.

Simulator Teaching of Cardiopulmonary Bypass Complications: A Prospective, Randomized Study

OBJECTIVE Complications of cardiopulmonary bypass (CPB) are rare, but life-threatening events that need prompt and rehearsed actions involving a team. This is not adequately taught to cardiothoracic surgical trainees. The objective of this study was to assess the knowledge of cardiothoracic trainees required to manage these events after simulation-based vs. lecture-based teaching. PARTICIPANTS AND DESIGN Totally, 17 cardiac surgical trainees with no formal teaching in intraoperative complications of CPB management were randomly assigned by computer to either a study group receiving simulation-based complications of CPB teaching via the Orpheus simulator (n = 9) or a control group receiving complications of CPB teaching via a lecture (n = 8). Each subject undertook a written test comprising 20 multiple choice questions on complications of CPB before and after teaching. Trainees were then asked to rate their satisfaction with each session from 1 to 5, with 5 being most satisfied. SETTING St George Simulation and Clinical Skills Laboratory, St Georges Hospital, London. RESULTS There was no significant difference in the pretest scores between the 2 groups (p = 0.29). After teaching, both groups showed a statistically significant improvement in their knowledge (p < 0.05). The trainees in the simulation group performed better than the lecture-based group; however, this was not statistically significant (p = 0.21). Satisfaction levels in both the lecture session and the simulation session were very high with means of 4.4/5 and 4.8/5, respectively. CONCLUSION Despite the familiarity with CPB during surgery, the simulation group performed at least as well as the lecture group. Cardiothoracic trainees would benefit from formal teaching of complications of CPB management via either learning modality being incorporated into their training.

A Survey of Cardiothoracic Surgical Training in the United Kingdom: Realities of a 6-Year Integrated Training Program

BACKGROUND In recent years, cardiothoracic (CT) surgical training has faced several challenges, including a reduction in working hours and trainees favoring shorter training programs. We carried out a national survey in the United Kingdom (UK) to assess the CT 6-year training program. METHODS All CT trainees in the UK (n = 121) were sent an online survey. This was combined with a debate at the Society for CT Surgery of Great Britain and Ireland. RESULTS Ninety-one (75.2%) of all trainees responded. Despite 56 (68.1%) being rostered for more than a 48-hour week, 31 (34.1%) of all trainees work an extra 10 hours. The majority (56, 61.5%) thought that on-calls and night duty are useful. Just over half of the trainees (47, 51.6%) spend at least 2 full days in the operating room, but 79 (86.8%) thought that this is too little and would spend voluntary time operating. Simulation of operations is thought to be useful; however, few thought that this should take more precedence in their training program. The majority of trainees thought that the current assessment of surgical training is suboptimal and does not examine surgical skill. Similarly, the majority thought that a defined number of operations is required before qualification. CONCLUSIONS Trainees remain committed to their profession and are willing to dedicate more time perfecting their art. They believe that despite wanting extra operating experience, they will be ready for independent practice at the completion of their training. It rests with training bodies to find alternative assessments for surgical ability and to define experience at the exit point of training.

Surgical aortic-valve replacement with a transcatheter implant

We describe a bailout procedure when surgical aortic-valve replacement was not possible due to severe calcification of the ascending aorta and the root and a very small annulus. A 21-mm CoreValve Revalving prosthesis was inserted via the aortotomy in the presence of a mitral prosthesis.

Analysis of aortic area/height ratio in patients with thoracic aortic aneurysm and Type A dissection†

OBJECTIVES Significant proportions of aortic dissections occur at aortic diameters <5.5 cm. By indexing aortic area to height and correlating with absolute aortic diameter, we sought to identify those aneurysm patients with aortic diameters <5.5 cm who do not meet current size thresholds for surgery, yet with corresponding abnormal indexed aortic areas (IAAs) >10 cm2/m, are at increased risk of aortic complications. METHODS IAAs were calculated at 3 aortic locations in 187 aneurysm and 66 dissection patients operated on between 2010 and 2016 at our tertiary aortic centre. Proportions of patients with IAA >10 cm2/m, mean IAAs corresponding to aortic diameters <4.0 cm, 4.0-4.5 cm, 4.5-5.0 cm, 5.0-5.5 cm and >5.5 cm, and mean aortic diameters corresponding to IAAs 10-12 cm2/m, 12-14 cm2/m and >14 cm2/m were determined. RESULTS Proportions of patients with abnormal IAAs were similar in both groups. In all, 49.1% of aneurysm patients with aortic diameters 4.5-5.0 cm, and 98.5% with aortic diameters 5.0-5.5 cm had abnormal IAAs. Out of 200 separate aneurysms with IAAs >10 cm2/m between the mid-sinus and mid-ascending aorta, 139 (69.5%) would not warrant surgery according to existing guidelines. CONCLUSIONS Using the IAA, we identified a significant proportion of patients with thoracic aortic aneurysms who are at increased risk of aortic complications, despite current aortic guidelines not endorsing surgical intervention in this group. Our data suggests the IAA may be useful in preoperative risk evaluation and as a criterion for surgery.

Haemodynamic assessment of bicuspid aortic valve aortopathy: a systematic review of the current literature

Both genetic and haemodynamic theories explain the aetiology, progression and optimal management of bicuspid aortic valve aortopathy. In recent years, the haemodynamic theory has been explored with the help of magnetic resonance imaging and computational fluid dynamics. The objective of this review was to summarize the findings of these investigations with focus on the blood flow pattern and associated variables, including flow eccentricity, helicity, flow displacement, cusp opening angle, systolic flow angle, wall shear stress (WSS) and oscillatory shear index. A structured literature review was performed from January 1990 to January 2018 and revealed the following 3 main findings: (i) the bicuspid aortic valve is associated with flow eccentricity and helicity in the ascending aorta compared to healthy and diseased tricuspid aortic valve, (ii) flow displacement is easier to obtain than WSS and has been shown to correlate with valve morphology and type of aortopathy and (iii) the stenotic bicuspid aortic valve is associated with elevated WSS along the greater curvature of the ascending aorta, where aortic dilatation and aortic wall thinning are commonly found. We conclude that new haemodynamic variables should complement ascending aorta diameter as an indicator for disease progression and the type and timing of intervention. WSS describes the force that blood flow exerts on the vessel wall as a function of viscosity and geometry of the vessel, making it a potentially more reliable marker of disease progression.