Regional anaesthesia via parasternal catheters inserted preoperatively and postoperative delirium after cardiac surgery: A prospective unrandomised clinical trial.

VISUAL ABSTRACT: http://links.lww.com/EJA/A927.

Coupling hemodynamics with mechanobiology in patient-specific computational models of ascending thoracic aortic aneurysms.

BACKGROUND AND OBJECTIVE: The prevention of ascending thoracic aortic aneurysms (ATAAs), which affect thousands of persons every year worldwide, remains a major issue. ATAAs may be caused by anything that weakens the aortic wall. Altered hemodynamics, which concerns a majority of patients with bicuspid aortic valves, has been shown to be related to such weakening and to contribute to ATAA development and progression. However the underlying mechanisms remain unclear and computational modeling in this field could help significantly to elucidate how hemodynamics and mechanobiology interact in ATAAs. METHODS: Accordingly, we propose a numerical framework combining computational fluid dynamics and 4D flow magnetic resonance imaging (MRI) coupled with finite element (FE) analyses to simulate growth and remodeling (G&R) occurring in patient-specific aortas in relation with altered hemodynamics. The geometries and the blood velocities obtained from 4D flow MRI are used as boundary conditions for CFD simulations. CFD simulations provide an estimation of the wall shear stress (WSS) and relative residence time (RRT) distribution across the luminal surface of the wall. An initial insult is then applied to the FE model of the aortic wall, assuming that the magnitude of the insult correlates spatially with the normalized RRT distribution obtained from CFD simulations. G&R simulations are then performed. The material behavior of each Gauss point in these FE models is evolved continuously to compensate for the deviation of the actual wall stress distribution from the homeostatic state after the initial insult. The whole approach is illustrated on two healthy and two diseased subjects. The G&R parameters are calibrated against previously established statistical models of ATAA growth rates. RESULTS: Among the variety of results provided by G&R simulations, the analysis focused especially on the evolution of the wall stiffness, which was shown to be a major risk factor for ATAAs. It was shown that the G&R parameters, such as for instance the rate of collagen production or cell mechanosensitivity, play a critical role in ATAA progression and remodeling. CONCLUSIONS: These preliminary findings show that patient-specific computational modeling coupling hemodynamics with mechanobiology is a promising approach to explore aneurysm progression.

Significance of Hemodynamics Biomarkers, Tissue Biomechanics and Numerical Simulations in the Pathogenesis of Ascending Thoracic Aortic Aneurysms.

Guidelines for the treatment of aortic wall diseases are based on measurements of maximum aortic diameter. However, aortic rupture or dissections do occur for small aortic diameters. Growing scientific evidence underlines the importance of biomechanics and hemodynamics in aortic disease development and progression. Wall shear stress (WWS) is an important hemodynamics marker that depends on aortic wall morphology and on the aortic valve function. WSS could be helpful to interpret aortic wall remodeling and define personalized risk criteria. The complementarity of Computational Fluid Dynamics and 4D Magnetic Resonance Imaging as tools for WSS assessment is a promising reality. The potentiality of these innovative technologies will provide maps or atlases of hemodynamics biomarkers to predict aortic tissue dysfunction. Ongoing efforts should focus on the correlation between these non-invasive imaging biomarkers and clinico-pathologic situations for the implementation of personalized medicine in current clinical practice.

Hemodynamics alteration in patient-specific dilated ascending thoracic aortas with tricuspid and bicuspid aortic valves.

In this paper, we evaluate computationally the influence of blood flow eccentricity and valve phenotype (bicuspid (BAV) and tricuspid (TAV) aortic valve) on hemodynamics in ascending thoracic aortic aneurysm (ATAA) patients. 5 TAV ATAA, 5 BAV ATAA (ascending aorta diameter >35 mm) and 2 healthy subjects underwent 4D flow MRI. The 3D velocity profiles obtained from 4D flow MRI were given as input boundary conditions to a computational fluid dynamics analysis (CFD) model. After performing the CFD analyses, we verified that the obtained time-averaged velocity profiles and flow eccentricity were in good agreement with 4D flow MRI. Then we used the CFD analyses to evaluate the time-averaged wall shear stress (TAWSS) and the local normalized helicity (LNH). We found that the flow eccentricities at the aortic root were not significantly different (p > 0.05) between TAV and BAV phenotypes. TAWSS (R2 = 0.697, p = 0.025) and absolute LNH (R2 = 0.964, p < 0.001) are in good correlation with flow eccentricity. We conclude that eccentricity at the aortic root is a major determinant of hemodynamics patterns in ATAA patients regardless of the aortic valve phenotype.

Computational prediction of hemodynamical and biomechanical alterations induced by aneurysm dilatation in patient-specific ascending thoracic aortas.

The aim of the present work is to propose a robust computational framework combining computational fluid dynamics (CFD) and 4D flow MRI to predict the progressive changes in hemodynamics and wall rupture index (RPI) induced by aortic morphological evolutions in patients harboring ascending thoracic aortic aneurysms (ATAAs). An analytical equation has been proposed to predict the aneurysm progression based on age, sex, and body surface area. Parameters such as helicity, wall shear stress (WSS), time-averaged WSS, oscillatory shear index, relative residence time, and viscosity were evaluated for two patients at different stages of aneurysm growth, and compared with age-sex-matched healthy subjects. The study shows that evolution of hemodynamics and RPI, despite being very slow in ATAAs, is strongly affected by morphological alterations and, in turn could impact biomechanical factors and aortic mechanobiology. An aspect of the current work is that the patient-specific 4D MRI data sets were obtained with a follow-up of 1 year and the measured time-averaged velocity maps and flow eccentricity were compared with the CFD simulation for validation. The computational framework presented here is capable of capturing the blood flow patterns and the hemodynamic descriptors during the various stages of aneurysm growth. Further investigations will be conducted in order to verify these results on a larger cohort of patients and with long follow-up times to finally elucidate the link between deranged hemodynamics, AA geometry, and wall mechanical properties in ATAAs.

Evaluation of effectiveness and compliance with the mupirocin nasal ointment part of Staphylococcus aureus decolonization in real life using UPLC-MS/MS mupirocin quantification.

BACKGROUND: Preoperative decolonization is recommended in Staphylococcus aureus nasal carriers scheduled for cardiac surgery. We aimed to evaluate the effectiveness of and compliance with mupirocin use in nasal S. aureus carriers in a real-life setting. METHODS: Prospective study including consecutive patients scheduled for cardiac surgery screened for S. aureus nasal carriage at preoperative consultation. Carriers were prescribed mupirocin nasal ointment, chlorhexidine shower and mouthwash. Effectiveness of decolonization was evaluated with a postoperative nasal sample. Compliance was evaluated objectively by determination of nasal mupirocin concentration using UPLC-MS/MS and self-reported by questionnaire. RESULTS: Over 10 months, 361 patients were included, 286 had preoperative screening, 75 (26.2%) were S. aureus nasal carriers and 19 of them (25.3%) failed to be effectively decolonized. No resistance to mupirocin was documented. Preoperative and postoperative strains were identical in all cases. Declared good compliance was associated with decolonization success (OR = 24; 95% CI 4-143, P < 0.0001). Mupirocin detection was significantly associated with the level of compliance. Mupirocin was detected in 52.2% (24/46) of patients effectively decolonized and in 12.5% (2/16) of patients with decolonization failure (P < 0.01). In 2/19 patients, failure of decolonization was not associated with a compliance issue. Postoperative carriage was associated with an increased risk of S. aureus infection (OR = 9.8; 95% CI 1.8-53, P < 0.01). CONCLUSIONS: In real life, decolonization is not always effective, hence there is a persisting risk of S. aureus endogenous infection. Mupirocin concentration measurement may help to understand compliance issues and failures in decolonization.

Relationship Between Ascending Thoracic Aortic Aneurysms Hemodynamics and Biomechanical Properties.

OBJECTIVE: Ascending thoracic aortic aneu-rysm (aTAA) is a major cause of human deaths. Despite important recent progress to better understand its pathogenesis and development, the role played by deranged hemodynamics on aTAA risk of rupture is still partially unknown. Our aim was to develop and apply a novel methodology to assess the correlation between aTAA rupture risk and hemodynamic biomarkers combining for the first time in vivo, in vitro, and in silico analyses. METHODS: Computational fluid dynamic analyses were performed and validated on ten patients using patient-specific data derived from CT scan and four-dimensional MRI. Systolic wall shear stress, time-averaged wall shear stress (TAWSS), flow eccentricity (Floweccentricity), and helicity intensity (h2) were assessed. A bulge inflation test was carried out in vitro on the ten aTAA samples resected during surgical repair. The biomechanical and rupture properties of these samples were derived: the burst pressure, the physiological tangent elastic modulus (Ephysio), the Cauchy stress at rupture (σrupt), the rupture stretch (λrupt), and the rupture stretch criterion (Υstretch). Statistical analysis was performed to determine correlation between all variables. RESULTS: Statistically highly significant (p < 0.01) positive correlation between λrupt and the TAWSS (r = 0.867 and p = 0.001) was found. CONCLUSION: This study shows that relatively low TAWSS significantly correlates with reduced rupture properties in aTAAs. SIGNIFICANCE: Understanding the pathogenesis of aTAA remains crucial to reduce morbidity and mortality. Our aim is to establish possible correlations between aTAA rupture risk and hemodynamic biomarkers by combining for the first time in vivo, in vitro, and in silico analyses.

Does the Knowledge of the Local Thickness of Human Ascending Thoracic Aneurysm Walls Improve Their Mechanical Analysis?

Ascending thoracic aortic aneurysm (ATAA) ruptures are life threatening phenomena which occur in local weaker regions of the diseased aortic wall. As ATAAs are evolving pathologies, their growth represents a significant local remodeling and degradation of the microstructural architecture and thus their mechanical properties. To address the need for deeper study of ATAAs and their failure, it is required to analyze the mechanical behavior at the sub-millimeter scale by making use of accurate geometrical and kinematical measurements during their deformation. For this purpose, we propose a novel methodology that combined an accurate tool for thickness distribution measurement of the arterial wall, digital image correlation to assess local strain fields and bulge inflation to characterize the physiological and failure response of flat unruptured human ATAA specimens. The analysis of the heterogeneity of the local thickness and local physiological stress and strain was carried out for each investigated subject. At the subject level, our results state the presence of a non-consistent relationship between the local wall thickness and the local physiological strain field and high heterogeneity of the variables. At the inter-subject level, thicknesses were studied in relation to physiological strain and stress and load at rupture. The rupture pressure was correlated with neither the average thickness nor the lowest thickness of the specimens. Our results confirm that intrinsic material strength (hence structure) differs a lot from a subject to another and even within the same subject.

Evaluation of Peak Wall Stress in an Ascending Thoracic Aortic Aneurysm Using FSI Simulations: Effects of Aortic Stiffness and Peripheral Resistance.

PURPOSE: It has been reported clinically that rupture or dissections in thoracic aortic aneurysms (TAA) often occur due to hypertension which may be modelled with sudden increase of peripheral resistance, inducing acute changes of blood volumes in the aorta. There is clinical evidence that more compliant aneurysms are less prone to rupture as they can sustain such changes of volume. The aim of the current paper is to verify this paradigm by evaluating computationally the role played by the variation of peripheral resistance and the impact of aortic stiffness onto peak wall stress in ascending TAA. METHODS: Fluid-structure interaction (FSI) analyses were performed using patient-specific geometries and boundary conditions derived from 4D MRI datasets acquired on a patient. Blood was assumed incompressible and was treated as a non-Newtonian fluid using the Carreau model while the wall mechanical properties were obtained from the bulge inflation tests carried out in vitro after surgical repair. The Navier-Stokes equations were solved in ANSYS Fluent. The Arbitrary Lagrangian-Eulerian formulation was used to account for the wall deformations. At the interface between the solid domain and the fluid domain, the fluid pressure was transferred to the wall and the displacement of the wall was transferred to the fluid. The two systems were connected by the System Coupling component which controls the solver execution of fluid and solid simulations in ANSYS. Fluid and solid domains were solved sequentially starting from the fluid simulations. RESULTS: Distributions of blood flow, wall shear stress and wall stress were evaluated in the ascending thoracic aorta using the FSI analyses. We always observed a significant flow eccentricity in the simulations, in very good agreement with velocity profiles measured using 4D MRI. The results also showed significant increase of peak wall stress due to the increase of peripheral resistance and aortic stiffness. In the worst case scenario, the largest peripheral resistance (1010 kg s m-4) and stiffness (10 MPa) resulted in a maximal principal stress equal to 702 kPa, whereas it was only 77 kPa in normal conditions. CONCLUSIONS: This is the first time that the risk of rupture of an aTAA is quantified in case of the combined effects of hypertension and aortic stiffness increase. Our findings suggest that a stiffer TAA may have the most altered distribution of wall stress and an acute change of peripheral vascular resistance could significantly increase the risk of rupture for a stiffer aneurysm.

Ascending thoracic aorta aneurysm repair induces positive hemodynamic outcomes in a patient with unchanged bicuspid aortic valve.

We report a patient-specific case of bicuspid aortic valve with fusion of right and left coronary leaflets (R-L type I BAV), moderate aortic valve deficiency and ascending thoracic aortic aneurysms (ATAA) who was treated by only ascending aorta replacement preserving the BAV. The flow eccentricity, the helicity intensity (h2), the circumferential time averaged wall shear stress (TAWSScircumferential), the cumulative viscous energy loss at the systolic peak (EL') and the pulse wave velocity (PWV) were calculated by combining 4D flow MRI and CFD analysis before (Stage I) and after (Stage II) the surgical procedure. CFD analyses assumed rigid walls, a non-Newtonian behavior for the blood and MRI measured patient-specific blood flow profiles as inlet boundary conditions. Stage II results showed suppression of recirculation in the ascending aorta, loss of jet flow impingement onto the aortic wall, maximum TAWSScircumferential decrease (from 6.69 Pa in Stage I to 6 Pa in Stage II), reduction of flow helicity (from 10.97 in Stage I to 8.47 in Stage II) and EL' (from 15.8 mW in Stage I to 11.2 mW in Stage II). However, Floweccentricity and PWV were found higher in Stage II due to the diameter reduction (Floweccentricity = 0.60 in Stage I and Floweccentricity = 0.91 in Stage II; PWV = 3.80 m/s in Stage I and PWV = 9.37 m/s in Stage II). Our work has permitted to compute for the first time the hemodynamic alterations obtained after restoration of normal ascending aorta and sinotubular junction geometry even preserving an R-L type I BAV with still acceptable function.

Proof of Concept of an Endoscopic Sutureless Valve Sizer.

OBJECTIVE: In this paper, we present an endoscopic expandable sizer conceived to allow thoracoscopic aortic valve replacement with a sutureless prosthesis using a dynamic sizing of the aortic annulus. METHODS: Ten aortic torsos were prepared using a five-trocar thoracoscopic setting. Once the aortotomy was performed and the aortic valve leaflets removed, the technical feasibility of the endoscopic sizing (introduction into the trocar, expansion into the aortic annulus, determination of the valve size, and retraction) with the device was assessed. In case of successful thoracoscopic sizing, endoscopic implantation of a sutureless valve (five LivaNova Perceval prosthesis and five Medtronic 3f Enable bioprosthesis) was performed. Before ascending aorta closure, we assessed the appropriate sealing of the bioprosthesis in the native annulus with camera visualization and a nerve hook inspection. RESULTS: All the 10 endoscopic sizings were technically feasible. The scheduled aortic sutureless valve implantations were successfully performed. In all cases, fitting and placement of the sutureless bioprosthesis in the flaccid heart was satisfactory, with no paraprosthetic leakage detectable by the nerve hook. CONCLUSIONS: The use of the endoscopic expandable sizer is technically possible. In this early-stage test in the flaccid heart, selection of the valve size was satisfactory during thoracoscopic sutureless aortic bioprosthesis implantation. Further laboratory evaluation with fluid dynamics (aortic root pressurization) will be performed before a clinical study is started.

First in Human Totally Endoscopic Perceval Valve Implantation.

Totally endoscopic cardiac operations for coronary procedures and atrial septal defect repair have demonstrated improved quality of life, but they have required longer cross-clamp times compared with open operations. Although transcatheter valve implantation remains appropriate for inoperable patients, the totally endoscopic approach could be an effective treatment for lower risk patients, including complete removal of the stenotic aortic valve, while minimizing surgical chest wall trauma, and providing excellent early quality of life. Totally endoscopic aortic valve replacement procedures were previously performed with the 3f Enable bioprosthesis. We present the first case, to our knowledge, of Sorin Perceval implantation.

Mid-term results of mitral valve repair for ischemic mitral regurgitation with ETlogix ring: A single-center study.

BACKGROUND: Ischemic mitral regurgitation (IMR) is a common complication of coronary artery disease and represents an independent predictor of mortality. In the IMR the pattern of mitral valve annular dilatation is asymmetrical: this can explain the long-term incidence of recurrent mitral regurgitation after surgical annular size reduction with a symmetrical ring. The aim of this study is to analyze early and mid-term results of mitral valve repair (MVR) with the CMA IMR ETlogix ring, specifically developed for the surgical correction of IMR. METHODS: Retrospectively, we studied 157 consecutive patients who underwent MVR with the CMA ETlogix ring for the treatment of grade ≥2 IMR in our center between June 2006 and December 2012. We reported clinical and echocardiographic early and mid-term results of this surgical technique. RESULTS: Postoperative 30days mortality was 6.3%. Postoperative echocardiography evaluation at discharge revealed the absence of residual MR in 70%, mild MR in 26.5% and moderate MR in 3.5% of patients respectively. Median echographic follow-up time was 28 (3-84) months: survival rate was 92.1% at 32months; free from mitral valve reoperation rate was 97.5% and grade >2 MR recurrence free survival rate was 96.6%. CONCLUSION: There are a few reports in the literature concerning the mid-term results of IMR surgical correction with CMA Etlogix ring. Our study, taking into account a large series of patients and an important follow-up period, demonstrates the effectiveness of this surgical repair technique reporting a low mid-term incidence of recurrent MR.

Idiopathic Aortic Root to Right Atrial Fistula.

An aorta to right atrium fistula is rare. We report a case of idiopathic aortic root to right atrial fistula with right heart failure and review the literature. doi: 10.1111/jocs.12751 (J Card Surg 2016;31:373-375).

Closed chest human aortic valve removal and replacement: Technical feasibility and one year follow-up.

BACKGROUND: Minimally invasive aortic valve replacement has so far required a minithoracotomy or a ministernotomy. We present here the first series of totally endoscopic aortic valve replacement (TEAVR). METHODS: Between June 2013 and April 2015, 14 consecutive patients (12 males, mean age=76 ± 5.4 years) with a mean EuroSCORE II of 2.72 ± 0.03% underwent TEAVR. A five trocar setting was used in all patients: after ablation of the native valve, a Nitinol stented sutureless 3f Enable Medtronic valve, compressed into the main working trocar, was introduced into the thorax and then expanded in the aortic root. RESULTS: Among the 14 patients, a thoracoscopic approach was successful in 13 (92.8%) and conversion into an open surgery using the right anterior minithoracotomy was necessary to close the aortotomy in one case. Mean cross-clamping and cardiopulmonary (CPB) times were 112 ± 18 and 161 ± 31 min, respectively. All patients left the surgical unit within 8 days after the operation without any paravalvular leakage. There was no paravalvular regurgitation, conductive block or any major adverse event at a mean follow-up of 10 ± 4 months (range 2-16). CONCLUSIONS: TEAVR is feasible and safe in a selected subset of patients. Closed chest surgery has the potential to become the future approach of the isolated aortic valve replacement in low risk patients but further technical refinement and larger studies are necessary to reduce operative durations and enhance reproducibility.

Two Hundred Consecutive Implantations of the Sutureless 3f Enable Aortic Valve: What We Have Learned.

BACKGROUND: In this article we present a consecutive single-center experience of implantation of the Medtronic 3f Enable aortic valve (Medtronic Inc, Minneapolis, MN). METHODS: Between March 2011 and October 2014, 200 consecutive patients (mean age, 76.4 ± 5.9 years; logistic EuroScore, 7.8% ± 7.0%) in our unit received the 3f Enable valve. This is a retrospective analysis of this prospective monocentric cohort. RESULTS: The 3f Enable valve could be implanted in all the scheduled 141 isolated aortic valve replacement (AVR) procedures (14 full sternotomies, 73 ministernotomies, 44 minithoracotomies, and 10 thoracoscopic approaches) and 59 combined procedures (all using full sternotomy). Reclamping was necessary in 7 (3.5%) patients (paravalvular leakage [PVL] was ≥ grade 1 because of undersizing or prosthetic misalignment); mean cross-clamp and cardiopulmonary bypass (CPB) times were 65 ± 31 and 91 ± 39 minutes, respectively. Sixteen (8%) patients required early implantation of a pacemaker (PM). At a mean follow-up of 12.6 ± 8.1 months, mean transvalvular gradient and effective orifice area (EOA) were 9.8 ± 4.4 mm Hg and 1.87 ± 0.6 cm(2), respectively. Mild PVL was present in 7 (3.5%) patients and moderate PVL was present in 5 (2.5%) patients. No device migration was registered, and no moderate PVL was detected in the last 100 patients of the cohort. Overall, 3-year survival was 78%. CONCLUSIONS: The 3f Enable valve shows excellent results regarding PVL but in our experience required a learning curve and a refinement of the technique of implantation. Use of the prosthesis was possible in various less invasive approaches.

Sutureless aortic bioprosthesis valve implantation and bicuspid valve anatomy: an unsolved dilemma?

Interest is growing in the clinical use of sutureless (SU) valves. However, indications in some anatomical sub-settings, like bicuspid aortic valves (BAV), have been so far limited. We discuss herein our initial experience with the implantation of the 3f Enable SU bioprosthesis in patients with a BAV. Patients with a BAV were selected in our unit between March 2011 and September 2014 for a SU 3f Enable valve implantation. Twenty of the 198 patients who underwent a 3f Enable valve implantation in our unit had a BAV. Procedural success was 100 %, but reclamping was necessary in one (5 %) case. Median size of implanted bioprosthesis was 23 mm. After a mean follow-up of 13.8 ± 10.7 months, survival was 100 %. Two patients (10 %) showed an immediate grade 1 paravalvular leak (PVL) that progressed to grade 2 and 3+ (moderate/severe), respectively, during follow-up. Type of bicuspidy (Sievers classification) in these two patients was 0 and intraoperatively aortic annuli admitted the 25 mm calibrator. Among the 18 patients without PVL, no one had a type 0 large BAV. At 1 year, implantation of the 3f Enable SU bioprosthesis appears to be safe in patients with BAV type I and II, while in type 0 use of the SU valve seems to be safe only if the annular diameter is <25 mm. Larger studies are necessary to confirm our findings in order to clarify the indications for SU technology in the subset of bicuspid patients.