Blood flow characteristics after aortic valve neocuspidization in paediatric patients: a comparison with the Ross procedure

Analysis of Fluid-Structure Interaction Mechanisms for a Native Aortic Valve, Patient-Specific Ozaki Procedure, and a Bioprosthetic Valve

The Ozaki procedure is a surgical technique which avoids to implant foreign aortic valve prostheses in human heart, using the patient's own pericardium. Although this approach has well-identified benefits, it is still a topic of debate in the cardiac surgical community, which prevents its larger use to treat valve pathologies. This is linked to the actual lack of knowledge regarding the dynamics of tissue deformations and surrounding blood flow for this autograft pericardial valve. So far, there is no numerical study examining the coupling between the blood flow characteristics and the Ozaki leaflets dynamics. To fill this gap, we propose here a comprehensive comparison of various performance criteria between a healthy native valve, its pericardium-based counterpart, and a bioprosthetic solution, this is done using a three-dimensional fluid-structure interaction solver. Our findings reveal similar physiological dynamics between the valves but with the emergence of fluttering for the Ozaki leaflets and higher velocity and wall shear stress for the bioprosthetic heart valve.

Advances in the Computational Assessment of Disturbed Coronary Flow and Wall Shear Stress: A Contemporary Review

Coronary artery blood flow is influenced by various factors including vessel geometry, hemodynamic conditions, timing in the cardiac cycle, and rheological conditions. Multiple patterns of disturbed coronary flow may occur when blood flow separates from the laminar plane, associated with inefficient blood transit, and pathological processes modulated by the vascular endothelium in response to abnormal wall shear stress. Current simulation techniques, including computational fluid dynamics and fluid-structure interaction, can provide substantial detail on disturbed coronary flow and have advanced the contemporary understanding of the natural history of coronary disease. However, the clinical application of these techniques has been limited to hemodynamic assessment of coronary disease severity, with the potential to refine the assessment and management of coronary disease. Improved computational efficiency and large clinical trials are required to provide an incremental clinical benefit of these techniques beyond existing tools. This contemporary review is a clinically relevant overview of the disturbed coronary flow and its associated pathological consequences. The contemporary methods to assess disturbed flow are reviewed, including clinical applications of these techniques. Current limitations and future opportunities in the field are also discussed.

Incidence and predictors of continued ascending aortic dilatation after TAVI in patients with bicuspid aortic stenosis

BACKGROUND

Patients undergoing transcatheter aortic valve implantation (TAVI) for bicuspid aortic stenosis (AS) frequently present with ascending aortic (AAo) dilatation which is left untreated. The objective of this study was to study the natural progression and underlying mechanisms of AAo dilatation after TAVI for bicuspid AS.

METHODS

Patients with a native bicuspid AS and a baseline AAo maximum diameter > 40 mm treated by TAVI and in whom post-TAVI computed tomography (CT) scans beyond 1 year were available were included. AAo dilatation was deemed to be either continuous (≥ 2 mm increase) or stable (< 2 mm increase or decrease). Uni- and multivariate logistic regression analysis was utilized in order to identify factors associated with continuous AAo dilatation post-TAVI.

RESULTS

A total of 61 patients with a mean AAo maximum diameter of 45.6 ± 3.9 mm at baseline were evaluated. At a median follow-up of 2.9 years, AAo dimensions remained stable in 85% of patients. Continuous AAo dilatation was observed in 15% of patients at a rate of 1.4 mm/year. Factors associated with continuous AAo dilatation were raphe length/annulus mean diameter ratio (OR 4.09, 95% CI [1.40-16.7], p = 0.022), TAV eccentricity at the leaflet outflow level (OR 2.11, 95%CI [1.12-4.53], p = 0.031) and maximum transprosthetic gradient (OR 1.30, 95%CI [0.99-1.73], p = 0.058).

CONCLUSIONS

Ascending aortic dilatation in patients undergoing TAVI for bicuspid AS remains stable in the majority of patients. Factors influencing TAV stent frame geometry and function were identified to be associated with continuous AAo dilatation after TAVI; this should be confirmed in future larger cohort studies.

Assessment of aortic hemodynamics in patients with thoracoabdominal aortic aneurysm using four-dimensional magnetic resonance imaging: a cross-sectional study

Background

Thoracoabdominal aortic aneurysms (TAAAs) are rare but complicated aortic pathologies that can result in high morbidity and mortality. The whole-aorta hemodynamic characteristics of TAAA survivors remains unknown. This study sought to obtain a comprehensive view of flow hemodynamics of the whole aorta in patients with TAAA using four-dimensional flow (4D flow) magnetic resonance imaging (MRI).

Methods

This study included patients who had experienced TAAA or abdominal aortic aneurysm (AAA) and age- and sex-matched volunteers who had attended China Hospital from December 2021 to December 2022 in West. Patients with unstable ruptured aneurysm or other cardiovascular diseases were excluded. 4D-flow MRI that covered the whole aorta was acquired. Both planar parameters [(regurgitation fraction (RF), peak systolic velocity (Vmax), overall wall shear stress (WSS)] and segmental parameters [pulse wave velocity (PWV) and viscous energy loss (VEL)] were generated during postprocessing. The Student's t-test or Mann-Whitney test was used to compare flow dynamics among the three groups.

Results

A total of 11 patients with TAAA (mean age 53.2±11.9 years; 10 males), 19 patients with AAA (mean age 58.0±11.7 years; 16 males), and 21 controls (mean age 55.4±15.0 years; 19 males) were analyzed. The patients with TAAA demonstrated a significantly higher RF and lower Vmax in the aortic arch compared to healthy controls. The whole length of the aorta in patients with TAAA was characterized by lower WSS, predominantly in the planes of pulmonary artery bifurcation and the middle infrarenal planes (all P values <0.001). As for segmental hemodynamics, compared to controls, patients with TAAA had a significantly higher PWV in the thoracic aorta (TAAA: median 11.41 m/s, IQR 9.56-14.32 m/s; control: median 7.21 m/s, IQR 5.57-7.79 m/s; P<0.001) as did those with AAA (AAA: median 8.75 m/s, IQR 7.35-10.75 m/s; control: median 7.21 m/s, IQR 5.57-7.79 m/s; P=0.024). Moreover, a greater VEL was observed in the whole aorta and abdominal aorta in patients with TAAA.

Conclusions

Patients with TAAA exhibited a stiffer aortic wall with a lower WSS and a greater VEL for the whole aorta, which was accompanied by a higher RF and lower peak velocity in the dilated portion of the aorta.

Aortic valve neocuspidization and bioprosthetic valves: Evaluating turbulence haemodynamics

Aortic valve disease is often treated with bioprosthetic valves. An alternative treatment is aortic valve neocuspidization which is a relatively new reparative procedure whereby the three aortic cusps are replaced with patient pericardium or bovine tissues. Recent research indicates that aortic blood flow is disturbed, and turbulence effects have yet to be evaluated in either bioprosthetic or aortic valve neocuspidization valve types in patient-specific settings. The aim of this study is to better understand turbulence production in the aorta and evaluate its effects on laminar and turbulent wall shear stress. Four patients with aortic valve disease were treated with either bioprosthetic valves (n=2) or aortic valve neocuspidization valvular repair (n=2). Aortic geometries were segmented from magnetic resonance images (MRI), and 4D flow MRI was used to derive physiological inlet and outlet boundary conditions. Pulsatile large-eddy simulations were performed to capture the full range of laminar, transitional and turbulence characteristics in the aorta. Turbulence was produced in all aortas with highest levels occurring during systolic deceleration. In the ascending aorta, turbulence production is attributed to a combination of valvular skew, valvular eccentricity, and ascending aortic dilation. In the proximal descending thoracic aorta, turbulence production is dependent on the type of arch-descending aorta connection (e.g., a narrowing or sharp bend) which induces flow separation. Laminar and turbulent wall shear stresses are of similar magnitude throughout late systolic deceleration and diastole, although turbulent wall shear stress magnitudes exceed laminar wall shear stresses between 27.3% and 61.1% of the cardiac cycle. This emphasises the significance of including turbulent wall shear stress to improve our comprehension of progressive arterial wall diseases. The findings of this study recommend that aortic valve treatments should prioritise minimising valvular eccentricity and skew in order to mitigate turbulence generation.

Does the AVNeo valve reduce wall stress on the aortic wall? A cardiac magnetic resonance analysis with 4D-flow for the evaluation of aortic valve replacement with the Ozaki technique

OBJECTIVES

Aortic valve neocuspidalization aims to replace the 3 aortic cusps with autologous pericardium pre-treated with glutaraldehyde, and it is a surgical alternative to the classical aortic valve replacement (AVR). Image-based patient-specific computational fluid dynamics allows the derivation of shear stress on the aortic wall [wall shear stress (WSS)]. Previous studies support a potential link between increased WSS and histological alterations of the aortic wall. The aim of this study is to compare the WSS of the ascending aorta in patients undergoing aortic valve neocuspidalization versus AVR with biological prostheses.

METHODS

This is a prospective nonrandomized clinical trial. Each patient underwent a 4D-flow cardiac magnetic resonance scan after surgery, which informed patient-specific computational fluid dynamics models to evaluate WSS at the ascending aortic wall. The adjusted variables were calculated by summing the residuals obtained from a multivariate linear model (with ejection fraction and left ventricle outflow tract-aorta angle as covariates) to the mean of the variables.

RESULTS

Ten patients treated with aortic valve neocuspidalization were enrolled and compared with 10 AVR patients. The aortic valve neocuspidalization group showed a significantly lower WSS in the outer curvature segments of the proximal and distal ascending aorta as compared to AVR patients (P = 0.0179 and 0.0412, respectively). WSS levels remained significantly lower along the outer curvature of the proximal aorta in the aortic valve neocuspidalization population, even after adjusting the WSS for the ejection fraction and the left ventricle outflow tract-aorta angle [2.44 Pa (2.17-3.01) vs 1.94 Pa (1.72-2.01), P = 0.02].

CONCLUSIONS

Aortic valve neocuspidalization hemodynamical features are potentially associated with a lower WSS in the ascending aorta as compared to commercially available bioprosthetic valves.

Ozaki procedure-re-construction of aortic valve leaflets using autologous pericardial tissue: a review

The Ozaki procedure has emerged as a valuable option for treating various aortic valve pathologies. This review article delves into the intricacies of this innovative surgical approach by exploring its adaptation to the complex anatomy and physiology of the aortic root. The diverse etiologies of aortic valve diseases, ranging from congenital anomalies to degenerative changes, make treatment selection a complex challenge. Aortic valve replacement has traditionally been the gold standard, but emerging evidence supports valve repair techniques, emphasizing the importance of preserving native tissue. Nevertheless, issues like lifelong anticoagulation with mechanical valves and patient-prosthetic mismatch remain. The Ozaki procedure offers a compelling alternative by utilizing autologous pericardium or a tissue substitute to construct new aortic valve leaflets. This technique, standardized by Dr. Ozaki in 2007, provides a customizable and adaptable solution. The article highlights the anatomy of the aortic root, emphasizing the critical role of the sinus of Valsalva and interleaflet triangles in maintaining proper valve function. The procedure's unique adaptation to aortic root dynamics allows for reduced mechanical stress during systole and diastole, mimicking the natural valve's behavior. Furthermore, Ozaki leaflets exhibit promising hemodynamics and reduced risks of complications, such as permanent pacemaker implantation and patient-prosthetic mismatch. The use of autologous pericardium in the Ozaki procedure presents advantages, including enhanced tissue strength, minimal immunogenicity, and reduced risk of immune-mediated calcification. These factors contribute to the longevity and resilience of the reconstructed valve. This comprehensive review aims to shed light on the procedure's intricacies, its alignment with aortic root anatomy and physiology, and its potential as a valuable tool in the armamentarium of aortic surgeons.

The year 2022 in the European Heart Journal-Cardiovascular Imaging: Part I

The European Heart Journal-Cardiovascular Imaging with its over 10 years existence is an established leading multi-modality cardiovascular imaging journal. Pertinent publications including original research, how-to papers, reviews, consensus documents, and in our journal from 2022 have been highlighted in two reports. Part I focuses on cardiomyopathies, heart failure, valvular heart disease, and congenital heart disease and related emerging techniques and technologies.

Outcomes of Ozaki Procedure/Aortic Valve Neocuspidization for Aortic Valve Diseases: A Systematic Review

BACKGROUND

Perfect heart valve prostheses have optimized hemodynamics, reduced surgical morbidity, long-lasting durability, and extended patient survival with greater quality of life. Mechanical valves are recommended; however, young children may need anticoagulant medication for life. In this study, we looked at the success rate and viability of aortic valve neocuspidization (AVNeo) surgery for a variety of aortic disorders.

METHODS

A methodical search strategy was used to fully evaluate the AVNeo results. Boolean operators were used to combine important words like 'Ozaki Procedure,' 'Aortic Valve Neocuspidization,' 'AVNeo,' and associated terms. Reputable databases such as PubMed, MEDLINE, Embase, Web of Science, and Scopus were the focus of our search. Study quality was assessed using a critical evaluation created with the Critical Appraisal Skills Programme tool.

RESULTS

The findings are summarized in the 'Results' section that contains descriptive and critical analysis, ramifications, and explanations. According to research, AVNeo improved valve function and had few side effects. Aortic valve neocuspidization has a lower mean pressure gradient and a larger mean efficient orifice area than Trifecta. Aortic valve neocuspidization surgery reduces aortic valve regurgitation and pressure gradients. Postoperative echocardiograms indicated a decrease in peak and a rise in mean pressure gradient.

CONCLUSION

The Ozaki method restores a healthy laminar flow pattern while preventing bivalvular disease. Ozaki procedure should be explored for valve repair in infants with truncal valve and congenital aortic disease. Aortic valve tricuspidization with glutaraldehyde-treated autologous pericardium results in considerable effective orifice area, modest pressure gradients, and little regurgitation.

Effectiveness and Safety of the Ozaki Procedure for Aortic Valve Disease in Pediatric Patients: A Systematic Review and Meta-Analysis

The surgical treatment options for pediatric aortic valve disease are limited and have debatable long-term durability. In the current situation, the Ross procedure is considered in children for aortic valve disease(s). It is a complex surgical procedure with the risk of neo-aortic dilatation, converting a single valve disease into double valve disease, and associated with future re-interventions. Conversely, the Ozaki procedure has shown promising results in adults. Thus, the present study aimed to provide comparative evidence on the effectiveness and safety of the Ozaki versus Ross procedure for pediatric patients by performing a meta-analytic comparison of reporting outcomes. A total of 15 relevant articles were downloaded and among them, seven articles (one prospective study, five retrospective studies, and one case series) were used in the analysis. Primary outcomes such as physiological laminar flow pattern and hemodynamic parameters, and secondary outcomes such as hospital stays, adverse effects, mortality, and numbers of re-intervention(s) were measured in the meta-analysis. There were no significant differences in the age of patients between children who underwent the Ozaki procedure and those who underwent the Ross procedure at the time of surgeries. The Ozaki procedure is a good solution to an aortic problem(s) similar to the Ross procedure. Unlike the Ross procedure, the Ozaki procedure has restored a physiological laminar flow pattern in the short-term follow-up without the bi-valvular disease. Mean hospital stays (p = 0.048), mean follow-up (p = 0.02), adverse effects (p = 0.02), death, and numbers of re-intervention(s) of children who underwent the Ozaki procedure were fewer than those who underwent the Ross procedure. The time required for re-intervention(s) is higher for children who underwent the Ozaki procedure than those who underwent the Ross procedure. None of the procedures, including the Ozaki procedure for aortic valve disease(s), has significant effects on hemodynamic parameters and the frequent death rate of children after surgeries. Based on our analysis, we may suggest the Ozaki procedure for aortic valve disease surgery in children.

Ross procedure versus pulmonary homograft versus mechanical valve versus bioprosthetic valve versus Ozaki procedure for surgical aortic valve replacement: a frequentist network meta-analysis

BACKGROUND

There has been a resurgence in interest regarding the Ross procedure due to recent publications detailing positive long-term outcomes. Conversely, surgical aortic valve replacement (SAVR) with a pulmonary homograft (PH), mechanical (MV), bioprosthetic (BV), or the Ozaki procedure each has its own technical advantages and disadvantages. Therefore, we performed a network meta-analysis (NMA) comparing other alternatives to Ross procedure.

METHODS

Medical databases were comprehensively searched for studies comparing the Ross procedure with AVR using a PH, MV, BV, or the Ozaki procedure. Outcomes were pooled as risk ratios (RR) with their 95% confidence intervals (95% CI).

RESULTS

A total of 7816 patients were pooled for our NMA from 24 studies. Compared to Ross procedure, both BV and MV were associated with significantly higher rates of 30-day mortality of RR (2.37, 95% CI 1.20-4.67) and (1.88 95% CI 1.04-3.40), respectively, with no significant difference regarding PH or Ozaki. However, only MV was associated with a higher risk of 30-day stroke (RR 8.42, 95% CI 1.57-45.23) with no significant difference in the other alternatives, as well as 30-day MI which showed no significant differences between any of the aortic conduits compared to the Ross procedure. Regarding 30-day major bleeding, MV was associated with a higher when compared to the Ross procedure RR (4.58, 95% CI 1.94-10.85), PH was associated with a lower risk of major bleeding with RR (0.35, 95% CI 0.17-0.71), and BV showed no significant difference. With a mean follow-up duration of 8.5 years compared to the Ross procedure, BV, PH, and MV were associated with a higher risk of long-term mortality with RR (1.89, 95% CI 1.38-2.58), (1.38, 95% CI 1.0-1.87), and (1.94, 95% CI 1.52-2.47), respectively, with the Ozaki procedure showed no significant difference. Regarding long-term stroke-with a mean of 6.3-year follow-up duration-there were no significant differences between any of the aortic conduits compared to the Ross procedure. Nevertheless, long-term need for reintervention-with a mean follow-up duration of 17.5 years-was significant of higher risk with both BV and PH with RR (3.28, 95% CI 1.21-8.84) and (2.42, 95% CI 1.05-5.58), respectively, compared to Ross procedure with MV and Ozaki having no significant difference.

CONCLUSIONS

The Ross procedure is a viable treatment option for patients undergoing SAVR, showing promising outcomes at short- and long-term follow-ups.

Aortic valve repair in the pediatric population: emerging role of aortic valve neocuspidization (AVNeo procedure)

Management of aortic valve diseases in children is challenging owing to the quality and quantity of the native tissue for repair, limitations in the currently available biological materials to supplement the repair and to achieve a long-lasting durable repair in an annulus where there is still growth potential. The aortic valve neocuspidization (AVNeo) procedure has emerged as a versatile alternative strategy in the armamentarium of pediatric aortic valve reconstructions that are currently available. In this review article, the focus of the discussion will be on the various aortic valve repair procedures in the pediatric population, with a special emphasis on the emerging role of AVNeo procedure in pediatrics and its outcomes.

Aortic valve neocuspidization using the Ozaki technique: A meta-analysis of reconstructed patient-level data

BACKGROUND

Aortic valve neocuspidization using the Ozaki technique has shown promising results both in adults and children.

METHODS

A systematic search of the PubMed and Cochrane databases was performed up to November 13, 2021. Individual patient data were reconstructed and analyzed from the Kaplan-Meier curves of all eligible studies for time-to-event outcomes.

RESULTS

We included a total of 22 studies reporting on 1,891 patients that underwent Ozaki reconstruction. Mean age at the time of surgery was 43.2 ± 24.5 years (65 ± 12.3 years for adult patients and 12.3 ± 3.8 years for pediatric patients). The most common indication was aortic stenosis (46.4%, 95% CI 34.1-58.6). Mean cross-clamp and cardiopulmonary bypass duration were 106.8 ± 24.8 minutes and 135.2 ± 35.1 minutes, respectively. Permanent pacemaker was implanted in 0.7% (95% CI 0.4-1.2) of the patients. At discharge, mean effective orifice area was 2.1 ± 0.5 cm²/m². At latest follow-up, peak gradient was 15.7 ± 7.4 mm Hg and only 0.25% (95% CI 0-2.3) had moderate aortic insufficiency. In-hospital mortality was 0.7% (95% CI 0.1-1.7). Late mortality was 1.9% during a mean follow-up of 38.1 ± 23.8 months. One-year, 3-year, and 5-year freedom from reoperation rates were 98.0 %, 97.0 % and 96.5%, respectively. More than half of the reoperations were due to infective endocarditis (51.5%, 95% CI 18.3-84.0). In our cohort, the risk of endocarditis per patient per year was 0.5%.

CONCLUSIONS

The midterm outcomes of the Ozaki procedure are excellent in terms of hemodynamics, survival, and freedom from reoperation. Acquiring long-term follow-up will help solidify this technique in the cardiac surgery armamentarium.

Aortic valve neocuspidization and its technical nuance

Aortic valve neocuspidization or Ozaki procedure represents an advanced surgical strategy for the management of patients with aortic valvulopathy. It has been shown to have clinical and hemodynamic outcomes that compare favorably with aortic valve replacement as it restores physiological aortic valve function and left ventricular remodeling. There are, however, a new set of issues including structural valve deterioration, leaflet tear/perforation, and need for reoperation. A keen understanding of the technical nuances involved with the Ozaki procedure may help in reducing the incidence of such adverse outcomes.