Possible Subclinical Leaflet Thrombosis in Bioprosthetic Aortic Valves

Cerebrovascular Events in Patients Undergoing Transcatheter Aortic Valve Replacement: A Review

Cerebrovascular events (CVEs) are a dreaded complication of transcatheter aortic valve replacement (TAVR). They are associated with significant mortality, morbidity, and reduced quality of life and impose a significant burden to health care systems. Although the rates of clinical stroke have reduced since the advent of TAVR, it remains an important complication, particularly as TAVR is increasingly utilized. CVE may occur at the time of the TAVR, as a direct consequence of the procedure, or may occur later, related to thrombosis of the prosthetic valve, atrial fibrillation, and other comorbidities. Imaging of the brain has revealed a high prevalence of subclinical cerebral infarcts (68%-98%) associated with the TAVR procedure. Although their clinical significance has not been fully established, clinically evident CVE ranges between 3% and 5% in patients considered at high operative risk to between 1% and 3% in low operative risk patients. Periprocedural CVEs are largely the result of embolization of the thrombus and tissue derived from the valve, vasculature, or myocardium. Cerebral embolic protection devices have been studied in multiple trials, with some evidence supporting a reduction in new cerebral lesion volume, number, and potentially disabling strokes. However, thus far, there is no robust evidence that they reduce the overall stroke rate. The number and severity of comorbidities, in particular, new-onset atrial fibrillation, are associated with CVEs. Valve thrombosis diagnosed using computed tomography as areas of hypoattenuated leaflet thickening has been identified in 10% to 15% of patients. This is a dynamic process associated with an increase in CVEs, but that resolves with anticoagulation or sometimes without it. Routine use of anticoagulation compared with a single antiplatelet agent is associated with an increased risk of bleeding, without any additional alleviation in risk of thromboembolism. Future studies to improve risk stratification could facilitate the tailoring of preventive therapies to patients at high risk of CVE, who stand to gain the most benefit.

Prediction of hypoattenuating leaflet thickening in patients undergoing transcatheter aortic valves replacement based on clinical factors and 4D-computed tomography morphological characteristics: A retrospective cross-sectional study

BACKGROUND

The rapid increase in the number of transcatheter aortic valve replacement (TAVR) procedures in China and worldwide has led to growing attention to hypoattenuating leaflet thickening (HALT) detected during follow-up by 4D-CT. It's reported that HALT may impact the durability of prosthetic valve. Early identification of these patients and timely deployment of anticoagulant therapy are therefore particularly important.

METHODS

We retrospectively recruited 234 consecutive patients who underwent TAVR procedure in Fuwai Hospital. We collected clinical information and extracted morphological characteristics parameters of the transcatheter heart valve (THV) post TAVR procedure from 4D-CT. LASSO analysis was conducted to select important features. Three models were constructed, encapsulating clinical factors (Model 1), morphological characteristics parameters (Model 2), and all together (Model 3), to identify patients with HALT. Receiver operating characteristic (ROC) curves and decision curve analysis (DCA) were plotted to evaluate the discriminatory ability of models. A nomogram for HALT was developed and verified by bootstrap resampling.

RESULTS

In our study patients, Model 3 (AUC = 0.738) showed higher recognition effectiveness compared to Model 1 (AUC = 0.674, p = 0.032) and Model 2 (AUC = 0.675, p = 0.021). Internal bootstrap validation also showed that Model 3 had a statistical power similar to that of the initial stepwise model (AUC = 0.723 95%CI: 0.661-0.786). Overall, Model 3 was rated best for the identification of HALT in TAVR patients.

CONCLUSION

A comprehensive predictive model combining patient clinical factors with CT-based morphology parameters has superior efficacy in predicting the occurrence of HALT in TAVR patients.

Subclinical leaflet thrombosis and anticoagulation strategy following trans-catheter aortic valve replacement: A systematic review

Objective

Subclinical leaflet thrombosis (SLT) develops in 15% of patients undergoing trans-catheter aortic valve replacement (TAVR). TAVR is a procedure in which a faulty aortic valve is replaced with a mechanical one. An aortic valve replacement can be done with open-heart surgery; this is called surgical aortic valve replacement (SAVR). A significant problem is defining the best course of treatment for asymptomatic individuals with SLT post-TAVR, including the use of oral anticoagulation (OAC) in it.

Study design

Systematic review.

Method

The most pertinent published research (original papers and reviews) in the scientific literature were searched for and critically assessed using the online, internationally indexed databases PubMed, Medline, and Cochrane Reviews. Keywords like "Transcatheter valve replacement" and "Subclinical leaflet thrombosis" were used to search the papers. Selected studies were critically assessed for inclusion based on predefined criteria.

Results

The review examined the prevalence and characteristics of SLT after TAVR. To note, the incidence of SLT is seen to be higher in TAVR compared SAVR. Dual antiplatelet therapy, which is utilized in antithrombotic regimens post-TAVR, can possibly hasten SLT progression which could result in the impaired mobility of leaflets and the worsening of pressure gradients.

Conclusion

The use of dual antiplatelet drugs in routine antithrombotic therapy tends to accelerate initial subclinical leaflet thrombosis after TAVI, which results in a developing restriction of leaflet mobility and an increase in pressure differences.

[Cerebral protection in transcatheter aortic valve implantation]

The review is devoted to transcatheter aortic valve implantation (TAVI). Aortic stenosis (AS) is one of the most common valve diseases in the world and cause of premature death. TAVI is an important advance in the treatment of patients with severe aortic stenosis, particularly in those with moderate and high surgical risk. However, this method has some complications. Stroke prevention and development of strategies reducing the incidence of this event are not only important therapeutic goals for patients undergoing TAVI, but also have significant economic implications.

The role of four-dimensional computed tomography in transcatheter aortic valve replacement prosthesis endocarditis with concurrent leaflet thrombosis: a case report

Background

Transcatheter aortic valve replacement (TAVR) is becoming increasingly utilized for the treatment of severe aortic valvular heart disease. Infective endocarditis of TAVR is rare but associated with higher mortality and morbidity. The potential for leaflet thrombosis following TAVR is also becoming increasingly recognized. Diagnosis of these conditions on echocardiography can be challenging due to prosthesis artefact.

Case summary

An 84-year-old man with a previous transcatheter aortic valve replacement presented with a febrile illness and bacteraemia. Transthoracic and transoesophageal echocardiography demonstrated high transvalvular gradients with features of prosthesis endocarditis, though leaflet morphology could not be fully assessed due to prosthesis artefact. Four-dimensional computed tomography revealed hypo-attenuated leaflet thickening with reduced leaflet motion, consistent with prosthesis leaflet thrombosis. The patient was successfully treated with antibiotics and anticoagulation, with resolution of the infection and normalization of the transvalvular gradient after 6 weeks.

Discussion

Echocardiography should be the first-line investigation for assessing leaflet morphology in suspected prosthetic valve endocarditis or leaflet thrombosis but its accuracy may be limited by artefact. Our case highlights that four-dimensional computed tomography provides further evaluation of prosthesis leaflet morphology/motion, providing valuable diagnostic information.

Aortic valve neo-cuspidation using the Ozaki technique for acquired and congenital disease: where does this procedure currently stand?

The surgical treatment options for pediatric aortic valve disease are limited. The Ozaki procedure, which involves templated creation of new aortic valve leaflets, has proved to be a promising surgical technique. This review aims at elaborating the indications, technical intricacies, and outcomes of the aortic valve neo-cuspidization procedure (Ozaki procedure) in the pediatric population.

Impact of BASILICA on Sinus and Neo-Sinus Hemodynamics after Valve-in-Valve with and without Coronary Flow

BACKGROUND/PURPOSE

This study aims at evaluating the impact of BASILICA on neo-sinus and sinus hemodynamics with and without coronary flow. Leaflet thrombosis after valve-in-valve (ViV) may compromise not only leaflet mobility but also affect valve durability and performance.

METHODS/MATERIALS

In a 23 mm transparent surgical aortic valve model, a 23 mm Edwards SAPIEN 3 and a 26 mm Medtronic Evolut were deployed before and after leaflet laceration, in models with and without coronary flow. Neo-sinus and sinus hemodynamics were evaluated in the aortic position of a pulse duplicator and particle image velocimetry was performed in order to quantify sinus flow hemodynamics along with sinus and neo-sinus washout.

RESULTS

BASILICA-type leaflet laceration procedure led to (a) an increase in the velocities in the sinus and the neo-sinus by 50% for Evolut ViV with and without coronary flow, 70% for non-coronary SAPIEN 3 ViV and 10% for coronary SAPIEN 3 ViV, and (b) an improvement in overall washout up to 2 cycles in the neo-sinus and 0.5 cycles in the sinus.

CONCLUSIONS

A BASILICA-type leaflet laceration approach may improve sinus and neo-sinus hemodynamics through decreasing flow stasis and enabling less confined blood flow. BASILICA confers coronary sinus flow patterns to the non-coronary sinus.

Antithrombotic Therapy in Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) has recently emerged as an effective alternative to medical treatment or surgical aortic valve replacement in all symptomatic patients with severe aortic stenosis and high or prohibitive risk and in intermediate risk when transfemoral access is feasible. Patients undergoing TAVR are often at high risk for either bleeding or cerebrovascular complications, or both, so adjuvant antithrombotic therapies are commonly used before, during and after the procedure. Today, there is no clear evidence on the best antithrombotic regimen in this context. In this review, we will try to go through the mechanisms involved in bleeding and embolic complications and we will discuss the current points of antithrombotic treatment in patients during and after TAVR, with or without oral anticoagulation (OAC) indication.

Sinus Hemodynamics Variation with Tilted Transcatheter Aortic Valve Deployments

Leaflet thrombosis is a complication associated with transcatheter aortic valve (TAV) replacement (TAVR) correlated with sinus flow stasis. Sinus hemodynamics are important because they dictate shear stress and washout necessary to avoid stasis on TAV leaflets. Sinus flow is controlled by TAV axial deployment position but little is known regarding TAV axis misalignment effect. This study aims to elucidate TAV angular misalignment with respect to aortic root axis effect on sinus flow stasis potentially leading to leaflet thrombosis. Sinus hemodynamics were assessed in vitro using particle-image velocimetry in three different angular misalignments with respect to aorta axis: untilted, tilted away from the sinus and tilted towards sinus. A 26 mm Edwards SAPIEN3 was implanted in a 3D printed model of an anatomically realistic aortic root. TAV hemodynamics, sinus vortex tracking, leaflet shear stress probability density functions, and sinus blood time to washout were calculated. While pressure gradients differed insignificantly, blood velocity and vorticity decreased significantly in both tilted cases sinuses. Shear stress probability near the leaflet decreases with tilt indicating stasis. TAV tilted away from the sinus is the most unfavorable scenario with poor washout. TAV axial misalignment adds to factors list that could influence leaflet thrombosis risk through modifying sinus hemodynamics and washout.

A Novel Sensorized Heart Valve Prosthesis: Preliminary In Vitro Evaluation

Background: Recent studies have shown that subclinical valve thrombosis in heart valve prosthesis (HVP) can be responsible for reduced leaflet motion detectable only by advanced imaging diagnostics. We conceived a novel sensorized HVP able to detect earlier any thrombus formation that may alter the leaflets motion using an electric impedance measurement, IntraValvular Impedance (IVI). Methods: For IVI measurement, dedicated electrodes are embedded in the structure of the HVP to generate a local electric field that is altered by the moving valve leaflets during their cyclic opening/closing. We present preliminary in vitro results using a first prototype of sensorized mechanical heart valve connected to an external impedance measurement system. The prototype was tested on a circulatory mock loop system and the IVI signals were recorded during both normal dynamics and experimentally induced altered working of the leaflets. Results: Recordings showed a very repetitive and stable IVI signal during the normal cyclic opening/closing of the HVP. The induced alterations in leaflet motion were reflected in the IVI signal. Conclusions: The novel sensorized HVP has great potential to give early warning of possible subclinical valve thrombosis altering the valve leaflet motion, and to help in tailoring the anticoagulation therapy.

TAVR Vs. SAVR in Intermediate-Risk Patients: What Influences Our Choice of Therapy

PURPOSE OF REVIEW

To determine what influences patients and physicians to choose between transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) in intermediate-surgical-risk patients with severe, symptomatic aortic stenosis.

RECENT FINDINGS

Advances in transcatheter valve technology, techniques, and trials demonstrating non-inferiority compared to surgical aortic valve replacement (SAVR) have led to expanded eligibility of transcatheter aortic valve replacement (TAVR) to both intermediate-risk patients in clinical practice and low-risk patients in pivotal trials. Since lower-risk individuals tend to be younger and good operative candidates, concerns of valve durability, procedure-related morbidity, and patient survivability require careful consideration. Results from the PARTNER II intermediate risk trials and SURTAVI trials have given us insight into the benefits and potential risks of both treatment modalities. In this article, we review the brief yet remarkable history of TAVR and discuss its role in the treatment of intermediate-surgical-risk patients.

Implantation Depth and Rotational Orientation Effect on Valve-in-Valve Hemodynamics and Sinus Flow

BACKGROUND

This study evaluated the effect of transcatheter aortic valve implantation depth and rotation on pressure gradient (PG), leakage fractions (LF), leaflet shear stress, and sinus washout in an effort to understand factors that may dictate optimal positioning for valve-in-valve (ViV) procedures. Sinus flow stasis is often associated with prosthetic leaflet thrombosis. Although recent ViV in vitro studies highlighted potential benefits of transcatheter aortic valve supraannular implantation to minimize PGs, the relationship between transcatheter aortic valve depth and other determinates of valve function remains unknown. Among these, LFs, shear stress, and poor sinus washout have been associated with poorer valve outcomes.

METHODS

ViV hemodynamic performance was evaluated in vitro vs axial positions -9.8, -6.2, 0, and +6 mm and angular orientations 0, 30, 60, and 90 degrees in a degenerated surgical aortic valve. PGs, LFs, and sinus shear stress and washout were compared. Leaflet high-speed imaging and particle-image velocimetry were performed to elucidate hemodynamic mechanisms.

RESULTS

(1) The PG varies as a function of axial position, with supraannular deployments yielding a maximum benefit of 7.85 mm Hg less than PGs for subannular deployments irrespective of commissural alignment (p < 0.01); (2) in contrast, LF decreased in relationship to subannular deployment; and (3) at peak systole, sinus flow shear stress increased with deployment depth as did sinus washout with and without coronary flow.

CONCLUSIONS

First, supraannular axial deployment is associated with lower PGs irrespective of commissural alignment. Second, subannular deployment is associated with more favorable sinus hemodynamics and less LF. Further in vivo studies are needed to substantiate these observations and facilitate optimal prosthesis positioning during ViV procedures.

A matter of thrombosis: different thrombus-like formations in balloon-expandable transcatheter aortic valve prostheses

OBJECTIVES

Transcatheter aortic valve implantation is a treatment strategy for degenerated aortic valve prostheses, but there is some concern regarding valve thrombosis. The optimal anticoagulation strategy for implantation of a transcatheter aortic valve prosthesis remains unclear.

METHODS

Aortic root models with the Sapien-XT and S3 prostheses (sizes 23 and 26) fixed in a Perimount Magna Ease bioprosthesis (sizes 23 and 25) were constructed. The haemodynamics of the left ventricle were imitated in a proved in vitro model. Milk was used for coagulation after 90s. Different areas of the leaflets (W: wall coagulation, C: commissure coagulation left/right and S: sinus coagulation) were examined and the number of thrombus-like formations was counted.

RESULTS

A total of 54% of the thrombus-like formations were found in the sinus, 28% at the wall area, 13% at the right commissure and 10% at the left commissure. Significant differences were detected at the wall area. S3 prostheses had significantly more thrombus-like formations than the XT prostheses. Additionally, in the S3 prostheses, the thrombus-like formation resembled a film whereas in the XT prostheses, the thrombus-like formation was like the crumbs of a cake. We noted exactly the same pattern in explanted prostheses from patients.

CONCLUSIONS

The Sapien prostheses tend to form thromboses due to their flow properties. More than half of the thrombus-like formations were seen in the sinus. The S3 prostheses had significantly more thrombus-like formations than the XT prostheses in the wall area. There are different patterns of thrombus-like formations in XT and S3 prostheses used for transcatheter aortic valve implantation both in vivo and in vitro.

Impact of patient-specific morphologies on sinus flow stasis in transcatheter aortic valve replacement: An in vitro study

OBJECTIVE

The goal of this study is to evaluate how sinus flow patterns after transcatheter aortic valve replacement in realistic representative patient roots vary. Sinus flow can affect transcatheter aortic valve operation and likely leaflet thrombosis occurrence due to stasis and poor washout. How the interaction between transcatheter aortic valve and representative patient aortic roots affects sinus hemodynamics is important to establish for future individualization of transcatheter aortic valve replacement therapy.

METHODS

Two representative patient aortic roots were selected, segmented and 3-dimensional printed followed by deployment of Medtronic CoreValve (Medtronic Inc, Irvine, Calif) and Edwards SAPIEN (Edwards Lifesciences, Irvine Calif) transcatheter aortic valves. Sinus hemodynamics were assessed in vitro using high spatio-temporal resolution particle-image-velocimetry. Detailed sinus vortex tracking, shear stress probability density functions, and sinus washout were evaluated and assessed as a function of valve type and representative patient morphology as independent case studies.

RESULTS

Peak velocity in the sinus with SAPIEN valve was approximately 3 times higher than with CoreValve for both models (0.30 ± 0.02 m/s and 0.34 ± 0.041 m/s vs 0.13 ± 0.01 m/s and 0.10 ± 0.02 m/s) (P < .01). Between representative patient models, vorticity magnitudes were significantly different (75 ± 1.1 s^-1, 77 ± 3.2 s^-1, 109 ± 2.3 s^-1, and 250 ± 4.1 s^-1) (P < .01) regardless of valve type. Sinus blood washout characteristic as a function of cardiac cycles was strongly both patient related and valve specific. Fluid dynamics favored shear stresses and washout characteristics due to a smaller sinus and sinotubular junction, further amplified by the SAPIEN valve.

CONCLUSIONS

Sinus flow dynamics are highly sensitive to aortic root characteristics and transcatheter aortic valve aortic root interaction. Differences in sinus-flow washout and stasis regions between representative patient models may be reflected in different risks of leaflet thrombosis or valve degeneration.

Transcatheter Heart Valve Thrombosis: Incidence, Predictors, And Clinical Outcomes

Since its initial approval, the number of transcatheter aortic valve replacement procedures performed has increased exponentially with evolving indications that now include patients at intermediate risk for perioperative mortality following surgery. Multiple studies and reports have observed the phenomenon of leaflet dysfunction and thrombosis on follow-up imaging that may be associated with serious adverse outcomes. This review provides an insight into the incidence, predictors, management, and follow-up of transcatheter heartvalve thrombosis.

Reversible bioprosthetic valve thrombosis from eosinophilia

A 31-year-old man with a mitral bioprosthetic valve presented with recent worsening of exertional dyspnoea 7 years after the mitral valve replacement. Evaluation revealed an increased gradient across the thickened mitral bioprosthetic valve leaflets. Marked eosinophilia was present and was considered as a putative cause for bioprosthetic valve thrombosis. The treatment with systemic corticosteroids and oral anticoagulation led to complete resolution of symptoms with significant decrease in mitral bioprosthetic valve gradient and leaflet thinning. The case is reported to highlight the fact that eosinophilia may cause reversible bioprosthetic valve thrombosis.

Delayed Coronary Occlusion After Transcatheter Aortic Valve Implantation: Implications for New Transcatheter Heart Valve Design and Patient Management

Transcatheter aortic valve implantation has revolutionised the treatment of patients with severe aortic stenosis and is the preferred treatment option for patients with elevated surgical risk. Outcomes have continually improved, but because of the nature of the procedure infrequent catastrophic complications, such as coronary obstruction, persist. Recently, data were published regarding delayed coronary obstruction (DCO), a phenomenon in which the obstruction occurs after the index procedure. DCO has important consequences for future research. In this article we will explore the implications for new transcatheter heart valve design and approaches to patient management to minimise the risk of DCO occurring.

Transcatheter aortic valve replacement in intermediate and low risk patients-clinical evidence

The encouraging results of the PARTNER 2 (Placement of AoRtic TraNscathetER Valves 2) trial led to the approval of transcatheter aortic valve replacement (TAVR) in intermediate-surgical-risk patients. Recently, the SURTAVI (SUrgical Replacement and Transcatheter Aortic Valve Implantation) investigators demonstrated the feasibility of TAVR with self-expanding valves in intermediate-risk patients. The focus has now shifted to clinical trials comparing TAVR to surgery in low-surgical-risk populations with a goal to expand TAVR to all-risk patients. However, low-surgical-risk patients continue to be acceptable candidates for surgical aortic valve replacement, with proven outcomes over many decades. Although new data has emerged showing feasibility of TAVR in young patients with bicuspid valves, with newer generation TAVR valves there will be minimal tolerance for adverse outcomes in the low risk category. To expand the reach of TAVR into low-surgical-risk patients, important questions about valve durability, leaflet thrombosis, higher rates of paravalvular leak and permanent pacemakers (PPM) will need to be addressed. However, as TAVR technology continues to evolve, it seems to be just a matter of time before TAVR establishes itself as a modality for aortic valve replacement regardless of surgical risk.

Aortic sinus flow stasis likely in valve-in-valve transcatheter aortic valve implantation

OBJECTIVE

Valve-in-valve procedures using transcatheter aortic valves are increasingly performed to treat degenerated bioprosthetic surgical aortic valves because they are less invasive than redo aortic valve replacement. The objective of this study is to quantify the changes in aortic sinus blood flow dynamics before and after a valve-in-valve procedure to gain insight into mechanisms for clinical and subclinical thrombosis of leaflets.

METHODS

A detailed description of the sinus hemodynamics for valve-in-valve implantation was performed in vitro. A Medtronic Hancock II (Medtronic Inc, Minneapolis, Minn) porcine bioprosthesis was modeled as a surgical aortic valve, and Medtronic CoreValve and Edwards Sapien (Edwards Lifesciences, Irvine, Calif) valves were used as the transcatheter aortic valves. High-resolution particle image velocimetry was used to compare the flow patterns from these 2 valves within both the left coronary and noncoronary sinuses in vitro.

RESULTS

Velocity and vorticity within the surgical valve sinuses reached peak values of 0.7 m/s and 1000 s^-1, with a 70% decrease in peak fluid shear stress near the aortic side of the leaflet in the noncoronary sinus. With the introduction of transcatheter aortic valves, peak velocity and vorticity were reduced to approximately 0.4 m/s and 550 s^-1 and 0.58 m/s and 653 s^-1 without coronary flow and 0.60 m/s and 631 s^-1 and 0.81 m/s and 669 s^-1 with coronary flow for the CoreValve and Sapien valve-in-valve implantations, respectively. Peak shear stress was approximately 38% higher along the aortic side of the coronary versus noncoronary transcatheter aortic valve leaflet.

CONCLUSIONS

Decreased flow and shear stress in valve-in-valve procedures indicate a higher risk of leaflet thrombosis secondary to flow stasis, perhaps more so in the noncoronary sinus.

On the Mechanics of Transcatheter Aortic Valve Replacement

Transcatheter aortic valves (TAVs) represent the latest advances in prosthetic heart valve technology. TAVs are truly transformational as they bring the benefit of heart valve replacement to patients that would otherwise not be operated on. Nevertheless, like any new device technology, the high expectations are dampened with growing concerns arising from frequent complications that develop in patients, indicating that the technology is far from being mature. Some of the most common complications that plague current TAV devices include malpositioning, crimp-induced leaflet damage, paravalvular leak, thrombosis, conduction abnormalities and prosthesis-patient mismatch. In this article, we provide an in-depth review of the current state-of-the-art pertaining the mechanics of TAVs while highlighting various studies guiding clinicians, regulatory agencies, and next-generation device designers.

Transcatheter aortic valves produce unphysiological flows which may contribute to thromboembolic events: An in-vitro study

PURPOSE

Transcatheter aortic valve implantation (TAVI) has been associated with large incidence of ischemic events, whose sources are still unclear. In fact, sub-acute complications cannot be directly related to the severity of the calcification in the host tissues, nor with catheter manipulation during the implant. A potential cause could be local flow perturbations introduced by the implantation approach, resulting in thrombo-embolic consequences. In particular, contrary to the surgical approach, TAVI preserves the presence of the native leaflets, which are expanded in the paravalvular space inside the Valsalva sinuses. The purpose of this study is to verify if this configuration can determine hemodynamic variations which may promote blood cell aggregation and thrombus formation.

METHODS

The study was performed in vitro, on idealized models of the patient anatomy before and after TAVI, reproducing a range of physiological operating conditions on a pulse duplicator. The fluid dynamics in the Valsalva sinuses was analyzed and characterized using phase resolved Particle Image Velocimetry.

RESULTS

Comparison of the flow downstream the valve clearly indicated major alterations in the fluid mechanics after TAVI, characterized by unphysiological conditions associated with extended stagnation zones at the base of the sinuses.

CONCLUSION

The prolonged stasis observed in the Valsalva sinuses for the configuration modelling the presence of transcatheter aortic valves provides a fluid dynamic environment favourable for red blood cell aggregation and thrombus formation, which may justify some of the recently reported thromboembolic and ischemic events. This suggests the adoption of anticoagulation therapies following TAVI, and some caution in the patients׳ selection.