Incidence and risk factors of hemolysis after transcatheter aortic valve implantation with a balloon-expandable valve

A review of polymeric heart valves leaflet geometric configuration and structural optimization

Valvular heart disease (VHD) is a major cause of loss of physical function, quality of life and longevity, and its prevalence is growing worldwide due to increased survival rates and an aging population. The most common treatment for VHD is surgical heart valve replacement with mechanical heart valves (MHVs) and bioprosthetic heart valves (BHVs), but with different limitations. Polymeric heart valves (PHVs) exhibit promising material properties, valve dynamics and biocompatibility, representing the most feasible alternative to existing artificial heart valves. However, inadequate fatigue performance remains a critical obstacle to their clinical translation. In this case, geometry and material design are essential to obtain the best mechanical properties of the PHV. In this study, we summarized the effects of optimal design of PHVs from geometrical configuration optimization (valve height, thickness and design curve) and structural material optimization (anisotropy, fiber reinforcement, variable thickness, microstructure and asymmetric optimization), and selected the parameters including Effective Orifice Area (EOA), Regurgitant fraction (RF), and Stress Distribution to compare the performance of valves. It would provide the theoretical support for the optimal design of PHVs.

Prediction model for leaflet thrombosis in patients undergoing transcatheter aortic valve implantation: the EFFORT study

BACKGROUND

Leaflet thrombosis (LT) is a multifaceted and underexplored condition that can manifest following transcatheter aortic valve implantation (TAVI). The objective of this study was to formulate a prediction model based on laboratory assessments and clinical parameters, providing additional guidance and insight into this relatively unexplored aspect of post-TAVI complications.

METHODS

The present study was an observational prospective hypothesis-generating study, including 101 patients who underwent TAVI and a screening for LT (the primary endpoint) by multidetector computed tomography (MDCT). All images were acquired on a third-generation dual-source CT system. Levels of von Willebrand factor (vWF) activity, hemoglobin (Hb), and lactate dehydrogenase (LDH) were measured among other parameters. A predictive score utilizing binary logistic regression, Kaplan-Meier time-to-event analysis, and receiver operating characteristics (ROC) analysis was established.

RESULTS

LT (11 subclinical and 2 clinical) was detected in 13 of 101 patients (13%) after a median time to screening by MDCT of 105 days (IQR, 98-129 days). Elevated levels of vWF activity (> 188%) pre-TAVI, decreased Hb values (< 11.9 g/dL), as well as increased levels of LDH (> 312 U/L) post-TAVI and absence of oral anticoagulation (OAC) were found in patients with subsequent LT formation as compared to patients without LT. The established EFFORT score ranged from - 1 to 3 points, with an increased probability for LT development in patients with ≥ 2 points (85.7% of LT cases) vs < 2 points (14.3% of LT cases; p < 0.001). Achieving an EFFORT score of ≥ 2 points was found to be significantly associated with a 10.8 times higher likelihood of developing an LT (p = 0.001). The EFFORT score has an excellent c-statistic (area under the curve (AUC) = 0.89; 95% CI 0.74-1.00; p = 0.001) and a high negative predictive value (98%).

CONCLUSION

An EFFORT score might be a helpful tool to predict LT development and could be used in risk assessment, if validated in confirmatory studies. Therefore, the score has the potential to guide the stratification of individuals for the planning of subsequent MDCT screenings.

Recognition and management of hemolysis following transcatheter aortic valve replacement in a patient with chronic kidney disease

A 79-year-old female with chronic kidney disease (CKD) and transthoracic aortic valve replacement presented with exertional dyspnea and was found to have hemolysis due to moderate paravalvular leak. Balloon dilatation resolved symptoms and anemia. Detecting hemolysis related to paravalvular leak is challenging due to CKD, possibly leading to bone marrow suppression.

Research on fatigue optimization simulation of polymeric heart valve based on the iterative sub-regional thickened method

Prosthetic polymeric heart valves (PHVs) have the potential to overcome the inherent material and design limitations of traditional valves in the treatment of valvular heart disease; however, their durability remains limited. Optimal design of the valve structure is necessary to improve their durability. This study aimed to enhance the fatigue resistance of PHVs by improving the stress distribution. Iterative subregional thickening of the leaflets was used, and the mechanical stress distribution and hemodynamics of these polymeric tri-leaflet valves were characterized using a fluid-structure interaction approach. Subregional thickening led to a reduction in stress concentration on the leaflet, with the effective orifice area still meeting ISO 5840-3 and the regurgitant volume achieving a similar value to those in previous studies. The maximum stress in the final iteration was reduced by 28% compared with that of the prototype. The proposed method shows potential for analyzing the stress distribution and hemodynamic performance of subregional thickened valves and can further improve the durability of PHVs.

A review of numerical simulation in transcatheter aortic valve replacement decision optimization

BACKGROUND

Recent trials indicated a further expansion of clinical indication of transcatheter aortic valve replacement to younger and low-risk patients. Factors related to longer-term complications are becoming more important for use in these patients. Accumulating evidence indicates that numerical simulation plays a significant role in improving the outcome of transcatheter aortic valve replacement. Understanding mechanical features' magnitude, pattern, and duration is a topic of ongoing relevance.

METHODS

We searched the PubMed database using keywords such as "transcatheter aortic valve replacement" and "numerical simulation" and reviewed and summarized relevant literature.

FINDINGS

This review integrated recently published evidence into three subtopics: 1) prediction of transcatheter aortic valve replacement outcomes through numerical simulation, 2) implications for surgeons, and 3) trends in transcatheter aortic valve replacement numerical simulation.

INTERPRETATIONS

Our study offers a comprehensive overview of the utilization of numerical simulation in the context of transcatheter aortic valve replacement, and highlights the advantages, potential challenges from a clinical standpoint. The convergence of medicine and engineering plays a pivotal role in enhancing the outcomes of transcatheter aortic valve replacement. Numerical simulation has provided evidence of potential utility for tailored treatments.

Mechanical Hemolysis Complicating Transcatheter Interventions for Valvular Heart Disease: JACC State-of-the-Art Review

Mechanical intravascular hemolysis is frequently observed following procedures on heart valves and uncommonly observed in native valvular disease. In most cases, its severity is mild. Nevertheless, it can be clinically significant and even life threatening, requiring multiple blood transfusions and renal replacement therapy. This paper reviews the current knowledge on mechanical intravascular hemolysis in valvular disease, before and after correction, focusing on pathophysiology, approach to diagnosis, and impact of other hematological conditions on the resultant anemia. The importance of a multidisciplinary management is underscored. Laboratory data are provided about subclinical hemolysis that is commonly observed following the implantation of surgical and transcatheter valve prostheses and devices. Finally, clinical scenarios are reviewed and current medical and surgical treatments are discussed, including alternative options for inoperable patients.

Atrial and ventricular flows across a transcatheter mitral valve

 

OBJECTIVES

The objective of this study was to evaluate the haemodynamic performance of transcatheter mitral valve replacement (TMVR) Implant with a focus on turbulence and washout adjacent to the ventricular surface of the leaflets. TMVR holds the promise of treating a large spectrum of mitral valve diseases. However, the haemodynamic performance and flow dynamics of such replacements are not fully understood.

METHODS

A tri-leaflet biopsrosthetic TMVR represented by Caisson implant of size 36A was implanted in the mitral position of a left heart simulator pulse duplicating system under physiological conditions. The 36A implant covers an anterior-posterior range of 26-32 mm and a commissure-to-commissure range of 30-36 mm. Transmitral pressure gradient, effective orifice area and regurgitant fraction were calculated. Particle image velocimetry was performed to evaluate turbulence in 2 perpendicular planes (Reynolds and viscous shear stresses, respectively). Additionally, dye experiments were performed to visualize washout.

RESULTS

Transmitral pressure gradient was 1.29 ± 0.27 mmHg and effective orifice area was 2.96 ± 0.28 cm2. Regurgitant fraction was 14.13 ± 0.08%. Total washout was 4.27 cardiac cycles. Largest viscous shear stress reaches 3.7 Pa and 2.4 Pa in ventricle and atrium, respectively. Reynolds shear stress in the atrial side was <10 Pa. In the ventricular side, the largest Reynolds shear stress reached ∼35 Pa.

CONCLUSIONS

TMVR leads to favourable haemodynamics with low degree of turbulence combined with fast washout around the leaflets indicating promising potential for freedom from blood damage potential and thrombosis corroborated by initial clinical studies as part of the valves's Early Feasibility Study.

Intravascular haemolysis after transcatheter aortic valve implantation with self-expandable prosthesis: incidence, severity, and impact on long-term mortality

We aimed to determine the incidence, severity, and long-term impact of intravascular haemolysis after self-expanding transcatheter aortic valve implantation (TAVI). We believe this should be evaluated before extending the indications of TAVI to younger low-risk patients. Prospective, academic, single centre study of 94 consecutive patients treated with supra-annular self-expandable TAVI prosthesis between April 2009 and January 2014. Haemolysis at 1-year post-TAVI was defined per the published criteria based on levels of haemoglobin, reticulocyte and schistocyte count, lactate dehydrogenase (LDH), and haptoglobin. All patients had long-term clinical follow-up (6 years). The incidence of haemolysis at 1-year follow-up varied between 9% and 28%, based on different haemolysis definitions. Haemolysis was mild in all cases, no patient had markedly increased LDH levels. The presence of moderate/severe paravalvular aortic regurgitation was associated with haemolysis (7.7% vs. 23.1%, P = 0.044) and aortic valve area post-TAVI did not differ between groups with or without haemolysis (1.01 vs. 0.92 cm²/m², P = 0.23) (definition including schistocyte count). The presence of haemolysis did not have any impact on patient prognosis after 6 years with log-rank test P = 0.80. Intravascular haemolysis after TAVI with self-expandable prosthesis is present in 9–28% of patients depending on the definition of haemolysis. The presence of haemolysis is associated with moderate/severe paravalvular aortic regurgitation but not with post-TAVI aortic valve area. Haemolysis is mild with no impact on prognosis.

Incidence, predictors, and outcome of prosthesis-patient mismatch after transcatheter aortic valve replacement: A meta-analysis

BACKGROUND

Prosthesis-patient mismatch (PPM) following transcatheter aortic valve replacement (TAVR) is common, but the incidence, predictors and outcome of PPM are still controversial.

METHODS

A total of 18 articles incorporating 72,016 patients were identified form PubMed and Embase online database.

RESULTS

The pooled incidences of overall, and severe PPM following TAVR were 32.0% and 10.0% separately. Comparing to surgical aortic valve replacement (SAVR), TAVR had lower incidence of overall (OR, 0.31, 95% CI, 0.20-0.50) and severe PPM (OR, 0.38, 95% CI, 0.28-0.52). PPM was associated with a larger body surface area (BSA), larger body mass index (BMI) and previous myocardial infarction in comparison with those patients without PPM. Although PPM was not rare after TAVR, no significant differences were observed both in short- and mid-term all-cause mortality (30 day: OR: 1.51, 95% CI, 0.79-2.87, 1 year: OR: 1.02, 95% CI, 0.96-1.08, and 2 years: OR: 0.99, 95% CI, 0.79-1.24) between patients with PPM and those without PPM.

CONCLUSIONS

Despite the fact that the incidence of PPM was lower than that of SAVR, PPM was not seen to have an impact on short- and mid-term survival.

Fetal Transcatheter Trileaflet Heart Valve Hemodynamics: Implications of Scaling on Valve Mechanics and Turbulence

The scarcity of data available on the best approach for pulmonary fetal valve replacement or implantation necessitate an investigation on whether practices using adult transcatheter valves could be translated to fetal applications. The objective of this study is to evaluate the hemodynamic characteristics and the turbulent properties of a fetal sized trileaflet transcatheter pulmonary valve in comparison with an adult balloon-expandable valve in order to assess the possibility of designing valves for fetal applications using dynamic similarity. A 6 mm fetal trileaflet valve and a 26 mm SAPIEN 3 valve were assessed in a pulse duplicator. Particle image velocimetry was performed. Pressure gradient (ΔP), effective orifice area (EOA), regurgitant fractions (RF), pinwheeling indices (PI) and turbulent stresses were evaluated. ΔP was 8.56 ± 0.139 and 7.76 ± 0.083 mmHg with fetal valve and SAPIEN respectively (p < 0.0001); EOA was 0.10 ± 0.0007 and 2.1 ± 0.025 cm2 with fetal valve and SAPIEN respectively (p < 0.0001); RF with the fetal valve was 2.35 ± 1.99% and with SAPIEN 10.92 ± 0.11% (p < 0.0001); PI with fetal valve was 0.404 ± 0.01 and with SAPIEN 0.37 ± 0.07; The flow regime with the fetal valve was turbulent and Reynolds numbers reached about 7000 while those with the SAPIEN reached about 20,000 at peak velocity. Turbulent stresses were significantly higher with fetal valve compared with SAPIEN. Instantaneous viscous shear stresses with fetal valve were 5.8 times higher than those obtained with SAPIEN and Reynolds shear stresses were 2.5 times higher during peak systole. The fetal valve implantation leads to a turbulent flow (specific to this particular type and design of valve) regime unlike what is expected of a small valve with different flow properties compared to adult valves.

In-vitro characterization of self-expandable textile transcatheter aortic valves

OBJECTIVE

This study aims at assessing the global dynamic behavior, closing energy and turbulence characteristics of self-expandable textile (inclined and straight yarn) transcatheter aortic valves (TAV) versus bioprosthetic TAVs.

METHODS

Two self-expandable textile TAVs one with inclined yarn textile and another with straight yarn textile leaflets were assessed in a pulse duplicator and compared with a self-expandable commercial bioprosthetic TAV under physiological pressure and flow. Particle Image Velocimetry and high-speed imaging were performed. Effective orifice areas (EOA), leakage fractions (LF), Pinwheeling indices (PI), closing energy (E), viscous shear stresses (VSS) and Reynolds shear stresses (RSS) were calculated.

RESULTS

(a) EOAs and LFs were 2.27 ± 0.03 cm2, 31.7 ± 0.6%; 2.25 ± 0.08 cm2, 26.6 ± 0.7%; and 1.63 ± 0.01 cm2, 29.1 ± 1.25% for inclined textile, bioprosthetic and straight textile TAV respectively (p < 0.0001). (b) Following same order, PIs were significantly different going from 1.16 ± 0.21%, 8.48 ± 0.8% and 8.865 ± 0.58% with the exception of CoreValve and straight yarn valve (p = 0.37); (c) E is lowest for straight textile TAV (0.0024 ± 0.0017 J), followed by bioprosthetic valve (0.00259 ± 0.0011 J) and then 45° Oriented Yarn Valve (0.00334 ± 0.03 J) (d) At peak systole, the highest RSS distribution was with the Straight textile TAV reaching up to 330Pa. The bioprosthetic TAV shows the smallest range with RSS reaching around 230Pa and the inclined textile TAV up to 280Pa. VSS limits were comparable among the 3 valves ranging between 5.2Pa and 5.7Pa.

CONCLUSION

Hemodynamic similarities were found between the textile self-expandable valves and the bioprosthetic valve. This study constitutes another step towards showing the potential that textile valves have to become an alternative for the biological ones.

The hemodynamics of transcatheter aortic valves in transcatheter aortic valves

BACKGROUND

The durability of transcatheter aortic valves (TAVs) remains their greatest disadvantage, given that fixed tissue leaflets are not immune to structural degeneration from calcification and thrombosis. Therefore, a second intervention is necessary, especially given that TAV in low-risk patients has shown noninferior outcomes compared with surgery. This study aimed to assess the hemodynamic and turbulent properties of the flow downstream with different TAV-in-TAV configurations, to offer basic hemodynamic guidance for future interventions when currently implanted valves structurally degrade.

METHODS

Six TAV-in-TAV configurations were chosen: 23 mm Evolut-in-26 mm Evolut, 23 mm Evolut-in-23 mm SAPIEN 3, 26 mm Evolut-in-26 mm Evolut, 26 mm Evolut-in-23 mm SAPIEN 3, 23 mm SAPIEN3-in-26 mm Evolut, and 23 mm SAPIEN3-in-23 mm SAPIEN 3. Their hemodynamic performance was assessed in a pulse duplicator for 100 cycles. High-speed imaging and particle image velocimetry were performed to assess turbulence. Effective orifice area (EOA), pinwheeling index (PI), and Reynolds shear stress (RSS) were evaluated.

RESULTS

The largest mean EOA was obtained with 23 mm SAPIEN-in-26 mm Evolut (2.07 ± 0.06 cm²), and the smallest was obtained with 23 mm Evolut-in-23 mm SAPIEN (1.50 ± 0.04 cm²) (P < .001). The highest mean PI was obtained with SAPIEN-in-SAPIEN (26.5 ± 2.00%), and the lowest was obtained with 26 mm Evolut-in-26 mm Evolut (7.5 ± 1.6%) (P < .01). At peak systole, the least detrimental RSS range was obtained with 23 mm Evolut-in-26 mm Evolut (up to ∼340 Pa), and the most detrimental RSS range was obtained with 23 mm Evolut-in-SAPIEN (∼900 Pa) (P < .01).

CONCLUSIONS

This study shows that best hemodynamic parameters are TAV-specific (implanted and to be implanted). In addition, it shows that RSS levels, which are indicative of turbulence levels and associated with blood damage, are 2- to 3-fold higher after TAV-in-TAV.

On the Modeling of Patient-Specific Transcatheter Aortic Valve Replacement: A Fluid-Structure Interaction Approach

PURPOSE

Transcatheter aortic valve replacement (TAVR) is a minimally invasive treatment for high-risk patients with aortic diseases. Despite its increasing use, many influential factors are still to be understood and require continuous investigation. The best numerical approach capable of reproducing both the valves mechanics and the hemodynamics is the fluid-structure interaction (FSI) modeling. The aim of this work is the development of a patient-specific FSI methodology able to model the implantation phase as well as the valve working conditions during cardiac cycles.

METHODS

The patient-specific domain, which included the aortic root, native valve and calcifications, was reconstructed from CT images, while the CAD model of the device, metallic frame and pericardium, was drawn from literature data. Ventricular and aortic pressure waveforms, derived from the patient's data, were used as boundary conditions. The proposed method was applied to two real clinical cases, which presented different outcomes in terms of paravalvular leakage (PVL), the main complication after TAVR.

RESULTS

The results confirmed the clinical prognosis of mild and moderate PVL with coherent values of regurgitant volume and effective regurgitant orifice area. Moreover, the final release configuration of the device and the velocity field were compared with postoperative CT scans and Doppler traces showing a good qualitative and quantitative matching.

CONCLUSION

In conclusion, the development of realistic and accurate FSI patient-specific models can be used as a support for clinical decisions before the implantation.

Cardiac prostheses-related hemolytic anemia

Hemolysis is an unintended sequel of temporary or permanent intracardiac devices. However, limited data exist on the characteristics and treatment of hemolysis in patients with cardiac prostheses. This entity, albeit uncommon, often poses significant diagnostic and management challenges to the clinical cardiologist. In this article, we aim to provide a contemporary overview of the incidence, mechanisms, diagnosis, and management of cardiac prosthesis‐related hemolysis.

Concurrent mechanical haemolytic anaemia and heparin-induced thrombocytopenia following transcatheter aortic valve replacement

A 78-year-old man with a history of severe aortic stenosis presented with confusion, irregular behaviour and dyspnoea 8 days following transcatheter aortic valve replacement. His exam was consistent with a heart failure exacerbation and he had elevated aminotransferases, bilirubin and prothrombin time suggestive of shock liver. A CT head scan demonstrated a subacute large left temporoparietal infarction. His aminotransferase and prothrombin time levels normalised with diuresis, but his indirect bilirubin remained elevated and he developed anaemia and thrombocytopenia consistent with a haemolytic anaemia. A transthoracic echocardiogram demonstrated a paravalvular leak. His thrombocytopenia continued to worsen prompting testing for antibodies against heparin-PF4 complexes which was positive. A serotonin release assay later returned positive, confirming the diagnosis of heparin-induced thrombocytopenia. This case illustrates that the presence of haemolytic anaemia does not necessarily exclude other causes of thrombocytopenia that may occur concurrently.

A second-derivate fitting algorithm for the quantification of free hemoglobin in human plasma

BACKGROUND

Assessment of hemolysis in vivo is becoming increasingly relevant in critical care. Current methods (Harboe, 1959) for quantifying the free hemoglobin (fHb) content produce unsatisfactory results in case of hyperbilirubinemia, a frequent condition in patients at risk for intravascular hemolysis.

METHODS

A novel evaluation method based on second-derivative fitting to quantify fHb content was developed. The method uses spectrophotometric data from 350 to 650 nm recorded with standard instruments as input. To evaluate the power of the new method, plasma of patients and non-icteric plasma of healthy volunteers were spiked with fHb concentrations up to 2000 mg/L and compared to methods described in the literature by Harboe, Noe and Fairbanks. All measurements were done in compliance with the bioanalytical method validation protocol from the European Medicines Agency.

RESULTS

Both the second-derivative fitting algorithm as well as the methods of Harboe, Noe and Fairbanks quantified fHb accurately in non-icteric samples, with inaccuracy and imprecision below 10%. For icteric specimen, false high results were obtained with the established formulas for fHb concentrations below 700 mg/L. In contrast, no interference was found with the second-derivate fitting method for bilirubin concentrations up to 465 μmol/L. The lower limits of quantifications for the second-derivative fitting algorithm were specified in agreement with the EMA guideline with 25 mg/L fHb for both non-icteric and icteric specimens.

CONCLUSIONS

A user-friendly, computer-based algorithm is reported that allows the accurate quantification of fHb concentrations in the presence of high bilirubin concentrations. The new method allows for uniform sample preparation with only a single dilution step and can be readily implemented in any laboratory on standard spectrophotometers using the provided supplementary Microsoft Excel macro.

Frequency and Significance of Intravascular Hemolysis Before and After Transcatheter Aortic Valve Implantation in Patients With Severe Aortic Stenosis

Intravascular hemolysis (IVH) has been identified in patients with surgical prosthetic valves, but few have been reported after transcatheter aortic valve implantation (TAVI). We conducted a prospective analysis of 64 TAVI patients. The hemolysis profiles were collected at baseline and 6 months after TAVI. The echocardiography was performed at baseline and 6 months after TAVI. There are 14 patients (21.9%) with IVH before and 24(37.5%) after TAVI. The serum haptoglobin values before and 6 months after TAVI are 126.7 ± 75.1 vs 86.3 ± 57.1 mg/dl (p < 0.001). More ≥moderate paravalvular leakage (PVL) (50% vs 7.5%, p < 0.001), bicuspid aortic valve (BAV) (33.3% vs 5.0%, p = 0.004), use of 23 mm prosthesis (29.2% vs 7.5%, p = 0.03), higher residual valvular pressure gradient (17.9 ± 6.8 mm Hg vs 14.7 ± 5.7 mm Hg, p = 0.05), and lower effective orifice area index (1.05 ± 0.21 vs 1.21 ± 0.29, p = 0.03) were observed in patients with post-TAVI IVH. On multivariate regression analysis, BAV and ≥moderate PVL are independently related to post-TAVI IVH. With log-rank test, 1-year rates of readmission due to cardiovascular cause were significantly higher in patients with post-TAVI IVH (odds ratio 4.5; 95% confidence interval 1.3 to 15.6; p = 0.02), after adjusting age and gender. In conclusion, ≥moderate PVL and BAV are predictors of post-TAVI IVH, which is associated with increased cardiovascular readmission in 1-year follow-up.

Patient-prosthesis mismatch in patients treated with transcatheter aortic valve implantation - predictors, incidence and impact on clinical efficacy. A preliminary study

Introduction

Patient-prosthesis mismatch (PPM) is relatively frequent after surgical aortic valve replacement (SAVR) and negatively impacts prognosis.

Aim

We sought to determine the frequency and clinical effects of PPM after transcatheter aortic valve implantation (TAVI).

Material and methods

Overall, 238 patients who underwent TAVI were screened. Moderate PPM was defined as indexed effective orifice area (EOAi) between 0.65 and 0.85 cm²/m², and severe PPM as < 0.65 cm²/m². All-cause mortality and the Valve Academic Research Consortium 2 (VARC-2) defined composite of clinical efficacy at 1 year were the primary endpoints.

Results

Finally, 201 patients were included (mean age: 79.6 ±7.4 years, 52% females). The femoral artery served as the delivery route in 79% and most of the prostheses were self-expanding (68%). Any PPM was present in 48 (24%) subjects, and only 7 (3.5%) had severe PPM. Body surface area (BSA) independently predicted any PPM (OR = 16.9, p < 0.001) whereas post-dilation tended to protect against PPM (OR = 0.46, p = 0.09). All-cause mortality was similar in patients with moderate or severe PPM as compared to those with no PPM (14.6% vs. 14.3% vs. 13.1%, respectively, log-rank p = 0.98). Neither moderate (OR = 1.6, 95% CI: 0.8-3.2, p = 0.16) nor severe PPM (OR = 1.67, 95% CI: 0.36-7.7, p = 0.51) had a significant impact on composite endpoint, or its elements, with the exception of transvalvular pressure gradient > 20 mm Hg.

Conclusions

Severe PPM after TAVI is rare, can be predicted by larger BSA and does not seem to affect mid-term mortality or composite clinical outcome. Larger studies are needed to find different independent predictors of PPM and elucidate its impact in terms of device durability and long-term clinical efficacy.

Late subclinical hemolysis and long-term outcomes after aortic valve replacement with On-X mechanical prostheses - a preliminary single-center report

Introduction

Aortic valve replacement (AVR) with a mechanical prosthesis is not free from late complications.

Aim

To evaluate the prevalence of subclinical hemolysis after AVR with On-X prostheses and assess its impact on long-term outcomes.

Material and methods

The prospective study included 84 consecutive patients aged 58.3 ±10.3 years who underwent AVR. They were retrospectively split into group H (n = 12; 14.3%) with prosthesis-related subclinical hemolysis and a control group (C; n = 72; 85.7%). All operations were performed via median sternotomy using cardio-pulmonary bypass. At the end of follow-up, echocardiography was carried out and blood samples for morphology and biochemistry (lactate dehydrogenase (LDH), bilirubin, haptoglobin) were taken.

Results

The rate of subclinical hemolysis in patients with properly working prostheses was 14.3% and it was the highest (33.3%) for the smallest valves. Although an improvement in functional status was noted in both groups, it was less evident in group H than in group C (p = 0.007). At the end of follow-up, 97.2% in group C and 75.0% in group H were found in NYHA classes I and II. Patients in group H had significantly lower hemoglobin, hematocrit, and haptoglobin and higher LDH activity than group C subjects. In group H, systolic gradients of On-X valves were higher whereas effective orifice area was smaller than in group C.

Conclusions

Our study proved that prosthesis-induced subclinical hemolysis is seen even after implantation of the latest generation mechanical prostheses, particularly of small diameter, and its degree may impact late outcome.

Incidence, Predictors and Outcome of Prosthesis-Patient Mismatch after Transcatheter Aortic Valve Replacement: a Systematic Review and Meta-analysis

The aim of this study was to investigate the incidence, predictors and outcome of prosthesis-patient mismatch (PPM) following transcatheter aortic valve replacement (TAVR). A total of 30 articles incorporating 4,691 patients were identified. The pooled incidences of overall, moderate and severe PPM following TAVR were 33.0%, 25.0% and 11.0% respectively. Medtronic CoreValve (MCV) had lower incidence of overall (32% vs: 40%, P < 0.0001) and moderate (23% vs 32%, P < 0.0001) than Edwards Sapien (ESV). PPM was associated with a younger age, smaller annulus diameter and lower left ventricular ejection fraction in comparison with those patients without PPM. Post-dilation (OR, 0.51, 95% CI, 0.38 to 0.68, p < 0.001) during TAVR would decrease the incidence of PPM. Although PPM was common after TAVR, no significant differences were observed both in short- and mid-term all-cause mortality (30 day: OR: 1.1, 95% CI, 0.70 to 1.73 and 2 year: OR: 1.01, 95% CI, 0.74 to 1.38) between patients with PPM and those without PPM. In conclusion, despite being common after TAVR, the incidence of PPM was lower than that of surgical aortic valve replacement (SAVR) and decreased with the experience accumulating, and PPM was not seen to impact on short- and mid-term survival, regardless of its magnitude.

Evaluation of an aortic valve prosthesis: Fluid-structure interaction or structural simulation?

Bio-inspired polymeric heart valves (PHVs) are excellent candidates to mimic the structural and the fluid dynamic features of the native valve. PHVs can be implanted as prosthetic alternative to currently clinically used mechanical and biological valves or as potential candidate for a minimally invasive treatment, like the transcatheter aortic valve implantation. Nevertheless, PHVs are not currently used for clinical applications due to their lack of reliability. In order to investigate the main features of this new class of prostheses, pulsatile tests in an in-house pulse duplicator were carried out and reproduced in silico with both structural Finite-Element (FE) and Fluid-Structure interaction (FSI) analyses. Valve kinematics and geometric orifice area (GOA) were evaluated to compare the in vitro and the in silico tests. Numerical results showed better similarity with experiments for the FSI than for the FE simulations. The maximum difference between experimental and FSI GOA at maximum opening time was only 5%, as compared to the 46.5% between experimental and structural FE GOA. The stress distribution on the valve leaflets clearly reflected the difference in valve kinematics. Higher stress values were found in the FSI simulations with respect to those obtained in the FE simulation. This study demonstrates that FSI simulations are more appropriate than FE simulations to describe the actual behaviour of PHVs as they can replicate the valve-fluid interaction while providing realistic fluid dynamic results.

Assessment of turbulent viscous stress using ICOSA 4D Flow MRI for prediction of hemodynamic blood damage

Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal blood flow, but quantifying of these effects, which are dominated by shear stresses in highly fluctuating turbulent flow, has not been feasible. This study evaluated the novel application of turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing hemodynamic stresses and corresponding blood damage index (BDI) in stenotic turbulent blood flow. The results showed that 4D Flow MRI underestimates the maximum principal shear stress of laminar viscous stress (PLVS), and overestimates the maximum principal shear stress of Reynolds stress (PRSS) with increasing voxel size. PLVS and PRSS were also overestimated by about 1.2 and 4.6 times at medium signal to noise ratio (SNR) = 20. In contrast, the square sum of the turbulent viscous shear stress (TVSS), which is used for blood damage index (BDI) estimation, was not severely affected by SNR and voxel size. The square sum of TVSS and the BDI at SNR >20 were underestimated by less than 1% and 10%, respectively. In conclusion, this study demonstrated the feasibility of 4D Flow MRI based quantification of TVSS and BDI which are closely linked to blood damage.

Percutaneous Closure of Paravalvular Regurgitation After Transcatheter Aortic Valve Implantation: A Systematic Review

Paravalvular regurgitation (PVR) remains one of the drawbacks of transcatheter aortic valve implantation (TAVI). Details of percutaneous closure (PCC) of PVR after TAVI remain obscure. We aimed to explore the patient characteristics, procedural details, closure devices used, and outcomes of PCC after TAVI. A systematic search of the MEDLINE/PubMed and Embase databases from January 2002 to September 2015 was conducted. Reports considered to include same patient were excluded and only the studies with largest cohorts were included. A total of 14 studies including 58 patients (61 cases) were included in the study. A balloon-expandable (BE) valve was used more frequently compared with a self-expandable (SE) valve (72.6% vs 27.4%, respectively). The mean success rate was 86.9% (100% and 77.8%, respectively; P = 0.097). The median number of closure devices used was 1 (range, 1-4) and did not differ between SE and BE valves (P = 0.71). Mean time from index procedure to PCC did not differ between SE and BE valves (295 ± 380 days vs 379 ± 353 days; P = 0.71). Seven patients had history of valve-in-valve and 6 patients had procedural success. Among the patients with available follow-up data (94.8%), there were 15 deaths (27.3%). Percutaneous closure of PVR after TAVI had a high success rate in selected patients in both BE and SE valves. The success rate, timing, and number of closure devices were similar between BE and SE valves. However, prognosis remains fairly poor.