A mechanistic investigation of the EDWARDS INTUITY Elite valve's hemodynamic performance

Effect of leaflet laceration on transcatheter aortic valve replacement fluid mechanics and comparison with surgical aortic valve replacement

BACKGROUND

Leaflet thrombosis after surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) may be caused by blood flow stagnation in the native and neosinus regions. To date, aortic leaflet laceration has been used to mitigate coronary obstruction following TAVR; however, its influence on the fluid mechanics of the native and neosinus regions is poorly understood. This in vitro study compared the flow velocities and flow patterns in the setting of SAVR vs TAVR with and without aortic leaflet lacerations.

METHODS

Two valves, (23-mm Perimount and 26-mm SAPIEN 3; Edwards Lifesciences) were studied in a validated mock flow loop under physiologic conditions. Neosinus and native sinus fluid mechanics were quantified using particle image velocimetry in the left and noncoronary cusp, with an increasing number of aortic leaflets lacerated or removed.

RESULTS

Across all conditions, SAVR had the highest average sinus and neosinus velocities, and this value was used as a reference to compare against the TAVR conditions. With an increasing number of leaflets lacerated or removed with TAVR, the average sinus and neosinus velocities increased from 25% to 70% of SAVR flow (100%). Diastolic velocities were substantially augmented by leaflet laceration. Also, the shorter frame of the SAVR led to higher flow velocities compared with the longer frame of the TAVR, even after complete leaflet removal.

CONCLUSIONS

Leaflet laceration augmented TAVR native and neosinus flow fields, approaching that of SAVR. These findings may have potential clinical implications for the use of single or multiple leaflet lacerations to reduce leaflet thrombosis and thus potentially improve TAVR durability.

Sutureless vs. rapid-deployment valve: a systemic review and meta-analysis for a direct comparison of intraoperative performance and clinical outcomes

Background

Sutureless and rapid-deployment valves are bioprostheses anchoring within the aortic annulus with few sutures, and they act as a hybrid of conventional surgical and transcatheter valves under aortic valve replacement. Considering that the 3F Enable valve is now off-market, the only two sutureless and rapid-deployment valves available on the world marketplace are the Perceval and Intuity valves. However, a direct comparison of the function of these two valves eludes researchers.

Purpose

Against this background, we performed this systematic review and meta-analysis comparing the intraoperative performance and early clinical outcomes between the Perceval valve and the Intuity valve under sutureless and rapid-deployment aortic valve replacement.

Methods

We systematically searched electronic databases through PubMed/MEDLINE, OvidWeb, Web of Science, and Cochrane Central Register of Controlled Trials (from the establishment of the database to November 17, 2022, without language restriction) for studies comparing the sutureless valve (the Perceval) and the rapid-deployment valve (the Intuity) under aortic valve replacement. Our primary outcomes were early mortality and postoperative transvalvular pressure gradients. The secondary outcomes were defined to include aortic cross-clamp and cardiopulmonary bypass time, paravalvular leak (any paravalvular leak, moderate-to-severe paravalvular leak) after aortic valve replacement, need for pacemaker implantation, postoperative neurological events (stroke), and intensive care unit stay.

Results

This meta-analysis included ten non-randomized trials with 3,526 patients enrolled (sutureless group = 1,772 and rapid-deployment group = 1,754). Quality assessments were performed, with the mean scores of the studies reading 6.90 (SD = 0.99) out of 9 according to the Newcastle-Ottawa Scale. Compared with rapid-deployment aortic valve replacement, sutureless aortic valve replacement was associated with higher mean and peak transvalvular pressure gradients postoperatively. In contrast, aortic cross-clamp and cardiopulmonary time were needed less in sutureless aortic valve replacement vs. rapid-deployment aortic valve replacement. There was no evidence of significant publication bias observed by the funnel plot and Egger's test.

Conclusions

For postoperative hemodynamics, sutureless aortic valve replacement was associated with increased mean and peak transvalvular pressure gradients compared with rapid-deployment aortic valve replacement. In sharp contrast, sutureless aortic valve replacement significantly reduced the amount of time needed for fixing the aortic cross-clamp and the cardiopulmonary bypass procedure.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022343884.

Rapid-Deployment Aortic Valve Replacement: Patient Selection and Special Considerations

Sutureless or rapid deployment valves in the setting of aortic valve replacement (AVR) is an emerging surgical technique using the transcatheter valve technology, which may lead to reduction in cross-clamp time and potentially better hemodynamics compared to a stented bioprosthetic valve. The absence of subannular pledgets results to excellent hemodynamic performance with reduced turbulent flow and larger effective orifice area. However, complications from both surgical and transcatheter AVR may still occur and impact survival. The incidence of paravalvular leakage and permanent pacemaker implantation are not low. Although technical modifications can improve these outcomes, there is a learning curve effect. Therefore, technical and anatomical considerations as well as better patient selection are paramount for better outcomes. In this review, we discuss the use of sutureless or rapid deployment valves in setting of (1) complex procedures, (2) minimally invasive AVR, and (3) small aortic annulus. The advantage of sutureless or rapid deployment valves in terms of mortality remains to be clarified; therefore, it is necessary to accumulate long-term outcomes in an appropriate patient cohort.

Effect of Native Aortic Leaflet Geometry Modification on Transcatheter Aortic Valve Neo-sinus and Aortic Sinus Flow: An In-vitro Study

PURPOSE

Leaflet thrombosis is a potentially fatal complication after transcatheter aortic valve replacement (TAVR). Blood flow stagnation in the neo-sinus and aortic sinuses are associated with increased thrombus severity. Native aortic leaflet modification may be a potential strategy to improve the neo-sinus and aortic sinus fluid dynamics. However, limited data exist on the effect of leaflet geometry modification on the flow within the neo-sinus and aortic sinus regions. We evaluate the effect of aortic leaflet modification on the neo-sinus and aortic sinus flow stagnation after simulated TAVR.

METHODS

Particle image velocimetry measurements were performed under nominal (5 LPM) and low (2.5 LPM) cardiac output conditions for an intact leaflet (control) case, and 3 modified leaflet geometries. Aortic leaflet geometry modification via leaflet splay was simulated with increasing splay geometry (leaflet splay distance: 5 mm-narrow, 10 mm-medium, and 20 mm-wide).

RESULTS

Leaflet geometry modification influenced flow features throughout the cardiac cycle, at both cardiac outputs, and allowed for flow communication between the neo-sinus and aortic sinus regions compared to the control. In the aortic sinus, flow stagnation reduced by over 64% at 5LPM, and over 36% at 2.5LPM for all simulated modified leaflet geometries compared to the control. However, only the medium and wide splay geometries enabled a reduction in neo-sinus flow stagnation compared to the control case.

CONCLUSIONS

These findings suggest that aortic leaflet geometry modification (of at least 10 mm leaflet splay distance) may reduce flow stasis and potentially decrease valve thrombosis risk.

Long-term durability of a new surgical aortic valve: A 1 billion cycle in vitro study

Background

This study assessed the long-term hemodynamic functional performance of the new Inspiris Resilia aortic valve after accelerated wear testing (AWT).

Methods

Three 21-mm and 23-mm Inspiris valves were used for the AWT procedure. After 1 billion cycles (equivalent to 25 years), the valves' hemodynamic performance was compared with that of the corresponding zero-cycled condition. Next, 1 AWT cycled valve of each valve size was selected at random for particle image velocimetry (PIV) and leaflet kinematic tests, and the data were compared with data for an uncycled Inspiris Resilia aortic valve of the same size. PIV was used to quantitatively evaluate flow fields downstream of the valve. Valves were tested according to International Standards Organization 5840-2:2015 protocols.

Results

The 21-mm and 23-mm valves met the International Organization for Standardization (ISO) durability performance requirements to 1 billion cycles. The mean effective orifice areas for the 21-mm and 23-mm zero-cycled and 1 billion–cycled valves were 1.89 ± 0.02 cm² and 1.94 ± 0.01 cm², respectively (P < .05) and 2.3 ± 0.13 cm² and 2.40 ± 0.11 cm², respectively (P < .05). Flow characterization of the control valves and the study valves demonstrated similar flow characteristics. The velocity and shear stress fields were also similar in the control and study valves.

Conclusions

The Inspiris Resilia aortic valve demonstrated very good durability and hemodynamic performance after an equivalent of 25 years of simulated in vitro accelerated wear. The study valves exceeded 1 billion cycles of simulated wear, 5 times longer than the standard requirement for a tissue valve as stipulated in ISO 5840-2:2015.

Peri-procedural Trans-esophageal Echocardiographic Sizing of the Native Left Ventricular Outflow Tract During Edwards INTUITY Valve Implantation

Background: The Edwards INTUITY rapid deployment valve was anchored on the left ventricular outflow tract (LVOT) by radial force akin to transcatheter balloon-expandable valves. This design feature facilitates minimally invasive and complex procedures but comes at the price of compressing the atrioventricular conduction bundle and potential requirement for pacemaker implantation.

Methods: A retrospective observational study was conducted on 30 consecutive patients who received the INTUITY valve at our institution from August 2018 to January 2021. Demographical, clinical, and echocardiographic parameters were collected for 90 days post-operatively. The diameter of the native LVOT at the landing site of the sub-annular stent was retrospectively measured using archived trans-esophageal echocardiographic images. A line was drawn from the inner edge of the septal endocardium to the inner edge of the anterior mitral leaflet in mid-systole, parallel to the aortic annulus, 6–8 mm apical to the aortic annulus depending on the valve size and the corresponding stent length. Risk factors associated with new onset conduction disturbances, defined as the occurrence of bundle branch block or complete heart block, were analyzed.

Results: Operative mortality was 3.3%. Pre-operatively, permanent pacemakers were required for two patients who were excluded from the subsequent analysis. New onset conduction disturbances occurred in four of the remaining 28 patients (14.3%). This included two incidences of persistent left bundle branch block and two incidences of permanent pacemaker implantation due to complete heart block. Univariate analysis identified over-sizing of the native LVOT by 5 mm or more as a significant risk factor associated with conduction disturbance.

Conclusion: During INTUITY vale implantation, in addition to the aortic annulus, the landing site of the sub-annular stent within the native LVOT should also be sized pre-bypass. Over-sizing the native LVOT by 5 mm or more was associated with an increased risk of new onset conduction disturbances and should be avoided.

Heart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation

The field of heart valve biomechanics is a rapidly expanding, highly clinically relevant area of research. While most valvular pathologies are rooted in biomechanical changes, the technologies for studying these pathologies and identifying treatments have largely been limited. Nonetheless, significant advancements are underway to better understand the biomechanics of heart valves, pathologies, and interventional therapeutics, and these advancements have largely been driven by crucial in silico, ex vivo, and in vivo modeling technologies. These modalities represent cutting-edge abilities for generating novel insights regarding native, disease, and repair physiologies, and each has unique advantages and limitations for advancing study in this field. In particular, novel ex vivo modeling technologies represent an especially promising class of translatable research that leverages the advantages from both in silico and in vivo modeling to provide deep quantitative and qualitative insights on valvular biomechanics. The frontiers of this work are being discovered by innovative research groups that have used creative, interdisciplinary approaches toward recapitulating in vivo physiology, changing the landscape of clinical understanding and practice for cardiovascular surgery and medicine.

Direct comparison of rapid deployment versus sutureless aortic valve replacement: a meta-analysis

Background

This meta-analysis was conducted to compare the procedural and early outcomes of aortic valve replacement (AVR) using rapid deployment valve (RD group) versus sutureless valve (SU group).

Methods

A literature search of 5 online databases was conducted. The primary outcomes were mean transvalvular pressure gradient (MPG) after AVR, the incidence of paravalvular leak (PVL) and the need for a permanent pacemaker implantation (PPI). The secondary outcomes included aortic cross-clamp (ACC) and cardiopulmonary bypass (CPB) times, early mortality and other postoperative complications, such as atrial fibrillation, bleeding reoperation and stroke.

Results

Eight articles were included, and all outcomes except MPG after AVR in matched valve sizes were extracted from 7 studies (RD group =842 patients and SU group =1,386 patients). The pooled analysis demonstrated a lower MPG in the RD group than in the SU group, with mean difference (MD) of 2.64 mmHg. The pooled risk ratios of any PVL and grade ≥2 (or moderate) PVL were not significantly different between the groups; however, the incidence of PPI was significantly lower in the RD group than in the SU group, with a risk ratio of 0.69. The pooled analyses showed that the ACC and CPB times were significantly longer in the RD group than in the SU group, with weighted MDs of 8.74 (P<0.001) and 9.94 (P<0.001) minutes, respectively. The risks of early mortality and other postoperative complications were not significantly different between the groups.

Conclusions

AVR using RD valve was associated with better valve hemodynamics in terms of the MPG than AVR using SU valve, and better outcomes were observed in the RD group regarding PPI. Procedural times were longer in AVR using RD valve than SU valve. Early clinical outcomes showed no difference between RD and SU valve.

A new technique that prevents paravalvular leakage after aortic valve replacement using a rapid-deployment valve system

BACKGROUND

We report our 1-year single-center experience of a new technique of aortic valve replacement using a rapid-deployment valve (RD-AVR) to avoid postoperative complications. We also report the unexpected pitfalls and handling techniques that we have seen in past cases.

METHODS

We performed aortic valve replacement on 38 patients between May 2019 and April 2020. Their mean age was 74 years. The primary outcomes were in-hospital mortality and short-term results during a 1-year follow-up period, while the secondary outcomes were related to prosthetic valve function, especially paravalvular leakage (PVL). We further analyzed the relationship between the new technique and its outcomes.

RESULTS

The mean operative time was 196 min. There were no in-hospital deaths, and the mean duration of postoperative hospital stay was 11.8 days. Valvular measurements using three-dimensional computed tomography were larger and more accurate than those measured using ultrasonic echocardiography. Postoperative RD-AVR prosthetic valve function was excellent. However, PVL occurred in four cases 1 week and 1 year postoperatively and regurgitation did not improve. A gap associated with PVL was identified below the right-noncoronary commissure. To prevent PVL, we additionally stitched this gap in the later 18 cases; there was no case of PVL and no new pacemaker implantation in these cases.

CONCLUSIONS

PVL is more likely to occur if there is a gap below the R-N commissure, especially in cases with a large annulus; therefore, applying an additional stitch to the R-N commissure is extremely useful.

Sutureless valve and rapid deployment valves: a systematic review and meta-analysis of comparative studies

Background

The treatment of aortic valve disease is the most common valvular surgery in industrialized nations, with 3-9% of the population over the age of eighty having at least moderate aortic stenosis. As transcatheter aortic valve replacement (TAVR) has become more established, newer surgical prostheses have been developed with a variety of anchoring systems that do not rely solely on sutures to hold the valve in an appropriate position. The Edwards Intuity valve is a bovine pericardial prosthesis that is modelled on the widely implanted Perimount MagnaEase aortic prosthesis. The Perceval valve is a bovine pericardial valve attached to a self-expanding nitinol stent, which uses the radial force exerted on the patient's aortic annulus and aortic root by the stent portion to hold the valve in position. This meta-analysis compares the outcomes of comparative studies of these two valve systems.

Methods

This systematic review and meta-analysis compares the outcomes of rapid deployment valves (RDV) and sutureless valves (SURD) and was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations and guidance. The search strategy interrogated six electronic databases. Outcomes measured included all-cause mortality at latest follow up, stroke, cross-clamp and cardiopulmonary bypass (CPB) times, pacemaker implantation rates, paravalvular leak and post-operative transvalvular gradient.

Results

The search strategy identified 407 unique papers for initial assessment with seven studies qualifying for inclusion in the analysis. The outcomes of 4,076 patients (1,650 RDV, 2,426 SURD) were included. There was no difference in mortality, stroke or moderate or worse paravalvular regurgitation between the two groups. SURD had significantly shorter CPB time by 15.7 minutes [95% confidence interval (CI): 4.2-27.1; P=0.007] and a shorter cross-clamp time by 11.3 minutes (95% CI: 6.3-16.3; P<0.001) compared to RDV. RDV had a lower post-operative transvalvular gradient by 2.5 mmHg (95% CI: 1.2-3.8; P<0.001) and a lower rate of mild paravalvular regurgitation (OR 2.51; 95% CI: 1.435-4.768; P=0.004).

Conclusions

Both valve types have an adequate safety profile and are comparable to conventional sutured prostheses. There was a significant reduction in cross-clamp and CPB times associated with SURD. This may be of benefit for patients requiring multiple concomitant procedures and increases the utility of minimally invasive valve replacement. However, SURD was associated with higher post-operative transvalvular gradients and a higher incidence of paravalvular regurgitation.