Structural Integrity of Balloon-Expandable Stents After Transcatheter Aortic Valve Replacement

Late expansion of mechanically expanding transcatheter aortic valves

Several studies have demonstrated better hemodynamic stability of mechanically expanding valves following transcatheter aortic valve replacement (TAVR). This study aims to assess the expansion or recoil of transcatheter aortic valves using multidetector computed tomography (MDCT). This was a retrospective study. Among 873 patients who underwent TAVR with balloon-expandable (SAPIEN 3) or mechanically expanding valves (LOTUS) at Keio University Hospital between 2013 and 2020, those who underwent serial MDCT and echocardiographic assessment (pre-procedure, discharge, 6 months, 1 year, and 2 years post-TAVR) as our hospital protocol were included in this analysis (N = 30; LOTUS = 12; SAPIEN 3 = 18). The pre- and post-procedural echocardiographic data and the valve expansion rate evaluated by MDCT were compared between the groups. In LOTUS valves, late-phase expansion was observed on computed tomography (mean expansion rate, 83.8% at discharge and 86.8%, 2 years postoperative, p < 0.001), and a gradual increase in the aortic valve area was observed on echocardiography (aortic valve area: 1.45 cm² at discharge and 1.51 cm², 2 years postoperative, p = 0.01). Conversely, in SAPIEN 3, valve expansion was not seen in the late phase (mean expansion rate, 84.5% at discharge and 83.8%, 2 years postoperative) with a decrease in the aortic valve area (1.41 cm² at discharge and 1.37 cm², 2 years postoperative, p = 0.04). The expansion of the middle portion of the LOTUS valves was attributed to the increase in the aortic valve area. In conclusion, this study demonstrated the greater late-phase expansion and better valve performance of mechanically expanding valves.

Role of computed tomography in transcatheter aortic valve implantation and valve-in-valve implantation: complete review of preprocedural and postprocedural imaging

: Since 2002, transcatheter aortic valve implantation (TAVI) has revolutionized the treatment and prognosis of patients with aortic stenosis. A preprocedural assessment of the patient is vital for achieving optimal outcomes from the procedure. Retrospective ECG-gated cardiac computed tomography (CT) today it is the gold-standard imaging technique that provides three-dimensional images of the heart, thus allowing a rapid and complete evaluation of the morphology of the valve, ascending aorta, coronary arteries, peripheral access vessels, and prognostic factors, and also provides preprocedural coplanar fluoroscopic angle prediction to obtain complete assessment of the patient. The most relevant dimension in preprocedural planning of TAVI is the aortic annulus, which can determine the choice of prosthesis size. CT is also essential to identify patients with increased anatomical risk for coronary artery occlusion in Valve in Valve (ViV) procedures.Moreover, CT is very useful in the evaluation of late complications, such as leakage, thrombosis and displacements. At present, CT is the cornerstone imaging modality for the extensive and thorough work-up required for planning and performing each TAVI procedure, to achieve optimal outcomes. Both the CT procedure and analysis should be performed by trained and experienced personnel, with a radiological background and a deep understanding of the TAVI procedure, in close collaboration with the implantation team. An accurate pre-TAVI CT and post-processing for the evaluation of all the points recommended in this review allow a complete planning for the choice of the valve dimensions and type (balloon or self-expandable) and of the best percutaneous access.

Hemodynamic and Imaging Assessment of Transcatheter Aortic Valve Replacement with the Inovare® Proseal using Multislice Computed Tomography

Objective

To evaluate the hemodynamic performance (i.e., gradients and paravalvular leakage [PVL]) of the new and experimental Braile Inovare^® Proseal. Additionally, we aimed to assess pre and postoperatively the aortic annulus and the transcatheter prosthesis using multislice computed tomography (MSCT).

Methods

Patients were selected by a multidisciplinary heart team and referred for transcatheter aortic valve replacement (TAVR). MSCT was performed before and after surgery. Measurements of the aortic valve and prosthesis were conducted and correlated with the valve gradient and residual PVL.

Results

Twenty-one patients were selected for the protocol. Patients had a mean age of 79 years and 38% of them were of female sex. The mean EuroSCORE II value was 12.5%±10.8. Mean gradient was reduced from 45.8±11.04 mmHg to 5.59±2.61 mmHg and there were no instances of PVL worse than mild. There were no cases of coronary obstruction or procedural death. Circularity was present in all prostheses evaluated. Circularity indexes for the prostheses were: inflow 0.05±0.03, middle third 0.04±0.02, and outflow 0.04±0.02 (P=0.08). The mean distance between the prosthesis and the left and right coronary ostia were 14.8 mm±3.3 and 17.3 mm±3, respectively. Oversizing was appropriate with a mean of 22.14%±6%.

Conclusion

Braile Inovare^® Proseal transcatheter device has demonstrated low gradients with low rates of PVL. Oversizing by annular measurements was adequate. MSCT was adequate to evaluate device sizing and has demonstrated preserved expansibility and circularity in the evaluated cases.

Surgically implanted aortic valve bioprostheses deform after implantation: insights from computed tomography

OBJECTIVE

Little is known about the prevalence and degree of deformation of surgically implanted aortic biological valve prostheses (bio-sAVRs). We assessed bio-sAVR deformation using multidetector-row computed tomography (MDCT).

METHODS

Three imaging databases were searched for patients with MDCT performed after bio-sAVR implantation. Minimal and maximal valve ring diameters were obtained in systole and/or diastole, depending on the acquired cardiac phase(s). The eccentricity index (EI) was calculated as a measure of deformation as (1 - (minimal diameter/maximal diameter)) × 100%. EI of < 5% was considered none or trivial deformation, 5-10% mild deformation, and > 10% non-circular. Indications for MDCT and implanted valve type were retrieved.

RESULTS

One hundred fifty-two scans of bio-sAVRs were included. One hundred seventeen measurements were performed in systole and 35 in diastole. None or trivial deformation (EI < 5%) was seen in 67/152 (44%) of patients. Mild deformation (EI 5-10%) was seen in 59/152 (39%) and non-circularity was found in 26/152 (17%) of cases. Overall, median EI was 5.5% (IQR 3.4-7.8). In 77 patients, both systolic and diastolic measurements were performed from the same scan. For these scans, the median EI was 6.5% (IQR 3.4-10.2) in systole and 5.1% (IQR3.1-7.6) in diastole, with a significant difference between both groups (p = 0.006).

CONCLUSIONS

Surgically implanted aortic biological valve prostheses show mild deformation in 39% of cases and were considered non-circular in 17% of studied valves.

KEY POINTS

• Deformation of surgically implanted aortic valve bioprostheses (bio-sAVRs) can be adequately assessed using MDCT. • Bio-sAVRs show at least mild deformation (eccentricity index > 5%) in 56% of studied cases and were considered non-circular (eccentricity index > 10%) in 17% of studied valves. • The higher deformity rate found in bio-sAVRs with (suspected) valve pathology could suggest that geometric deformity may play a role in leaflet malformation and thrombus formation similar to that of transcatheter heart valves.

A Computational Study on Deformed Bioprosthetic Valve Geometries: Clinically Relevant Valve Performance Metrics

Transcatheter aortic valves (TAV) are symmetrically designed, but they are often not deployed inside cylindrical conduits with circular cross-sectional areas. Many TAV patients have heavily calcified aortic valves, which often result in deformed prosthesis geometries after deployment. We investigated the effects of deformed valve annulus configurations on a surgical bioprosthetic valve as a model for TAV. We studied valve leaflet motions, stresses and strains, and analog hydrodynamic measures (using geometric methods), via finite element (FE) modeling. Two categories of annular deformations were created to approximate clinical observations: (1) noncircular annulus with valve area conserved, and (2) under-expansion (reduced area) compared to circular annulus. We found that under-expansion had more impact on increasing stenosis (with geometric orifice area metrics) than noncircularity, and that noncircularity had more impact on increasing regurgitation (with regurgitation orifice area metrics) than under-expansion. We found durability predictors (stress/strain) to be the highest in the commissure regions of noncircular configurations such as EllipMajor (noncircular and under-expansion areas). Other clinically relevant performance aspects such as leaflet kinematics and coaptation were also investigated with the noncircular configurations. This study provides a framework for choosing the most challenging TAV deformations for acute and long-term valve performance in the design and testing phase of device development.

CT in planning transcatheter aortic valve implantation procedures and risk assessment

For surgical aortic valve replacement, the Society of Thoracic Surgeons score (STSS) is the reference standard for the prediction of operative risk. In transcatheter aortic valve implantation (TAVI) though, where the procedure itself is minimally invasive, the traditional risk assessment is supplemented by CTA. Through a consistent approach to the acquisition of high-quality images and the standardised reporting of annular measurements and adverse root and vascular features, patients at risk of complications can be identified. In turn, this may allow for a personalised procedural approach and treatment strategies devised to potentially reduce or mitigate this risk. This article provides a systematic and standardised approach to pre-procedural work-up with computed tomography angiography (CTA) and explores the current state of evidence and future areas of development in this rapidly developing field.

Intermediate outcomes of transcatheter pulmonary valve replacement with the Edwards Sapien 3 valve - German experience

Background: After encouraging results with the Edwards Sapien and XT valves, this study aimed to review procedural data and early outcomes for the Sapien 3 valves for transcatheter pulmonary valve replacement (TPVR). Methods: We performed a multicenter, retrospective analysis of cases who underwent a Sapien 3 TPVR between 2015 and 2017 in 7 centers in Germany with a follow-up of up to 2 years. Results: 56 patients could be enrolled (weight 58,5 ± 25,0 kg; 53% Tetralogy of Fallot, 45% native RVOT). Most procedures were two-stage procedures (82,1%) with 100% prestenting. Valve sizes were 20 mm (n = 1), 23 mm (n = 15), 26 mm (n = 27), 29 mm (n = 13). Procedural success rate was 96.4%. Two patients underwent surgical valve implantation after balloon rupture during TPVR. Follow-up data were available up to 24-month post TPVR. The rate of patients with ? moderate and severe pulmonary regurgitation decreased to 0% after TPVR, peak systolic gradient decreased from 24,2 (SD±20,9) mmHg to 7,1 mmHg (SD±5,0). There were no endocarditis, severe tricuspid valve impairment or stent fractures. Conclusions: With the Edwards Sapien 3 valve, the patient pool for TPVR can be substantially extended. Continued data collection is necessary to verify long-term results.

A dynamic model-based approach to motion and deformation tracking of prosthetic valves from biplane x-ray images

PURPOSE

Transcatheter aortic valve replacement (TAVR) is a minimally invasive procedure in which a prosthetic heart valve is placed and expanded within a defective aortic valve. The device placement is commonly performed using two-dimensional (2D) fluoroscopic imaging. Within this work, we propose a novel technique to track the motion and deformation of the prosthetic valve in three dimensions based on biplane fluoroscopic image sequences.

METHODS

The tracking approach uses a parameterized point cloud model of the valve stent which can undergo rigid three-dimensional (3D) transformation and different modes of expansion. Rigid elements of the model are individually rotated and translated in three dimensions to approximate the motions of the stent. Tracking is performed using an iterative 2D-3D registration procedure which estimates the model parameters by minimizing the mean-squared image values at the positions of the forward-projected model points. Additionally, an initialization technique is proposed, which locates clusters of salient features to determine the initial position and orientation of the model.

RESULTS

The proposed algorithms were evaluated based on simulations using a digital 4D CT phantom as well as experimentally acquired images of a prosthetic valve inside a chest phantom with anatomical background features. The target registration error was 0.12 ± 0.04 mm in the simulations and 0.64 ± 0.09 mm in the experimental data.

CONCLUSIONS

The proposed algorithm could be used to generate 3D visualization of the prosthetic valve from two projections. In combination with soft-tissue sensitive-imaging techniques like transesophageal echocardiography, this technique could enable 3D image guidance during TAVR procedures.

Impact of device-host interaction on paravalvular aortic regurgitation with different transcatheter heart valves

AIMS

We sought to evaluate the interaction of different aortic root phenotypes with self-expanding (SEV), balloon-expandable (BEV) and mechanically expanded (MEV) and the impact on significant aortic regurgitation.

METHODS AND RESULTS

We included 392 patients with a SEV (N = 205), BEV (N = 107) or MEV (N = 80). Aortic annulus eccentricity index and calcification were measured by multi-slice CT scan. Paravalvular aortic regurgitation was assessed by contrast aortography (primary analysis) and transthoracic echocardiography (secondary analysis). In mildly calcified roots paravalvular regurgitation incidence was similar for all transcatheter heart valves (SEV 8.4%; BEV 9.1%; MEV 2.0% p = 0.27). Conversely, in heavily calcified roots paravalvular regurgitation incidence was significantly higher with SEV (SEV 45.9%; BEV 0.0%; MEV 0.0% p < 0.001). When paravalvular regurgitation was assessed by TTE, the overall findings were similar although elliptic aortic roots were associated with more paravalvular regurgitation with SEV (20.5% vs. BEV 4.5% vs. MEV 3.2%; p = 0.009).

CONCLUSIONS

In heavily calcified aortic roots, significant paravalvular aortic regurgitation is more frequent with SEV than with BEV or MEV, but similar in mildly calcified ones. These findings may support patient-tailored transcatheter heart valve selection.

CLASSIFICATIONS

Aortic stenosis; multislice computed tomography; transcatheter aortic valve replacement; paravalvular aortic regurgitation.

CONDENSED ABSTRACT

We sought to evaluate the interaction of different aortic root phenotypes with self-expanding (SEV), balloon-expandable (BEV) and mechanically expanded (MEV) and the impact on significant aortic regurgitation. We included 392 patients with a SEV (N = 205), BEV (N = 107) or MEV (N = 80). Aortic annulus eccentricity index and calcification were measured by multi-slice CT scan. Paravalvular aortic regurgitation was assessed by contrast aortography and transthoracic echocardiography. We found that in heavily calcified aortic roots, significant paravalvular aortic regurgitation is more frequent with SEV than with BEV or MEV, but similar in mildly calcified ones.

Comparison of self-expanding and balloon-expandable transcatheter aortic valves morphology and association with paravalvular regurgitation: Evaluation using multidetector computed tomography

OBJECTIVES

Compare final morphology of self-expanding and balloon-expandable prosthesis and association with paravalvular regurgitation (PVR).

BACKGROUND

PVR after transcatheter aortic valve replacement (TAVR) remains a frequent complication. A better understanding of the prosthesis geometry may be important to improve selection of the best device for each case and possibly reduce the rates of PVR.

METHODS

Retrospective study including patients consecutively submitted to transcatheter aortic valve replacement: August/2007-October/2016. Three months after the procedure a multidetector computed tomography (MDCT) was performed to assess prosthesis geometry: dimensions, eccentricity, and expansion.

RESULTS

A total of 147 individuals were included (mean age of 78.8 ± 6.7 and 50.3% males), 57% treated with a self-expanding prosthesis. On the postprocedure MDCT, the self-expanding group had higher eccentricity index (15.0 vs. 7.1%, p < .001) and lower expansion (68.3 vs. 82.8%, p < .001). In that group, the volume of calcium of landing zone had a significant correlation with eccentricity index and under-expansion. Patients with ≥mild PVR presented higher eccentricity (12.6 vs. 7.9%, p < .001) and lower expansion (68 vs. 75%, p = .012). Eccentricity index and landing zone calcium volume were independent predictors of PVR.

CONCLUSIONS

Self-expanding prosthesis have greater eccentricity and under-expansion. Calcium burden exerts more influence in the final morphology of that type of valve. Calcification and eccentricity are associated with the development of PVR. These factors should be considered in the selection of the most appropriate type of prosthesis for each scenario.

Aortic Valve Annular Sizing: Intraoperative Assessment Versus Preoperative Multidetector Computed Tomography

BACKGROUND

Appropriate valve sizing is critical in aortic valve replacement. We hypothesized that direct intraoperative valve sizing results in smaller aortic annular diameters compared with sizing based on systolic-phase multidetector computerized tomographic (MDCT) imaging.

METHODS AND RESULTS

We retrospectively analyzed 78 patients undergoing surgical aortic valve replacement for severe aortic stenosis between 2012 and 2014 at our institution. Preoperative MDCT measurements of the aortic annulus served as basis for assignment to a theoretical surgical valve size, which was then (1) compared to the implanted valve size and (2) to a theoretical transcatheter aortic valve replacement valve size. To quantify the resulting differences, geometric orifice areas (GOA) were calculated. MDCT-based sizing produced the same valve size for n=34 patients (group CT-same), a larger valve with a 25% increased GOA in n=32 patients (group CT-Lg) and a smaller GOA by 22% in n=12 patients (group CT-Sm). On the basis of MDCT measurements, 41% of valves implanted were undersized. The comparison of intraoperative implanted to a theoretical transcatheter aortic valve replacement valve size resulted in GOAs 25% larger for patients in group CT-same, 40.6% larger in group CT-Lg and 14.6% larger in group CT-Sm.

CONCLUSIONS

Preoperative MDCT measurements differ substantially from direct intraoperative assessment of the aortic annulus. Implanted surgical aortic valve replacement valves were smaller relative to MDCT-based sizing in 41% of patients, and the potential GOA was between 25% and 40.6% larger if patients had undergone transcatheter aortic valve replacement.

Stent and leaflet stresses in a 26-mm first-generation balloon-expandable transcatheter aortic valve

OBJECTIVE

Transcatheter aortic valve replacement is established therapy for high-risk and inoperable patients with severe aortic stenosis, but questions remain regarding long-term durability. Valve design influences durability. Increased leaflet stresses in surgical bioprostheses have been correlated with degeneration; however, transcatheter valve leaflet stresses are unknown. From 2007 to 2014, a majority of US patients received first-generation balloon-expandable transcatheter valves. Our goal was to determine stent and leaflet stresses in this valve design using finite element analyses.

METHODS

A 26-mm Sapien Transcatheter Heart Valve (Edwards Lifesciences, Inc, Irvine, Calif) underwent high-resolution microcomputed tomography scanning to develop precise 3-dimensional geometry of the leaflets, the stent, and the polyethylene terephthalate elements. The stent was modeled using 3-dimensional elements and the leaflets were modeled using shell elements. Stent material properties were based on stainless steel, whereas those for leaflets were obtained from surgical bioprostheses. Noncylindrical Sapien valve geometry was also simulated. Pressure loading to 80 mm Hg and 120 mm Hg was performed using ABAQUS finite element software (Dassault Systèmes, Waltham, Mass).

RESULTS

At 80 mm Hg, maximum principal stresses on Sapien leaflets were 1.31 megaspascals (MPa). Peak leaflet stress was observed at commissural tips where leaflets connected to the stent. Maximum principal stresses for the stent were 188.91 MPa and located at stent tips where leaflet commissures were attached. Noncylindrical geometry increased peak principal leaflet stresses by 16%.

CONCLUSIONS

Using exact geometry from high-resolution scans, the 26-mm Sapien Transcatheter Heart Valve showed that peak stresses for both stent and leaflets were present at commissural tips where leaflets were attached. These regions would be prone to leaflet degeneration. Understanding stresses in first-generation transcatheter valves allows comparison to future designs for relative durability.

Transcatheter Valve Underexpansion Limits Leaflet Durability: Implications for Valve-in-Valve Procedures

Transcatheter aortic valve (TAV) implantation within a failed bioprosthetic valve is a growing trend for high-risk patients. The non-compliant stent of the previous prosthesis may prevent full expansion of the TAV, which has been shown to distort the leaflet configuration, and has been hypothesized to adversely affect durability. In this study, TAV leaflet fatigue damage under cyclic pressurization in the setting of stent underexpansion by 0 (fully expanded), 1, 2 and 3 mm was simulated using finite element analysis to test this hypothesis. In the 2 and 3 mm underexpanded devices, the TAV leaflets exhibited severe pin-wheeling during valve closure, which increased leaflet stresses dramatically, and resulted in accelerated fatigue damage of the leaflets. The leaflet fatigue damage in the 1 mm underexpanded case was similar to that in the fully expanded case. Clinically a range of 10-15% underexpansion is generally considered acceptable; however, it was observed in this study that ≥2 mm (≥9.1%) underexpansion, will significantly impact device durability. Further study is necessary to determine the impact of various deployment conditions, i.e. non-uniform and non-circular deployments and different implantation heights, on differing TAV devices, but it is clear that the normal TAV leaflet configuration must be preserved in order to preserve durability.

Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement

Transcatheter aortic valve replacements (TAVRs) are a percutaneous alternative to surgical aortic valve replacements and are used to treat patients with aortic valve stenosis. This minimally invasive procedure relies on expansion of the TAVR stent to radially displace calcified aortic valve leaflets against the aortic root wall. However, these calcium deposits can impede the expansion of the device causing distortion of the valve stent and pericardial tissue leaflets. The objective of this study was to elucidate the impact of eccentric TAVR stent distortion on the dynamic deformation of the tissue leaflets of the prosthesis in vitro. Dual-camera stereophotogrammetry was used to measure the regional variation in strain in a leaflet of a TAVR deployed in nominal circular and eccentric (eccentricity index = 28%) orifices, representative of deployed TAVRs in vivo. It was observed that (i) eccentric stent distortion caused incorrect coaptation of the leaflets at peak diastole resulting in a 'peel-back' leaflet geometry that was not present in the circular valve and (ii) adverse bending of the leaflet, arising in the eccentric valve at peak diastole, caused significantly higher commissure strains compared with the circular valve in both normotensive and hypertensive pressure conditions (normotension: eccentric = 13.76 ± 2.04% versus circular = 11.77 ± 1.61%, p = 0.0014, hypertension: eccentric = 15.07 ± 1.13% versus circular = 13.56 ± 0.87%, p = 0.0042). This study reveals that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.

The future of transcatheter aortic valve implantation

Since the introduction of transcatheter aortic valve implantation (TAVI) into clinical practice, the treatment of aortic stenosis has changed dramatically. In the past, medical therapy with or without balloon aortic valvuloplasty was the only option for inoperable patients. More recently, TAVI has become the treatment of choice for these patients and the preferred alternative for high-risk operable patients. Surgical aortic valve replacement (SAVR) currently remains the gold standard for patients at low or intermediate operative risk. As randomized trials have demonstrated comparable results between TAVI and SAVR in the high-risk population, there is now a clear trend towards performing TAVI even in intermediate-risk patients while awaiting the results of randomized trials in that population. Nevertheless, there are still questions regarding TAVI involving paravalvular leak (PVL), stroke, pacemaker requirements, and durability that remain to be more definitively answered before TAVI can routinely be performed in a broader, lower risk population. Improvements in patient selection, imaging, and second and third generation devices have decreased the incidence of PVLs and vascular complications that followed the earliest TAVI procedures, but the rates of perioperative stroke and permanent pacemaker implantation must still be addressed. Furthermore, the long-term durability of TAVI devices and a role for post-procedure antithrombotic management remain unanswered. Until these questions are more clearly answered, it is the Heart Team's task to determine the optimal treatment for each patient based on risk scores, frailty metrics, comorbidities, patient preference, and potential for improvement in quality of life.

Impact of post-implant SAPIEN XT geometry and position on conduction disturbances, hemodynamic performance, and paravalvular regurgitation

OBJECTIVES

This report sought to study the impact of the balloon-expandable SAPIEN XT (Edwards Lifesciences, Irvine, California) transcatheter heart valve (THV) stent frame geometry and position on outcomes of transcatheter aortic valve replacement (TAVR).

BACKGROUND

Post-implant THV geometry and position might impact atrioventricular conduction, hemodynamic performance, and annular sealing.

METHODS

Eighty-nine consecutive patients who underwent TAVR with a Sapien XT THV had pre- and post-implant multidetector computed tomography, transthoracic echocardiography, and electrocardiograms performed to assess THV stent geometry, atrioventricular conduction, and hemodynamic performance.

RESULTS

The THV Circularity (THV eccentricity <10% [eccentricity = minimum stent diameter/maximum stent diameter]) and under-expansion (THV area/nominal THV area <90%) were present in 97.8% (2 of 89) and 0%, respectively. Low THV implantation was associated with new left bundle branch block and complete heart block (3.4 ± 2.0 mm vs. 5.5 ± 2.9 mm, p = 0.01) and with the need for permanent pacemaker implantation (3.5 ± 2.0 mm vs. 7.1 ± 2.5 mm, p = 0.001). In contrast, labeled THV size and THV area oversizing was not associated with atrioventricular conduction disturbances. The relation between inflow stent frame area and annular area was related to paravalvular regurgitation (p = 0.025). Labeled prosthesis size but not prosthesis expansion or eccentricity was related to valve gradient (p = 0.005) and effective orifice area (p < 0.001).

CONCLUSIONS

Low implantation depth of balloon-expandable THVs is associated with clinically significant new conduction disturbances and permanent pacemaker implantation. Importantly, annular area oversizing was not associated with these complications.

Imaging in Transcatheter Aortic Valve Replacement (TAVR): role of the radiologist

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is a novel technique developed in the last decade to treat severe aortic stenosis in patients who are non-surgical candidates because of multiple comorbidities.

METHODS

Since the technique is performed using a transvascular approach, pre-procedural assessment of the aortic valve apparatus, ascending aorta and vascular access is of paramount importance for both appropriate patient selection and correct device selection. This assessment is performed by a multi-disciplinary team with radiology being an integral and important part.

RESULTS

Among imaging modalities, there is growing scientific evidence supporting the crucial role of MDCT in the assessment of the aortic valve apparatus, suitability of the iliofemoral or alternative pathway, and determination of appropriate coaxial angles. MDCT also plays an important role in post-procedure imaging in the assessment of valve integrity and position.

CONCLUSION

This review outlines the principal aspects of TAVR, the multidisciplinary approach and utilisation of different imaging modalities, as well as a step-by-step approach to MDCT acquisition protocols, reconstruction techniques, pre-procedure measurements and post-procedure assessment.

TEACHING POINTS

• TAVR is a new technique to treat severe aortic stenosis in high-risk and nonsurgical candidates. • MDCT assessment of the aortic annulus is important for appropriate patient and device selection. • Multidisciplinary approach is required for patient selection, procedure planning and performance. • MDCT is required for assessment of the aortic root, iliofemoral or alternative vascular pathway.

Multidetector row computed tomography parameters associated with paravalvular regurgitation after transcatheter aortic valve implantation

Multidetector row computed tomographic (MDCT) assessment of aortic annulus dimensions and frame position and deployment have been associated with paravalvular aortic regurgitation (PAVR) after transcatheter aortic valve implantation (TAVI). The present evaluation investigated the (pre- and postprocedure) MDCT associates of PAVR ≥2+. In total, 123 patients referred for TAVI underwent clinical evaluation, transthoracic echocardiography, and pre- and post-TAVI MDCT. Pre-TAVI MDCT measurements of the aortic annular dimensions and post-TAVI MDCT evaluation of the position and deployment of the prosthesis in the native annulus were performed. At 1-month follow-up, PAVR ≥2+ was observed in 25 patients (20%). The difference between the MDCT-derived maximum aortic annulus and the nominal diameters of the implanted prosthesis (odds ratio 1.912, p = 0.002) and shallow position of the frame in the left ventricular outflow tract (<2 mm) (odds ratio 4.865, p = 0.017) were independently related to significant PAVR. A maximum annulus diameter ≥2 mm larger than the nominal frame diameter had 72% sensitivity and 61% specificity to predict PAVR. In conclusion, in patients undergoing TAVI, ≥2-mm difference between maximum aortic annulus and nominal prosthesis diameters and depth of the frame into the left ventricular outflow tract of <2 mm are independently associated with PAVR ≥2+.

Transcatheter aortic valve replacement with a new self-expanding transcatheter heart valve and motorized delivery system

OBJECTIVES

The aim of this study was to demonstrate feasibility and short- and midterm clinical outcomes with a new self-expanding transcatheter heart valve and motorized delivery system.

BACKGROUND

Refining transcatheter aortic valve replacement with newly designed bioprostheses and delivery systems is anticipated to facilitate the procedure, reduce the risk of complications, improve outcomes, and widen applicability.

METHODS

The CENTERA valve (Edwards Lifesciences, Irvine, California) was implanted in 15 patients with symptomatic severe aortic stenosis via femoral or axillary arterial percutaneous access. Patients underwent transesophageal echocardiography during and transthoracic echocardiography and multidetector computed tomography before and after valve implantation. Clinical and echocardiographic follow-up was obtained at 30 days and for the initial 10 patients after 1 year.

RESULTS

All 15 device implants were successful. Aortic valve area increased from 0.7 ± 0.1 cm(2) to 1.6 ± 0.4 cm(2) post-procedure (p < 0.01) and 1.8 ± 0.3 cm(2) at 1 year. Mean transaortic gradient decreased from 36.3 ± 14.2 mm Hg to 10.6 ± 5.4 mm Hg post-procedure (p < 0.001) and 10.8 ± 4.1 mm Hg at 1 year. Paravalvular aortic regurgitation at 30-day follow-up was none/trivial in 3 (23%), mild in 9 (69%), and moderate in 1 (8%) patient. Four patients (27%) received a new permanent pacemaker. Survival was 87% at 30 days and 80% at 1 year. All surviving patients were in New York Heart Association functional class I (25%) or II (75%) at 1 year.

CONCLUSIONS

Transcatheter aortic valve replacement with the CENTERA transcatheter heart valve and motorized delivery system is feasible and can lead to good short- and midterm clinical and hemodynamic outcomes.

Percutaneous Edwards SAPIEN(™) valve implantation for significant pulmonary regurgitation after previous surgical repair with a right ventricular outflow patch

BACKGROUND

Current indications for percutaneous pulmonary valve implantation (PPVI) are limited to patients who had their outflow tracts repaired with the use of a "full" condui-homograft. Patients after a patch repair are believed to have an unfavorable anatomy for PPVI.

OBJECTIVES

To evaluate a novel use of Edwards SAPIEN(TM) valve for percutaneous treatment of moderate and severe pulmonary regurgitation after tetralogy of Fallot (TF) repair with a right ventricular outflow (RVOT) patch.

METHODS

PPVI was intended in 10 patients (age 21-39 years, 2 ♂) with regurgitant fraction of 30-59%, measured by cardiac magnetic resonance imaging (CMRI) 16-30 years after repair with a RVOT patch. Balloon test-inflations were used for definitive measurements and location of the landing site for the valve. All RVOTs were prestented.

RESULTS

Successful valve implantation was achieved in nine patients. In one patient a bare-metal stent used for prestenting embolized into pulmonary artery. A 26-mm valve was implanted in seven and a 23-mm in two patients. CMRI at 1-2 month follow-up (n = 8) demonstrated both, sustained relief of pulmonary incompetence (regurgitant fraction = 0-14%) and significant decrease of the right ventricular end-diastolic volume indexes (from 169.9 ± 43.8 to 140.0 ± 40.3 ml/m(2) , P < 0.001). At that follow-up no adverse event occurred. No stent fractures were observed.

CONCLUSIONS

We report the first case series of patients with significant PR after a RVOT patch repair, successfully treated with a percutaneous Edwards SAPIEN(TM) valve implantation. The procedure is technically feasible and may be offered to patients with the outflow tracts larger than those limited by the Melody(®) system available currently.