Percutaneous aortic valve implantation using novel imaging guidance

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.

Optimal C-arm angulation during transcatheter aortic valve replacement: Accuracy of a rotational C-arm computed tomography based three dimensional heart model

AIM

To investigate the accuracy of a rotational C-arm CT-based 3D heart model to predict an optimal C-arm configuration during transcatheter aortic valve replacement (TAVR).

METHODS

Rotational C-arm CT (RCT) under rapid ventricular pacing was performed in 57 consecutive patients with severe aortic stenosis as part of the pre-procedural cardiac catheterization. With prototype software each RCT data set was segmented using a 3D heart model. From that the line of perpendicularity curve was obtained that generates a perpendicular view of the aortic annulus according to the right-cusp rule. To evaluate the accuracy of a model-based overlay we compared model- and expert-derived aortic root diameters.

RESULTS

For all 57 patients in the RCT cohort diameter measurements were obtained from two independent operators and were compared to the model-based measurements. The inter-observer variability was measured to be in the range of 0°-12.96° of angular C-arm displacement for two independent operators. The model-to-operator agreement was 0°-13.82°. The model-based and expert measurements of aortic root diameters evaluated at the aortic annulus (r = 0.79, P < 0.01), the aortic sinus (r = 0.93, P < 0.01) and the sino-tubular junction (r = 0.92, P < 0.01) correlated on a high level and the Bland-Altman analysis showed good agreement. The interobserver measurements did not show a significant bias.

CONCLUSION

Automatic segmentation of the aortic root using an anatomical model can accurately predict an optimal C-arm configuration, potentially simplifying current clinical workflows before and during TAVR.

Comparison of Manual and Automated Preprocedural Segmentation Tools to Predict the Annulus Plane Angulation and C-Arm Positioning for Transcatheter Aortic Valve Replacement

Background

Preprocedural manual multi-slice-CT-segmentation tools (MSCT-ST) define the gold standard for planning transcatheter aortic valve replacement (TAVR). They are able to predict the perpendicular line of the aortic annulus (PPL) and to indicate the corresponding C-arm angulation (CAA). Fully automated planning-tools and their clinical relevance have not been systematically evaluated in a real world setting so far.

Methods and Results

The study population consists of an all-comers cohort of 160 consecutive TAVR patients with a drop out of 35 patients for technical and anatomical reasons. 125 TAVR patients underwent preprocedural analysis by manual (M-MSCT) and fully automated MSCT-ST (A-MSCT). Method-comparison was performed for 105 patients (Cohort A). In Cohort A, CAA was defined for each patient, and accordance within 10° between M-MSCT and A-MSCT was considered adequate for concept-proof (95% in LAO/RAO; 94% in CRAN/CAUD). Intraprocedural CAA was defined by repetitive angiograms without utilizing the preprocedural measurements. In Cohort B, intraprocedural CAA was established with the use of A-MSCT (20 patients). Using preprocedural A-MSCT to indicate the corresponding CAA, the levels of contrast medium (ml) and radiation exposure (cine runs) were reduced in Cohort B compared to Cohort A significantly (23.3±10.3 vs. 35.3 ±21.1 ml, p = 0.02; 1.6±0.7 vs. 2.4±1.4 cine runs; p = 0.02) and trends towards more safety in valve-positioning could be demonstrated.

Conclusions

A-MSCT-analysis provides precise preprocedural information on CAA for optimal visualization of the aortic annulus compared to the M-MSCT gold standard. Intraprocedural application of this information during TAVR significantly reduces the levels of contrast and radiation exposure.

Trial Registration

ClinicalTrials.gov NCT01805739

Computed Tomography for Structural Heart Disease and Interventions

Transcatheter cardiac interventions are a fast evolving field. The past decade has seen the development of transcatheter aortic valve replacement, transcatheter mitral valve repair and replacement, septal defect closure devices and left atrial appendage closure devices for thromboprophylaxis. More than ever, medical imaging is taking a central role in the care of patients with structural heart disease. In this review article we outline the use of MSCT as a tool for diagnosis of structural heart interventions, as well as patient selection, pre-procedural planning, device sizing and post-procedural assessment. We focus on procedures targeting the aortic valve, the mitral valve, the inter-atrial septum and the left atrial appendage.

C-THV measures of self-expandable valve positioning and correlation with implant outcomes

BACKGROUND

Accurate positioning of the valve device during transcutaneous aortic valve implantation (TAVI) is of crucial importance. The Paieon C-THV navigation system has been designed to correctly guide device deployment during TAVI.

OBJECTIVES

Using this navigation system we aimed to determine the correlation between the anatomic measures of the native aortic valve and the deployed self-expandable valve positioning and to explore the impact upon procedural outcomes.

METHODS

We analyzed data of 68 patients with severe symptomatic aortic stenosis undergoing TAVI, using the catheter-based Medtronic-CoreValve self-expandable system. Patients were subdivided into two groups according to whether the C-THV system was used (50) or not (18) during the implantation process. Analysis of geometrical outcomes vs. clinical outcomes including postprocedural electrical conduction defect and/or para-valvular leaks was performed.

RESULTS

Taking the target implantation line as a reference; relatively lower vs. higher implantations correlated with a higher frequency of any new onset electrical conduction defect (ECD). The mean corresponding distance from valve inferior edge below the virtual aortic annulus line was 3.0 ± 1.6 mm vs. 1.2 ± 1.3 mm in patients with (38.5%) vs. without any new onset ECD, respectively (P = 0.05). The use of C-THV navigation seemed to correlate with higher valve implants but it had no impact on the occurrence of postprocedural paravalvular leaks.

CONCLUSIONS

Self-expandable valve implants guided by C-THV navigation seems to be associated with more precise implants and lower risk for postprocedural electrical conduction defects, due to higher location in relation to the target line.

Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

Background—

Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry.

Methods and Results—

The Global Valve-in-Valve Registry included 202 patients with degenerated bioprosthetic valves (aged 77.7±10.4 years; 52.5% men) from 38 cardiac centers. Bioprosthesis mode of failure was stenosis (n=85; 42%), regurgitation (n=68; 34%), or combined stenosis and regurgitation (n=49; 24%). Implanted devices included CoreValve (n=124) and Edwards SAPIEN (n=78). Procedural success was achieved in 93.1% of cases. Adverse procedural outcomes included initial device malposition in 15.3% of cases and ostial coronary obstruction in 3.5%. After the procedure, valve maximum/mean gradients were 28.4±14.1/15.9±8.6 mm Hg, and 95% of patients had ≤+1 degree of aortic regurgitation. At 30-day follow-up, all-cause mortality was 8.4%, and 84.1% of patients were at New York Heart Association functional class I/II. One-year follow-up was obtained in 87 patients, with 85.8% survival of treated patients.

Conclusions—

The valve-in-valve procedure is clinically effective in the vast majority of patients with degenerated bioprosthetic valves. Safety and efficacy concerns include device malposition, ostial coronary obstruction, and high gradients after the procedure.

Multicenter evaluation of Edwards SAPIEN positioning during transcatheter aortic valve implantation with correlates for device movement during final deployment

OBJECTIVES

This study sought to evaluate the exact location of Edwards SAPIEN (Edwards Lifesciences, Irvine, California) devices in different stages of implantation and to quantify possible operator-independent device movement during final deployment.

BACKGROUND

Accurate device positioning during transcatheter aortic valve implantation is crucial in order to achieve optimal results.

METHODS

This multicenter study consisted of 68 procedures with reliable pacemaker capture. Device positions were assessed using fluoroscopic images and the C-THV system (Paieon Medical, Rosh Ha'Ayin, Israel).

RESULTS

The location after implantation was significantly higher than in the final stage of rapid pacing: 16.7 ± 16.3% of device height below the plane of the lower sinus border versus 32.6 ± 13.8%, p < 0.0001. Operator-independent device-center upper movement during final deployment was 2 ± 1.43 mm, range: -1.3 to 4.6 mm. Device movement was asymmetrical, occurring more in the lower part of the device than in its upper part (3.2 ± 1.4 mm vs. 0.75 ± 1.5 mm, p < 0.001), resulting in device shortening. Multivariate analysis revealed that moderate and severe aortic valve calcification had 49% higher upward movement than mild calcification (p = 0.03), and aortic sinus volume was negatively correlated with movement size (r = -0.35, p = 0.005). This movement was independent of device version (SAPIEN vs. SAPIEN XT), procedural access (transfemoral vs. transapical), and interventricular septum width.

CONCLUSIONS

The final Edwards SAPIEN position is mostly aortic in relation to the lower sinus border. There is an operator-independent upward movement of the device center during the final stage of implantation. Anticipated upward movement of the device should influence its positioning before final deployment.

Multimodality imaging throughout transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is a novel, less-invasive technique used to treat selected patients with severe aortic valve stenosis with a high surgical risk. Noninvasive imaging before, during and after the procedure is of the utmost importance in this minimally invasive procedure. Screening of the patient and sizing of the aortic root by echocardiography and multislice computed tomography is of great importance to ensure success of the TAVI procedure. Echocardiography and fluoroscopy are essential during the procedure. During follow-up of the patients, echocardiography is important to evaluate the prosthesis function, durability and integrity. Additionally, multislice computed tomography and MRI might be helpful in the follow-up of selected cases. This article outlines the evolving role of multimodality imaging throughout TAVI in patients with severe aortic valve stenosis. It describes, in a stepwise approach, how multimodality imaging by echocardiography, angiography, multislice computed tomography and MRI enhances the TAVI procedure.

Prediction of optimal deployment projection for transcatheter aortic valve replacement: angiographic 3-dimensional reconstruction of the aortic root versus multidetector computed tomography

BACKGROUND

Identifying the optimal fluoroscopic projection of the aortic valve is important for successful transcatheter aortic valve replacement (TAVR). Various imaging modalities, including multidetector computed tomography (MDCT), have been proposed for prediction of the optimal deployment projection. We evaluated a method that provides 3-dimensional angiographic reconstructions (3DA) of the aortic root for prediction of the optimal deployment angle and compared it with MDCT.

METHODS AND RESULTS

Forty patients undergoing transfemoral TAVR at St Paul's Hospital, Vancouver, Canada, were evaluated. All underwent preimplant 3DA and 68% underwent preimplant MDCT. Three-dimensional angiographic reconstructions were generated from images of a C-arm rotational aortic root angiogram during breath-hold, rapid ventricular pacing, and injection of 32 mL contrast medium at 8 mL/s. Two independent operators prospectively predicted perpendicular valve projections. The implant angle was chosen at the discretion of the physician performing TAVR. The angles from 3DA, from MDCT, the implant angle, and the postdeployment perpendicular prosthesis view were compared. The shortest distance from the postdeployment perpendicular prosthesis projection to the regression line of predicted perpendicular projections was calculated. All but 1 patient had adequate image quality for reproducible angle predictions. There was a significant correlation between 3DA and MDCT for prediction of perpendicular valve projections (r=0.682, P<0.001). Deviation from the regression line of predicted angles to the postdeployment prosthesis view was 5.1±4.6° for 3DA and 7.9±4.9° for MDCT (P=0.01).

CONCLUSIONS

Three-dimensional angiographic reconstructions and MDCT are safe, practical, and accurate imaging modalities for identifying the optimal perpendicular valve deployment projection during TAVR.

Usefulness of TEE as the primary imaging technique to guide transcatheter transapical aortic valve implantation

OBJECTIVES

The aim of this study was to: 1) determine the usefulness of transesophageal echocardiography (TEE) as the primary technique to guide transapical (TA) transcatheter aortic valve implantation (TAVI); and 2) to compare TEE with angiography as the primary imaging modality for TA-TAVI guidance.

BACKGROUND

TEE has been routinely used as an adjunct to angiography during TA-TAVI procedures, but very few data exist on the use of TEE as the primary imaging technique guiding TA-TAVI.

METHODS

One hundred consecutive high-risk patients (mean age 79 ± 9 years, mean logistic EuroSCORE: 25.8 ± 17.6%) who underwent TA-TAVI in our center were included. The Edwards valve was used in all cases, and all procedures were performed in an operating room without hybrid facilities. The TA-TAVI was primarily guided by angiography in the first 25 patients (A-TAVI group) and by TEE in the last 75 patients (TEE-TAVI group). Procedural, 30-day, and follow-up results were evaluated.

RESULTS

No differences were observed between groups at baseline except for a higher (p = 0.001) prevalence of moderate or severe mitral regurgitation in the TEE-TAVI group. The procedure was successful in 97.3% and 100% of the patients in the TEE-TAVI and A-TAVI groups, respectively (p = 1.0), and a lower contrast volume was used in the TEE-TAVI group (12 [5 to 20] ml vs. 40 [20 to 50] ml, p < 0.0001). There were no differences between groups in the occurrence of valve malposition needing a second valve (TEE-TAVI: 5.3%; A-TAVI: 4%; p = 1.0) or valve embolization (TEE-TAVI: 1.3%; A-TAVI: 4%; p = 0.44). The results regarding post-procedural valve hemodynamic status and aortic regurgitation were similar between groups. The survival rates at 30-day and 1-year follow-up were 87% and 75% in the TEE-group and 88% and 84% in the A-TAVI group, respectively (log-rank = 0.49).

CONCLUSIONS

TEE-TAVI was associated with similar acute and midterm results as A-TAVI and significantly reduced contrast media use during the procedures. These results suggest the feasibility and safety of performing TA-TAVI procedures in an operating room without hybrid facilities, but larger studies are needed to confirm these findings.

The next revolution: percutaneous aortic valve replacement

Aortic valve replacement (AVR) is a treatment of choice for patients with symptomatic severe aortic stenosis (AS). However, a significant proportion of these patients do not undergo surgical AVR due to high-risk features. Transcatheter aortic valve implantation (TAVI) has emerged as an alternative for patients with severe AS who are not candidates for open-heart surgery. Since the introduction of TAVI to the medical community in 2002, there has been an explosive growth in procedures. The balloon-expandable Edwards SAPIEN valve and the self-expanding CoreValve ReValving(TM) system contribute the largest patient experience with more than 10,000 patients treated with TAVI to date. Clinical outcomes have stabilized in experienced hands, with 30-day mortality less than 10%. Careful patient selection, growing operator experience, and an integrated multidisciplinary team approach contribute to notable improvement in outcomes. In the first randomized pivotal PARTNER trial, in patients with severe AS not suitable candidates for surgical AVR, TAVI compared with standard therapy, significantly improved survival and cardiac symptoms, but was associated with higher incidence of major strokes and major vascular events. The results of randomized comparison of TAVI with AVR among high-risk patients with AS for whom surgery is a viable option are eagerly awaited to provide further evidence on the applicability of TAVI in these patients.