Integration of MDCT and fluoroscopy using C-arm computed tomography to guide structural cardiac interventions in the cardiac catheterization laboratory

Coronary Obstruction during Valve-in-Valve Transcatheter Aortic Valve Replacement: Pre-Procedural Risk Evaluation, Intra-Procedural Monitoring, and Follow-Up

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) is emerging as an effective treatment for patients with symptomatically failing bioprosthetic valves and a high prohibitive surgical risk; a longer life expectancy has led to a higher demand for these valve reinterventions due to the increased possibilities of outliving the bioprosthetic valve's durability. Coronary obstruction is the most feared complication of valve-in-valve (ViV) TAVR; it is a rare but life-threatening complication and occurs most frequently at the left coronary artery ostium. Accurate pre-procedural planning, mainly based on cardiac computed tomography, is crucial to determining the feasibility of a ViV TAVR and to assessing the anticipated risk of a coronary obstruction and the eventual need for coronary protection measures. Intraprocedurally, the aortic root and a selective coronary angiography are useful for evaluating the anatomic relationship between the aortic valve and coronary ostia; transesophageal echocardiographic real-time monitoring of the coronary flow with a color Doppler and pulsed-wave Doppler is a valuable tool that allows for a determination of real-time coronary patency and the detection of asymptomatic coronary obstructions. Because of the risk of developing a delayed coronary obstruction, the close postprocedural monitoring of patients at a high risk of developing coronary obstructions is advisable. CT simulations of ViV TAVR, 3D printing models, and fusion imaging represent the future directions that may help provide a personalized lifetime strategy and tailored approach for each patient, potentially minimizing complications and improving outcomes.

Echocardiographic guidance in transcatheter structural cardiac interventions

Catheter-based treatment of structural heart diseases (SHD) has seen tremendous advances in the past decades, thanks to the development of new devices and advances in imaging techniques. Today, we have an extensive armamentarium of imaging tools for preprocedural planning, intraprocedural guidance and follow-up of SHD. Intraprocedural guidance is based mainly on transoesophageal echocardiography; however, other imaging modalities are used as complementary or alternative techniques, each of them with its strengths and weaknesses. Thus, a multimodality imaging approach provides added values in this setting. As the field of imaging parallels the continuous technical improvements, this review will describe the state of the art imaging techniques, focusing on echocardiography during procedural guidance of the most common catheter-based interventions, providing tips and tricks for interventional cardiologists: in particular, how to guide transseptal crossing; left atrial appendage closure; transcatheter mitral or tricuspid valve repair or replacement; percutaneous closure of patent foramen ovale and atrial defects; and percutaneous closure of paravalvular leaks. Open challenges for the near future are the need for physicians with specific technical skills and competencies in SHD imaging, more attention to high levels of radiation exposure, and optimisation of intraprocedural and post-procedural evaluation.

Renaissance of Cardiac Imaging to Assist Percutaneous Interventions in Congenital Heart Diseases:The Role of Three-Dimensional Echocardiography and Multimodality Imaging

Percutaneous interventions have completely refashioned the management of children with congenital heart diseases (CHD) and the use of non-invasive imaging has become the gold standard to plan and guide these procedures in the modern era. We are now facing a dual challenge to improve the standard of care in low-risk patients, and to shift our strategies from the classic open chest surgery to imaging-guided percutaneous interventions in high-risk patients. Such rapid evolution of ultrasound technologies over the last 20 years have permitted the integration of transthoracic, transesophageal and intracardiac echocardiography into the interventional workflow to improve image guidance and reduce radiation burden from fluoroscopy and angiography. Specifically, miniaturization of transesophageal probe and advances in three-dimensional (3D) imaging techniques have enabled real-time 3D image guidance during complex interventional procedure, In addition, multimodality and fusion imaging techniques harness the strengths of different modalities to enhance understanding of anatomical and spatial relationship between different structures, improving communication and coordination between interventionalists and imaging specialists. In this review, we aim to provide an overview of 3D imaging modalities and multimodal fusion in procedural planning and live guidance of percutaneous interventions. At the present times, 3D imaging can no longer be considered a luxury but a routine clinical tool to improve procedural success and patient outcomes.

Patient selection, procedural planning and interventional guidance for transcatheter aortic valve intervention

Transcatheter aortic valve replacement (TAVR) is an established treatment for severe aortic stenosis across a broad spectrum of patient risk profiles. Pre-procedural planning using multislice computed tomography (MSCT) is a fundamental component to ensure acute and long-term procedural success. MSCT can establish the procedural feasibility, the type vascular of approach as well as the device which is more likely to give a good result. Moreover, MSCT is a key tool to estimate the risk of potentially life-threatening complications. In this review, the role of MSCT for pre-procedural TAVR planning will be discussed providing a panoramic overview of the key elements that should be considered when performing TAVR. Additionally, the adjunctive role of fluoroscopy and echocardiography to plan and guide a TAVR procedure will also be discussed.

Multimodality Cardiac Imaging for Procedural Planning and Guidance of Transcatheter Mitral Valve Replacement and Mitral Paravalvular Leak Closure

Transcatheter mitral valve interventions are an evolving and growing field in which multimodality cardiac imaging is essential for diagnosis, procedural planning, and intraprocedural guidance. Currently, transcatheter mitral valve-in-valve with a balloon-expandable valve is the only form of transcatheter mitral valve replacement (TMVR) approved by the FDA, but valve-in-ring and valve-in-mitral annular calcification interventions are increasingly being performed. Additionally, there are several devices under investigation for implantation in a native annulus. Paravalvular leak (PVL) is a known complication of surgical or transcatheter valve implantation, where regurgitant flow occurs between the prosthetic sewing ring and the native mitral annulus. We sought to describe the role and applications of multimodality cardiac imaging for TMVR, and PVL closure, including the use of Cardiovascular Computed Tomography Angiography and 3-Dimensional Transesophageal Echocardiography for diagnosis, prosthetic valve evaluation, pre-procedural planning, and intraprocedural guidance, as well as evolving technologies such as fusion imaging and 3D printing.

3D-XGuide: open-source X-ray navigation guidance system

PURPOSE

With the growing availability and variety of imaging modalities, new methods of intraoperative support have become available for all kinds of interventions. The basic principles of image fusion and image guidance have been widely adopted and are commercialized through a number of platforms. Although multimodal systems have been found to be useful for guiding interventional procedures, they all have their limitations. The integration of more advanced guidance techniques into the product functionality is, however, not easy due to the proprietary solutions of the vendors. Therefore, the purpose of this work is to introduce a software system for image fusion, real-time navigation, and working points documentation during transcatheter interventions performed under X-ray (XR) guidance.

METHODS

An interactive software system for cross-modal registration and image fusion of XR fluoroscopy with CT or MRI-derived anatomic 3D models is implemented using Qt application framework and VTK visualization pipeline. DICOM data can be imported in retrospective mode. Live XR data input is realized by a video capture card application interface.

RESULTS

The actual software release offers a graphical user interface with basic functionality including data import and handling, calculation of projection geometry and transformations between related coordinate systems, rigid 3D-3D registration, and template matching-based tracking and motion compensation algorithms in 2D and 3D. The link to the actual software release on GitHub including source code and executable is provided to support independent research and development in the field of intervention guidance.

CONCLUSION

The introduced system provides a common foundation for the rapid prototyping of new approaches in the field of XR fluoroscopic guidance. As a pure software solution, the developed system is potentially vendor-independent and can be easily extended to be used with the XR systems of different manufacturers.

Fusion imaging for transcatheter mitral and tricuspid interventions

Image guidance for transcatheter mitral and tricuspid valve intervention commonly utilizes the unique advantages of both fluoroscopy and live echocardiography. In some cases, pre-procedural computed tomography is also needed. Classically, they are displayed separately even if modalities are in simultaneous use. This requires procedural operators to watch separate images displaying complementary information and mentally combine these data sources. New hybrid, or fusion, imaging systems allow for multiple imaging modalities to be overlaid on one another to provide the most relevant information on a single screen. While this technological advancement may have some advantages in certain procedures, more data is needed to understand if these systems will improve procedural or clinical outcomes.

Cardiac Computed Tomography for Structural Heart Disease Assessment and Therapeutic Planning: Focus on Prosthetic Valve Dysfunction

Of the 100,000-plus valve surgeries performed each year in the United States, up to 6% of those develop complications from prosthetic valve dysfunction. Prosthetic valve dysfunction (PVD) can be life threatening and often challenging to diagnose. In this review, we discuss the prevalence and incidence of PVD, explore its different etiologies, and assess the role of multimodality imaging with an emphasis on cardiac multidetector computed tomography (MDCT) for evaluating patients with PVD. We also investigate the utility of MDCT in preprocedural planning for transcatheter devices and redo surgical planning and discuss management strategies for patients with PVD.

Emerging 3D technologies and applications within congenital heart disease: teach, predict, plan and guide

3D visualization technologies have evolved to become a mainstay in the management of congenital heart disease (CHD) with a growing presence within multiple facets. Printed and virtual 3D models allow for a more comprehensive approach to educating trainees and care team members. Computational fluid dynamics can take 3D modeling to the next level, by predicting post-procedural outcomes and helping to determine surgical approach. 3D printing and extended reality are developing resources for pre-procedural planning and intra-procedural guidance with the potential to revolutionize decision-making and procedural success. Challenges still remain within existing technologies and their applications to the CHD field. Addressing these gaps, both by those within and outside of CHD, will transform education and patient care within our field.

Three-dimensional rotational angiography in congenital heart disease: Present status and evolving future

Three-dimensional rotational angiography (3D-RA) enables volumetric imaging through rotation of the C-arm of an angiographic system and real-time 3D reconstruction during cardiac catheterization procedures. In the field of congenital heart disease (CHD), 3D-RA has gained considerable traction, owing to its capability for enhanced visualization of spatial relationships in complex cardiac morphologies and real time image guidance in an intricate interventional environment. This review provides an overview of the current applications, strengths, and limitations of 3D-RA acquisition in the management of CHD and potential future directions. In addition, issues of dosimetry, radiation exposure, and optimization strategies will be reviewed. Further implementation of 3D-RA will be driven by patient benefits relative to existing 3D imaging capabilities and fusion techniques balanced against radiation exposure.

Clinical utility of intraprocedural three-dimensional integrated image guided transcatheter aortic valve implantation using novel automated computed tomography software: A single-center preliminary experience

OBJECTIVES

Novel automated computed tomography (CT) software (Valve ASSIST 2) has been developed for transcatheter aortic valve implantation (TAVI), which not only provides three-dimensional (3D) reconstruction of multidetector (MD) CT images, but also enables intraprocedural real-time fusion of fluoroscopic and MDCT images. We aimed to clarify the reproducibility and accuracy of this software in the aortic annulus assessment and verify the potential of intraprocedural integrated MDCT imaging for TAVI.

METHODS AND RESULTS

We examined 50 patients with severe aortic stenosis undergoing transfemoral TAVI. Aortic annulus measurements were performed using 3mensio and the novel planning software. For intraprocedural imaging, preoperative CT dataset was overlaid onto fluoroscopy with the fusion software. The two images were aligned using the aortic root anatomy visible on both modalities. Novel planning software provided excellent reproducibility for the measurement of aortic annulus area (intraobserver intraclass correlation coefficients [ICC] 0.959, interobserver ICC 0.941), and perimeter (intraobserver ICC 0.915, interobserver ICC 0.912). Excellent correlation was found between novel planning software and 3mensio (ICC 0.952 for aortic annulus area, and 0.923 for perimeter). Intraprocedural fusion image of CT aortography and fluoroscopic aortic root aortography generated by this novel software identified coronary orifices and the distribution of aortic valve calcification during the device positioning. Fusion image displayed coronary orifices after device implantation.

CONCLUSIONS

Novel planning software showed excellent reproducibility and accuracy in the assessment of aortic root anatomy. Furthermore, the integrated 3D fusion image might have a potential as an intraprocedural imaging modality to contribute to the development of a safer TAVI procedure.

Transcatheter closure of a sinus venosus atrial septal defect using 3D printing and image fusion guidance

A 63‐year‐old man with cirrhosis, hepatocellular carcinoma, and coagulopathy was diagnosed with a sinus venosus atrial septal defect (ASD) and partial anomalous pulmonary venous return (PAPVR) of the right upper pulmonary vein (RUPV). Transcatheter repair by positioning a stent graft in the superior vena cava was planned. Based on three‐dimensional (3D) reconstruction of gated cardiac CTA, a 28 mm × 7 cm Endurant II^® aortic extension stent graft (Medtronic, MN) was chosen. A 3D model printed from the CTA was used to simulate device deployment, demonstrating successful exclusion of the sinus venosus ASD with return of the RUPV to the left atrium (LA). Post simulation, the 3D model was used for informed consent. The patient was then taken to the hybrid operating room. On‐table cone beam CT was performed and registered with the CTA images. This enabled overlay of 3D regions of interest to live 2D fluoroscopy. The stent graft was then deployed using 3D regions of interest for guidance. Hemodynamics and angiography demonstrated successful exclusion of the sinus venosus ASD and unobstructed return of RUPV to the LA. This is the first report of comprehensive use of contemporary imaging for planning, simulation, patient consent, and procedural guidance for patient‐centered complex structural intervention in repair of sinus venosus ASD with PAPVR. We propose this as a process model for continued innovation in structural interventions.

Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to facilitate anatomical guidance is of huge interest for complex cardiac interventions like TAVI procedures with cerebral protection. Co-registration of CTA and XR has been introduced either based on additional intraoperative non-/contrast-enhanced cone-beam computed tomography (CBCT) or two separate aortograms. With the related increase of radiation exposure and/or contrast agent (CA) dose, a potential additional risk for the patient is introduced. Here, we propose a modified co-registration approach making use of arteriograms of the iliofemoral arteries, routinely performed during the femoral puncture and sheath introduction. On-the-fly refinement of the co-registration during the on-going procedure enables accurate co-registration without any additional angiograms, thus reducing CA, XR dose and procedure time, while simultaneously improving operator confidence and procedure safety.

Complex Structural Interventions: The Role of Computed Tomography, Fluoroscopy, and Fusion Imaging

Noninvasive cardiac imaging has played a critical part in the evaluation, monitoring, and follow-up of structural heart disease. This review will highlight the role of cardiac computed tomography, fluoroscopy, and fusion imaging in guiding transcatheter aortic valve replacement and other percutaneous strategies used to diagnose and treat complex structural heart complications.

The Pivotal Role of Imaging in TAVR Procedures

PURPOSE OF REVIEW

Transcatheter aortic valve replacement (TAVR) is underpinned by an array of imaging techniques designed to not only select an appropriately sized implant but also to identify potential obstacles to procedural success. This review presents currently important aspects of TAVR imaging, describing the salient features of each modality as well as recent developments in the field.

RECENT FINDINGS

The latest data on TAVR outcomes reflects the increasing experience of operators and the significant role of pre-procedural imaging. Debate continues as to which modality sizes the aortic annulus most accurately, 3D transoesophageal echocardiography (TEE) or MDCT, as well as to whether the merits of real-time peri-procedural 3D imaging guidance outweigh the possible adverse consequences of general anaesthesia which is requisite for intraprocedural 3D TEE. TAVR is now largely based on pre-acquired roadmaps of the truncal vasculature and intense pre-procedural planning. TEE and Multi-detector computed tomography (MDCT) have been shown to perform similarly in annulus sizing. However, given the complexity of many TAVR patients and the importance of identifying the most suitable pathway to the valve as well as any potentially confounding other structural or functional heart disease, both modalities remain relevant in current TAVR.

Fusion Imaging for Procedural Guidance

The field of percutaneous structural heart interventions has grown tremendously in recent years. This growth has fueled the development of new imaging protocols and technologies in parallel to help facilitate these minimally-invasive procedures. Fusion imaging is an exciting new technology that combines the strength of 2 imaging modalities and has the potential to improve procedural planning and the safety of many commonly performed transcatheter procedures. In this review we discuss the basic concepts of fusion imaging along with the relative strengths and weaknesses of static vs dynamic fusion imaging modalities. This review will focus primarily on echocardiographic-fluoroscopic fusion imaging and its application in commonly performed transcatheter structural heart procedures.

Multi-Modality Imaging in the Evaluation and Treatment of Mitral Regurgitation

OPINION STATEMENT

Mitral regurgitation (MR) is frequent and associated with increased mortality and morbidity when severe. It may be caused by intrinsic valvular disease (primary MR) or ventricular deformation (secondary MR). Imaging has a critical role to document the severity, mechanism, and impact of MR on heart function as selected patients with MR may benefit from surgery whereas other will not. In patients planned for a surgical intervention, imaging is also important to select candidates for mitral valve (MV) repair over replacement and to predict surgical success. Although standard transthoracic echocardiography is the first-line modality to evaluate MR, newer imaging modalities like three-dimensional (3D) transesophageal echocardiography, stress echocardiography, cardiac magnetic resonance (CMR), and computed tomography (CT) are emerging and complementary tools for MR assessment. While some of these modalities can provide insight into MR severity, others will help to determine its mechanism. Understanding the advantages and limitations of each imaging modality is important to appreciate their respective role for MR assessment and help to resolve eventual discrepancies between different diagnostic methods. With the increasing use of transcatheter mitral procedures (repair or replacement) for high-surgical-risk patients, multimodality imaging has now become even more important to determine eligibility, preinterventional planning, and periprocedural guidance.

Real-time three dimensional CT and MRI to guide interventions for congenital heart disease and acquired pulmonary vein stenosis

To validate the feasibility and spatial accuracy of pre-procedural 3D images to 3D rotational fluoroscopy registration to guide interventional procedures in patients with congenital heart disease and acquired pulmonary vein stenosis. Cardiac interventions in patients with congenital and structural heart disease require complex catheter manipulation. Current technology allows registration of the anatomy obtained from 3D CT and/or MRI to be overlaid onto fluoroscopy. Thirty patients scheduled for interventional procedures from 12/2012 to 8/2015 were prospectively recruited. A C-arm CT using a biplane C-arm system (Artis zee, VC14H, Siemens Healthcare) was acquired to enable 3D3D registration with pre-procedural images. Following successful image fusion, the anatomic landmarks marked in pre-procedural images were overlaid on live fluoroscopy. The accuracy of image registration was determined by measuring the distance between overlay markers and a reference point in the image. The clinical utility of the registration was evaluated as either "High", "Medium" or "None". Seventeen patients with congenital heart disease and 13 with acquired pulmonary vein stenosis were enrolled. Accuracy and benefit of registration were not evaluated in two patients due to suboptimal images. The distance between the marker and the actual anatomical location was 0-2 mm in 18 (64%), 2-4 mm in 3 (11%) and >4 mm in 7 (25%) patients. 3D3D registration was highly beneficial in 18 (64%), intermediate in 3 (11%), and not beneficial in 7 (25%) patients. 3D3D registration can facilitate complex congenital and structural interventions. It may reduce procedure time, radiation and contrast dose.

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.

The Changing Paradigm in the Treatment of Structural Heart Disease and the Need for the Interventional Imaging Specialist

Percutaneous interventions in structural heart diseases are emerging rapidly. The variety of novel percutaneous treatment approaches and the increasing complexity of interventional procedures are associated with new challenges and demands on the imaging specialist. Standard catheterisation laboratory imaging modalities such as fluoroscopy and contrast ventriculography provide inadequate visualisation of the soft tissue or three-dimensional delineation of the heart. Consequently, additional advanced imaging technology is needed to diagnose and precisely identify structural heart diseases, to properly select patients for specific interventions and to support fluoroscopy in guiding procedures. As imaging expertise constitutes a key factor in the decision-making process and in the management of patients with structural heart disease, the sub-speciality of interventional imaging will likely develop out of an increased need for high-quality imaging.

Percutaneous Paravalvular Leak Closure

Symptomatic paravalvular leak (PVL) complicates up to 12 % of surgical valve replacements. When patients present with congestive heart failure and/or haemolysis, reoperation for repeat valve replacement may be undertaken, but presents greater risk and lower likelihood of success than the initial operation. Therefore, percutaneous approaches to PVL closure have been developed by specialists in structural cardiac intervention. Large series demonstrate high levels of procedural success and promising clinical outcomes for this complex intervention. A thorough understanding of multimodality imaging is necessary for the diagnosis of PVL and the safe and successful performance of these closure procedures.