Optimal Imaging for Guiding TAVR: Transesophageal or Transthoracic Echocardiography, or Just Fluoroscopy?

Current Usefulness of Transesophageal Echocardiography in Patients Undergoing Transcatheter Aortic Valve Replacement

This review article describes in depth the current usefulness of transesophageal echocardiography in patients who undergo transcatheter aortic valve replacement. Pre-intervention, 3D-transesophageal echocardiography allows us to accurately evaluate the aortic valve morphology and to measure the valve annulus, helping us to choose the appropriate size of the prosthesis, especially useful in cases where the computed tomography is not of adequate quality. Although it is not currently used routinely during the intervention, it remains essential in those cases of greater complexity, such as for patients with greater calcification and bicuspid valve, mechanical mitral prosthesis, and "valve in valve" procedures. Three-dimensional transesophageal echocardiography is the best technique to detect and quantify paravalvular regurgitation, a fundamental aspect to decide whether immediate valve postdilation is needed. It also allows to detect early any immediate complications such as cardiac tamponade, aortic hematoma or dissection, migration of the prosthesis, malfunction of the prosthetic leaflets, or the appearance of segmental contractility disorders due to compromise of the coronary arteries ostium. Transesophageal echocardiography is also very useful in follow-up, to check the proper functioning of the prosthesis and to rule out complications such as thrombosis of the leaflets, endocarditis, or prosthetic degeneration.

Results of new-generation balloon vs. self-expandable transcatheter heart valves for bicuspid aortic valve stenosis

Background

Data comparing new-generation self-expandable (SEV, Evolut R/PRO) vs. balloon-expandable (BEV, SAPIEN 3/3Ultra) transcatheter heart valve replacement (TAVR) in bicuspid aortic valve stenosis (BAV) is limited. Our aim was to compare 30-day results of SEV and BEV implantations in patients with BAV.

Methods

A total of 2009 patients underwent TAVR between April 2015 and June 2021 at our Centre. From our institutional registry, we identified 106 consecutive patients with BAV who underwent TAVR using SEV and BEV.

Results

A 106 patients (n = 68 BEV; n = 38 SEV) were included. Mean age was 74.6 ± 8.8 years (BEV) vs.75.3 ± 8.7 years (SEV) (p = 0.670) and Society of Thoracic Surgeons score was 2.6 ± 1.9 (BEV) vs. 2.6 ± 1.6 (SEV) (p = 0.374), respectively. Device landing zone calcium volume (DLZ-CV) was 1168 ± 811 vs. 945 ± 850 mm3 (p = 0.192). Valve Academic Research Consortium (VARC)-3 device success at 30 days was similar (BEV 80.9% vs. SEV 86.8%; p = 0.433). More post-dilatations were performed in SEVs (23.5% BEV vs. 52.6% SEV; p = 0.002). Overall mean gradient at 30 days follow-up was 11.9 ± 4.6 mmHG (BEV) vs. 9.2 ± 3.0 mmHG (SEV) (p = 0.002). A mild-moderate degree of paravalvular leak (PVL) was detected more often in the SEV group (7.4% vs. 13.2%; p = 0.305). A trend towards higher rate of permanent pacemaker implantation was observed in SEV (11.8% vs. 23.7%; p = 0.109).

Conclusions

Treatment of BAV revealed similar performance using BEV and SEV. In this retrospective cohort study, hemodynamics were more favorable with the SEV, although there was a trend toward more PVL and significantly more post-dilations.

Transesophageal Echocardiography vs. Transthoracic Echocardiography for Methicillin-Sensitive Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Endocarditis

Infective endocarditis is an infection of the inner layers of the heart, seen often in intravenous drug users and patients with valvular lesions or prosthetic heart valves. This entity has high mortality and morbidity. The most common causative microorganism is Staphylococcus aureus. In this comprehensive literature review, we focused on both Staphylococcus aureus infections, i.e., methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) endocarditis, demographics, use of transthoracic echocardiogram and/or transesophageal echocardiogram for diagnostics, and treatments. Although clinical criteria are relevant, transesophageal echocardiogram plays a vital role in establishing and identifying the presence of infective endocarditis and its local complications, with higher sensitivity in patients with prosthetic valves. The antibiotic selection posed a great challenge for clinicians due to antibiotic resistance and the aggressive nature of Staphylococcus aureus. Early diagnosis of infective endocarditis, when suspected, and effective management by a multispecialty team can improve the outcome for the patients.

An Unexpected Free-Floating Aortic Valve Leaflet Avulsion in the Left Atrium on Transesophageal Echocardiography During Transcatheter Aortic Valve Implantation Under Extracorporeal Membrane Oxygenation

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Aortic valve leaflet avulsion is a rare complication during TAVI.

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Avulsed leaflet traveled to the LA with ECMO flow and migrated to the aorta.

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TEE aided in timely management and helped complete the transcatheter intervention.

A time-efficient protocol for transthoracic echocardiography during transfemoral transcatheter aortic valve implantation: early identification and effective management of intraprocedural complications

Transfemoral transcatheter aortic valve implantation (TAVI) under conscious sedation is the most widely used method of implantation. Echocardiography is used to detect complications and to assess the implantation result. The aim of this paper is to provide a time-efficient protocol when transthoracic echocardiography (TTE) is used to guide TAVI procedures.

Safety and efficacy of minimalist transcatheter aortic valve implantation using a new-generation balloon-expandable transcatheter heart valve in bicuspid and tricuspid aortic valves

BACKGROUND

Bicuspid aortic valve may be associated with increased complications during transcatheter aortic valve implantation (TAVI).

AIMS

Compare balloon-expandable transcatheter heart valve (THV) safety and efficacy in severe tricuspid (TAV) and bicuspid (BAV) aortic stenosis.

METHODS

Transfemoral TAVI was performed in 743 patients (Jan 2014-June 2019) using the SAPIEN 3 THV. Aortic valve morphology was determined using computed tomography. Valve Academic Research Consortium-2 (VARC-2) derived safety and efficacy endpoints at 1 year were evaluated.

RESULTS

BAV patients (n = 78), were younger (77 [72, 81] vs. 81 [78, 85] years, p < 0.001) with lower surgical risk (EuroSCORE II 2.96% vs. 4.51% p < 0.001). Bicuspid valves were more calcified (BAV 1308mm³, TAV 848mm³ p < 0.001) with more asymmetric calcification (BAV 63/78 (81%), TAV 239/665 (36%), p < 0.001). Device success (BAV 94%, TAV 90%, p = 0.45) and major vascular complications (BAV 6%, TAV 9%, p = 0.66) were comparable. At 1 year, there was a trend toward lower combined all-cause mortality and rehospitalization for congestive heart failure in BAV patients (BAV 7%, TAV 13%, p = 0.08) with significantly lower all-cause mortality in this cohort (BAV 1%, TAV 9%, p = 0.020). VARC-2 time-related valve safety (BAV 22%, TAV 20%, p = 0.60) was comparable; however, bioprosthetic valve thrombosis remained more common in BAV patients (BAV 7%, TAV 2%, p = 0.010, Hazard ratio 3.57 [95% confidence interval 1.26, 10.10]). After propensity score matching, only bioprosthetic valve thrombosis remained significantly different.

CONCLUSIONS

Safety and efficacy of the SAPIEN 3 balloon-expandable THV in BAV is comparable with TAV. Higher rates of bioprosthetic valve thrombosis require further investigation.

Application of Balloon-Expandable Transcatheter Heart Valve in Bicuspid Aortic Valve

Bicuspid aortic valve (BAV) remains challenging in transcatheter aortic valve replacement (TAVR) because of unfavorable anatomy. New-generation balloon-expandable valve (BEV) appears to be a valid alternative to surgery, especially in some Asian countries with a higher prevalence of BAV. This tutorial review summarizes current thinking about how to plan and implant BEV in BAVs using versatile techniques. First, the authors depict the main morphological characteristics of BAVs and their effects on the TAVR procedure. Next, the authors provide preprocedural analysis on sizing, obtaining the optimal deployment projection, and how to simplify valve-crossing. Finally, the authors provide step-by-step guidance on how to deploy the BEVs with evolved iterations in terms of specific anatomies, calcified annulus, and giant annulus.

Technical and clinical study of x-ray-based surface echo probe tracking using an attached fiducial apparatus

PURPOSE

Several types of structural heart intervention (SHI) use information from multiple imaging modalities to complete an interventional task. For example, in transcatheter aortic valve replacement (TAVR), placement and deployment of a bioprosthetic aortic valve in the aorta is primarily guided by x-ray fluoroscopy (XRF), and echocardiography provides visualization of cardiac anatomy and blood flow. However, simultaneous interpretation of independent x-ray and echo displays remains a challenge for the interventionalist. The purpose of this work was to develop a novel echo/x-ray co-registration solution in which volumetric transthoracic echo (TTE) is transformed to the x-ray coordinate system by tracking the three-dimensional (3D) pose of a probe fiducial attachment from its appearance in two-dimensional (2D) x-ray images.

METHODS

A fiducial attachment for a commercial TTE probe consisting of rings of high-contrast ball bearings was designed and fabricated. The 3D pose (position and orientation) of the fiducial attachment is estimated from a 2D x-ray image using an algorithm in which a virtual point cloud model of the attachment is iteratively rotated, translated, and forward-projected onto the image until the average sum-of-squares of grayscale values at the projected points is minimized. Fiducial registration error (FRE) and target registration error (TRE) of this approach were evaluated in phantom studies using TAVR-relevant gantry orientations and four standard acoustic windows for the TTE probe. A patient study was conducted to assess the clinical suitability of the fiducial attachment prototype during TTE imaging of patients undergoing SHI. TTE image quality for the task of guiding a transcatheter procedure was evaluated in a reviewer study.

RESULTS

The 3D FRE ranged from 0.32 ± 0.03 mm (mean ± SD) to 1.31 ± 0.05 mm, depending on C-arm orientation and probe acoustic window. The 3D TRE ranged from 1.06 ± 0.03 mm to 2.42 ± 0.06 mm. Fiducial pose estimation was stable when >75% of the fiducial markers were visible in the x-ray image. A panel of reviewers graded the presentation of heart valves in TTE images from 48 SHI patients. While valve presentation did not differ significantly between acoustic windows (P > 0.05), the mitral valve did achieve a significantly higher image quality compared to the aortic and tricuspid valves (P < 0.001). Overall, reviewers perceived sufficient image quality in 76.5% of images of the mitral valve, 54.9% of images of the aortic valve, and 48.6% of images of the tricuspid valve.

CONCLUSIONS

Fiducial-based tracking of a commercial TTE probe is compatible with clinical SHI workflows and yields 3D target registration error of less than 2.5 mm for a variety of x-ray gantry geometries and echo probe acoustic windows. Although TTE image quality with respect to target valve anatomy was sufficient for the majority of cases examined, prescreening of patients for sufficient TTE quality would be helpful.

Evaluation of a Low-Dose Radiation Protocol During Transcatheter Aortic Valve Implantation

We aimed to evaluate the efficacy and safety of a low-dose imaging protocol to reduce intraprocedural radiation during transcatheter aortic valve implantation (TAVI). Observational analysis: 802 transfemoral TAVI patients receiving balloon-expandable devices ≥23 mm at a high-volume centre. After propensity score matching, a standard-dose group (SD, n = 333) treated between January 2014 and February 2016 was compared with a low-dose group (LD, n = 333) treated between August 2017 and March 2019 after departmental uptake of a low-dose imaging protocol (reduced field size, high table height, use of "fluoro save," 3.75 frames/second acquisition, increased filtering). Primary end point was dose-area product (DAP). Secondary safety end points were VARC-2 device success and a composite of in-hospital complications. The LD protocol was associated with lower DAP (4.64 [2.93, 8.42] vs 22.73 [12.31, 34.58] Gy⋅cm², p <0.001) and fluoroscopy time (10.4 [8.1, 13.9] vs 11.5 [9.1, 15.3] minutes, p = 0.001). Contrast use was higher in the LD group (LD 110 [94, 130] vs SD 100 [80, 135] milliliters, p = 0.042). Device success (LD 88.3% vs SD 91.3%, p = 0.25), and the composite end point (LD 8.1% vs SD 11.4%, p = 0.19) were similar. In multivariate analysis, the low-dose protocol was associated with a 19.8 Gy⋅cm² reduction in procedural DAP (p <0.001). In conclusion, compared with standard imaging, a low-dose protocol for TAVI significantly reduced radiation dose without compromising outcomes.

TAVR-related echocardiographic assessment - status quo, challenges and perspectives

Transcatheter aortic valve replacement (TAVR) is an emerging and a well-established procedure for high-risk and inoperable patients worldwide. Recent studies revealed furthermore that TAVR is equal or even superior to surgical valve replacement in intermediate risk patients. Therefore, a successful procedure is not only dependent on precise preprocedural patient selection but also on careful intraprocedural multimodal imaging guidance and adequate postprocedural follow-up. Up to date, 2D/3D transthoracic and/or transoesophageal echocardiography is an easy and goal-oriented tool for periprocedural TAVR-assessment regarding annulus measurements, cardiac function and concomitant valve diseases. Further procedural success is directly related to prevention of severe early and late complications. Thus, a careful intra- and postprocedural echocardiographic guidance is crucial to evaluate prosthetic function, position and its haemodynamic implication and changes in the integrity of the left ventricle during intra- and postprocedural management. We explored the role of echocardiography for pre-, intra- and postprocedural TAVR-assessment, illustrated by cases and possible algorithms, in a comprehensive literature review. Furthermore, we describe the role of fusion imaging, that is, real-time fusion of transoesophageal echocardiography and fluoroscopy (EchoNavigator Release System^® I and II) during TAVR.

Echocardiographic guidance of interventions in adults with congenital heart defects

Cardiac catheterization procedures have revolutionized the treatment of adults with congenital heart disease over the past six decades. Patients who previously would have required open heart surgery for various conditions can now undergo percutaneous cardiac catheter-based procedures to close intracardiac shunts, relieve obstructive valvular lesions, stent stenotic vessels, or even replace and repair dysfunctional valves. As the complexity of percutaneous cardiac catheterization procedures has increased, so has the use of echocardiography for interventional guidance in adults with congenital heart disease. Transthoracic, transesophageal, intracardiac, and three-dimensional echocardiography have all become part and parcel of the catheterization laboratory experience. In this review, we aim to describe the different echocardiographic techniques and their role in various cardiac catheterization interventions specific to adults with congenital heart disease.

Paravalvular Regurgitation After Transcatheter Aortic Valve Replacement: Is the Problem Solved?

Paravalvular regurgitation is a frequent complication after transcatheter aortic valve replacement and its association with worse outcomes depends on the degree of its severity. Despite substantial improvement in transcatheter heart valve design, sizing and implantation technique, moderate or severe paravalvular regurgitation still occurs in 2% to 7% of patients and is associated with a more than 2-fold increase in mortality. This review provides a state-of-the-art approach to (i) paravalvular regurgitation prevention by optimizing patient selection, valve sizing, and positioning and (ii) the detection, quantitation and management of paravalvular regurgitation during and after valve implantation.

Catheterization Laboratory: Structural Heart Disease, Devices, and Transcatheter Aortic Valve Replacement

The cardiac catheterization laboratory is advancing medicine by performing procedures on patients who would usually require sternotomy and cardiopulmonary bypass. These procedures are done percutaneously, allowing them to be performed on patients considered inoperable. Patients have compromised cardiovascular function or advanced age. An anesthesiologist is essential for these procedures in case of hemodynamic compromise. Interventionalists are becoming more familiar with transcatheter aortic valve replacement and the device has become smaller, both contributing to less complications. Left atrial occlusion and the endovascular edge-to-edge mitral valve repair devices were approved. Although these devices require general anesthesia, an invasive surgery and cardiopulmonary bypass machine are not necessary for deployment.

Interventional Echocardiography: Field of Advanced Imaging to Support Structural Heart Interventions

Multimodality imaging, particularly echocardiography, is paramount in planning and guiding structural heart disease interventions. Transesophageal echocardiography remains unique in its ability to provide real-time 2D and 3D imaging of valvular heart disease and anatomic cardiac defects, which directly impacts the strategy and outcome of these procedures. This review summarizes the role of transesophageal echocardiography in patients undergoing the most common structural heart disease interventions.

The role of echocardiography and CT angiography in transcatheter aortic valve implantation patients

The transcatheter aortic valve implantation (TAVI) consist an alternative treatment in patients with severe aortic stenosis. Multimodality imaging using transthoracic echocardiography (TTE) or transesophageal echocardiography (TOE) and multislice CT (MSCT) constitute cornerstone techniques for the pre-operative management, peri-procedural guidance, follow up and recognition of possible transcatheter valve related complications. CT angiography is much more accurate regarding the total definition of aortic annulus diameter and circumferential area. Two-dimensional (2D) echocardiography, underestimates the aortic valve annulus diameter compared to 3D imaging techniques (MSCT, MRI and 3D TOE). Three-dimensional TOE imaging provides measurements of the aortic valve annulus similar to those delivered by MSCT. The pre-procedural MSCT constitutes the gold standard modality minimizing the presence of paravalvular aortic regurgitation, one of the most frequent complications. TOE/TTE and MSCT performance could predict the possibility of pacemaker implantation post-procedural. The presence of a new transient or persisting MR can be assessed well by TOE. Both TTE and TOE, consist initially the basic examination for post TAVI evaluation. In case of transcatheter heart valve failure, the MSCT could be used as additional imaging technique.

Evaluation of Imaging Strategy to Optimize and Improve Outcome of Transcatheter Aortic Valvular Implantation

Cardiac computed tomography (CT) provides additional information with ultrasound in the transcatheter heart valve (THV) size selection. However, the influence of these incremental data on outcomes has not been evaluated in a randomized study. A single-center prospective, randomized, and open study was performed. Patients referred for transfemoral transcatheter aortic valve implantation with a balloon-expandable endoprothesis were included. THV size selection was performed using either transthoracic and transesophageal echocardiography data (control group) or ultrasound and CT results (CT group). The primary composite end point included the occurrence of stroke, major vascular complications, and moderate or severe paravalvular aortic regurgitation (PAR) at 1 year. Fifty patients (n = 25 in the control and CT groups) were enrolled. The primary composite end point occurred in 40% and 8% of patients from the control and CT groups, respectively (p = 0.008). The Kaplan-Meier analysis revealed a pejorative association with not performing the CT (p = 0.007). A decrease in the occurrence of PAR was observed in the CT group compared with the control group (PAR 28% vs 4%, p = 0.04; major vascular complications 12% vs 4%, p = 0.6; all-cause death 16% vs. 4%, p = 0.34; no stroke). In conclusion, the use of cardiac CT in addition to ultrasound data in THV size selection reduced the long-term occurrence of cardiovascular events.

Intracardiac Echocardiography for Structural Heart and Electrophysiological Interventions

PURPOSE OF REVIEW

With an increasing number of interventional procedures performed for structural heart disease and cardiac arrhythmias each year, echocardiographic guidance is necessary for safe and efficient results. The purpose of this review article is to overview the principles of intracardiac echocardiography (ICE) and describes the peri-interventional role of ICE in a variety of structural heart disease and electrophysiological interventions.

RECENT FINDINGS

Both transthoracic (TTE) and transesophageal echocardiography have limitations. ICE provides the advantage of imaging from within the heart, providing shorter image distances and higher resolution. ICE may be performed without sedation and avoids esophageal intubation as with transesophageal echocardiography (TEE). Limitations of ICE include the need for additional venous access with possibility of vascular complications, potentially higher costs, and a learning curve for new operators. Data supports the use of ICE in guiding device closure of interatrial shunts, transseptal puncture, and electrophysiologic procedures. This paper reviews the more recent reports that ICE may be used for primary guidance or as a supplement to TEE in patients undergoing left atrial appendage (LAA) closure, interatrial shunt closure, transaortic valve implantation (TAVI), percutaneous mitral valve repair (PMVR), paravalvular leak (PVL) closure, aortic interventions, transcatheter pulmonary valve replacement (tPVR), ventricular septal defect (VSD), and patent ductus arteriosus (PDA) closure. ICE imaging technology will continue to expand and help improve structural heart and electrophysiology interventions.

Paravalvular Regurgitation after Transcatheter Aortic Valve Replacement: Comparing Transthoracic versus Transesophageal Echocardiographic Guidance

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is increasingly being performed in cardiac catheterization laboratories using transthoracic echocardiography (TTE) to guide valve deployment. The risk of paravalvular regurgitation (PVR) remains a concern.

METHODS

We retrospectively reviewed 454 consecutive patients (mean age, 82 ± 8; 58% male) who underwent transfemoral TAVR at Emory Healthcare from 2007 to 2014. Two hundred thirty-four patients underwent TAVR in the cardiac catheterization laboratory with TTE guidance (TTE-TAVR; mean Society of Thoracic Surgeons score, 10%), while 220 patients underwent the procedure in the hybrid operating room with transesophageal echocardiography (TEE) guidance (TEE-TAVR; mean Society of Thoracic Surgeons score, 11%). All patients received an Edwards valve (SAPIEN 55%, SAPIEN-XT 45%). Clinical and procedural characteristics, echocardiographic parameters, and incidence of PVR were compared.

RESULTS

The incidence of at least mild PVR at discharge was comparable between TTE-TAVR and TEE-TAVR (33% vs 38%, respectively; P = .326) and did not differ when stratified by valve type. However, in the TTE-TAVR group, there was a higher incidence of second valve implantation (7% vs 2%; P = .026) and postdilation (38% vs 17%; P < .001) during the procedure. Although not independently associated with PVR at discharge (odds ratio = 1.12; 95% CI, 0.69-1.79), TTE-TAVR was associated with PVR-related events: the combined outcome of mild PVR at discharge, intraprocedural postdilation, and second valve insertion (odds ratio = 1.58; 95% CI, 1.01-2.46). There were no significant differences in PVR at 30 days, 6 months, and 1 year between the two groups.

CONCLUSIONS

TTE-TAVR in a high-risk group of patients was associated with increased incidence of intraprocedure PVR-related events, although it was not associated with higher rates of PVR at follow-up. Multicenter randomized trials are required to confirm the cost-effectiveness and safety of TTE-TAVR.

Standard imaging techniques in transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) has become a widely accepted therapeutic option for patients with severe, symptomatic aortic stenosis at intermediate, high, or extreme risk for conventional surgery as determined through a heart team approach. Two valve prostheses are currently available and the Food and Drug Administration (FDA) approved in the United States for TAVR: the self-expandable Medtronic CoreValve (Medtronic, Inc., Minneapolis, MN, USA) and the balloon-expandable Edwards Sapien Valve (Edwards Lifesciences, Irvine CA, USA). The preoperative evaluation for TAVR includes transthoracic echocardiography (TTE) for the diagnosis of aortic stenosis. Cardiac computed tomography (CTA) has become the imaging modality of choice for annular sizing. Aortic root dimensions and coronary ostia height, and the degree of annular and left ventricular outflow tract calcification are also assessed to estimate the risk of coronary obstruction, annular rupture, and postoperative aortic regurgitation. Finally, CTA is essential to determine the adequacy of the peripheral vasculature for a transfemoral approach. Intraoperatively, fluoroscopy is mandatory for valve positioning, whereas the use of TTE or transesophageal echocardiography (TEE) varies by center. TTE is used for postoperative surveillance of valve function.

Is TAVR Ready for the Global Aging Population?

The emergence of the global pandemic of chronic diseases necessitates critical assessment of interventions that can be targeted at both the individual and population levels. Among cardiovascular diseases, the increasing prevalence of valvular heart diseases such as aortic stenosis parallels the rising burden of atherosclerotic cardiovascular diseases. As an alternative to surgical aortic valve replacement, technological innovation has allowed development of minimally invasive transcatheter aortic valve replacement (TAVR). This review examines whether TAVR can be applicable in low-resource regions across the world. Although revolutionary, TAVR is currently complex and requires a "Heart Team" approach for optimized patient care. We propose the emergence of telemedicine networks, newer valve designs that allow implementation of minimal approaches, and the use of minimal numbers of specialists for adapting TAVR to settings where surgical backup is not available. With efforts to reduce resource utilization, these alternate strategies have the potential to affect implementation of TAVR globally.

Real-time pose estimation of devices from x-ray images: Application to x-ray/echo registration for cardiac interventions

In recent years, registration between x-ray fluoroscopy (XRF) and transesophageal echocardiography (TEE) has been rapidly developed, validated, and translated to the clinic as a tool for advanced image guidance of structural heart interventions. This technology relies on accurate pose-estimation of the TEE probe via standard 2D/3D registration methods. It has been shown that latencies caused by slow registrations can result in errors during untracked frames, and a real-time ( > 15 hz) tracking algorithm is needed to minimize these errors. This paper presents two novel similarity metrics designed for accurate, robust, and extremely fast pose-estimation of devices from XRF images: Direct Splat Correlation (DSC) and Patch Gradient Correlation (PGC). Both metrics were implemented in CUDA C, and validated on simulated and clinical datasets against prior methods presented in the literature. It was shown that by combining DSC and PGC in a hybrid method (HYB), target registration errors comparable to previously reported methods were achieved, but at much higher speeds and lower failure rates. In simulated datasets, the proposed HYB method achieved a median projected target registration error (pTRE) of 0.33 mm and a mean registration frame-rate of 12.1 hz, while previously published methods produced median pTREs greater than 1.5 mm and mean registration frame-rates less than 4 hz. In clinical datasets, the HYB method achieved a median pTRE of 1.1 mm and a mean registration frame-rate of 20.5 hz, while previously published methods produced median pTREs greater than 1.3 mm and mean registration frame-rates less than 12 hz. The proposed hybrid method also had much lower failure rates than previously published methods.

A Practical Approach to Managing Transcatheter Aortic Valve Replacement With Sedation

Transcatheter aortic valve replacement is increasingly performed as a minimally invasive treatment option for aortic valve disease. The typical anesthetic management for this procedure was traditionally similar to surgical aortic valve replacement and involved general anesthesia and transesophageal echocardiography. In this review, we discuss the technological advances in transcatheter valve systems that have improved outcomes and allow for use of sedation instead of general anesthesia. We describe an anesthetic protocol that avoids general anesthesia and utilizes transthoracic echocardiography for procedural guidance.

Intracardiac echocardiography for guidance of transcatheter aortic valve implantation under monitored sedation: a solution to a dilemma?

Transcatheter aortic valve implantation (TAVI) has been established as a valuable alternative to surgical aortic valve replacement in patients deemed to have high or prohibitive perioperative risk. However, there are several technical constraints and procedural risks inherent to TAVI. These risks include annulus rupture, ventricular perforation, aortic dissection, coronary occlusion, and dislodgement or migration of the valve prosthesis to the aorta or the left ventricle (LV). Other complications may be related to inappropriate valve deployment and subsequent paravalvular leak. Most complications cannot be detected at an early stage without echocardiographic guidance. Although not addressed by current guidelines, some European centres have advocated a 'minimalist' approach with exclusively fluoroscopic and angiographic guidance. Transoesophageal echocardiography (TEE), including real-time three-dimensional (RT-3D) imaging, has been established as a standard approach for peri-interventional guidance of TAVI. However, TEE monitoring almost always necessitates general anaesthesia and endotracheal intubation. A potential alternative to TEE is intracardiac echocardiography (ICE) that may provide a solution to a common dilemma: the most important advantage of ICE being the compatibility with monitored anaesthesia care without endotracheal intubation. Other advantages of ICE include uninterrupted monitoring, no fluoroscopic interference, and precise Doppler-based assessment of pulmonary artery pressures. Limitations of ICE include the need for additional venous access, the learning curve associated with a new device, and potentially increased cost.