Abstract
The American Society of Echocardiography recommendations published in 2024 for evaluating prosthetic heart valve (PHV) function with cardiovascular imaging include new recommendations for the use of cardiac magnetic resonance imaging, cardiac computed tomography, and cardiac positron emission tomography. Additionally, they now provide normative echocardiographic values for right-sided PHVs and transcatheter heart valves in native valves and when used for valve-in-valve procedures. Furthermore, the recommendations include definitions to improve the recognition and classification of prosthetic heart valve dysfunction. The aim of this review is to summarize these key changes compared to the 2009 update and to include useful tables and figures to aid the reader in assessment of PHV function.
Graphical abstract
Highlights
- •
Reviews new recommendations for the use of complimentary imaging modalities.
- •
Discusses the updated definitions for structural valve deterioration.
- •
Summarizes new echo criteria and thresholds for prosthetic heart valve (PHV) stenosis and regurgitation.
- •
Emphasizes core practices when assessing PHVs.
- •
Highlights expanded normal echo valves for contemporary PHVs in all positions.
Introduction
The American Society of Echocardiography (ASE) recommendations for the assessment of prosthetic heart valves (PHVs) with cardiovascular imaging were last updated in 2009. During the intervening 15 years, there have been many changes. First, there has been the development of transcatheter heart valves (THVs) to treat native valve diseases. These THVs have also been used for valve-in-valve (ViV) and valve-in-ring procedures to address failing bioprosthetic or repaired valves. With widespread adoption of these THV interventions, normative echocardiographic values are now available. Furthermore, work from the Valve Academic Research Consortium has resulted in definitions that improve the recognition and classification of bioprosthetic heart valve dysfunction. Finally, cardiac imaging modalities such as three-dimensional (3D) echocardiography, cardiac magnetic resonance imaging (CMR), cardiac computed tomography (CCT), and cardiac positron emission tomography (PET) have become widely available and integrated into clinical practices. These imaging modalities have improved our assessment of PHVs, addressing important diagnostic questions pertaining to PHV dysfunction severity and mechanism.
The aim of this review is to summarize key changes in the updated ASE recommendations for evaluating prosthetic valves with cardiovascular imaging compared to the 2009 update. We will review central concepts in assessing PHVs, the role of echocardiography and multimodality imaging, and changes in assessing PHVs in specific cardiac positions. It must be noted that these PHV recommendations are meant to be complimentary to the ASE publication in 2019 for assessing regurgitation related to percutaneous valve repair or replacement.
General Considerations
Fueled by the clinical need for therapeutic strategies to treat severe aortic stenosis in patients with prohibitive surgical risk and subsequent clinical trial successes in lower-risk patients, both balloon-expandable (e.g., SAPIEN, Edwards Lifesciences) and self-expandable transcatheter aortic valve implantation (TAVI) valves (e.g., Evolut, Medtronic) are now commonly used. This success has led to the development of transcatheter pulmonary valves for failing conduits and the use of TAVI valves to treat deteriorating bioprosthetic valves and surgically repaired valves with annuloplasty rings. While surgical bioprosthetic and mechanical prostheses are still widely implanted, over the past decade, there has been a trend toward fewer mechanical valves, possibly explained by the growing use of transcatheter valves and a belief in the potential for future transcatheter interventions for failing bioprosthetic valves.
In this landscape, information on the implanted valve type, position, and size remains central in these guidelines on PHV assessment. This is due to differences in the imaging characteristics as well as the hemodynamic and complication profiles between surgical mechanical, surgical bioprosthetic, and transcatheter heart valves. The echocardiographer requires this knowledge to not only recognize normal PHV function but also to diagnose and grade levels of dysfunction based on deviations from expected measurement values. The 2009 recommendations only included tables with normal echocardiographic reference values for prosthetic valves in the aortic and mitral positions. The updated recommendations provide normal reference values for common TAVI valve sizes and types implanted not only in the aortic position but also when these valves are employed as ViV or valve-in-ring implants in the aortic, mitral, tricuspid, and pulmonic valve positions. Normal values are also provided for surgical bioprosthetic and mechanical PHVs in the tricuspid and pulmonic positions, and for pulmonary homografts and valved conduits.
PHV Imaging
Echocardiography
While the role of multimodality cardiac imaging is expanded in these new recommendations, transthoracic echocardiography (TTE) remains the primary imaging modality for the initial and routine assessment of PHVs ( Figure 1 ). High-quality echocardiographic imaging that allows comparison of serial measurements remains an important principle in these updated guidelines. In general, fundamental 2D and Doppler echocardiographic concepts that impact PHV assessment, such as the pressure recovery phenomenon, are largely unchanged from 2009. Most decision-making on the presence and severity of PHV dysfunction is based on a combination of 2D echocardiographic appearances and Doppler-derived measurements. However, as will be discussed in the aortic PHV subsection, there have been changes in how stenotic lesions are diagnosed and graded for PHV in the aortic position and the criteria used to assess prosthesis-patient mismatch.
These updated guidelines also emphasize the importance of integrating both flow-dependent and less flow-dependent echocardiographic parameters when assessing PHVs for stenosis, especially in the aortic position. Flow-dependent parameters such as peak and mean gradients are subject to changes independent of valvular function due to alterations in heart rate and hemodynamic status. Integrating less flow-dependent parameters such as PHV orifice areas in stenosis helps avoid potential misdiagnosis from using flow-dependent measurements alone.
Transesophageal echocardiography (TEE) remains a mainstay in the evaluation of dysfunctional PHVs and for preprocedural assessments. Postintervention, it is vital in assessing PHV function and for complications, including paravalvular regurgitation. The updated guidelines highlight the value of 3D TEE, particularly for PHVs in the mitral position, where the en – face view allows complete visualization of the PHV in a single image ( Figure 2 ). Another addition to the updated recommendations is in the use of 2D and 3D TEE for guiding mitral and tricuspid transcatheter valve replacements and in treating PHV paravalvular regurgitation. The new recommendations also briefly outline helpful TEE views for transcatheter tricuspid valve procedures, including the deep esophageal inflow-outflow view located between 40 and 60° with the orthogonal 140° bi-plane view. Intracardiac echocardiography is included in this update for its role in transcatheter pulmonic valve replacement and potential role in tricuspid valve procedures.
Role of Multimodality Imaging
More guidance has been provided on the use of multimodality imaging, specifically on how and when to use cross-sectional (CCT and CMR) and metabolic tracer (cardiac PET) imaging ( Table 1 ). This has been driven by both widespread clinical experience and research performed during the intervening years between guidelines.
| Imaging strengths | Imaging limitations | Valves | |
|---|---|---|---|
| TEE |
|
|
|
| ICE |
|
|
|
| CCT |
|
|
|
| CMR |
|
|
|
Improvements in scanner capabilities and the advent of electrocardiographic gating have greatly enhanced the utility of CCT in assessing both bioprosthetic and mechanical PHVs ( Figure 3 ). Its high spatial resolution is particularly beneficial when dysfunction detected by echocardiography has an unclear etiology or when structural intervention is being considered. For patients with echocardiographic findings of PHV stenosis, CCT, in addition to TEE, provides valuable information on bioprosthetic anatomic orifice area and mechanical PHV occluder motion. Using contrast, CCT is also effective in differentiating between stenosis caused by thrombus and that caused by pannus formation. In cases of PHV regurgitation, CCT compliments TEE in assessing valve dehiscence. Additionally, complications of infective endocarditis, such as paravalvular leaks (PVLs) and pseudoaneurysms, can be localized by CCT, and delayed phase scanning can be particularly helpful in identifying abscess cavities.
All PHVs can be safely imaged by 1.5 or 3T magnetic resonance imaging scanners. , In cases where PHV regurgitation has been identified but echocardiographic findings are discrepant, CMR can improve grading of regurgitation severity. The guidelines highlight that CMR is particularly valuable for this purpose in patients with PHVs. CMR methods, such as through-plane phased contrast imaging, offer accurate quantification of regurgitation in PVL cases without relying on accurate 2D measurements of aortic valve annular or semilunar valve outflow tract dimensions, as required in echocardiography.
The predominant role of cardiac PET, typically with flurodeoxyglucose, in PHVs is in the assessment of infective endocarditis and/or root abscess ( Figure 4 ). , Its use should be complimentary to both echocardiography and computed tomography (CT), but caution is needed as tracer uptake in the aortic root can be a normal phenomenon up to 1 year postsurgery. ,
While the roles for echocardiography, CMR, CCT, and cardiac PET in assessing PHV are specifically delineated in the current guidelines, other modalities such as intracardiac echocardiography, stress echocardiography, cinefluoroscopy, and cardiac catheterization also provide valuable insights. The choice of imaging modality will depend on the type and position of the PHV, the strengths and limitations of each modality, the local availability and expertise, the patient’s clinical condition, and the suspected underlying etiology of the PHV stenosis or regurgitation.
Classification of Prosthetic Heart Valve Dysfunction
The 2024 ASE PHV recommendations have further refined the classification of heart valve dysfunction based on work from the Valve Academic Research Consortium 3. Four categories of PHV dysfunction are described in the new recommendations ( Figure 5 ). These include structural valve deterioration (SVD), nonstructural valve dysfunction, endocarditis, and thrombus. SVD is defined by intrinsic, irreversible, or permanent PHV damage such as leaflet “wear and tear,” calcification and fibrosis, leaflet disruption, and stent or strut fracture or deformation. Most of these pathological changes occur toward the end of a PHV’s lifespan. Nonstructural valve dysfunction is defined as “any abnormality of the prosthesis not related to the valve itself but still resulting in valve dysfunction.” This includes prosthesis-patient mismatch, PVLs, and pannus ingrowth causing leaflet entrapment. Endocarditis remains an important challenge in PHVs with a prevalence of 1% to 6%. , Knowledge of typical echocardiographic features of endocarditis in PHVs including complications such as PVL, abscess, and pseudoaneurysm is imperative to facilitate early diagnosis and appropriate treatment. Thrombus can occur on mechanical or bioprosthetic valves and are more common in right-sided than left-sided valves. Typical appearances of a homogenous, usually immobile, echogenic mass are not always present, and use of cardiac CT, particularly in bioprosthetic and TAVI valves where the only feature may be leaflet thickening and increased gradients, can improve discrimination from pannus.
