3D echocardiography: The present and the future

Current use of real-time three-dimensional transthoracic echocardiography in animals

This review includes 36 studies of transthoracic real-time three-dimensional echocardiography (RT3DE) in animals. Most of these studies concern cardiac chamber quantification of the left atrium and left ventricle, in dogs. Comparisons of RT3DE and different two-dimensional echocardiographic (2DE) methods have been reported in dogs with myxomatous mitral valve disease (MMVD), dilated cardiomyopathy, and in healthy control dogs. Comparisons of RT3DE and standard reference methods have been reported in healthy control dogs. In dogs with MMVD, volumetric RT3DE measurements of left atrium do not appear to provide superior prognostic value compared with 2DE methods using Simpson's method of discs in dogs with MMVD. The major advantages of RT3DE compared to 2DE include improvements in visualization of the complex morphology of the mitral valve, the estimation of mitral valve regurgitation, and improved visualization of complex congenital cardiac abnormalities.

Application of 4-D ultrasound-derived regional strain and proteomics analysis in Nkx2-5-deficient male mice

The comprehensive characterization of cardiac structure and function is critical to better understanding various murine models of cardiac disease. We demonstrate here a multimodal analysis approach using high-frequency four-dimensional ultrasound (4DUS) imaging and proteomics to explore the relationship between regional function and tissue composition in a murine model of metabolic cardiomyopathy (Nkx2-5183P/+). The presented 4DUS analysis outlines a novel approach to mapping both circumferential and longitudinal strain profiles through a standardized framework. We then demonstrate how this approach allows for spatiotemporal comparisons of cardiac function and improved localization of regional left ventricular dysfunction. Guided by observed trends in regional dysfunction, our targeted Ingenuity Pathway Analysis (IPA) results highlight metabolic dysregulation in the Nkx2-5183P/+ model, including altered mitochondrial function and energy metabolism (i.e., oxidative phosphorylation and fatty acid/lipid handling). Finally, we present a combined 4DUS-proteomics z-score-based analysis that highlights IPA canonical pathways showing strong linear relationships with 4DUS biomarkers of regional cardiac dysfunction. The presented multimodal analysis methods aim to help future studies more comprehensively assess regional structure-function relationships in other preclinical models of cardiomyopathy.NEW & NOTEWORTHY A multimodal approach using both four-dimensional ultrasound (4DUS) and regional proteomics can help enhance our investigations of murine cardiomyopathy models. We present unique 4DUS-derived strain maps that provide a framework for both cross-sectional and longitudinal analysis of spatiotemporal cardiac function. We further detail and demonstrate an innovative 4DUS-proteomics z-score-based linear regression method, aimed at characterizing relationships between regional cardiac dysfunction and underlying mechanisms of disease.

Transthoracic echocardiography and its limitations in the diagnosis of congenital supernumerary aortic valve in a Thoroughbred

Aortic valve malformation is a common congenital abnormality reported in human medicine. The malformation is characterised by an increased or decreased number of cusps. Anatomical variations of the aortic valve that have been documented in humans include unicuspid, bicuspid, quadricuspid and quinticuspid valves. Two reports described a quadricuspid aortic valve in horses associated with either a ventricular septal defect (VSD) or tetralogy of Fallot. In this case report we describe the clinical and echocardiographic findings of a horse with a quadricuspid aortic valve as single congenital abnormality, referred with history of exercise intolerance and an episode of paroxysmal atrial fibrillation. Limitations and risks of misdiagnosis that can be encountered with transthoracic echocardiography are also discussed. The reported case highlights the importance of echocardiographic screening in asymptomatic patients as congenital heart disease can be present without obvious cardiac signs. As advanced imaging on the equine thorax is still far from future possibilities for adult horses, this report may help to reach an accurate diagnosis with similar cases.

Next-Generation Approaches to Echocardiography: Clinical Perspectives

The application of imaging to cardiovascular diseases fosters the diagnosis, clinical management, and risk stratification of patients, thus leading to the early detection of cardiac and vascular diseases [...]

Fully Automated Mouse Echocardiography Analysis Using Deep Convolutional Neural Networks

Echocardiography (echo) is a translationally relevant ultrasound imaging modality widely used to assess cardiac structure and function in preclinical models of heart failure (HF) during research and drug development. Though echo is a very valuable tool, the image analysis is a time consuming, resource demanding process, and is susceptible to inter-reader variability. Recent advancements in deep learning have enabled researchers to automate image processing and reduce analysis time and inter-reader variability in the field of medical imaging. In the present study, we developed a fully automated tool - Mouse Echo Neural Net (MENN) - for the analysis of both long axis brightness (B)-mode and short axis motion (M)-mode images of the left ventricle. MENN is a series of fully convolutional neural networks that were trained and validated using manually segmented B-mode and M-mode echo images of the left ventricle. The segmented images were then used to compute cardiac structural and functional metrics. The performance of MENN was further validated in two preclinical models of HF. MENN achieved excellent correlations (Pearson's r = 0.85 to 0.99) and good to excellent agreement between automated and manual analyses. Further inter-reader variability analysis showed that MENN has better agreements with an expert analyst than both a trained analyst and a novice. Notably, the use of MENN reduced manual analysis time by >92%. In conclusion, we developed an automated echocardiography analysis tool that allows for fast and accurate analysis of B-mode and M-mode mouse echo data and mitigates the issue of inter-reader variability in manual analysis.

A Review of the Role of Imaging Modalities in the Evaluation of Viral Myocarditis with a Special Focus on COVID-19-Related Myocarditis

Viral myocarditis is inflammation of the myocardium secondary to viral infection. The clinical presentation of viral myocarditis is very heterogeneous and can range from nonspecific symptoms of malaise and fatigue in subclinical disease to a more florid presentation, such as acute cardiogenic shock and sudden cardiac death in severe cases. The accurate and prompt diagnosis of viral myocarditis is very challenging. Endomyocardial biopsy is considered to be the gold standard test to confirm viral myocarditis; however, it is an invasive procedure, and the sensitivity is low when myocardial involvement is focal. Cardiac imaging hence plays an essential role in the noninvasive evaluation of viral myocarditis. The current coronavirus disease 2019 (COVID-19) pandemic has generated considerable interest in the use of imaging in the early detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related myocarditis. This article reviews the role of various cardiac imaging modalities used in the diagnosis and assessment of viral myocarditis, including COVID-19-related myocarditis.

Current concepts in mitral valve prolapse--diagnosis and management

Although mitral valve prolapse as a disease entity has been recognized for over 50 years, its precise definition has been elusive. Initial reports based the diagnosis on auscultatory findings (late systolic click - murmur), with left ventricular angiography as a confirmative test. Echocardiography, first the M-mode, and subsequently the two-dimensional, became the dominant diagnostic modality. However, the early reports did not distinguish between billowing valve and flail valve. The advent of surgical repair techniques provided a different perspective; the surgical definition of mitral valve prolapse is often different from that of cardiologists. Intraoperative echocardiography gained wide acceptance necessitating a common language to describe precise terminology of the leaflet anatomy and definition of valve prolapse. The present report proposes a terminology and definitions of valve prolapse with relevance to surgical mitral valve repair. The addition of real-time 3D transesophageal echocardiography now provides highly accurate localization of lesions and the multi segment assessment of valve pathology. The etiologic considerations and surgical repair techniques with the role of echo - surgery team in improved patient outcome are described.

Imaging methodology and protocols for three-dimensional echocardiography

PURPOSE OF REVIEW

Three-dimensional echocardiography (3DE) is an additional ultrasound modality that is poised to become an integral part of the routine echocardiogram. Incorporating 3DE into clinical daily practice continues to be a challenge for many laboratories. The following review will focus on workflow processes related to methodology and protocols in order to incorporate 3DE into clinical practice.

RECENT FINDINGS

Several studies have shown the clinical utility and feasibility of both transthoracic and transesophageal 3DE. In addition, many centers performing 3DE studies utilize a focused 3DE protocol as opposed to a full 3DE protocol. A majority of the studies noted limitations with respect to artifacts inherent in gated imaging and preferred real-time 3DE or rather volume imaging. A recurrent message from several recent publications is that the ultimate success and widespread clinical application of 3DE will rely mainly on improved 3D image resolution and volume rates.

SUMMARY

Continuous technology improvements have led to real-time full-volume 3D imaging that is no longer prone to the artifact issues encountered with gated 3D imaging. Additional improvements to 3DE image quality and time-saving automatic quantitative analysis tools will continue to define the emerging role for routine 3DE.