Role of Cardiac Magnetic Resonance Imaging in Valvular Heart Disease: Diagnosis,Assessment, and Management

Purpose of Review

This article will review the current techniques in cardiac magnetic resonance imaging (CMR) for diagnosing and assessing primary valvular heart disease.

Recent Findings

The recent advancements in CMR have led to an increased role of this modality for qualifying and quantifying various native valve diseases. Phase-contrast velocity encoded imaging is a well-established technique that can be used to quantify aortic and pulmonic flow. This technique, combined with the improved ability for CMR to obtain accurate left and right ventricular volumetrics, has allowed for increased accuracy and reproducibility in assessing valvular dysfunction. Advancements in CMR technology also allows for improved spatial and temporal resolution imaging of various valves and their regurgitant or stenotic jets. Therefore, CMR can be a powerful tool in evaluation of native valvular heart disease.

Summary

The role of CMR in assessing valvular heart disease is growing and being recognized in recent guidelines. CMR has the ability to assess valve morphology along with qualifying and quantifying valvular disease. In addition, the ability to obtain accurate volumetric measurements may improve more precise management strategies and may lead to improvements in mortality and morbidity.

     

The role of cardiovascular magnetic resonance imaging in the diagnosis and prognosis of patients with heart failure

Cardiovascular magnetic resonance (CMR) imaging is a tomographic technique, which allows three-dimensional slice orientation without limitations from acoustic windows inherent to echocardiography. Further advantages of CMR are its high temporal and spatial resolution, its excellent soft tissue resolution and its high blood-to-tissue contrast. Cardiovascular magnetic resonance is currently the only imaging technique, which provides a comprehensive study of both structure and function of the heart as well as myocardial perfusion and viability. Moreover, post-processing of CMR images does not require any geometric assumptions as in echocardiography to determine ventricular dimensions. This is particularly important when evaluating ventricles of patients with chronic heart failure with severely altered morphology that may have regional variations in wall thickness and contractility at least in ischemic cardiomyopathy. The highly reproducible results of CMR imaging have turned this technique into a reference standard for the non-invasive assessment of ventricular dimensions, mass and function. In cases with indeterminate results of clinical, electrocardiographic and particularly echocardiographic findings CMR should be used early in the process of diagnosis of patients with heart failure. Not only can altered structure and degree of ventricular and valvular dysfunctions be accurately assessed but also regional perfusion deficits and/or myocardial scars are easily detected. For therapeutic and prognostic reasons a simple differentiation between ischemic and non-ischemic cardiomyopathy should be achieved as the first diagnostic step. In addition, the type and localization of the late gadolinium enhancement (LGE) phenomenon may aid in non-invasively differentiating the etiology of non-ischemic cardiomyopathy. CMR may also improve the assessment and extent of interventricular and intraventricular dyssynchrony in patients to be selected for cardiac resynchronization therapy (CRT). Lastly, the LGE phenomenon may provide independent prognostic information in patients with a CRT system implanted, as well as in patients with ischemic and non-ischemic cardiomyopathy. Thus, CMR imaging should be implemented early in the diagnostic process of patients with heart failure to significantly improve the speed and accuracy of diagnostic procedures, to control the effect of therapeutic measures, and to select patients with a limited prognosis by assessing the degree of ventricular dysfunction and the extent of myocardial scarring.     

Impact of three-dimensional echocardiography in valvular heart disease

PURPOSE OF REVIEW: Recent advances in the field of three-dimensional (3D) echocardiography have allowed improved visualization of cardiac structures. These advances have also provided valuable insights into cardiac function. The purpose of this review is to describe the recent developments in 3D echocardiography in assessing valvular heart disease. RECENT FINDINGS: Application of 3D echocardiography to valvular heart disease has improved with advances made in both the hardware and software components of 3D ultrasound systems. The most significant advancement has been the development of a matrix transducer that is capable of rapid real-time 3D acquisition and rendering. There have been many studies evaluating 3D echocardiographic assessment of mitral valve disease, aortic valve disease, as well as congenital heart disease using both real-time 3D transthoracic echocardiography (TTE) as well as off-line reconstructed 3D images from transesophageal echocardiography (TEE) using post image processing. More recent studies have combined the structural 3D information with color Doppler 3D imaging, providing qualitative functional information. SUMMARY: Developments in the field of 3D ultrasound imaging have allowed better qualitative assessment of valvular structures. The addition of color flow Doppler to the 3D imaging has provided improved visualization of regurgitant lesions and holds great promise for improved quantitative assessment of such lesions. The ongoing miniaturization of transducers and improvements in hardware and software components of ultrasound systems will certainly enhance both the ease of image acquisition as well as image quality, which should result in more precise quantitation of valvular dysfunction. However, clinical benefits of 3D echocardiography are yet to be demonstrated in properly conducted clinical trials, which are needed for wider acceptance of this technique.     

The Role Of Cardiac Magnetic Resonance In Valvular Heart Disease

The prevalence of valvular heart disease is increasing as the population ages. In diagnosing individuals with valve disease, echocardiography is the primary imaging modality used by clinicians both for initial assessment and for longitudinal evaluation. However, in some cases cardiovascular magnetic resonance has become a viable alternative in that it can obtain imaging data in any plane prescribed by the scan operator, which makes it ideal for accurate investigation of all cardiac valves: aortic, mitral, pulmonic, and tricuspid. In addition, CMR for valve assessment is noninvasive, free of ionizing radiation, and in most instances does not require contrast administration. The objectives of a comprehensive CMR study for evaluating valvular heart disease are threefold: (1) to provide insight into the mechanism of the valvular lesion (via anatomic assessment), (2) to quantify the severity of the valvular lesion, and (3) to discern the consequences of the valvular lesion     

CMR in Evaluating Valvular Heart Disease: Diagnosis,Severity, and Outcomes

Cardiac magnetic resonance (CMR) is a versatile imaging tool that brings much to the assessment of valvular heart disease. Although it is best known for myocardial imaging (even in valve disease), it provides excellent assessment of all 4 heart valves, with some distinct advantages, including a free choice of image planes and accurate flow and volumetric quantification. These allow the severity of each valve lesion to be characterized, in addition to optimal visualization of the surrounding outflow tracts and vessels, to deliver a comprehensive package. It can assess each valve lesion separately (in multiple valve disease) and is not affected by hemodynamic status. The accurate quantitation of regurgitant lesions and the ability to characterize myocardial changes also provides an ability to predict future clinical outcomes in asymptomatic patients. This review outlines how CMR can be used in cardiac valve disease to compliment echocardiography and enhance the patient assessment. It covers the main CMR methods used, their strengths and limitations, and the optimal way to apply them to evaluate valve disease.     

Heart involvement in rheumatoid arthritis: Multimodality imaging and the emerging role of cardiac magnetic resonance

Objectives

Patients with rheumatoid arthritis (RA) exhibit a high risk of cardiovascular disease (CVD). CVD in RA can present in many guises, commonly detected at a subclinical level only.

Methods

Modern imaging modalities that allow the noninvasive assessment of myocardial performance and are able to identify cardiac abnormalities in early asymptomatic stages may be useful tools in terms of screening, diagnostic evaluation, and risk stratification in RA.

Results

The currently used imaging techniques are echocardiography, single-photon emission computed tomography (SPECT), and cardiac magnetic resonance (CMR). Between them, echocardiography provides information about cardiac function, valves, and perfusion; SPECT provides information about myocardial perfusion and carries a high amount of radiation; and CMR—the most promising imaging modality—evaluates myocardial function, inflammation, microvascular dysfunction, valvular disease, perfusion, and presence of scar. Depending on availability, expertise, and clinical queries, “right technique should be applied for the right patient at the right time.”

Conclusions

In this review, we present a short overview of CVD in RA focusing on the clinical implication of multimodality imaging and mainly on the evolving role of CMR in identifying high-risk patients who could benefit from prevention strategies and early specific treatment targeting the heart. Advantages and disadvantages of each imaging technique in the evaluation of RA are discussed.     

Cardiac Imaging Integration in 2009 and Beyond: Cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) is currently well recognized in clinical practice for the diagnosis and management of cardiovascular diseases. CMR is helpful in the diagnosis and prognosis of patients with myocardial infarction. The high spatial resolution of CMR enables accurate assessment of tissue characterization in various types of cardiomyopathy. In addition, CMR may play a complementary role with echocardiography in clinical evaluation of patients with valvular and congenital heart disease.     

Cardiovascular magnetic resonance imaging for valvular heart disease

Valvular heart disease (VHD) is a clinically important diagnosis, with significant associated morbidity and mortality. Multiple imaging modalities exist to characterize valvular and associated cardiac anatomy. Cardiovascular magnetic resonance (CMR) has emerged as a comprehensive noninvasive imaging modality for VHD. With use of well-established, standardized imaging sequences, CMR can accurately and precisely diagnose valvular structural abnormalities, assess severity of regurgitant and stenotic lesions, and potentially define patient prognosis. This article reviews the clinical applications of CMR in assessment of VHD.     

Left Atrium: Still a Neglected Chamber?

It is widely recognized that an effective cardiovascular system is based upon both a good ventricular-vascular interplay and a good ventricular-atrial interaction in all the phases of cardiac cycle. Moreover, left atrial dysfunction has been identified to be contributory in several common cardiovascular conditions, such as heart failure, atrial fibrillation and valvular heart disease; for instance, a good anatomical and functional assessment of this cardiac chamber is mandatory. For this purpose a multimodality imaging approach – including two-dimensional and three-dimensional echocardiography, speckle tracking technique, cardiac computed tomography (CT) and cardiac magnetic resonance (CMR) – is the most suitable one to achieve the best functional and anatomical evaluation of this cardiac chamber.     

Imaging modalities in valvular heart disease

Evaluating valvular heart disease requires a multi-parametric analysis of valvular pathology, hemodynamic derangements, and impact on ventricular size and function. The capability to perform real-time three-dimensional (3-D) imaging has vastly strengthened the already established role of echocardiography. CT and MRI advances have led to their use as daily clinical tools. Two-dimensional and 3-D echocardiography and Doppler modalities allow for accurate assessment of valvular lesions, pressure gradients, stenotic valve orifice areas, pulmonary artery pressures, intracardiac pressures, and regurgitant volumes. Quantitation of chamber volumes has become more accurate and reproducible with 3-D echocardiography, CT, and cardiac MRI. Although ultrasound imaging is the primary tool, the other techniques provide adjuvant or alternate options to examine valvular heart disease. This array of imaging modalities is likely to provide greater insights into the pathophysiology of valvular heart disease, new pointers to prognosis, and also guide innovative treatment strategies.     

Imaging the right heart: the use of integrated multimodality imaging

During recent years, right ventricular (RV) structure and function have been found to be an important determinant of outcome in different cardiovascular and also pulmonary diseases. Currently, echocardiography and cardiac magnetic resonance (CMR) imaging are the two imaging modalities most commonly used to visualize the RV. Most structural abnormalities of the RV can be reliably described by echocardiography but due its complex geometrical shape, echocardiographic assessment of RV function is more challenging. Newer promising echocardiographic techniques are emerging but lack of validation and limited normal reference data influence their routine clinical application. Cardiac magnetic resonance is generally considered the clinical reference technique due to its unlimited imaging planes, superior image resolution, and three-dimensional volumetric rendering. The accuracy and reliability of CMR measurements make it the ideal tool for serial examinations of RV function. Multidetector computed tomography (MDCT) plays an important role in the diagnosis of pulmonary emboli but can also be used for assessing RV ischaemic disease or as an alternative for CMR if contra-indicated. Radionuclide techniques have become more obsolete in the current era. The different imaging modalities should be considered complimentary and each plays a role for different indications.     

The most important publications of the past year in echocardiography

We review the published literature on clinical echocardiography of the past year. Key topics were valvular heart disease, in particular aortic stenosis, and the imaging requirements for transcatheter aortic valve implantation. Three-dimensional echocardiography and deformation imaging have yielded important new insights in valvular heart disease. Other key fields have been assessment of heart failure, in particular heart failure with preserved ejection fraction, and the relationship of this condition with diastolic dysfunction and left atrial function. Functional imaging of cardiomyopathies was also an important topic.     

The Role of Imaging in Hypertensive Heart Disease

Hypertensive heart disease (HHD) describes a spectrum of target organ response that includes left ventricular hypertrophy, systolic, and diastolic dysfunction. A variety of imaging techniques can be used to assess the various aspects of HHD. Echocardiography has for many years been the main imaging technique in the evaluation of HHD, but there is an increasing role for cardiovascular magnetic resonance (CMR) imaging due to its ability to provide an unrestricted field of view and noninvasive tissue characterization. This article reviews the current role of imaging for HHD with particular focus on echocardiography and CMR applications.     

Imaging and quantifying valvular heart disease using magnetic resonance techniques

Opinion statement Echocardiography remains the cornerstone of noninvasive valvular heart disease evaluation. There are instances where MRI can be of use. Aside from the obvious advantage where limited acoustic windows are present, cardiac magnetic resonance (CMR) allows for imaging in any desired plane, and advantage can be taken of the ability to align with any regurgitant or stenotic flow jet. The high spatial resolution and contrast allow for accurate detail of valvular anatomy, but it must be remembered that the images represent a composite of eight to 12 heart cycles. For visualizing multiple valvular abnormalities simultaneously, cardiac MRI has a distinct advantage. Finally, a CMR valvular examination can be combined with accurate assessments of left and right ventricular function, myocardial stress perfusion imaging, and detailed viability determinations in a single examination. This provides a comprehensive presurgical evaluation of cardiac physiology.     

Pulmonary Regurgitation after Tetralogy of Fallot Repair: A Diagnostic and Therapeutic Challenge

Background:

Pulmonary regurgitation is the key hemodynamically significant lesion in repaired tetralogy of Fallot contributing to progressive right ventricular (RV) dilatation and biventricular dysfunction. The timing for pulmonary valve replacement remains a controversial topic, and the decision to intervene depends on assessment of RV size and RV function.

Objectives:

This review aims to discuss the echocardiographic techniques that can be used to assess patients with pulmonary regurgitation after the repair of tetralogy of Fallot defect. While cardiac magnetic resonance (CMR) imaging is the clinical reference method, there is an important role of echocardiography in identifying patients with significant pulmonary regurgitation and assessing the RV size and function. The different echocardiographic techniques that can be used in this context are discussed. Newer techniques for assessing RV size and function include three-dimensional (3D) echocardiography, tissue Doppler and strain imaging. 3D RV volumetric reconstruction based on two-dimensional imaging is a promising new technique that could potentially replace CMR for RV volumetric assessment.

Conclusions:

Developments in echocardiographic techniques provide new insights into the impact of pulmonary regurgitation on RV structure and function. Echocardiography and CMR are complementary modalities and further research is required to define the optimal use of both techniques for this indication.     

3-D echocardiography: new developments and future prospects

Due to limitations in transthoracic and occasionally transesophageal 2-D echocardiography with respect to volumetric analysis and morphologic and functional assessment in patients with congenital malformations and valvular heart disease, additional diagnostic tools have been established. In parallel with the rapid evolution in computer technology, 3-D echocardiography has grown into a well-developed technique, such as volume-rendered 3-D reconstruction, capable of displaying dynamic morphology depicting depth of the structures, their attachment, and spatial relation to the surrounding tissue. Nevertheless, the complexity of data acquisition and data processing required for adequate dynamic 3-D echocardiographic imaging and volumetric analysis does not allow to use this approach routinely. The commonly used dynamic 3-D echocardiography means off-line computer-assisted image reconstruction from a series of cross-sectional echocardiographic images using currently available transesophageal and transthoracic transducers. Alternatively, real-time 3-D echocardiography based on novel matrix, phased-array transducer technology has been introduced. Although this technique can be easily combined with any routine examination, its clinical use is limited because of a lower image quality in comparison with dynamic 3-D echocardiography. Up to now, there is no transesophageal approach available using real-time 3-D echocardiography. Recently, dynamic 3-D echocardiographic technique has matured noticeably. Beside the well-known sequential scanning, which is characterized by a fixed probe and patient in space and predetermined motion of the transducer, the freehand scanning using an electromagnetic location system has found its way to clinical environment. The main advantage of this technique is that the transducer can be freely moved by the examiner and, thus, the data set acquired within a routine examination. Also 3-D rendering and display have been developed further. In this respect, especially the "real-time rendering mode" allowing the reconstructed 3-D image to be animated and moved in space and to look at it from different perspectives has gained increasing acceptance. In valvular heart disease, reconstructive surgical treatment is aspired. 3-D echocardiographic imaging is the only technique providing "surgical views" prior to opening the heart. It is capable of distinguishing particular destructive substructures of the valves and the valvular apparatus. Especially in mitral valvular reconstruction, it is of clinical importance to achieve optimal surgical results. With respect to volumetric and mass analysis, 3-D echocardiography is more accurate and reproducible in comparison with conventional 2-D analysis. It provides data independent of geometric assumptions, what may considerably influence the results in the presence of wall motion abnormalities, especially in aneurysmatic ventricles. Volumetric analysis of the aneurysmal portion may also be helpful prior to surgical resection. 3-D echocardiography can also be recommended as a valuable additional approach to atrial septal defect (ASD), corrected transposition of the great arteries, cor triatriatum, and, within limits, to ventricular septal defect (VSD) as well. Especially with respect to ASD and VSD, the potential significance of 3-D echocardiography prior to device closure is emphasized. At present, its additional information in decision-making and the increasing number of clinical cases that can be addressed and answered already justify the clinical use of this technique.     

Exercise Doppler: functional evaluation of right heart dynamics

Exercise echocardiography is a versatile technique that includes not only two-dimensional imaging, but also Doppler of aortic, mitral, and tricuspid valves. Doppler echocardiography can be useful in the evaluation of global left ventricular systolic and diastolic function, valvular function, transvalvular gradients, and pulmonary artery pressure. The technique lends itself to the study of the cardiac response to exercise in a variety of disease states, including pulmonary, coronary artery, valvular, and congenital heart disease. We review our experience using agitated saline-enhanced Doppler of tricuspid insufficiency to determine pulmonary artery pressure throughout exercise in chronic lung disease.     

Stress echocardiography: current methodology and clinical applications

Stress echocardiography is commonly employed for the clinical management of known or suspected coronary artery disease. This review discusses the accuracy of the technique, which is equivalent to that of competing imaging techniques, as well as its overall role in patient management. The utilization of stress echocardiographic modalities in clinical presentations, such as chest pain, congestive heart failure, and valvular heart disease, and preoperative risk assessment, as well as determining myocardial viability, are discussed.     

The emerging clinical role of cardiovascular magnetic resonance imaging

Starting as a research method little more than a decade ago, cardiovascular magnetic resonance (CMR) imaging has rapidly evolved to become a powerful diagnostic tool used in routine clinical cardiology. The contrast in CMR images is generated from protons in different chemical environments and, therefore, enables high-resolution imaging and specific tissue characterization in vivo, without the use of potentially harmful ionizing radiation.CMR imaging is used for the assessment of regional and global ventricular function, and to answer questions regarding anatomy. State-of-the-art CMR sequences allow for a wide range of tissue characterization approaches, including the identification and quantification of nonviable, edematous, inflamed, infiltrated or hypoperfused myocardium. These tissue changes are not only used to help identify the etiology of cardiomyopathies, but also allow for a better understanding of tissue pathology in vivo. CMR tissue characterization may also be used to stage a disease process; for example, elevated T2 signal is consistent with edema and helps differentiate acute from chronic myocardial injury, and the extent of myocardial fibrosis as imaged by contrast-enhanced CMR correlates with adverse patient outcome in ischemic and nonischemic cardiomyopathies.The current role of CMR imaging in clinical cardiology is reviewed, including coronary artery disease, congenital heart disease, nonischemic cardiomyopathies and valvular disease.     

Three-dimensional Echocardiography in Valvular Heart Disease

Recent technologic advances in 3-dimensional (3D) echocardiography, using parallel processing to scan a pyramidal volume, have allowed for a superior ability to describe valvular anatomy using both transthoracic and transesophageal echocardiography. Although still in evolution and at an early phase of adaptation with respect to its clinical application, 3D echocardiography has emerged as an important clinical tool in the assessment of valvular heart disease. Three-dimensional echocardiography provides unique perspectives of valvular structures by presenting "en face" views of valvular structures, allowing for a better understanding of the topographical aspects of pathology, and a refined definition of the spatial relationships of intracardiac structures. Three-dimensional echocardiography makes available indices not described by 2D echocardiography and has been demonstrated to be superior to 2D echocardiography in a variety of valvular disease scenarios. The information gained from 3D echocardiography has especially made an impact in guiding clinical decisions in the evaluation of mitral valve (MV) disease. The decision of early surgery in degenerative MV disease is based on the suitability of repair, and the suitability of repair is generally based on echocardiography. The superior understanding of MV anatomy afforded by 3D echocardiography has been shown to be quite valuable in this setting. This review will describe the contemporary use of 3D echocardiography in the assessment of valvular heart disease, including MV, aortic, tricuspid, and prosthetic valve abnormalities. This article illustrates how 3D echocardiography can complement current echocardiography techniques in the management of valvular heart disease.