Page 13 - Advanced echocardiography in characterization and management of patients with secondary mitral regurgitation

Introduction
Severe mitral regurgitation is one of the most common valvular diseases worldwide [1▪▪]. The advent of transcatheter therapies has influenced the decision making of patients with symptomatic severe mitral regurgitation, particularly those with high-operative risk or contraindications for surgery. These therapies include devices that target the leaflets (MitraClip, Abbott Vascular, Santa Clara, CA; Neochord, Inc., St Louis Park, MN; Pascal, Edwards Lifesciences, Irvine, CA), the mitral valve annulus (Cardioband, Edwards Lifesciences; Carillon Mitral Contour System, Cardiac Dimensions, Kirkland, WA) or replace the mitral valve (apical tethered system – Tendyne [Abbott Vascular]; radial force system – Intrepid [Medtronic, Inc., Redwood City, CA]; and native leaflet engagement – Tiara valve [Neovasc Tiara]) (Fig. 1). Selection of patients for these therapies requires accurate quantification of mitral regurgitation, assessment of the mitral valve anatomy and evaluation of the left ventricular dimensions and systolic function as well as left atrial dimensions. In contrast to surgery, the mitral valve cannot be inspected during the procedure and the interventionalists need to have accurate visualization of the mitral valve apparatus. Three-dimensional-imaging techniques have become indispensable tools to plan and guide these transcatheter interventions: three- dimensional transesophageal echocardiography and computed tomography provide unparalleled views of the mitral valve and the key measurements to select the type and size of the device. In addition, three-dimensional transesophageal echocardiography provides the soft-tissue resolution that can be overlaid on to fluoroscopy to accurately guide the procedure. Cardiovascular magnetic resonance (CMR) is less frequently used but is an excellent imaging modality to quantify left ventricular dimensions and function and the severity of mitral regurgitation. In addition, late gadolinium contrast-enhanced techniques permit tissue characterization of the myocardium and may have important implications in the timing of intervention. This review will discuss the role of different imaging techniques to evaluate patients with mitral regurgitation for transcatheter interventions.
Echocardiography
Two-dimensional transthoracic echocardiography is the imaging modality of first choice in diagnosing mitral regurgitation and assessing its severity. The mechanism of mitral regurgitation can be assessed with two-dimensiontal transthoracic echocardiography; however, the advent of three-dimensional echocardiography has permitted a systematic approach to define the lesion that causes the mitral regurgitation (Fig. 2). In general, mitral regurgitation is divided into primary (when the lesion is primarily of the mitral leaflets) and secondary (when the coaptation failure is because of left ventricular dilation
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Ch 1