Abstract
Cardiovascular magnetic resonance (CMR) is increasingly used to assess patients with mitral regurgitation. Its advantages include quantitative determination of ventricular volumes and function and the mitral regurgitant fraction, and in ischemic mitral regurgitation, regional myocardial function and viability. In addition to these, identification of leaflet prolapse or restriction is necessary when valve repair is contemplated. We describe a systematic approach to the evaluation of mitral regurgitation using CMR which we have used in 149 patients with varying etiologies and severity of regurgitation over a 15 month period.Following standard ventricular cine acquisitions, including 2, 3 and 4 chamber long axis views and a short axis stack for biventricular function, we image movements of all parts of the mitral leaflets using a contiguous stack of oblique long axis cines aligned orthogonal to the central part of the line of coaptation. The 8–10 slices in the stack, orientated approximately parallel to a 3-chamber view, are acquired sequentially from the superior (antero-lateral) mitral commissure to the inferior (postero-medial) commissure, visualising each apposing pair of anterior and posterior leaflet scallops in turn (A1-P1, A2-P2 and A3-P3). We use balanced steady state free precession imaging at 1.5 Tesla, slice thickness 5 mm, with no inter-slice gaps. Where the para-commissural coaptation lines curve relative to the central region, two further oblique cines are acquired orthogonal to the line of coaptation adjacent to each commissure. To quantify mitral regurgitation, we use phase contrast velocity mapping to measure aortic outflow, subtracting this from the left ventricular stroke volume to calculate the mitral regurgitant volume which, when divided by the left ventricular stroke volume, gives the mitral regurgitant fraction. In patients with ischemic mitral regurgitation, we further assess regional left ventricular function and, with late gadolinium enhancement, myocardial viability.Comprehensive assessment of mitral regurgitation using CMR is feasible and enables determination of mitral regurgitation severity, associated leaflet prolapse or restriction, ventricular function and viability in a single examination and is now routinely performed at our centre. The mitral valve stack of images is particularly useful and easy to acquire.
Highlights
Mitral regurgitation is a relatively common and important heart valve lesion in clinical practice, and adequate assessment is fundamental to decisions on management
Qualitative grading of mitral regurgitation severity Because the methods we suggest for quantifying mitral regurgitation by Cardiovascular magnetic resonance (CMR) rely on more than one set of measurements, each of which could contribute to inaccuracy if not optimally performed, it is important to support quantitative measurements with a qualitative visual assessment of severity
The etiologies of mitral regurgitation were varied with 42% due to ischemia or infarction, 41% degenerative, 9% due to rheumatic valve disease and 8% due to cardiomyopathy
Summary
Mitral regurgitation is a relatively common and important heart valve lesion in clinical practice, and adequate assessment is fundamental to decisions on management. Type II dysfunction, as seen in mitral valve prolapse, is present when the free edge of the valve leaflet moves at least 2 mm above the plane of the mitral annulus during LV systole (Fig 6, see additional file 1: Figure 6b movie). This results in an eccentric regurgitant jet directed away from the leaflet that is prolapsing. A further feature of severe mitral regurgitation is reversal of flow in the pulmonary veins during LV systole, which may be visible in the 4 chamber and certain mitral stack cines
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