Mechanistic insights into functional mitral regurgitation

Abstract

Effective valve repair in patients with mitral regurgitation (MR) demands an understanding of its mechanism. In patients with ischemic heart disease and functional MR, which doubles late mortality, normal leaflets are apically displaced. This reflects an altered balance of forces acting on the leaflets: increased tethering forces restricting closure, resulting from an altered geometry of leaflet attachments, and decreased ventricular forces acting to close the leaflets. Extensive evidence confirms a central and predominant role of tethering as the final common pathway inducing functional MR; left ventricular (LV) pressure dynamically modulates the orifice area. Because ischemic MR is a disease of the entire mitral complex, including the remodeling LV, reducing annular size alone is often ineffective. Undersizing rings attempts to compensate for tethering; new and potentially more effective strategies directly address tethering by infarct plication, papillary muscle repositioning with a localized patch, or basal chordal cutting to increase coaptational surface area without prolapse. A comprehensive understanding of the valve in its ventricular context, therefore, provides new opportunities for successful valve repair in patients.

Thalamic Resting-State Functional Networks: Disruption in Patients with Mild Traumatic Brain Injury

“…Our fi ndings suggest that the disrupted inhibitory properties of thalamic nuclei secondary to subtle injury resulted in upregulated thalamocortical connectivity in patients with MTBI. Although the possibility of thalamic network compensatory mechanisms has been previously suggested and supported by some functional imaging studies and by results of event-related potential investigations in patients with head injuries (52)(53)(54), the mechanism for thalamic functional compensation is still largely unclear in brain trauma. Investigating these abnormal thalamic RSNs and clin ical posttraumatic symptoms in a longitudinal design will better illustrate the underlying mechanisms.…”

Noninvasive Measurements of the Mitral Annulus Geometry by Newly-developed Quantitation Software With Real-time Three-dimensional Echocardiography: A Validation Study

“…Quantitative analysis of cardiac geometry by 3D echocardiography is expected to contribute to the evaluation of mechanism of valve diseases and thereby improve therapy. Therefore, a robust method that allows simple 3D quantitative assessment of the mitral apparatus had been required, especially in the assessment of functional MR, in which the valve itself is normal but abnormalities in left ventricular volume, function, and shape have led to MR [10,11]. Annuloplasty is a common surgical strategy for ischemic/functional MR, however MR often persists after annuloplasty [12][13][14][15].…”

Echocardiographic evaluation of systolic heart failure

“…Leaflet motion is restricted with apical displacement of the coaptation zone, causing incomplete systolic closure of the mitral valve or “systolic tenting” 22 . Ischaemic MR results from complex alterations of spatial relationships between the LV and mitral apparatus 23 and a recent study confirmed that MR severity is related to systolic tenting and not LV dysfunction 24 .…”