Three-Dimensional Assessment of Left Ventricular Geometry and Annular Dilatation Provides New Mechanistic Insights into the Surgical Correction of Ischemic Mitral Regurgitation

RT-3D TEE: characteristics of mitral annulus using mitral valve quantification (MVQ) program

AIM

To evaluate the mitral annulus characteristics in significant mitral regurgitant lesions using mitral valve quantification (MVQ) program.

METHODS

We examined 117 patients (39 women), aged 18-86. Patients were separated into four subgroups: 35 patients with ischemic mitral regurgitation, 42 patients with isolated prolapse of the mitral valve, 12 patients with Barlow disease, and 28 healthy controls. Mitral annulus was examined in end-systole. The following parameters were assessed: anteroposterior and intercommissural diameter, perimeter of annulus, area of minimal surface spanning annulus and height of the mitral annulus. A new parameter--mitral annulus height index (height/circumference × 100) was introduced. Values of these parameters in subgroups with mitral pathology were compared with corresponding parameters of control group using Student t-test.

RESULTS

In subgroups with mitral pathology all parameters except mitral annulus height and mitral annulus height index were significantly higher than those in the control group. Mitral annulus height was significantly higher in Barlow disease, significantly lower in mitral prolapse group and comparable to normal controls in the ischemic regurgitation group. Mitral annulus height index was significantly higher in Barlow disease and significantly lower in patients with prolapse and ischemic regurgitation.

CONCLUSIONS

Barlow disease is characterized by dilation and vertical deformation of the mitral annulus (annulus height and height index increase). Prolapse of the mitral valve and ischemic regurgitation of mitral annulus involve dilation and flattening of the annulus (annulus height decreases in prolapse group significantly, in ischemic regurgitation nonsignificantly, while annulus height index decreases significantly in both subgroups).

On the calculation of principle curvatures of the left-ventricular surfaces

A local description of the shape of the left ventricle is relevant in assessing the process of adverse ventricular remodeling, associated with most cardiac pathologies, and in monitoring reverse remodeling by therapy. To quantify local shape of the left ventricle, one can calculate the curvature of its epicardial or endocardial surface. The 3D geometry of the heart and especially the ventricles, can typically be described using finite element meshes. From a mathematical point of view these meshes provide a local parametrization of the surface in the 3-dimensional space. We discuss the analytic derivation of the principle curvatures of the left-ventricular surfaces given their smooth finite-element meshes and apply this derivation to assess the regional shape of the normal porcine left ventricle.

Expectations of surgeons from an imager

In the last decade, we have witnessed an extraordinary development of new cardiac imaging techniques. Some are already in routine use while other promising techniques, such as 3D and intracardiac echocardiography, are still taking their first steps in clinical applications and have not yet revealed all their potential. Heart failure surgery is also evolving rapidly toward less-invasive procedures with the introduction of video-assisted robotic valve repair/replacement surgery, percutaneous delivery of epicardial restraint devices, mitral edge-to-edge clips, coronary sinus mitral annuloplasty rings, and stem cell therapy. These rapid developments are challenging for the imager and the surgeon and mandate a close collaboration between the two disciplines to minimize surgical risk and improve the outcome of patients who have heart failure.