1357732 - 4 Dimensional rendering of an extremely dysplastic mitral valve with severe regurgitation.

A two year old healthy young boy presented to an outside institution with a 2/6 systolic murmur best heard in the left lower sternal border.  An echocardiogram performed demonstrated a dysplastic thickened mitral valve with severe mitral valve regurgitation and concern for multiple papillary muscles.  The left heart was severely dilated, and the left ventricular systolic function was normal.  Further preoperative imaging was requested to delineate the mitral valve architecture and function.


Diagnostic Techniques and Their Most Important Findings:

4D Flow MRI was performed on a 3T platform (GE 750W) with a large 16 element flex coil with an acquired spatial resolution of 1 mm x 1 mm x 1.2 mm resolution, temporal resolution of 20 milliseconds, and velocity encoding of 280 cm/s.  The patient was sedated and intubated during the exam, and allowed to free-breathe.  Volumetric analysis and stroke volume analysis using Arterys software was analyzed from the 4D flow dataset.  The left atrium was severely dilated, and the left ventricle was severely dilated with normal left ventricular systolic function (LVEDV: 75 mL, LVEDVi: 141 mL/m2, LVEF: 62%).  CMR confirmed severe mitral valve regurgitation with a regurgitant fraction of 55% by left ventricle and right ventricle stroke volume comparison, and 61% by left ventricular stroke volume and aortic flow comparison.  4 dimensional rendering of the mitral valve and heart was performed to further define the mechanism for mitral valve insufficiency.  A coaptation defect between A2 and P2 mitral valve scallops resulted in a central regurgitant jet.  Severe dilation of the mitral valve annulus and prolapse of both the anterior and posterior leaflets were present.  The leaflet tips were severely thickened as seen on the echo.   Unexpectedly, the posterior mitral valve had three separate clefts.   Furthermore, 8 papillary muscles connected the mitral valve to the left ventricle.  Four dimensional rendering allowed the entire mitral valve apparatus in addition to the regurgitant jet to be visualized in a single movie.  The heart was 3D printed from the 4D flow dataset. 

Anatomy of the mitral valve as described from CMR was confirmed intraoperatively.  The patient underwent mitral valve repair consisting of closure of the posterior mitral valve clefts, mitral valve annuloplasty, and an Alfieri stitch. Postoperative TEE demonstrated  no stenosis and trace insufficiency.  The patient is currently doing well.    

 


 

Learning Points from this Case:

1.     High resolution 4D flow MRI can be used to comprehensively evaluate mitral valve insufficiency, including delineation of minute anatomic abnormalities.

2.     Four dimensional rendering of 4D can be used to visualize the entire mitral valve apparatus and regurgitant flow in great detail.