Dataset Information

Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry.

ABSTRACT:

Introduction

Mitral Valve (MV) 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE) devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR). Finite element method (FEM) modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions.

Method

With the present retrospective pilot study we describe a method to transfer MV geometric data to 3D Slicer 2 software, an open-source medical visualization and analysis software package. A newly developed software program (ROIExtract) allowed selection of a region-of-interest (ROI) from the TEE data and data transformation for use in 3D Slicer. FEM models for quantitative volumetric studies were generated.

Results

ROI selection permitted the visualization and calculations required to create a sequence of volume rendered models of the MV allowing time-based visualization of regional deformation. Quantitation of tissue volume, especially important in myxomatous degeneration can be carried out. Rendered volumes are shown in 3D as well as in time-resolved 4D animations.

Conclusion

The visualization of the segmented MV may significantly enhance clinical interpretation. This method provides an infrastructure for the study of image guided assessment of clinical findings and surgical planning. For complete pre- and intraoperative 3D MV FEM analysis, three input elements are necessary: 1. time-gated, reality-based structural information, 2. continuous MV pressure and 3. instantaneous tissue elastance. The present process makes the first of these elements available. Volume defect analysis is essential to fully understand functional and geometrical dysfunction of but not limited to the valve. 3D Slicer was used for semi-automatic valve border detection and volume-rendering of clinical 3D echocardiographic data. FEM based models were also calculated.

Method

A Philips/HP Sonos 5500 ultrasound device stores volume data as time-resolved 4D volume data sets. Data sets for three subjects were used. Since 3D Slicer does not process time-resolved data sets, we employed a standard movie maker to animate the individual time-based models and visualizations. Calculation time and model size were minimized. Pressures were also easily available. We speculate that calculation of instantaneous elastance may be possible using instantaneous pressure values and tissue deformation data derived from the animated FEM.

SUBMITTER: Verhey JF

PROVIDER: S-EPMC1421418 | biostudies-literature | 2006 Mar

REPOSITORIES: biostudies-literature

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Publications

Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry.

Verhey Janko F JF Nathan Nadia S NS Rienhoff Otto O Kikinis Ron R Rakebrandt Fabian F D'Ambra Michael N MN

Biomedical engineering online 20060303

<h4>Introduction</h4>Mitral Valve (MV) 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE) devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR). Finite element method (FEM) modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions.<h4>Method</h4>With the present retrospective p ...[more]

PMID: 16512925

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Project description:BackgroundTranscatheter aortic valve replacement has proved its safety and effectiveness in intermediate- to high-risk and inoperable patients with severe aortic stenosis. However, despite current guideline recommendations, the use of transcatheter aortic valve replacement (TAVR) to treat severe aortic valve stenosis caused by degenerative leaflet thickening and calcification has not been widely adopted in low-risk patients. This reluctance among both cardiac surgeons and cardiologists could be due to concerns regarding clinical and subclinical valve thrombosis. Stent performance alongside increased aortic root and leaflet stresses in surgical bioprostheses has been correlated with complications such as thrombosis, migration and structural valve degeneration.Materials and methodsSelf-expandable catheter-based aortic valve replacement (Medtronic, Minneapolis, MN, USA), which was received by patients who developed transcatheter heart valve thrombosis, was investigated using high-resolution biomodelling from computed tomography scanning. Calcific blocks were extracted from a 250 CT multi-slice image for precise three-dimensional geometry image reconstruction of the root and leaflets.ResultsDistortion of the stent was observed with incomplete cranial and caudal expansion of the device. The incomplete deployment of the stent was evident in the presence of uncrushed refractory bulky calcifications. This resulted in incomplete alignment of the device within the aortic root and potential dislodgment.ConclusionA Finite Element Analysis (FEA) investigation can anticipate the presence of calcified refractory blocks, the deformation of the prosthetic stent and the development of paravalvular orifice, and it may prevent subclinical and clinical TAVR thrombosis. Here we clearly demonstrate that using exact geometry from high-resolution CT scans in association with FEA allows detection of persistent bulky calcifications that may contribute to thrombus formation after TAVR procedure.

Project description:We present a case of mitral valve (MV) replacement that resulted in multiple complications, as diagnosed by transesophageal echocardiography (TEE), including left ventricular outflow tract obstruction, aortic dissection and left ventricular rupture. We also describe that identification of bleeding originating from the posterior aspect of the heart by the surgical team should trigger a complete TEE evaluation for adequate diagnosis. An 84-year-old woman underwent a MV replacement. Weaning from cardiopulmonary bypass (CPB) revealed a late-peaking gradient of 44 mmHg over the left ventricular outflow tract caused by obstruction from a bioprosthetic strut. After proper surgical correction, TEE evaluation showed a type A aortic dissection that was subsequently repaired. After separation from CPB, the surgical team identified a major bleed that originated from the posterior aspect of the heart. Although the initial suspicion was injury to the atrioventricular groove, a complete TEE evaluation confirmed a left ventricular free wall rupture by showing the dissecting jet using colour-flow Doppler. TEE is an essential component in cardiac surgery for assessment of surgical repair and potential complications. Posterior bleeding should trigger a complete TEE examination with assessment of nearby structures to rule out a life-threatening pathology. Left ventricular free wall rupture can be identified using colour-flow Doppler.Multiple complications may occur after MVR.TEE is an essential component in the evaluation of surgical repair and its potential associated complications, including LVOT obstruction, aortic dissection and LV rupture.Posterior bleeding, from the region of AV groove, should trigger a complete TEE examination with assessment of nearby structures such as the atria, coronary sinus and myocardium to rule out a life threatening pathology.The diagnosis of a LV rupture can be confirmed with 2-D imaging and colour-flow Doppler demonstrating a dissecting jet through the myocardium.

Dataset Information

Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry.

Introduction

Method

Results

Conclusion

Method

Publications

Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry.

Similar Datasets

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