- Poster presentation
- Open Access
Successful integration of MRI derived scar distribution during VT ablation procedures. Initial experience in 12 patients
© Geest et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Ventricular Tachycardia
- Right Coronary Artery
- Registration Error
- Left Main
- Late Enhancement
Substrate based ventricular tachycardia (VT) ablation requires extensive electroanatomical voltage mapping (EAM) to delineate the myocardial scar and its border zone. Integration of three-dimensional (3D) information from late enhancement (LE) MRI may be feasible and may provide additional information on VT substrate mapping. This study was conducted to test the feasibility of merging 3D MR derived scar information during the VT ablation procedure.
In 12 patients (all men; age 64 ± 10) referred for catheter ablation of VT late after myocardial infarction CMR was performed 2–3 days prior to VT ablation. LE MR was performed in multiple slices covering the complete LV in short-axis (slice thickness 10 mm, 5 mm overlap) and long-axis views (two-chamber, four-chamber views, slice thickness 12 mm, 6 mm overlap). In addition, a black-blood imaging sequence was used to image the proximal aorta and the origin of the left main (LM) and right coronary artery (RCA). In the short-axis LE scan, endocardial and epicardial boundaries were derived semi-automatically. The myocardium was divided in an endocardial and epicardial layer and for each layer, at each location, the extent of scar was computed. Subsequently, 3D endocardial and epicardial surface meshes were constructed. Mesh points were color coded based on the extent of scar at the respective myocardial location and layer. In addition, 3D meshes were constructed of the ascending aorta and origin of the LM and RCA.
Prior to VT ablation the generated meshes were imported into the 3D mapping system (CARTO, research version). Based on the 3D catheter tracking capabilities of this system, the MRI derived meshes were registered with the endocardial EAM using the LM position and the endocardial surface as landmarks. After the procedure, 3D mapping point positions and the corresponding bipolar electrogram voltages were saved and superimposed on the original LE MRI data for comparison. Presence of scar from EAM was based on a cut off value of 1.5 mV.
It was demonstrated that integration of MRI derived scar information into a 3D mapping system is feasible. The observed registration errors are small compared to the expected amount of cardiac and respiratory motion and the slice thickness of the LE MRI acquisition. The additional information provided by MRI, especially in regions of non-transmural scar, may be helpful to assess the anatomical substrate of VT and to improve the efficiency and outcome of VT ablation procedures.
This article is published under license to BioMed Central Ltd.