Epicardial Radiofrequency Catheter Ablation of Ventricular Tachycardia in the Vicinity of Coronary Arteries Is Facilitated by Fusion of 3-Dimensional Electroanatomical Mapping With Multislice Computed Tomography
A 65-year-old male patient was referred for radiofrequency catheter ablation of a ventricular tachycardia (VT). The patient had a history of an anterior non–Q-wave infarction. Angiography revealed no significant lesions and normal left ventricular (LV) function.
Before ablation, a contrast-enhanced 64-slice computed tomography (CT) scan was acquired. CT data were loaded into an electroanatomical (EA) mapping system (Biosense Webster, Inc, Diamond Bar, Calif) to provide 3-dimensional (3D) CT surface reconstruction of the coronary arteries and LV. Endocardial voltage mapping of the LV was performed during sinus rhythm and the 3D EA mapping data were merged with the 3D surface reconstruction data, allowing real-time visualization of the catheter tip in relation to the surface reconstruction (Figure 1). The clinical VT (cycle length 314 ms) was induced (Figure 2A). Endocardial mapping revealed a wide breakthrough area located in the inferolateral wall preceding the QRS complex by 16 ms, which was suggestive of an intramural or epicardial reentrant circuit (Figure 2B). Therefore, a 3D EA epicardial activation map was obtained after a subxiphoid pericardial puncture. This map revealed an early activated inferolateral epicardial site (52 ms before onset of the QRS complex) representing a target site for ablation(Figure 2D). Damage to a coronary artery is a potential and serious complication of epicardial ablation procedures, and usually coronary angiography is performed to visualize the relationship between radiofrequency target sites and the coronary arteries. This approach, however, requires frequent coronary contrast injections in different projections. The fusion of CT and endocardial and epicardial EA mapping data provides real-time visualization of the catheter tip in relation to the epicardial coronary arteries (Figure 3A). A comparison of CT data with coronary angiographic data was performed, and the relationship between the catheter tip and the coronary artery was confirmed (Figure 3B). A single radiofrequency application at this site terminated the VT without complications. This report illustrates that the fusion of pre-acquired CT images with real-time 3D EA mapping data is accurate and may enhance the safety of epicardial catheter ablation procedures by establishing the relationship between the catheter tip and major coronary arteries.