Epicardial catheter ablation of ventricular tachycardia (original) (raw)

T he feasibility of catheter ablation of ventricular tachycardia (VT) associated with structural heart disease has improved dramatically with the use of substrate identification using the electroanatomical mapping systems and cardiac MRI. Sustained VT after valve surgery has been reported either early after surgery or years later, and a reentrant mechanism in a region of scar is the most common mechanism. 1-3 However, in patients with prior mechanical mitral and aortic valves, the access to the left ventricle (LV) is limited, preventing an endocardial approach to ablation via a retrograde aortic or atrial transseptal approach. Here, to the best of our knowledge, we report the largest series of ablation for VT in these patients, demonstrate approaches including epicardial catheter ablation via a surgical pericardial window, surgical epicardial cryoablation, and surgical approach to endocardial catheter mapping, and provide the details of the arrhythmia substrate. Methods Patients with drug refractory VTs with aortic and mitral mechanical valve prostheses were included in the study. Ethical approval was obtained from the local institutional review committee. All patients gave their informed consent when retrospective data collection started. Echocardiography was performed, and the LV function was evaluated before the catheter ablation. All patients were anticoagulated with warfarin for the mechanical valves, and the warfarin was discontinued and bridged with a heparin infusion before the ablation or open-heart surgery. Heparin was discontinued 4 hours before the procedure. Multielectrode catheters were inserted and placed at the His recording site, coronary sinus and right ventricular apex. Programmed stimulation was performed to identify the target VT. Bundle branch re-entry or VT originating from the right ventricle was ruled out. If the VT was from the LV, a surgical pericardial window was used as an access to the epicardium with anticipation of pericardial adhesions. A 3-dimensional electroanatomical mapping system (Carto system, Biosense Webster, or EnSite NavX, St. Jude Medical) was used to identify the substrate and map the VT if allowed. Sites with abnormal potentials, such as fractionated signals,