49 Ultra High-Density Multipolar Mapping With Double Ventricular Access: A Novel Technique for Ablation of Ventricular Tachycardia RODERICK TUNG, M.D., ∗ SHIRO NAKAHARA, M.D., Ph.D., ∗ GIUSEPPE MACCABELLI, M.D.,† ERIC BUCH, M.D., ∗ ISAAC WIENER, M.D., ∗ NOEL G. BOYLE, M.D., Ph.D., ∗ CORRADO CARBUCICCHIO, M.D.,† PAOLO DELLA BELLA, M.D.,† and KALYANAM SHIVKUMAR, M.D., Ph.D. ∗ From the ∗ UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine at UCLA, Los Angeles, California, USA; and †Centro Cardiologico Monzino, Institute of Cardiology of University of Milan, Milan, Italy Ultra High-Density Multipolar Mapping With Double Ventricular Access. Background: Analogous to the use of circular loop catheters to guide ablation around the pulmonary veins, it may be advantageous to use a multipolar catheter in the ventricle for rapid mapping and to guide ablation. We describe a technique using double access into the left ventricle for multipolar electroanatomic mapping and ablation of scar-mediated ventricular tachycardia (VT). Methods: Double access into the left ventricle was obtained via transseptal technique. Endocardial mapping was performed via the first transseptal sheath using a steerable duodecapolar catheter. Higher density mapping was performed in areas of dense scar (<0.5 mV) and border zone (0.5–1.5 mV). All late potentials (LPs) observed on the 20 poles were tagged and pacemapping was performed at these sites for comparison with the clinical or induced VT 12-lead template. If VT was hemodynamically tolerated, entrainment mapping was attempted at sites demonstrating diastolic activity. Ablation was performed through the second transseptal sheath with an open-irrigated catheter at target sites identified by LPs, pacemapping, and/or entrainment on the duodecapolar catheter. Results: Seventeen patients (88% ischemic cardiomyopathy) underwent electroanatomic mapping and ablation with double transseptal access. The mean number of endocardial mapping points was 819 ± 357 with an average mapping time of 31 ± 7 minutes. The mean number of VTs induced was 2.8 ± 1.6, mean cycle length 418 ms ± 101. LPs were seen in all patients during endocardial mapping with the duodecapolar catheter. Good (56%) and perfect (44%) pacemaps were seen in all patients when performed. Concealed entrainment, guided by the earliest diastolic activity seen on the duodecapolar catheter, was demonstrated in 4 patients (24%). Acute success was achieved in 94% of patients with complete success in 47% and partial success in 47%. The intermediate success rate (free of VT recurrence) was 69%, with an average follow-up of 8 ± 3 months. Conclusion: Mapping and ablation of scar-mediated VT using a multipolar catheter results in ultra high-density delineation of the left ventricular substrate. A novel double ventricular access strategy has the potential to facilitate identification of LPs, pacemapping, and entrainment mapping. (J Cardiovasc Electrophysiol, Vol. 22, pp. 49-56, January 2011) ventricular tachycardia, mapping, catheter ablation, coronary artery disease, cardiomyopathy Introduction Catheter ablation of ventricular tachycardia (VT) is ef- fective in reducing the recurrence of ventricular arrhythmias and implantable cardioverter-defibrillator (ICD) therapies in patients with structural heart disease. 1-4 When entrainment Drs. Tung and Della Bella report honoraria for lectures on VT mapping and ablation. Other authors: No disclosures. Address for correspondence: Roderick Tung, M.D., UCLA Cardiac Arrhyth- mia Center, Ronald Reagan UCLA Medical Center, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1679, USA. Fax: 310 794 6492; E-mail: rtung@mednet.ucla.edu Manuscript received 11 May 2010; Revised manuscript received 9 June 2010; Accepted for publication 14 June 2010. doi: 10.1111/j.1540-8167.2010.01859.x mapping cannot be performed due to hemodynamic instabil- ity, noninducibility, or pleiomorphism, electroanatomic map- ping (EAM) systems are critical to guide substrate-based approaches. 5,6 Ablation strategies targeting late potentials (LPs) have been demonstrated to be effective at reducing VT recurrence. 7,8 However, substrate-based ablation procedures often require long procedural times due to extensive point- by-point mapping. A method to improve mapping density for the identification of LPs over a larger myocardial area holds promise for facilitating and expediting VT ablation. Multipolar mapping has been shown to be accurate and expeditious in the mapping of complex reentrant atrial ar- rhythmias. 9 Analogous to the use of circular loop catheters to guide ablation around the pulmonary veins, 10 it may be advantageous to use a multipolar catheter in the ventricle for rapid mapping and to guide ablation. In this series, we de- scribe a technique using double access into the left ventricle for multipolar EAM and ablation of scar-mediated VT.