Abstract session 10: clinical electrophysiology II: new insights and observations in atrial arrhythmias

S18 requiring in most cases a new catheter to complete the procedure. There were no unanticipated adverse events. Selective site pacing was effective with successful lead placement at all pre-specified sites in the majority of the patients, with satisfactory lead and catheter handling. Technical improvements of the guiding catheter will further facilitate selective site pacing. 54 Analysis of atrial pacing impedance variations using an isolated heart model *Timothy G. Laske, MS, *Alex J. Hill, PhD, *Nicholas D. Skadsberg, MS, *Sarah A. Vincent, BS and *Paul A. Iaizzo, PhD. Univ of Minnesota, Minneapolis, MN and Medtronic, Inc, Minneapolis, MN. Introduction: Variations in atrial pacing impedances at implantation are commonly seen. This study aims to recreate clinical situations that resultin unusually high pacing impedances in order to provide insight into the clinical consequence of these situations. Methods: Five porcine hearts were reanimated and perfused on an isolated heart apparatus (the Visible Heart®) with a modified Krebs perfusate allowing for direct, intracardiac visualization. A videoendoscope was used to record intra-atrial behavior while recording pacing performance parameters. A fixed screw, bipolar pacing lead was implanted in the atrium using an endocardial approach (N⫽24 across the 5 isolated hearts). Pacing performance parameters (impedance, P-wave amplitude, and pacing threshold) were recorded for the following situations: 1) lead free in atrium, 2) helix contacting tissue, 3) helix 1 turn fixed, 4) helix fully fixed (2 turns), 5) lead body overtorqued 1 turn, and 6) lead body overtorqued 2 turns. Results: Excessive torque applied to the lead resulted in two situations: 1) tissue partially wrapping around the tip of the lead, producing higher than expected pacing impedances (N⫽12; impedances of up to 1463 ohms) or 2) damage to the tissue at the electrode interface (“cored” tissue) with relatively stable impedances (N⫽12). These two situations are plotted separately in the figure below (statistically significant changes are noted for pacing impedances). Conclusions: Excessive torque applied to active fixation pacing leads can produce higher than expected pacing impedances and can damage atrial tissue.

ABSTRACT SESSION 10: CLINICAL ELECTROPHYSIOLOGY II: New Insights and Observations in Atrial Arrhythmias Thursday, May 20, 2004 2:15 p.m.–3:45 p.m. 55 Tachycardias from the Bachmann region observed in the course of atrial fibrillation ablation Pierre Jaı¨s, MD, Prashanthan Sanders, MD, PhD, Li-Fern Hsu, MBBS, Martin Rotter, MD, Fre´ de´ ric Sacher, MD, Ste´ phane Garrigue, MD, Pierre Bordachar, MD, Me´ le`ze Hocini, MD, Jean-Luc Pasquie´ , MD, PhD, Dipen C. Shah, MD, Yoshihide Takahashi, MD, Jacques Cle´ menty, MD and Michel Haı¨ssaguerre, MD. Hoˆ pital Cardiologique du HautLe´ veˆ que, Bordeaux-Pessac, France and Hopital Cantonal de Geneve, Geneve, Switzerland. Atrial fibrillation (AF) is amenable to RF ablation using pulmonary vein isolation (PVI) and if required linear lesions. Various organized atrial arrhythmias have been observed after such procedures. The role of Bachmann‘s Bundle (BB) region in these arrhythmias has not been reported in Humans. Methods: 275 consecutive pts undergoing ablation of drug resistant paroxysmal (200) or chronic (75) AF were studied. Ablation was performed using an irrigated tip catheter with patients having PV ablation alone (58), PV ⫹ mitral isthmus (106), PV⫹LA roof (23) and PV⫹LA roof⫹mitral isthmus (88). Organized atrial arrhythmias following AF ablation were mapped in all pts and their mechanism studied using entrainment mapping and/or electroanatomical mapping, and confirmed by ablation

Heart Rhythm, Vol 1, No 1, May Supplement 2004 Results: 14 pts (5%) (11 were female; 65 ⫾ 13yrs) demonstrated tachycardia localized to BB insertion. 10 had chronic and 4 paroxysmal AF, and 10 had structural heart disease. Delayed BB conduction pattern defined by a negative terminal p wave in inferior leads was present in 7 pts pre ablation. The mean tachycardia CL was 325 ⫾ 125 ms. Entrainment was demonstrated in all with a PPI at the anterior LA of 9 ⫾ 10ms. Electroanatomic mapping in 6 pts demonstrated CW rotation in 4 and CCW in 2. The circuit was bounded by the roofline in 12 and/or the mitral isthmus in 12 and an area of spontaneous block at the junction of the anterior LA and left septum (4), roof (3) and/or left appendage (3). Low voltage areas during tachycardia were present in the anterior LA (6) extending to the septum in 2, coinciding with the slow conduction area. Fractionated mid diastolic low amplitude and long duration potentials (200 ⫾ 80 ms) were found in this region occupying 63 ⫾ 22 % of the CL. Ablation at this site terminated the tachycardia within 30 ⫾ 24 sec and RF energy was delivered for 4 ⫾ 4 min resulting in all being non inducible. Conclusion: Reentrant circuits involving BB region are observed in 5% of the pts ablated for AF affecting predominantly female with structural heart disease and chronic AF. The slow conduction area of the circuit (low amplitude fractionated potentials) is the target of choice. 56 ‘Focal’ isthmuses of reentry at the left atrial appendage root– left superior pulmonary vein os junction after afib ablation *Dipen C. Shah, MD, Henri Sunthorn, MD, Haran Burri, MD and Ulrich Sigwart, MD. Hopital Cantonal Universitaire de Geneve, Geneva, Switzerland. Unlike the right atrium, different isthmuses specific to different tachycardias have been targeted to eliminate fixed reentrant arrhythmias in the left atrium (LA). We describe focal isthmuses at the left atrial appendage (LAA) root–left superior pulmonary vein (LSPV) os junction critical for the maintenance of reentrant tachycardias after AF ablation. Methods: Patients with monomorphic atrial tachycardia after catheter ablation for atrial fibrillation (AF) were studied with a combination of conventional multielectrode and 3D mapping and entrainment to localize the circuit and delineate critical isthmuses. RF energy was delivered at isthmus sites using an irrigated catheter (50° C, 45 W) with the endpoint of tachycardia termination and noninducibility. Results: Out of 66 patients ablated for AF, 7 (all male, 54 ⫾ 5 y, including 4 with linear LA ablation) were studied for a persistent regular monomorphic atrial tachycardia (cycle length 245 ⫾ 30ms, ⫹ve in V1) presenting 66 ⫾ 78 days after the AF procedure. Mapping localized the reentry circuit to the vicinity of the left PV ostia in 4/7resulting in a characteristic surface ECG (wide ⫹ve P in II, III, avF; -ve in I, avL; late ⫹ve in V1). 3D activation mapping confirmed a small reentry circuit around the LPV os and or root of the LAA with a zone of pronounced slow conduction producing fractionated low amplitude diastolic electrograms (100-180ms). A single focal RF application in this zone terminated and eliminated the tachycardia in all 4. Dual loop reentry around the LPV and RPV os and around the LPV os and LAA-roof was present in 2 patients. An isthmus in the coronary sinus maintained the last reentry circuit. Appropriate multilesion ablation (8-15 min) across the LA roof and in the coronary sinus eliminated these 3 tachycardias. Conclusions: The LAA root–LPV os is a consistent site of very small isthmuses critical for the maintenance of small fixed reentry around the isolated left PV ostia and or LAA root. Regional anisotropy and remnant PV myocardium modified by RF ablation may be responsible for such tachycardias which should be preventable by more complete and proximal left PV isolation. 57 Atrial tachycardia arising from the Coronary Sinus (CS) musculature: Electrophysiologic characteristics and long term follow up Nitish Badhwar, MD, Jonathan M. Kalman, MBBS, PhD, Paul B. Sparks, MD, PhD, Peter M. Kistler, MBBS, Randall

Session 10 J. Lee, MD, PhD and Melvin M. Scheinman, MD. Univ of California-San Francisco, San Francisco, CA and Royal Melbourne Hosp, Melbourne, Australia. Background: Atrial tachycardia arising from the muscle deep within the coronary sinus (Cs) has been described in isolated case reports. We report the electrophysiologic features and long-term response to catheter ablation in five patients. Electrophysiologic findings: The study included five patients (three males) with a mean age of 29 ⫾ 16 years. In sinus rhythm, a discrete potential (P) was noted after the Cs atrial electrogram (A) and recorded 4-5 cm within the Cs. Tachycardia was noted spontaneously (2 patients) or initiated with atrial extrastimuli during isoproterenol infusion (3 patients). During tachycardia the surface p wave was noted to be negative in leads II, III, avF and V6, positive in avL and V1 and biphasic in lead I. During tachycardia, the Cs (P) preceded the Cs (A) or surface P wave by 35-50 ms. In addition, all patients showed spontaneous or adenosine induced atrioventricular (AV) block and AV dissociation in response to ventricular overdrive pacing during tachycardia. Tachycardia termination associated with loss of Cs (P) was documented transiently in two patients during mapping that was attributed to mechanical trauma. Ablation of the tachycardia initially attempted from the earliest site in the left atrium (LA) in 3 patients was unsuccessful. In one patient during LA ablation, the Cs (P) was dissociated from the Cs (A). In all patients the tachycardia was successfully ablated at a site 4-5 cm within the Cs. There has been no recurrence over a follow up of 26 ⫾ 9 months. Conclusion: Atrial tachycardia emanating deep within the Cs musculature (or Ligament of Marshall) can be recognized by a discrete potential associated with Cs (A) both during sinus rhythm and tachycardia. Long-term success can be accomplished by ablating in close proximity to the Cs (P).

58 Novel insights in focal atrial tachycardia using highdensity localized mapping Prashanthan Sanders, MD, PhD, Li-Fern Hsu, MBBS, *Pierre Jaı¨s, MD, Me´ le`ze Hocini, MD, Christophe Scave´ e, MD, Jean-Luc Pasquie´ , MD, PhD, Yoshihide Takahashi, MD, Martin Rotter, MD, Fre´ de´ ric Sacher, MD, Ste´ phane Garrigue, MD, Jacques Cle´ menty, MD and *Michel Haı¨ssaguerre, MD. Hoˆ pital Cardiologique du Haut-Le´ veˆ que, Bordeaux-Pessac, France. Background: Ablation of focal atrial tachycardias (AT) using conventional mapping techniques may fail in 5-10% due to elusive focal discharge, multiple foci or complex anatomy. Methods: 6 pts (46 ⫾ 15yrs) with AT who had failed prior ablation attempts using conventional mapping were studied. 1 pt had moderate mitral regurgitation and 2 had impaired left ventricular function. We used a new high-density localized 5 spine (20 pole) catheter (Biosense-Webster) that facilitated: (i) vector mapping for quick identification of the region of interest; and (ii) local catheter application for regional high-density mapping to determine the earliest site of activity. Results: AT was localized to the RA appendage, LA septum or to regions of localized scar in 5 pts, while 1 pt had multifocal origin mapped to 6 distinct sites (pulmonary veins, posterior LA and LA roof). In all cases local ablation terminated AT. High-density mapping demonstrated the following findings: (i) In 3 pts, AT was identified to arise from a focal site which could be bracketed, demonstrating centrifugal activation (in 2 arising from within localized scar). In 2 pts, where

S19 conventional mapping had suggested centrifugal activation, the entire cycle length of AT was mapped within a localized region of scar with fractionated and mid-diastolic activity (although entrainment could not be performed due to a pacing threshold ⬎20mA); (ii) In 1 pt an isolated region along the crista demonstrated ultra rapid bursts of activity (CL 83 ms) that failed to conduct to the remaining atria; and (iii) Varying degrees of intra-atrial conduction block (radial to the site of origin), at times mimicking the termination of AT on ECG were observed in 2 pts. Conclusion: High-density localized mapping can identify the origin of complex AT. It has demonstrated the following electrophysiological findings that have previously been unreported in humans: (i) some seemingly focal AT result from atrial reentry; (ii) high frequency rapid activity within the atria; and (iii) variable intra atrial conduction resulting in misleading electrophysiologic manifestations. 59 Focal atrial tachycardias: Differences in right verus left atrial foci Deepak Bhakta, MD, Amer Suleman, MD and *John M. Miller, MD. Indiana Univ, Indianapolis, IN and Medical Ctr of Plano, McKinney, TX. Focal (non-reentrant) atrial tachycardias (AT) appear to have a point source with uniform centrifugal spread of activation. Methods: In order to study whether right (RA) and left atrial (LA) foci have similar characteristics, we evaluated a consecutive series of 79 patients (24 men, mean age 48 ⫾ 16 yrs) undergoing radiofrequency catheter ablation (RFCA) for AT at our institution. Results: Initiation of AT occurred either spontaneously (n ⫽ 26), or with isoproterenol (50), epinephrine (2), or dopamine (1). Sites of origin included the crista terminalis (21), pulmonary veins (16), para-Hisian (6), coronary sinus ostium (3), LA appendage (2), other RA sites (22), and other LA sites (9). The average interval from earliest atrial deflection to P-wave onset (pre-P interval) was 42 ⫾ 17 ms. Differences were observed between right and left atrial foci with regard to patient age, initiation requiring pharmacologic agents, tachycardia cycle length, and pre-P interval. (Table) ATs originating from the left atrial appendage had the longest pre-P interval (60 ⫾ 7 ms) and those originating from the coronary sinus ostium had the shortest (30 ⫾ 9 ms), p ⫽ 0.04. Ablation was successful in 67/79 (85%) cases, with recurrence of AT in 5 patients (LA 2, RA 3), complication precluding success in 3 (all in LA), failed RFCA in 2 (both in RA), and no ablation attempted in 2 cases of RA foci. Conclusions: Mapping characteristics of right versus left atrial tachycardias are not identical, with different sites exhibiting different clinical and electrophysiologic properties. These findings have important implications for RFCA of these tachycardias.

60 The eutachian ridge is not always a barrier of the reentry circuit during typical atrial flutter–A novel finding Jin-Long Huang, MD, Ching-Tai Tai, MD, Tu-Ying Liu, MD, Pi-Chang Lee, MD, Satoshi Higa, MD, Yu-An Ding, MD and Shih-Ann Chen, MD. Veterans General Hosp-Taichung, Taichung, Taiwan Republic of China, Taipei Veterans General Hosp, Taipei, Taiwan Republic of China, Chutung Veterans’ Hosp, Chutung, Taiwan Republic of China and Univ of the Ryukyus, Nishihara, Okinawa, Japan. Background: Previous studies using the multiple electrode catheter for mapping of typical atrial flutter (AFL) demonstrated that the eustachian ridge (ER) is an important posterior barrier in AFL. However, some

S20 pathologic studies showed myocardial fibers within the ER, thus AFL activation wavefront may pass through ER. The purpose: of this study was to demonstrate the role of ER in the typical AFL using the high density noncontact mappng. Methods and Results: A total of 34 patients (mean age 62 ⫾ 17 yrs, M/F ⫽ 26/8) with typical AFL underwent electrophysiological study and detailed mapping of atrial activation using the non-contact mapping system (Ensite 3000). The ER was located between IVC and coronary sinus ostium (CSO). Conduction block in the ER was defined as wavefront propagation along the one side of the ER, turning around the CSO, and traveling along to the other side of the ER. Twenty-two patients (Group I, 65%) had a complete line of block in the ER and 12 patients (Group II, 35%) had conduction through the ER during typical AFL. The virtual unipolar electrogram on the ER showed widely split double potentials (97 ⫾ 13 ms) in the Group I patients. Among the Group II, 6 (II A) passed through a gap in the ER with narrowly split double potentials (45 ⫾ 4 ms) (5 from the upper gap between CS and ER, one from the lower gap between ER and IVC), and the other 6 (II B) had conduction with a broad wavefront underneath the ER. Conclusion: The ER is not always a posterior barrier during typical CCWR AFL. Radiofrequency ablation from the CSO to TA would not cure the AFL with ER gap.

ABSTRACT SESSION 11: NONINVASIVE EVALUATION II: Noninvasive Assessment of Right Ventricular Tachycardia Thursday, May 20, 2004 4:30 p.m.– 6:00 p.m. 61 A new electrocardiographical approach for differential diagnosis between ARVC and Brugada syndrome Kenji Yodogawa, MD, Norishige Morita, Toshihiko Ohara, Katsuhiko Tateoka, Hiroshi Taniguchi, Atsushi Ueno, Tsutomu Horie, Yasuhiro Hirasawa, Junko Abe, MD, Yuki Iwasaki, Mitsunori Maruyama, Hideo Takayama, Yasushi Miyauchi, MD, Yoshiyuki Hirayama, Yoshinori Kobayashi, Takao Katoh and Teruo Takano. Nippon Medical School, Tokyo, Japan. Background: Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy (ARVC) are both associated with fatal ventricular arrhythmias. However, their standard ECGs mimic each other. Late potential (LP) by signal averaged electrocardiogram (SAECG) is often positive in both diseases. Therefore a new approach is expected for discriminating between these 2 diseases. Methods: This study was comprised of 30patients (10 Brugada patients 39.5 ⫾ 16.0y.o., 10 ARVC patients 43.4 ⫾ 16.7y.o., and 10 normal subjects 40.4 ⫾ 14.2y.o.). Brugada syndrome was diagnosed by its typical electrocardiograms and pilsicainide challenge test (all patients changed to the coved type of ST segment) and electrophysiologic study (ventricullar fibrillation was induced in all patients). Diagnosis of ARVC was made by the diagnostic standard of McKenna. Time-frequency analysis using wavelet transform was performed for QRS complex of each electrocardiogram, and power value at 10-200Hz was assesed against time course. LP was also evaluated by SAECG. Results: LP was positive in 7 (70%) of Brugada patients, 9 (90%) of ARVC patients, and none of normal subjects. Wavelet transformed QRS in normal subjects was mainly composed of low frequency (10-50Hz) components with high power, and high frequency (80-150Hz) components with low power. On the other hand, in all of Brugada patients, high frequency components had high power at the middle of QRS complex, and the abnormal signal was mainly developed at 80Hz. In ARVC patients, high frequency components with substantial power was developed at the termi-

Heart Rhythm, Vol 1, No 1, May Supplement 2004 nal portion of QRS complex, but it mainly developed at 150Hz. In comparison of the high frequency components between two diseases, the frequency level showing the greatest power was significantly higher in ARVC patients than that in Brugada patients (149.1 ⫾ 15.2Hz vs 80.4 ⫾ 20.4Hz, p ⬍ 0.005). Conclusion: The frequency levels with high power by wavelet transform analysis obviously differs between ARVC and Brugada syndrome. Wavelet transform analysis of QRS complex may be a novel tool for differential diagnosis between these two diseases. 62 Exercise induced ST-segment elevation in arrhythmogenic right ventricular dysplasia Kalpana R. Prakasa, MD, Darshan Dalal, MBBS, Chandra Bomma, MD, Mary Corretti, MD and Hugh Calkins, MD. Johns Hopkins Univ School of Medicine, Baltimore, MD. Background: Arrhythmogenic Right Ventricular Dysplasia (ARVD) is characterized by local and diffuse wall motion abnormalities of right ventricle (RV) due to replacement of myocardium with fibrofatty tissue. It has been well documented in the literature that patients with Q wave infarction may have exercise induced ST-segment elevation which corresponds to the site of left ventricle (LV) wall motion abnormality. We sought to test the hypothesis that exercise induced ST-segment elevation may appear in leads corresponding to the site of RV wall motion abnormality in ARVD. Methods and Results: We enrolled 18 ARVD patients (mean age 36 ⫾ 13yrs, 8 men) with (11 patients) and without (7 patients) RV wall motion abnormalities by conventional Echocardiography (ECHO). All patients had normal LV systolic function by ECHO (Ejection Fraction 58% ⫾ 8). Organic coronary lesions were ruled out in all of them by cardiac catheterization. Clinical ARVD diagnosis was made based on Task Force criteria. All patients underwent a symptom limited or sub maximal Exercise Treadmill Test according to Modified Bruce Protocol. Inter group means were compared using Student’s t test. They achieved a maximum predicted heart rate of 91% ⫾ 12 and metabolic equivalents of 14 ⫾ 4. None of them had angina during exercise. Eleven out of 18 patients had premature ventricular contractions (61%) during exercise. The development of 0.10mv (1mm) or greater of J point elevation, persistently elevated greater than 0.10mv at 60-80msec after the J point in three consecutive beats with a stable baseline, was considered an abnormal response. ST-segment elevation in leads II, III, AVF and V1-V3 was found in 10 out of 11 patients with RV wall motion abnormality, while only one patient in the group without RV wall motion abnormality had ST-segment elevation (p ⬍ 0.05). Conclusion: Exercise induced ST-segment elevation in leads corresponding to the RV wall motion abnormality may add to the diagnosis of ARVD. The absence of organic coronary lesions could suggest the role of mechanical factors in the genesis of exercise induced ST-segment elevation. 63 Electrocardiographic evidence of progression of arrhythmogenic right ventricular dysplasia Jonathan P. Piccini, MD, Khurram Nassir, MD, Chandra Bomma, MD, Darshan Dalal, MBBS, Harikrishna Tandri, MD, Crystal Tichnell, Cynthia James, PhD and Hugh Calkins, MD. Johns Hopkins Hosp, Baltimore, MD and Johns Hopkins Univ School of Medicine, Baltimore, MD. Background: ARVD is a hereditary cardiomyopathy characterized by fibrous fatty infiltration of the right ventricular free wall which predisposes to abnormal repolarization and sudden death. Accurate diagnosis of ARVD is challenging and is based upon the International Task Force Criteria (TFC). The 12 lead electrocardiogram (ecg) is an essential component in the diagnosis of ARVD, and has several characteristics germane to ARVD, including precordial T-wave inversion, epsilon waves, and right bundle branch block. Recently, we have found that prolongation of the S wave upstroke in leads V1, V2, and V3 is the most prevalent ecg abnormality in