- Email: [email protected]
A novel nonfluoroscopic catheter visualization system (LocaLisa) to reduce radiation exposure during catheter ablation of supraventricular tachycardias
extensive, empiric intervention, such as by a surgical Maze procedure involving partitioning of the left as well as the right atrium.13 Up to a third of patients with CHD and atrial tachycardia who require cardioversion may have AF, as well as the more prevalent IART. Patients with significant unrepaired lesions may be relatively more prone to AF. Both types of arrhythmias require intervention with increasing frequency over time. 1. Bink-Boelkens, MT, Meuzelaar KJ, Eygelaar A. Arrhythmias after repair of secundum atrial septal defect: the influence of surgical modification. Am Heart J 1988;115:629 – 633. 2. Roos-Hesselink J, Perlroth MG, McGhie J, Spitaels S. Atrial arrhythmias in adults after repair of tetralogy of Fallot. Correlations with clinical, exercise, and echocardiographic findings. Circulation 1995;91:2214 –2219. 3. Gelatt M, Hamilton RM, McCrindle BW, Connelly M, Davis A, Harris L, Gow RM, Williams WG, Trusler GA, Freedom RM. Arrhythmia and mortality after the Mustard procedure: a 30-year single-center experience. J Am Coll Cardiol 1997;29:194 –201. 4. Gelatt M, Hamilton RM, McCrindle BW, Gow RM, Williams WG, Trusler
GA, Freedom RM. Risk factors for atrial tachyarrhythmias after the Fontan operation. J Am Coll Cardiol 1994;24:1735–1741. 5. Rodefeld MD, Bromberg BI, Schuessler RB, Boineau JP, Cox JL, Huddleston CB. Atrial flutter after lateral tunnel construction in the modified Fontan operation: a canine model. J Thorac Cardiovasc Surg 1996;111:514 –526. 6. Love BA, Collins KK, Walsh EP, Triedman JK. Electroanatomic characterization of conduction barriers in sinus/atrially paced rhythm and association with intra-atrial reentrant tachycardia circuits following congenital heart disease surgery. J Cardiovasc Electrophysiol 2001;12:17–25. 7. Ascher H, Feingold H. Repairable Systems Reliability. New York: Marcel Dekker, Inc, 1984. 8. Meeker WQ, Escobar LA. Statistical Methods for Reliability Data. New York: John Wiley & Sons, 1998. 9. Morton JB, Byrne MJ, Power JM, Raman J, Kalman JM. Electrical remodeling of the atrium in an anatomic model of atrial flutter. Circulation 2002;105:258 –264. 10. Triedman JK, Bergau DM, Saul JP, Epstein MR, Walsh EP. Efficacy of radiofrequency ablation for control of intraatrial reentrant tachycardia in patients with congenital heart disease. J Am Coll Cardiol 1997;30:1032–1038. 11. Deal BJ, Mavroudis C, Backer CL, Johnsrude CL, Rocchini AP. Impact of arrhythmia circuit cryoablation during Fontan conversion for refractory atrial tachycardia. Am J Cardiol 1999;83:563–568. 12. Timmermans C, Rodriguez LM, Reuter D, Stappers J, Barenbrug PJ, Cheriex EC, Wellens HJ. Management of atrial arrhythmias secondary to severe congenital heart disease with the Atrioverter. PACE 2000;23:1181–1183. 13. Theodoro DA, Danielson GK, Porter CJ, Warnes CA. Right-sided maze procedure for right atrial arrhythmias in congenital heart disease. Ann Thorac Surg 1998;65:149 –153.
A Novel Nonfluoroscopic Catheter Visualization System (LocaLisa) to Reduce Radiation Exposure During Catheter Ablation of Supraventricular Tachycardias Paulus Kirchhof, MD, Peter Loh, MD, Lars Eckardt, MD, Michael Ribbing, MD, Sascha Rolf, MD, Olaf Eick, PhD*, Fred Wittkampf, PhD*, Martin Borggrefe, MD, Gu¨nter Breithardt, MD, and Wilhelm Haverkamp, MD adiofrequency catheter ablation has become the standard treatment for reentrant tachycardias of R the atrioventricular junction, accessory bypass tracts,
and atrial flutter.1 Recent technical and pathophysiologic progress suggests that more complex catheter ablation procedures may offer treatment options for other tachyarrhythmias, such as focally triggered atrial fibrillation, multifocal atrial tachycardias, and atypical atrial flutter.2– 4 Catheter ablation is associated with relatively high exposure to ionizing radiation.5,6 Deterministic radiation effects that will occur in any patient when a certain radiation dose is applied, mainly skin erythema,7,8 and the so-called stochastic From the Department of Cardiology and Angiology, University Hospital Mu¨nster, and Institute for Arteriosclerosis Research, University of Mu¨nster, Mu¨nster, Germany; Bakken Research Center, Maastricht, The Netherlands; Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; and Department of Cardiology and Angiology, University of Mannheim, Mannheim, Germany. Dr. Kirchoff’s address is: Medizinische Klinik C—Kardiologie und Angiologie, Universita¨ tskliniken Mu¨nster, D-48129 Mu¨nster, Germany. Email: [email protected]. Manuscript received January 23, 2002; revised manuscript received and accepted April 1, 2002. *Dr. Eick is an employee of Medtronic Inc. (Minneapolis, Minnesota), the company that markets LocaLisa. Dr.Wittkampf is the inventor of the LocaLisa system.
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©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 August 1, 2002
radiation-related predisposition to late malignant tumors, are therefore a persistent concern in patients undergoing catheter ablation.5,6 The LocaLisa system (Medtronic Inc., Minneapolis, Minnesota) nonfluoroscopically displays the position of electrophysiologic catheters9 and therefore has the potential to partially replace fluoroscopy during catheter ablation procedures. We therefore tested whether the routine use of LocaLisa reduces radiation exposure during mapping and catheter ablation of supraventricular tachycardias. •••
All patients were studied in the fasting, nonabsorptive state and were off all antiarrhythmic drugs. Written informed consent was obtained from all patients before the procedure. This study was undertaken as part of the European Safety and Efficacy Trial (“LocaLisa Clinical Study—A Novel Method to Localize Intracardiac Electrodes”). Standard multipolar electrophysiologic catheters were advanced through the femoral veins and placed in the right ventricular apex, in the region of the His bundle, and in the high right atrium. If necessary, additional catheters were placed in the coronary sinus, lateral right atrium, and left atrium. Left atrial mapping was performed via transseptal punctures. Using conventional electrophysi0002-9149/02/$–see front matter PII S0002-9149(02)02481-5
undergoing catheter ablation at the University of Mu¨ nster were screened for eligibility. We included all patients with an indication for catheter ablation of supraventricular tachycardias who consented to be studied using LocaLisa in addition to conventional fluoroscopy. The control patients were selected from our database and matched according to the following mandatory criteria: same operator, same arrhythmia type, same number of radiofrequency pulses, same year of procedure, and same gender. If the number of radiofrequency pulses was ⬎30, a maximal variation of 10% in the number of pulses was accepted. In addition, patients were matched as close as possible for age. All procedures were performed using the same biplane pulsed fluoroscopic system (Philips Optimus M 200, Philips Medizinsysteme, Hamburg, Germany). The system did not offer a last-image-hold option. Positioning of standard catheters was performed using monoplane posterior-anterior fluoroscopy. For mapping and ablation, biplane fluoroscopy was used, usually in the right and left anterior oblique projections. Fluoroscopic time and radiation dose were continuously monitored FIGURE 1. Use of LocaLisa. (A) Display of the proximal to distal His (blue), the coronary sinus (CS) (green), and ablations spots in the inferior atrioventricular node (red) at each of the 2 radiation generators in a patient with atrioventricular nodal reentrant tachycardia. Left panel, a 30ⴗ right by means of 2 dose-area product anterior oblique projection (RAO); right panel, a 75ⴗ left anterior oblique projection meters (PTW-Diamentor, PTW Prod(AP-LAO, orthogonal to the bundle of His). (B) Fluoroscopic and LocaLisa display of the ucts, Freiburg, Germany). Total flu10 electrodes of a decapolar perimetric pulmonary vein catheter (Lasso) placed in the oroscopic time and radiation dose right superior pulmonary vein during an ablation of focally triggered atrial fibrillation. were read from the meters directly Left panel, a 30ⴗ RAO fluoroscopic projection; right panel, a 60ⴗ LAO projection. Arrows, the perimetric catheter in the pulmonary vein. The inserts show the LocaLisa disafter each procedure. play of the decapolar catheter in an identical projection, obtained by sequential disThe technique and function of play of all 10 electrodes of the catheter. LocaLisa have been previously described in detail.9 In brief, 3 low intensity (1 mA) high-frequency ologic techniques and stimulation protocols, the target (approximately 30 kHz) currents are constantly aparrhythmia was identified and mapped. An ablation plied through the patient’s body in the x, y, and z axes catheter (Biosense Webster Inc., Diamond Bar, Cali- by means of adhesive gel-covered skin electrodes. fornia, or Medtronic EP-Systems, Minneapolis, Min- These transthoracic currents generate 3 orthogonal nesota) was inserted through a femoral vein or artery, electrical fields in the heart. By measuring the voltage depending on the ablation target. Radiofrequency en- of these signals via standard catheter electrodes, the ergy was applied in a temperature-controlled mode position of an intracardiac electrode can be calculated between the tip of the ablation catheter and a gel- relative to a stationary reference electrode. A comcovered hip pad electrode using a radiofrequency en- puter generates a 3-dimensional picture of the actual ergy generator (Stockert EP Shuttle, Biosense Web- and previous electrode positions from these measurester, Inc., or ATAKR, Medtronic Inc.). ments (Figure 1). After installation of LocaLisa in the catheter ablaLocaLisa was used as an adjunct to conventional tion laboratory of the University of Mu¨ nster, the op- fluoroscopy as soon as the reference catheter had been erators practiced using the system during 5 catheter placed in a stable position. Usually, the second elecablation procedures. All operators were experienced trode of the high right atrial catheter or the tip of the electrophysiologists familiar with mapping and abla- right ventricular catheter served as the LocaLisa reftion procedures. After that training period, all patients erence. LocaLisa was used to mark electroanatomic BRIEF REPORTS
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Two-sided p values ⬍0.05 were considered significant. Control LocaLisa Twenty-nine patients were included in each study group. The abAge (yrs) 47 ⫾ 17 (18–83) 47 ⫾ 16 (18–75) lated arrhythmias included 15 ablaHeight (cm) 171 ⫾ 7 (160–189) 173 ⫾ 8 (160–185) Weight (kg) 74 ⫾ 13 (50–100) 73 ⫾ 12 (52–105) tions at the inferior atrioventricular 25 ⫾ 5 (19–34) 24 ⫾ 3 (20–32) Body mass index (kg/m2) node for treatment of atrioventricular No. of radiofrequency pulses 8 ⫾ 7 (1–30) 9 ⫾ 7 (1–33) nodal reentrant tachycardias, 4 ablaAll values are given as mean ⫾ SD and range (minimum to maximum). There was no significant tions of accessory atrioventricular difference between the 2 patient groups. pathways, 3 ablations in the isthmus between the inferior vena cava and the tricuspid annulus for common type atrial flutter, 3 ablations of ectopic atrial tachycardias, and 4 ablations in the pulmonary veins for treatment of focally triggered atrial fibrillation. The clinical characteristics of the patients were not different between the 2 study groups (Table 1). LocaLisa accurately depicted catheter positions during all procedures. Fluoroscopic catheter positioning and mapping using conventional fluoroscopic and electrophysiologic criteria allowed delineation of electroanatomic structures, such as the His bundle, the coronary sinus, or the pulmonary veins (Figure 1). LocaLisa was used to mark targets for catheter ablation, such as the circumference of the pulmonary veins, the origin of a focal atrial tachycardia, or a line between the tricuspid annulus and the vena cava inferior, and facilitated reallocation of the ablation catheter to such targets. The total radiation dose was 35% lower in the FIGURE 2. Mean radiation dose product (mGy*cm2) in the control LocaLisa patients than in the control patients (Figure group and in the LocaLisa patients. Radiation dose was mea2). Reduced radiation exposure was present in all sured by dose product meters. The average total radiation dose arrhythmia types, and this difference was statistically per procedure is shown, that is, the sum of the doses measured significant for ablation of atrioventricular nodal reenat each of the 2 radiation generators. Radiation dose was 35% trant tachycardia (p ⫽ 0.015, Table 2). Group sizes lower in the LocaLisa patients (p ⴝ 0.03). All values given as were too small to detect statistically significant differmean and SD. See text for details. ences in the other subgroups (Table 2). Fluoroscopic times were shorter in the left anterior oblique projection TABLE 2 Radiation Dose Product for LocaLisa and Control Patients Split by in the LocaLisa group (27% differArrhythmia Type ence, p ⬍0.05). Right anterior Control LocaLisa oblique and/or posteroanterior fluoroscopic times (10% shorter in the Atrioventricular nodal reentrant tachycardia 424 ⫾ 129 189 ⫾ 58* Accessory bypass tract 661 ⫾ 249 541 ⫾ 118 LocaLisa group) were not different Atrial fibrillation 831 ⫾ 249 765 ⫾ 118 between groups; this was probably Atrial flutter 366 ⫾ 288 265 ⫾ 136 due to fluoroscopy needed to perEctopic atrial tachycardia 706 ⫾ 288 725 ⫾ 136 form additional interventions (e.g., Radiation dose product was lower in the LocaLisa patients for all arrhythmia types. transseptal puncture), and especially *Significant differences between groups. to the continuous use of fluoroscopy For most tachycardia types, group sizes were too small to perform statistical tests. All values given in 2 during radiofrequency applications. mGy*cm as mean ⫾ SE. See text for details. TABLE 1 Clinical Characteristics of the Study Patients
•••
landmarks. During mapping, LocaLisa continuously visualized the position of the ablation catheter. Fluoroscopy was used as deemed necessary by the operator. Conventional fluoroscopic monitoring was mandatory during all radiofrequency current applications. The fluoroscopic times, radiation dose, and clinical variables were compared between the 2 groups by univariate measures using an SPSS software package (Version 8.0, SAS Institute, Cary, North Carolina). 342 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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Use of LocaLisa reduced total radiation exposure by 35% compared with a wellmatched control group. Fluoroscopic times in the control group were correlated with previously published values.5,8,10 The use of a magnetic catheter localization system can reduce radiation exposure during catheter ablation of atrial flutter.10,11 Our data suggest that LocaLisa reduces radiation exposure during catheter ablation procedures regardless of the arrhythmia substrate. In contrast to other systems, LocaLisa AUGUST 1, 2002
can be used to visualize the position of any electrophysiologic catheter. This may have implications for the regular use of such a system. Radiation exposure during catheter ablation of supraventricular tachycardias depends on the operator and the fluoroscopic system used.12,13 To minimize the effect of these confounding variables, patients were matched by operator in the present study, and all procedures were performed in the same year by the same electrophysiologic team, using an identical fluoroscopic system. Furthermore, patient groups were almost identical for nonmatched variables such as body mass index. Because this study was part of the initial European Safety Trial of LocaLisa, we used continuous fluoroscopy during all radiofrequency current applications in this study to minimize potential risks related to the use of LocaLisa. The growing experience with the system and technical improvements of LocaLisa may further reduce radiation exposure. The routine use of a new nonfluoroscopic catheter visualization system reduces procedure-related exposure to ionizing radiation by 35% during ablation of supraventricular tachycardias after a short training phase. These results encourage the use of LocaLisa for catheter ablation procedures and may warrant further evaluation of the system in randomized trials. 1. Morady F. Radio-frequency ablation as treatment for cardiac arrhythmias. N Engl J Med 1999;340:534 –544.
2. Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G,
Garrigue S, LeMouroux A, LeMetayer P, Clementy J. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659 –666. 3. Nakagawa H, Shah N, Matsudaira K, Overholt E, Chandrasekaran K, Beckman KJ, Spector P, Calame JD, Rao A, Hasdemir C, et al. Characterization of reentrant circuit in macroreentrant right atrial tachycardia after surgical repair of congenital heart disease: isolated channels between scars allow “focal” ablation. Circulation 2001;103:699 –709. 4. Jais P, Shah DC, Haissaguerre M, Hocini M, Peng JT, Takahashi A, Garrigue S, LeMetayer P, Clementy J. Mapping and ablation of left atrial flutters. Circulation 2000;101:2928 –2934. 5. Calkins H, Niklason L, Sousa J, el-Atassi R, Langberg J, Morady F. Radiation exposure during radiofrequency catheter ablation of accessory atrioventricular connections. Circulation 1991;84:2376 –2382. 6. Kovoor P, Ricciardello M, Collins L, Uther J, Ross D. Risk to patients from radiation associated with radiofrequency ablation for supraventricular tachycardia. Circulation 1998;98:1534 –1540. 7. Park TH, Eichling JO, Schechtman KB, Bromberg BI, Smith JM, Lindsay BD. Risk of radiation induced skin injuries from arrhythmia ablation procedures. Pacing Clin Electrophysiol 1996;19:1363–1369. 8. Rosenthal LS, Mahesh M, Beck TJ, Saul JP, Miller JM, Kay N, Klein LS, Huang S, Gillette P, Prystowsky E, et al. Predictors of fluoroscopy time and estimated radiation exposure during radiofrequency catheter ablation procedures. Am J Cardiol 1998;82:451–458. 9. Wittkampf F, Wever E, Derksen R, Wilde A, Ramanna H, Hauer R, Robles de Medina E. LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes. Circulation 1999;99:1312–1317. 10. Willems S, Weiss C, Ventura R, Ruppel R, Risius T, Hoffmann M, Meinertz T. Catheter ablation of atrial flutter guided by electroanatomic mapping (CARTO): a randomized comparison to the conventional approach. J Cardiovasc Electrophysiol 2000;11:1223–1230. 11. Kottkamp H, Hugl B, Krauss B, Wetzel U, Fleck A, Schuler G, Hindricks G. Electromagnetic versus fluoroscopic mapping of the inferior isthmus for ablation of typical atrial flutter: a prospective randomized study. Circulation 2000;102: 2082–2086. 12. Calkins H, el-Atassi R, Kalbfleisch SJ, Langberg JJ, Morady F. Effect of operator experience on outcome of radiofrequency catheter ablation of accessory pathways. Am J Cardiol 1993;71:1104 –1105. 13. Wittkampf FH, Wever EF, Vos K, Geleijns J, Schalij MJ, van der Tol J, Robles de Medina EO. Reduction of radiation exposure in the cardiac electrophysiology laboratory. Pacing Clin Electrophysiol 2000;23:1638 –1644.
Effect of Repeated Sauna Therapy on Survival in TO-2 Cardiomyopathic Hamsters With Heart Failure Yoshiyuki Ikeda, MD, PhD, Sadatoshi Biro, MD, PhD, Yasuyuki Kamogawa, MD, Shiro Yoshifuku, MD, Takashi Kihara, MD, Shinichi Minagoe, MD, PhD, and Chuwa Tei, MD, PhD everal clinical and experimental studies have shown that vascular endothelial function is imS paired in chronic congestive heart failure (CHF), leading to vasoconstriction and clinical symptoms.1 We have recently reported that repeated sauna therapy using 60°C sauna, a new nonpharmacologic thermal vasodilation therapy, induces vasodilation of the systemic and pulmonary arteries and veins, reduces car-
From The First Department of Internal Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan. Dr. Tei’s address is: The First Department of Internal Medicine, Faculty of Medicine, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. Email: [email protected]. Manuscript received March 18, 2002; revised manuscript received and accepted April 12, 2002. ©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 August 1, 2002
diac preload and afterload, and improves hemodynamics and clinical symptoms in patients with CHF,2,3 probably due to improvement in vascular endothelial dysfunction3–5 and abnormality of neurohormonal systems.2,3 Therefore, we sought to determine whether repeated sauna therapy improves prognosis in CHF. Because it is difficult to evaluate the precise clinical effect of single treatment on survival in patients with CHF, we investigated whether repeated sauna therapy improves survival in CHF using cardiomyopathic hamsters. •••
The TO-2 cardiomyopathic hamsters (Bio Breeders, Fitchburg, Massachusetts) that were used in this study, an animal model of idiopathic dilated cardiomyopathy, reproducibly develop CHF (general edema, 0002-9149/02/$–see front matter PII S0002-9149(02)02482-7
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GA, Freedom RM. Risk factors for atrial tachyarrhythmias after the Fontan operation. J Am Coll Cardiol 1994;24:1735–1741. 5. Rodefeld MD, Bromberg BI, Schuessler RB, Boineau JP, Cox JL, Huddleston CB. Atrial flutter after lateral tunnel construction in the modified Fontan operation: a canine model. J Thorac Cardiovasc Surg 1996;111:514 –526. 6. Love BA, Collins KK, Walsh EP, Triedman JK. Electroanatomic characterization of conduction barriers in sinus/atrially paced rhythm and association with intra-atrial reentrant tachycardia circuits following congenital heart disease surgery. J Cardiovasc Electrophysiol 2001;12:17–25. 7. Ascher H, Feingold H. Repairable Systems Reliability. New York: Marcel Dekker, Inc, 1984. 8. Meeker WQ, Escobar LA. Statistical Methods for Reliability Data. New York: John Wiley & Sons, 1998. 9. Morton JB, Byrne MJ, Power JM, Raman J, Kalman JM. Electrical remodeling of the atrium in an anatomic model of atrial flutter. Circulation 2002;105:258 –264. 10. Triedman JK, Bergau DM, Saul JP, Epstein MR, Walsh EP. Efficacy of radiofrequency ablation for control of intraatrial reentrant tachycardia in patients with congenital heart disease. J Am Coll Cardiol 1997;30:1032–1038. 11. Deal BJ, Mavroudis C, Backer CL, Johnsrude CL, Rocchini AP. Impact of arrhythmia circuit cryoablation during Fontan conversion for refractory atrial tachycardia. Am J Cardiol 1999;83:563–568. 12. Timmermans C, Rodriguez LM, Reuter D, Stappers J, Barenbrug PJ, Cheriex EC, Wellens HJ. Management of atrial arrhythmias secondary to severe congenital heart disease with the Atrioverter. PACE 2000;23:1181–1183. 13. Theodoro DA, Danielson GK, Porter CJ, Warnes CA. Right-sided maze procedure for right atrial arrhythmias in congenital heart disease. Ann Thorac Surg 1998;65:149 –153.
A Novel Nonfluoroscopic Catheter Visualization System (LocaLisa) to Reduce Radiation Exposure During Catheter Ablation of Supraventricular Tachycardias Paulus Kirchhof, MD, Peter Loh, MD, Lars Eckardt, MD, Michael Ribbing, MD, Sascha Rolf, MD, Olaf Eick, PhD*, Fred Wittkampf, PhD*, Martin Borggrefe, MD, Gu¨nter Breithardt, MD, and Wilhelm Haverkamp, MD adiofrequency catheter ablation has become the standard treatment for reentrant tachycardias of R the atrioventricular junction, accessory bypass tracts,
and atrial flutter.1 Recent technical and pathophysiologic progress suggests that more complex catheter ablation procedures may offer treatment options for other tachyarrhythmias, such as focally triggered atrial fibrillation, multifocal atrial tachycardias, and atypical atrial flutter.2– 4 Catheter ablation is associated with relatively high exposure to ionizing radiation.5,6 Deterministic radiation effects that will occur in any patient when a certain radiation dose is applied, mainly skin erythema,7,8 and the so-called stochastic From the Department of Cardiology and Angiology, University Hospital Mu¨nster, and Institute for Arteriosclerosis Research, University of Mu¨nster, Mu¨nster, Germany; Bakken Research Center, Maastricht, The Netherlands; Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands; and Department of Cardiology and Angiology, University of Mannheim, Mannheim, Germany. Dr. Kirchoff’s address is: Medizinische Klinik C—Kardiologie und Angiologie, Universita¨ tskliniken Mu¨nster, D-48129 Mu¨nster, Germany. Email: [email protected]. Manuscript received January 23, 2002; revised manuscript received and accepted April 1, 2002. *Dr. Eick is an employee of Medtronic Inc. (Minneapolis, Minnesota), the company that markets LocaLisa. Dr.Wittkampf is the inventor of the LocaLisa system.
340
©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 August 1, 2002
radiation-related predisposition to late malignant tumors, are therefore a persistent concern in patients undergoing catheter ablation.5,6 The LocaLisa system (Medtronic Inc., Minneapolis, Minnesota) nonfluoroscopically displays the position of electrophysiologic catheters9 and therefore has the potential to partially replace fluoroscopy during catheter ablation procedures. We therefore tested whether the routine use of LocaLisa reduces radiation exposure during mapping and catheter ablation of supraventricular tachycardias. •••
All patients were studied in the fasting, nonabsorptive state and were off all antiarrhythmic drugs. Written informed consent was obtained from all patients before the procedure. This study was undertaken as part of the European Safety and Efficacy Trial (“LocaLisa Clinical Study—A Novel Method to Localize Intracardiac Electrodes”). Standard multipolar electrophysiologic catheters were advanced through the femoral veins and placed in the right ventricular apex, in the region of the His bundle, and in the high right atrium. If necessary, additional catheters were placed in the coronary sinus, lateral right atrium, and left atrium. Left atrial mapping was performed via transseptal punctures. Using conventional electrophysi0002-9149/02/$–see front matter PII S0002-9149(02)02481-5
undergoing catheter ablation at the University of Mu¨ nster were screened for eligibility. We included all patients with an indication for catheter ablation of supraventricular tachycardias who consented to be studied using LocaLisa in addition to conventional fluoroscopy. The control patients were selected from our database and matched according to the following mandatory criteria: same operator, same arrhythmia type, same number of radiofrequency pulses, same year of procedure, and same gender. If the number of radiofrequency pulses was ⬎30, a maximal variation of 10% in the number of pulses was accepted. In addition, patients were matched as close as possible for age. All procedures were performed using the same biplane pulsed fluoroscopic system (Philips Optimus M 200, Philips Medizinsysteme, Hamburg, Germany). The system did not offer a last-image-hold option. Positioning of standard catheters was performed using monoplane posterior-anterior fluoroscopy. For mapping and ablation, biplane fluoroscopy was used, usually in the right and left anterior oblique projections. Fluoroscopic time and radiation dose were continuously monitored FIGURE 1. Use of LocaLisa. (A) Display of the proximal to distal His (blue), the coronary sinus (CS) (green), and ablations spots in the inferior atrioventricular node (red) at each of the 2 radiation generators in a patient with atrioventricular nodal reentrant tachycardia. Left panel, a 30ⴗ right by means of 2 dose-area product anterior oblique projection (RAO); right panel, a 75ⴗ left anterior oblique projection meters (PTW-Diamentor, PTW Prod(AP-LAO, orthogonal to the bundle of His). (B) Fluoroscopic and LocaLisa display of the ucts, Freiburg, Germany). Total flu10 electrodes of a decapolar perimetric pulmonary vein catheter (Lasso) placed in the oroscopic time and radiation dose right superior pulmonary vein during an ablation of focally triggered atrial fibrillation. were read from the meters directly Left panel, a 30ⴗ RAO fluoroscopic projection; right panel, a 60ⴗ LAO projection. Arrows, the perimetric catheter in the pulmonary vein. The inserts show the LocaLisa disafter each procedure. play of the decapolar catheter in an identical projection, obtained by sequential disThe technique and function of play of all 10 electrodes of the catheter. LocaLisa have been previously described in detail.9 In brief, 3 low intensity (1 mA) high-frequency ologic techniques and stimulation protocols, the target (approximately 30 kHz) currents are constantly aparrhythmia was identified and mapped. An ablation plied through the patient’s body in the x, y, and z axes catheter (Biosense Webster Inc., Diamond Bar, Cali- by means of adhesive gel-covered skin electrodes. fornia, or Medtronic EP-Systems, Minneapolis, Min- These transthoracic currents generate 3 orthogonal nesota) was inserted through a femoral vein or artery, electrical fields in the heart. By measuring the voltage depending on the ablation target. Radiofrequency en- of these signals via standard catheter electrodes, the ergy was applied in a temperature-controlled mode position of an intracardiac electrode can be calculated between the tip of the ablation catheter and a gel- relative to a stationary reference electrode. A comcovered hip pad electrode using a radiofrequency en- puter generates a 3-dimensional picture of the actual ergy generator (Stockert EP Shuttle, Biosense Web- and previous electrode positions from these measurester, Inc., or ATAKR, Medtronic Inc.). ments (Figure 1). After installation of LocaLisa in the catheter ablaLocaLisa was used as an adjunct to conventional tion laboratory of the University of Mu¨ nster, the op- fluoroscopy as soon as the reference catheter had been erators practiced using the system during 5 catheter placed in a stable position. Usually, the second elecablation procedures. All operators were experienced trode of the high right atrial catheter or the tip of the electrophysiologists familiar with mapping and abla- right ventricular catheter served as the LocaLisa reftion procedures. After that training period, all patients erence. LocaLisa was used to mark electroanatomic BRIEF REPORTS
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Two-sided p values ⬍0.05 were considered significant. Control LocaLisa Twenty-nine patients were included in each study group. The abAge (yrs) 47 ⫾ 17 (18–83) 47 ⫾ 16 (18–75) lated arrhythmias included 15 ablaHeight (cm) 171 ⫾ 7 (160–189) 173 ⫾ 8 (160–185) Weight (kg) 74 ⫾ 13 (50–100) 73 ⫾ 12 (52–105) tions at the inferior atrioventricular 25 ⫾ 5 (19–34) 24 ⫾ 3 (20–32) Body mass index (kg/m2) node for treatment of atrioventricular No. of radiofrequency pulses 8 ⫾ 7 (1–30) 9 ⫾ 7 (1–33) nodal reentrant tachycardias, 4 ablaAll values are given as mean ⫾ SD and range (minimum to maximum). There was no significant tions of accessory atrioventricular difference between the 2 patient groups. pathways, 3 ablations in the isthmus between the inferior vena cava and the tricuspid annulus for common type atrial flutter, 3 ablations of ectopic atrial tachycardias, and 4 ablations in the pulmonary veins for treatment of focally triggered atrial fibrillation. The clinical characteristics of the patients were not different between the 2 study groups (Table 1). LocaLisa accurately depicted catheter positions during all procedures. Fluoroscopic catheter positioning and mapping using conventional fluoroscopic and electrophysiologic criteria allowed delineation of electroanatomic structures, such as the His bundle, the coronary sinus, or the pulmonary veins (Figure 1). LocaLisa was used to mark targets for catheter ablation, such as the circumference of the pulmonary veins, the origin of a focal atrial tachycardia, or a line between the tricuspid annulus and the vena cava inferior, and facilitated reallocation of the ablation catheter to such targets. The total radiation dose was 35% lower in the FIGURE 2. Mean radiation dose product (mGy*cm2) in the control LocaLisa patients than in the control patients (Figure group and in the LocaLisa patients. Radiation dose was mea2). Reduced radiation exposure was present in all sured by dose product meters. The average total radiation dose arrhythmia types, and this difference was statistically per procedure is shown, that is, the sum of the doses measured significant for ablation of atrioventricular nodal reenat each of the 2 radiation generators. Radiation dose was 35% trant tachycardia (p ⫽ 0.015, Table 2). Group sizes lower in the LocaLisa patients (p ⴝ 0.03). All values given as were too small to detect statistically significant differmean and SD. See text for details. ences in the other subgroups (Table 2). Fluoroscopic times were shorter in the left anterior oblique projection TABLE 2 Radiation Dose Product for LocaLisa and Control Patients Split by in the LocaLisa group (27% differArrhythmia Type ence, p ⬍0.05). Right anterior Control LocaLisa oblique and/or posteroanterior fluoroscopic times (10% shorter in the Atrioventricular nodal reentrant tachycardia 424 ⫾ 129 189 ⫾ 58* Accessory bypass tract 661 ⫾ 249 541 ⫾ 118 LocaLisa group) were not different Atrial fibrillation 831 ⫾ 249 765 ⫾ 118 between groups; this was probably Atrial flutter 366 ⫾ 288 265 ⫾ 136 due to fluoroscopy needed to perEctopic atrial tachycardia 706 ⫾ 288 725 ⫾ 136 form additional interventions (e.g., Radiation dose product was lower in the LocaLisa patients for all arrhythmia types. transseptal puncture), and especially *Significant differences between groups. to the continuous use of fluoroscopy For most tachycardia types, group sizes were too small to perform statistical tests. All values given in 2 during radiofrequency applications. mGy*cm as mean ⫾ SE. See text for details. TABLE 1 Clinical Characteristics of the Study Patients
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landmarks. During mapping, LocaLisa continuously visualized the position of the ablation catheter. Fluoroscopy was used as deemed necessary by the operator. Conventional fluoroscopic monitoring was mandatory during all radiofrequency current applications. The fluoroscopic times, radiation dose, and clinical variables were compared between the 2 groups by univariate measures using an SPSS software package (Version 8.0, SAS Institute, Cary, North Carolina). 342 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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Use of LocaLisa reduced total radiation exposure by 35% compared with a wellmatched control group. Fluoroscopic times in the control group were correlated with previously published values.5,8,10 The use of a magnetic catheter localization system can reduce radiation exposure during catheter ablation of atrial flutter.10,11 Our data suggest that LocaLisa reduces radiation exposure during catheter ablation procedures regardless of the arrhythmia substrate. In contrast to other systems, LocaLisa AUGUST 1, 2002
can be used to visualize the position of any electrophysiologic catheter. This may have implications for the regular use of such a system. Radiation exposure during catheter ablation of supraventricular tachycardias depends on the operator and the fluoroscopic system used.12,13 To minimize the effect of these confounding variables, patients were matched by operator in the present study, and all procedures were performed in the same year by the same electrophysiologic team, using an identical fluoroscopic system. Furthermore, patient groups were almost identical for nonmatched variables such as body mass index. Because this study was part of the initial European Safety Trial of LocaLisa, we used continuous fluoroscopy during all radiofrequency current applications in this study to minimize potential risks related to the use of LocaLisa. The growing experience with the system and technical improvements of LocaLisa may further reduce radiation exposure. The routine use of a new nonfluoroscopic catheter visualization system reduces procedure-related exposure to ionizing radiation by 35% during ablation of supraventricular tachycardias after a short training phase. These results encourage the use of LocaLisa for catheter ablation procedures and may warrant further evaluation of the system in randomized trials. 1. Morady F. Radio-frequency ablation as treatment for cardiac arrhythmias. N Engl J Med 1999;340:534 –544.
2. Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G,
Garrigue S, LeMouroux A, LeMetayer P, Clementy J. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659 –666. 3. Nakagawa H, Shah N, Matsudaira K, Overholt E, Chandrasekaran K, Beckman KJ, Spector P, Calame JD, Rao A, Hasdemir C, et al. Characterization of reentrant circuit in macroreentrant right atrial tachycardia after surgical repair of congenital heart disease: isolated channels between scars allow “focal” ablation. Circulation 2001;103:699 –709. 4. Jais P, Shah DC, Haissaguerre M, Hocini M, Peng JT, Takahashi A, Garrigue S, LeMetayer P, Clementy J. Mapping and ablation of left atrial flutters. Circulation 2000;101:2928 –2934. 5. Calkins H, Niklason L, Sousa J, el-Atassi R, Langberg J, Morady F. Radiation exposure during radiofrequency catheter ablation of accessory atrioventricular connections. Circulation 1991;84:2376 –2382. 6. Kovoor P, Ricciardello M, Collins L, Uther J, Ross D. Risk to patients from radiation associated with radiofrequency ablation for supraventricular tachycardia. Circulation 1998;98:1534 –1540. 7. Park TH, Eichling JO, Schechtman KB, Bromberg BI, Smith JM, Lindsay BD. Risk of radiation induced skin injuries from arrhythmia ablation procedures. Pacing Clin Electrophysiol 1996;19:1363–1369. 8. Rosenthal LS, Mahesh M, Beck TJ, Saul JP, Miller JM, Kay N, Klein LS, Huang S, Gillette P, Prystowsky E, et al. Predictors of fluoroscopy time and estimated radiation exposure during radiofrequency catheter ablation procedures. Am J Cardiol 1998;82:451–458. 9. Wittkampf F, Wever E, Derksen R, Wilde A, Ramanna H, Hauer R, Robles de Medina E. LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes. Circulation 1999;99:1312–1317. 10. Willems S, Weiss C, Ventura R, Ruppel R, Risius T, Hoffmann M, Meinertz T. Catheter ablation of atrial flutter guided by electroanatomic mapping (CARTO): a randomized comparison to the conventional approach. J Cardiovasc Electrophysiol 2000;11:1223–1230. 11. Kottkamp H, Hugl B, Krauss B, Wetzel U, Fleck A, Schuler G, Hindricks G. Electromagnetic versus fluoroscopic mapping of the inferior isthmus for ablation of typical atrial flutter: a prospective randomized study. Circulation 2000;102: 2082–2086. 12. Calkins H, el-Atassi R, Kalbfleisch SJ, Langberg JJ, Morady F. Effect of operator experience on outcome of radiofrequency catheter ablation of accessory pathways. Am J Cardiol 1993;71:1104 –1105. 13. Wittkampf FH, Wever EF, Vos K, Geleijns J, Schalij MJ, van der Tol J, Robles de Medina EO. Reduction of radiation exposure in the cardiac electrophysiology laboratory. Pacing Clin Electrophysiol 2000;23:1638 –1644.
Effect of Repeated Sauna Therapy on Survival in TO-2 Cardiomyopathic Hamsters With Heart Failure Yoshiyuki Ikeda, MD, PhD, Sadatoshi Biro, MD, PhD, Yasuyuki Kamogawa, MD, Shiro Yoshifuku, MD, Takashi Kihara, MD, Shinichi Minagoe, MD, PhD, and Chuwa Tei, MD, PhD everal clinical and experimental studies have shown that vascular endothelial function is imS paired in chronic congestive heart failure (CHF), leading to vasoconstriction and clinical symptoms.1 We have recently reported that repeated sauna therapy using 60°C sauna, a new nonpharmacologic thermal vasodilation therapy, induces vasodilation of the systemic and pulmonary arteries and veins, reduces car-
From The First Department of Internal Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan. Dr. Tei’s address is: The First Department of Internal Medicine, Faculty of Medicine, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. Email: [email protected]. Manuscript received March 18, 2002; revised manuscript received and accepted April 12, 2002. ©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 August 1, 2002
diac preload and afterload, and improves hemodynamics and clinical symptoms in patients with CHF,2,3 probably due to improvement in vascular endothelial dysfunction3–5 and abnormality of neurohormonal systems.2,3 Therefore, we sought to determine whether repeated sauna therapy improves prognosis in CHF. Because it is difficult to evaluate the precise clinical effect of single treatment on survival in patients with CHF, we investigated whether repeated sauna therapy improves survival in CHF using cardiomyopathic hamsters. •••
The TO-2 cardiomyopathic hamsters (Bio Breeders, Fitchburg, Massachusetts) that were used in this study, an animal model of idiopathic dilated cardiomyopathy, reproducibly develop CHF (general edema, 0002-9149/02/$–see front matter PII S0002-9149(02)02482-7
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