The conduction properties of accessory pathways (APs) are independent of location and conduction mode (except in patients with multiple, Mahaim, and slowly conducting APs). Patients with right-sided APs show higher rates of atrial fibrillation and longer arrhythmia cycle length due to slower anterograde conduction over the atrioventricular node during atrioventricular reentrant tachycardia. Â© 2005 by Excerpta Medica Inc

Arya, A.

Dehghani, M.R.

Emkanjoo, Z.

Fazelifar, A.F.

Haghjoo, M.

Jafari, A.

Sadr-Ameli, M.A.

eprints Iran University of Medical Sciences

10. Majumdar SR, Inui TS, Gurwitz JH, Gillman MW, McLaughlin TJ, SoumeraiSB. Influence of physician specialty on adoption and relinquishment of calciumchannel blockers and other treatments for myocardial infarction. J Gen InternMed 2001;16:351–359.11. Hohnloser SH, Kuck KH, Lilienthal J. Rhythm or rate control in atrialfibrillation—Pharmacological Intervention in Atrial Fibrillation (PIAF): a ran-domised trial. Lancet 2000;356:1789–1794.12. Carlsson J, Miketic S, Windeler J, Cuneo A, Haun S, Micus S, Walter S,Tebbe U, et al. Randomized trial of rate-control versus rhythm-control in persis-tent atrial fibrillation. The Strategies of Treatment of Atrial Fibrillation (STAF)study. J Am Coll Cardiol 2003;41:1690–1696.13. Greer AL. The state of the art versus the state of the science. The diffusion of newmedical technologies into practice. Int J Technol Assess Health Care 1988;4:5–26.14. Soumerai SB, McLaughlin TJ, Gerwitz JH, Guadagnoli E, Hauptman PJ,Borbas C, Morris N, McLaughlin B, Gao X, Willison DJ, et al. Effect of localmedical opinion leaders on quality of care for acute myocardial infarction: arandomized controlled trial. JAMA 1998;279:1358–1363.15. Williams ES, Miller JM. Results from late-breaking clinical trial sessions atthe American College of Cardiology 51st Annual Scientific Session. J Am ColCardiol 2002;40:1–18.16. Donohoe MT. Comparing generalists and specialist care: discrepancies,deficiencies and excesses. Arch Int Med 1998;58:1596–1605.17. Wattigney WA, Mensah GA, Croft JB. Increasing trends in hospitalization foratrial fibrillation in the United States, 1985 through 1999: implications forprimary prevention. Circulation 2003;108:711–716.18. Ozcan C, Jahangir A, Friedman PA, Hayes DL, Munger TM, Rea RG, LloydMA, Packer DL, Hodge DO, Gersh BJ, et al. Sudden death after radiofrequencyablation of the atrioventricular node in patients with atrial fibrillation. J Am CollCardiol 2002;40:105–110.Effect of Conduction Mode and Location onElectrophysiologic Characteristics ofAccessory PathwaysArash Arya, MD, Majid Haghjoo, MD, Abdollah Jafari, MD, Zahra Emkanjoo, MD,Amir Farjam Fazelifar, MD, Mohammad Reza Dehghani, MD,and Mohammad Ali Sadr-Ameli, MDThe conduction properties of accessory pathways(APs) are independent of location and conductionmode (except in patients with multiple, Mahaim, andslowly conducting APs). Patients with right-sided APsshow higher rates of atrial fibrillation and longerarrhythmia cycle length due to slower anterogradeconduction over the atrioventricular node duringatrioventricular reentrant tachycardia. 2005 byExcerpta Medica Inc.(Am J Cardiol 2005;95:1250–1252)The objective of this study was to determine thearrhythmia characteristics and electrophysiologicproperties of accessory pathways (APs) with respectto their location and conduction mode (bidirectionalvs concealed) in patients with single APs. Becausemost previous studies have assessed the influence ofAP location on electrophysiologic properties, such asdecremental and slow anterograde and/or retrogradeconduction,1–8 we excluded such patients (i.e., thosewith Mahaim and slowly conducting APs) from ourstudy.• • •From March 2002 to March 2004, 136 consecutivesymptomatic patients with single APs (overt or con-cealed) who underwent radiofrequency catheter abla-tion were included in this study. All patients gavewritten informed consent for electrophysiologic studyand ablation. The study was approved by our institu-tional review committee. Eighty-three of the patientswere men (61%) (mean age 33.6 13.5 years). Struc-tural heart disease was present in 8 patients (5.9%; 4with mitral valve prolapse, 2 with Ebstein’s anomaly,and 2 with valvular heart disease). The presentingsymptoms were palpitation, dizziness, syncope and/orpresyncope, and chest pain in 113, 10, 10, and 3patients, respectively. The sudden onset and offset ofsymptoms were noticed in 97 patients (71.3%) and 93patients (68.4%), respectively. The mean duration ofsymptoms before catheter ablation was 6  5 years.All antiarrhythmic medications were withdrawnbefore the electrophysiologic study for 5 half-lives.Three 6Fr quadripolar catheters (DAIG, St. Jude Med-ical, Inc., St. Paul, Minnesota) were introducedthrough the femoral veins and positioned at the rightventricular apex, the His bundle, and the high rightatrium. A 7Fr steerable decapolar catheter (Marinr,Medtronic, Inc., Minneapolis, Minnesota) was intro-duced through the right femoral vein and positioned inthe coronary sinus. Twelve-lead surface electrocardio-grams and bipolar filtered (30 to 500 Hz) and unipolarunfiltered electrograms were recorded, displayed, andstored on an electrophysiologic recording system(EPMed Systems, Inc., West Berlin, New Jersey).Mapping was done during sinus rhythm and arrhyth-mia. The locations of APs were determined on thebasis of standard fluoroscopic views (Figure 1).6 Thepresence of dual atrioventricular nodal physiology andconcomitant arrhythmias was assessed. The antero-grade and retrograde effective refractory periods(ERPs) of APs, the mode of conduction, and thearrhythmia cycle length were measured. An Atakr II(Medtronic, Inc.) radiofrequency energy generator (486kHz) was used for radiofrequency catheter ablation.We defined the anterograde ERP of an AP as thelongest atrial extrastimulus coupling interval thatFrom the Department of Pacemaker and Electrophysiology, RajaieCardiovascular Medical Center, Tehran, Iran. Dr. Arya’s address is:Department of Pacemaker and Electrophysiology, Rajaie Cardiovas-cular Medical Center, Mellat Park, Vali-Asr Avenue, Tehran1996911151, Iran. E-mail: arya@rhc.ac.ir. Manuscript received Oc-tober 13, 2004; revised manuscript received and accepted January17, 2005.1250 ©2005 by Excerpta Medica Inc. All rights reserved. 0002-9149/05/$–see front matterThe American Journal of Cardiology Vol. 95 May 15, 2005 doi:10.1016/j.amjcard.2005.01.060failed to conduct over the AP (absence of ventricularpreexcitation), the retrograde ERP of an AP as thelongest ventricular extrastimulus coupling intervalthat failed to conduct in a retrograde manner over theAP, and dual atrioventricular nodal physiology as a50-ms increase in the atrium–His bundle (AH) in-terval during programmed atrial stimulation in re-sponse to a 10-ms decrease in the atrial extrastimuluscoupling interval.Variables are expressed as mean  SD and per-centage. Differences in characteristics between 2groups were assessed by the independent-samples Stu-dent’s t test for continuous variables and the chi-square test (or Fisher’s exact test if necessary) fordiscrete variables. A 2-tailed p value 0.05 was con-sidered significant.During the study, 168 patients with APs were stud-ied and underwent radiofrequency catheter ablation atour center. Of these, 146 (87%) had single APs and 22(13%) had multiple APs. In the former group, wefurther excluded 10 patients with Mahaim (n  8) orslowly conducting (n  2) APs. We included theremaining 136 patients in our final analysis. Of these,112 patients (82%) had bidirectional APs, and 24patients (18%) had concealed APs. Seventy-one pa-tients (52%) had left-sided APs, and the remaining 65patients (48%) had right-sided APs. Septal and free-wall APs were observed in 49 patients (36%) and 87patients (64%), respectively (Figure 1).Orthodromic and antidromic atrioventricular reen-trant tachycardia (AVRT) were induced during pro-grammed electrical stimulation in 100 patients (73.5%)and 3 patients (2.5%), respectively. The arrhythmiacycle length was 335  56 ms. Arrhythmia other thanAVRT was observed in 25 patients (atrioventricularnodal reentrant tachycardia in 2 [1.5%] and atrialfibrillation in 23 [17%]). Dual atrioventricular nodalphysiology was observed in 33 patients (24%).Table 1 lists electrophysiologic findings on thebasis of AP location and mode of conduction. Antero-grade and retrograde ERPs of APs, gender distribution,and the conduction modes of APs were comparablebetween different locations. Patients with right-sidedAPs had longer arrhythmia cycle lengths and higherrates of atrial fibrillation. The prevalence of dual atrio-ventricular nodal physiology was comparable amongall locations and conduction modes of AP. In patientswith right- and left-sided APs, the AH intervals duringsinus rhythm were 80  16 and 85  21 ms, respec-tively (p  0.305). During arrhythmia, the AH inter-vals in patients with right- and left-sided APs were196  34 and 155  40 ms, respectively (p 0.001).• • •In patients with single APs (excluding Mahaim andslowly conducting APs), conduction properties did notdepend on the locations and conduction modes ofAPs. The prevalence of dual atrioventricular nodalphysiology was comparable among all locations andconduction modes of AP. Patients with right-sidedAPs had longer arrhythmia cycle lengths and higherrates of atrial fibrillation.Previous studies have shown that the location of anAP influences some of its electrophysiologic proper-ties (i.e., decremental and/or slow conduction).8 How-ever, our data showed that the conduction propertiesof APs (excluding those with decremental and/or slowconduction) are not affected by their location and/orconduction modes. De Chillou et al8 suggested that inpatients with left free-wall APs, symptoms occur laterin life compared with those with other APs. However,our findings did not show such a trend. The ages atpresentation were 34.6  13 and 33.4  13.7 years inpatients with left free-wall versus other APs, respec-tively (p  0.62). The duration of symptoms in the 2groups was also comparable (5.6  4.8 vs 6.8  5.2years, p  0.17).Contrary to previous studies,1 the rate of inducibleAVRT during the electrophysiologic study was com-parable in patients with (55.6%) and without (76.5%)atrial fibrillation (p  0.34), and inducible atrial fi-brillation during electrophysiologic study was moreprevalent in patients with concealed APs. These vari-ations may be explained by different electrophysi-ologic protocols and patient populations.We found that arrhythmia cycle lengths werelonger in patients with right-sided APs compared withthe rest of the patients. Because the retrograde ERP inleft- and right-sided APs was comparable (Table 1),we postulated that the difference might be due toslower anterograde atrioventricular nodal conduction.Our findings supported our assumption and showedthat in AVRTs incorporating right-sided APs, the AHinterval was longer than those incorporating left-sidedAPs. Liu et al5 also recently showed that in patientswith right free-wall APs, the anterograde conductionover the atrioventricular node is slower compared withthose with other AP locations.FIGURE 1. Representation of AP distribution along the left andright atrioventricular grooves in the left anterior oblique (LAO)view. CS  coronary sinus; LI  left inferior; LP  left posterior;LPI  left posteroinferior; LPS  left posterosuperior; LPSP  leftparaseptal; MA  mitral annulus; RA  right anterior; RAS right anterosuperior; RASP  right anteroseptal; RI  right infe-rior; RMS  right midseptal; RPSP  right paraseptal; RS  rightsuperior; TA  tricuspid annulus.BRIEF REPORTS 1251Acknowledgment: We want to thank the nursingand technical staff members in our department. With-out their dedicated work, this study would not havebeen possible as presented.1. Josephson ME. Pre-excitation syndromes. In: Josephson ME, ed. ClinicalCardiac Electrophysiology. 3rd Ed. Philadelphia: Lippincott Williams & Wilkins,2002:322–424.2. Murdock CJ, Leitch JW, Wee ST, Sharma AD, Yee R, Klein GJ. Character-istics of accessory pathways exhibiting decremental conduction. Am J Cardiol1991;67:506–510.3. Luria DM, Chugh SS, Munger TM, Friedman PA, Rea RF, Packer DL, JahangirA, Hammill SC, Shen WK. Electrophysiologic characteristics of diverse accessorypathway locations of antidromic reciprocating tachycardia. Am J Cardiol 2000;86:1333–1338.4. Strickberger SA, Hummel J, Gallagher M, Hasse C, Man KC, Williamson B,Vorperian VR, Kalbfleisch SJ, Morady F, Langberg JJ. Effect of accessorypathway location on the efficiency of heating during radiofrequency catheterablation. Am Heart J 1995;129:54–58.5. Liu S, Yuan S, Olsson SB. Conduction properties of accessory atrioven-tricular pathways: importance of the accessory pathway location and normalatrioventricular conduction. Scand Cardiovasc J 2003;37:43– 48.6. Farre J, Aanderson RH, Cabrera JA, Sanchez-Quintana D, Rubio JM, RomeroJ, Cabestrero F. Fluoroscopic cardiac anatomy for catheter ablation of tachycar-dia. Pacing Clin Electrophysiol 2002;25:76–94.7. Xie B, Heald SC, Camm AJ, Rowland E, Ward DE. Characteristics of bipolarelectrograms during anterograde mapping: the importance of accessory atrioven-tricular pathway location. Am Heart J 1996;131:720–723.8. de Chillou C, Rodriguez LM, Schlapfer J, Kappos KG, Katsivas A, Baiyan X,Smeets JL, Wellens HJ. Clinical characteristics and electrophysiologic propertiesof atrioventricular accessory pathways: importance of the accessory pathwaylocation. J Am Coll Cardiol 1992;20:666–671.Comparison of Clinical Presentation of AcuteMyocarditis Following Smallpox Vaccination to AcuteCoronary Syndromes in Patients <40 Years of Age*Robert E. Eckart, DO, Eric A. Shry, MD, Samuel O. Jones IV, MD, J. Edwin Atwood, MD,and John D. Grabenstein, RPh, PhDSmallpox vaccine–associated myopericarditis mayhave a similar presentation to acute coronary syn-drome (ACS). The clinical records of 78 young pa-tients (<40 years of age) presenting with ACS (n 16) or myocarditis after smallpox vaccination (n 62) were reviewed. Comparisons were made amongclinical presentation, cardiac enzymes, echocardio-graphic findings, and electrocardiographic changes.The presence of cardiac risk factors or focal wallmotion abnormalities on echocardiography were as-sociated with a diagnosis of ACS. There was a trendtoward earlier elevation of troponin-I and creatinekinase in patients with myocarditis compared withACS. 2005 by Excerpta Medica Inc.(Am J Cardiol 2005;95:1252–1255)Chest pain is a frequent complaint in young patientsseeking medical attention. Even after initial eval-uation with histories and physical and laboratory stud-ies, there is considerable clinical overlap betweenyoung patients with acute coronary syndrome (ACS)and those presenting with myocarditis.1–4 Recent re-ports have described the greater than expected inci-dence of myopericarditis after smallpox vaccination inUnited States military personnel,5–7 and all these pa-tients were identified after presentation for chestsymptoms. However, little information exists to dif-ferentiate these patients from those with prematureatherosclerosis causing ACS. The purpose of thisFrom Brooke Army Medical Center, Fort Sam Houston, Texas; WilfordHall Air Force Medical Center, Lackland AFB, Texas; Walter ReedArmy Medical Center, Washington, DC; and the Military VaccineAgency, Falls Church, Virginia. Dr. Eckart’s address is: Cardiac Ar-rhythmia Service (Cardiovascular Division), Brigham and Women’sHospital, 75 Francis Street, Boston, Massachusetts 02115. E-mail:robert.eckart@us.army.mil. Manuscript received September 23,2004; revised manuscript received and accepted January 14, 2005.*The opinions and research contained herein are the private ones ofthe investigators and are not to be considered as official or reflectingthe views of the United States government or the United States Depart-ment of Defense.TABLE 1 Electrophysiologic Findings Based on AP Location and Mode of ConductionVariableSeptal vs Free Wall Left vs Right Overt vs ConcealedSeptal Free Wall p Value Left Right p Value Overt Concealed p ValueAnterograde ERP (ms) 291  84 292  80 0.96 288  81 295  83 0.69 — — —Retrograde ERP (ms) 291  56 303  58 0.34 306  59 290  54 0.22 304  52 297  58 0.66Arrhythmia cycle length (ms) 347  58 330  54 0.15 322  55 352  55 0.045* 339  40 336  59 0.84Atrial fibrillation (n, %) 12 11 0.35 6 17 0.028* 14 (12.5%) 9 (37.5%) 0.037*Men/women (n) 29/20 55/32 0.24 46/25 38/27 0.30 67/45 17/7 0.36Dual atrioventricular nodalphysiology (%)25% 22% 0.41 20% 25% 0.33 22% 25% 0.47Concealed (%) 23% 15% 0.251 16% 20% 0.65 — — —Inducible AVRT (%) 74% 73% 0.728 74% 72% 0.477 68% 73% 0.630*p value (2-tailed) 0.05 was considered significant.1252 ©2005 by Excerpta Medica Inc. All rights reserved. 0002-9149/05/$–see front matterThe American Journal of Cardiology Vol. 95 May 15, 2005 doi:10.1016/j.amjcard.2005.01.061

Effect of conduction mode and location on electrophysiologic characteristics of accessory pathways

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Effect of conduction mode and location on electrophysiologic characteristics of accessory pathways

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