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238 The Morphology Changes in Limb Leads after Ablation of Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia and Their Correlation with Recurrence SHU-YUAN YAO, PH.D, JIAN-MIN CHU, M.D., PI-HUA FANG, M.D., KUI-JUN ZHANG, M.D., JIAN MA, M.D., and SHU ZHANG, M.D. From the Center of Arrhythmia, Fuwai Cardiovascular Hospital, Peking Union Medical College, Beijing; and Chinese Academy of Medical Sciences, Beijing, China The Morphology Changes in Limb Leads. Objectives: This study was designed to explore the morphology changes in limb leads of ECGs after successful ablation of verapamil sensitive idiopathic left ventricular tachycardia (ILVT) and their correlation with tachycardia recurrence. Methods: Between January 2001 and December 2006, 116 patients who underwent successful ablation of ILVT were included in the study. Twelve-lead surface ECG recordings during sinus rhythm were obtained in all patients before and after ablation to compare morphology changes in limb leads. Results: The ECG morphology changes after ablation were divided into two categories: one with new or deepening Q wave in inferior leads and/or disappearance of Q wave in leads I and aVL, and the other without change. The changes in any Lead II, III, or aVF after ablation occurred significantly more in patients without recurrence of ventricular tachycardia (VT) (P < 0.0001, 0.002, and 0.0001, respectively). The patients with recurrence of VT tended to have no ECG changes, compared with those without recurrence of VT (P = 0.009). The sensitivity of leads II, III, and aVF changes in predicting nonrecurrence VT were 66.7%, 78.7%, and 79.6%, specificity were 100%, 75%, and 87.5%, and nonrecurrence predictive value of 100%, 97.7%, and 98.9%, respectively. When inferior leads changes were combined, they could predict all nonrecurrence patients with 100% specificity. Conclusions: Successful radiofrequency ablation of ILVT could result in morphology changes in limb leads of ECG, especially in inferior leads. The combined changes in inferior leads can be used as an effective endpoint in ablation of this ILVT. (J Cardiovasc Electrophysiol, Vol. 19, pp. 238-241, March 2008) ventricular tachycardia, ablation, electrocardiogram Introduction Idiopathic left ventricular tachycardia (ILVT) with right bundle branch block (RBBB) and left axis deviation (LAD) is demonstrated to be verapamil sensitive and to originate in the Purkinje fiber network of the left posterior fascicle. 1-3 Radiofrequency ablation is effective in eliminating ventricu- lar tachycardia (VT) from those patients. Different strategies have been proposed for the ablation. In 1994, Wen et al. 4 first described the pacing map role in ablation of ILVT. Nak- agawa et al. 5 reported Purkinje potential recorded during VT could be used to identify the critical site for successful abla- tion. Tsuchiya et al. 6 demonstrated a significant late diastolic potential and suggested these potentials as markers for suc- cessful ablation. In addition, the role of Purkinje potential and diastolic potential in ablation of ILVT had been shown by Nogami et al. 7 and Arya et al. 8 However, no predictors for VT recurrence after ablation were reported. The aim of this study was to explore the morphology changes in limb Address for correspondence: Shu Zhang, Center of Arrhythmias, Fuwai Car- diovascular Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, BeiLiShi Road 167 # , 100037, Beijing, China. Fax: 86-10-68334688; E-mail: [email protected] Manuscript received 25 July 2007; Revised manuscript received 14 Septem- ber 2007; Accepted for publication 20 September 2007. doi: 10.1111/j.1540-8167.2007.01023.x leads after successful ablation and their correlation with VT recurrence. Methods Patients Between January 2001 and December 2006, 133 patients with verapamil sensitive ILVT underwent radiofrequency ab- lation at our center. Eleven patients with arrhythmia aris- ing from the left anterior fascicle were excluded from the study, and six patients with incessant tachycardia were also excluded for no ECG recording during sinus rhythm before ablation. A total of 116 patients were included in the study. Electrophysiological Study After signed written consent and withdrawal of antiar- rhythmic drugs, all patients underwent electrophysiologi- cal study. Briefly, two 6F quadripolar electrode catheters (Biosense-Webster, Diamond Bar, USA) were respectively positioned in the right ventricular apex and at the His-bundle region via the femoral veins. A 6F decapolar catheter with 2-5-2 mm interelectrode spacing (Biosense-Webster) was in- serted into the coronary sinus via the right internal jugular vein. Twelve-lead surface ECG as well as intracardiac elec- trograms from different sites were simultaneously displayed and recorded on a multichannel Bard recorder (Bard Elec- trophysiology Lab System, Lowell, MA, USA) at 100 mm/s speed. Standard electrophysiological criteria were used to

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Page 1: The Morphology Changes in Limb Leads after Ablation of Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia and Their Correlation with Recurrence

238

The Morphology Changes in Limb Leads after Ablationof Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia

and Their Correlation with RecurrenceSHU-YUAN YAO, PH.D, JIAN-MIN CHU, M.D., PI-HUA FANG, M.D., KUI-JUN ZHANG, M.D.,

JIAN MA, M.D., and SHU ZHANG, M.D.

From the Center of Arrhythmia, Fuwai Cardiovascular Hospital, Peking Union Medical College, Beijing; and Chinese Academyof Medical Sciences, Beijing, China

The Morphology Changes in Limb Leads. Objectives: This study was designed to explore themorphology changes in limb leads of ECGs after successful ablation of verapamil sensitive idiopathic leftventricular tachycardia (ILVT) and their correlation with tachycardia recurrence.

Methods: Between January 2001 and December 2006, 116 patients who underwent successful ablation ofILVT were included in the study. Twelve-lead surface ECG recordings during sinus rhythm were obtainedin all patients before and after ablation to compare morphology changes in limb leads.

Results: The ECG morphology changes after ablation were divided into two categories: one with new ordeepening Q wave in inferior leads and/or disappearance of Q wave in leads I and aVL, and the other withoutchange. The changes in any Lead II, III, or aVF after ablation occurred significantly more in patients withoutrecurrence of ventricular tachycardia (VT) (P < 0.0001, 0.002, and 0.0001, respectively). The patients withrecurrence of VT tended to have no ECG changes, compared with those without recurrence of VT (P =0.009). The sensitivity of leads II, III, and aVF changes in predicting nonrecurrence VT were 66.7%, 78.7%,and 79.6%, specificity were 100%, 75%, and 87.5%, and nonrecurrence predictive value of 100%, 97.7%,and 98.9%, respectively. When inferior leads changes were combined, they could predict all nonrecurrencepatients with 100% specificity.

Conclusions: Successful radiofrequency ablation of ILVT could result in morphology changes in limbleads of ECG, especially in inferior leads. The combined changes in inferior leads can be used as an effectiveendpoint in ablation of this ILVT. (J Cardiovasc Electrophysiol, Vol. 19, pp. 238-241, March 2008)

ventricular tachycardia, ablation, electrocardiogram

Introduction

Idiopathic left ventricular tachycardia (ILVT) with rightbundle branch block (RBBB) and left axis deviation (LAD)is demonstrated to be verapamil sensitive and to originate inthe Purkinje fiber network of the left posterior fascicle.1-3

Radiofrequency ablation is effective in eliminating ventricu-lar tachycardia (VT) from those patients. Different strategieshave been proposed for the ablation. In 1994, Wen et al.4

first described the pacing map role in ablation of ILVT. Nak-agawa et al.5 reported Purkinje potential recorded during VTcould be used to identify the critical site for successful abla-tion. Tsuchiya et al.6 demonstrated a significant late diastolicpotential and suggested these potentials as markers for suc-cessful ablation. In addition, the role of Purkinje potentialand diastolic potential in ablation of ILVT had been shownby Nogami et al.7 and Arya et al.8 However, no predictorsfor VT recurrence after ablation were reported. The aim ofthis study was to explore the morphology changes in limb

Address for correspondence: Shu Zhang, Center of Arrhythmias, Fuwai Car-diovascular Hospital, Peking Union Medical College and Chinese Academyof Medical Sciences, BeiLiShi Road 167#, 100037, Beijing, China. Fax:86-10-68334688; E-mail: [email protected]

Manuscript received 25 July 2007; Revised manuscript received 14 Septem-ber 2007; Accepted for publication 20 September 2007.

doi: 10.1111/j.1540-8167.2007.01023.x

leads after successful ablation and their correlation with VTrecurrence.

Methods

Patients

Between January 2001 and December 2006, 133 patientswith verapamil sensitive ILVT underwent radiofrequency ab-lation at our center. Eleven patients with arrhythmia aris-ing from the left anterior fascicle were excluded from thestudy, and six patients with incessant tachycardia were alsoexcluded for no ECG recording during sinus rhythm beforeablation. A total of 116 patients were included in the study.

Electrophysiological Study

After signed written consent and withdrawal of antiar-rhythmic drugs, all patients underwent electrophysiologi-cal study. Briefly, two 6F quadripolar electrode catheters(Biosense-Webster, Diamond Bar, USA) were respectivelypositioned in the right ventricular apex and at the His-bundleregion via the femoral veins. A 6F decapolar catheter with2-5-2 mm interelectrode spacing (Biosense-Webster) was in-serted into the coronary sinus via the right internal jugularvein. Twelve-lead surface ECG as well as intracardiac elec-trograms from different sites were simultaneously displayedand recorded on a multichannel Bard recorder (Bard Elec-trophysiology Lab System, Lowell, MA, USA) at 100 mm/sspeed. Standard electrophysiological criteria were used to

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Yao et al. The Morphology Changes in Limb Leads 239

diagnose VT. If the tachycardia did not occur spontaneously,attempts were made with ventricular programmed extrastim-ulation and burst ventricular pacing from the right ventricularapex to induce VT. If sustained VT was not inducible, isopro-terenol was infused (1–6 µg/min). Twelve-lead surface ECGrecordings during sinus rhythm were obtained in all patientsbefore and after ablation to compare morphology changes inlimb leads. The timing of the first ECGs was the first day afteradmission, and the second ECG was recorded within 4–12hours after ablation.

Mapping and Radiofrequency Ablation

A 7F steerable quadripolar electrode catheter with a4-mm tip (Biosense-Webster) was introduced into the leftventricular cavity through the femoral artery and used formapping and ablation. Radiofrequency energy was applied atthe site where the earliest ventricular activation was recordedduring tachycardia. Those earliest activations were mostlyPurkinje potential and/or diastolic potential recorded in thePurkinje fiber network of left posterior fascicle. In the pa-tients whose VT could not be induced or was not constant,the target was chosen at the site where the catheter recordeda sharp Purkinje potential at left posterior fascicle and/orthe pace mapping 12-lead ECG matched ≥11/12-lead con-cordance. In three patients with previous failed ablation at-tempts, CARTO (Biosense-Webster) electroanatomic map-ping or Ensite 3000 (St Jude Medical, St. Paul, MN, USA)mapping was performed.

The output current generated from a radiofrequencygenerator (EP-SHUTTLE, Biosense-Webster) was deliv-ered to the distal electrode of ablation catheter and adisposable skin electrode pad. If VT was terminated in10 seconds, booster currents were administered at the samesite. Radiofrequency current was also applied at the site ad-jacent to the successful target, especially in patients withabsence of inducible or sustained VT.

Follow-Up

Electrocardiography was monitored for 24 hours in all pa-tients after ablation. Patients returned to the outpatient clinicat 2 weeks, 1 month, and subsequently every 2–4 monthsafter discharge for follow-up.

Statistical Analysis

All statistical analyses were performed using SPSS 13.0for Windows. A chi-square test and unpaired t-test wereused and values were considered significant difference whenP < 0.05. Sensitivity, specificity, positive and negative pre-dictive values were calculated for changes or no change inlimb leads.

Results

Patients

Of 133 consecutive patients with ILVT who underwentsuccessful radiofrequency ablation, 116 patients were in-cluded in the study. They were 89 men and 27 women withmean age 28.7 ± 13.0 years, range 10–58. One hundred pa-tients had structurally normal hearts, six patients coincidedwith paroxysmal supraventricular tachycardia, four patientswith hypertension, three patients with congenital heart dis-

ease, two patients with second-degree atrioventricular blockdue to previous ablation, and one patient with atrial fibrilla-tion. All patients received from one to four antiarrhythmicdrugs with variable effect before referral and 23 patients hadpreviously failed ablation attempts.

Electrophysiological Study and Radiofrequency Ablation

VT could be induced reproducibly with right ventricularstimulation in 100 patients, and radiofrequency ablation wasperformed during tachycardia. At the targets of successful ab-lation, sharp Purkinje potential was recorded in 62 patients,diastolic potential was recorded in 17 patients and both po-tentials were recorded in 21 patients. The endocardial ven-tricular activation preceded the onset of QRS complex was55.5 ± 8.4 ms. Tachycardia could not be induced or was notconstant in 16 patients, and successful ablation was achievedby Purkinje potential guiding and/or pace mapping. The totalradiofrequency time and energy was 244.5 ± 193.3 secondsand 36.7 ± 9.4 watts, and the number of radiofrequency ap-plications was 6.0 ± 3.3.

Radiofrequency ablation was performed successfully inall patients. First-degree atrioventricular block was ob-served in one patient and transient right bundle branchblock in another patient. There were no other proceduralcomplications.

Surface ECG Changes in Limb Leads

Twelve-lead surface ECG recordings during sinus rhythmwere obtained in all patients before and after ablation. Com-pared with ECG recordings before the ablation, the changesafter successful ablation can be divided into two categories:(1) new Q wave (Fig. 1) or Q-wave deepening (Fig. 2) showedin inferior leads, and/or Q-wave disappearance or QRS com-plex transformation to rS pattern in leads I and aVL, (2)without change. The morphology changes in limb leads weresummarized in Table 1.

Follow-Up and Relative Factors of Recurrence

During follow-up of 3.5 ± 1.6 years (range 0.34–7.1),eight patients had recurrence of VT. There was a signifi-cant correlation between changes in leads II (P = 0.000), III(P = 0.002), and aVF (P = 0.000) and nonrecurrence of VT.There was also a significant correlation between no changeof ECG and recurrence of tachycardia (P = 0.009). The re-currence of VT was not related with any of the followingfactors: changes in leads I (P = 1.000) and aVL (P = 0.487),absence of inducible or sustained tachycardia (P = 0.228);different mapping strategies (P > 0.05, respectively); num-ber of ablation lesions (P = 0.304); temperature (P = 0.204);watts of energy (P = 0.703); and total radiofrequency time(P = 0.713).

Sensitivity, Specificity, and Predictive Accuracyof Changes in Limb Leads

Table 1 shows the sensitivity, specificity, and predictiveaccuracy. The changes in leads II, III, and aVF predictednonrecurrence of VT with a sensitivity of 66.7%, 78.7%, and79.6%, specificity of 100%, 75%, and 87.5%, and nonrecur-rence predictive value of 100%, 97.7%, and 98.9%, respec-tively. No change in limb leads predicted recurrence VT witha sensitivity of 62.5%, specificity of 82.4%, and recurrence

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240 Journal of Cardiovascular Electrophysiology Vol. 19, No. 3, March 2008

Figure 1. Q-wave appearance in inferiorleads after ablation.

predictive value of 20.8%. When inferior leads changes werecombined, they could predict all nonrecurrence patients with100% specificity.

Discussion

The most common form of verapamil sensitive ILVTis thought to arise from left posterior fascicle and hasmorphology of RBBB and LAD.1,2 Radiofrequency ablationguided by presystolic Purkinje potential, diastolic potential,early endocardial activation, or pace mapping has been pro-posed and demonstrated to be highly effective in eliminatingthis tachycardia.4-9 Though those strategies have differenttarget points, all the radiofrequency energy is delivered inthe Purkinje network of the left posterior fascicle. We hy-pothesize that focal ablation at these sites can damage theleft posterior fascicle conduction, resulting in ECG changesin limb leads; thus, the changes can be used as a predictor ofrecurrence.

In the retrospective study of 116 patients with successfulablation, QRS complex changes in limb leads after success-ful ablation occurred in most patients, compared with thosebefore ablation. The most frequency changes were Q-waveappearance or deepening in inferior leads, and Q-wave disap-

Figure 2. Q-wave deepening in inferior leadsafter ablation.

pearance or QRS complex transformation in leads I and aVL.These changes could relate to the ablation damage. Previousstudies by Nath et al.10 and Wood et al.11 have demonstratedthat the application of radiofrequency energy can result in sig-nificant changes in myocardial cellular electrophysiologicalproperties not only in the anatomic lesion but also the tissuesurrounding the lesion. Therefore, the radiofrequency energythat was applied in the Purkinje fiber network of the left pos-terior fascicle can damage the conduction in the left posteriorseptum area and create these ECG changes. Gambetta et al.,12

De Pasquale et al.,13 and Li et al.14 also suggested the mech-anism that new Q wave without acute myocardial infractionwas due to an early localized conduction disturbance. How-ever, the ECG changes that met the criteria of left posteriorfascicular block appeared only in a few patients, and mostcases without a diagnosis of typical left posterior fascicularblock did not have a shift of axis to the right. Similar findingswere reported by Chen et al.15 and David et al.16 In viewof thicker structure, dual blood supply, and extensive inter-connection of the left posterior fascicle,17 the focal ablationcould only modify the conduction properties of the Purkinjenetwork without blocking the conduction of the left posteriorfascicle, and thus did not affect the global activation of theleft ventricle.

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Yao et al. The Morphology Changes in Limb Leads 241

TABLE 1

The Number of Morphology Changes in Limb Leads and Calculated Sensitivity, Specificity, Predictive Values of Changes Indicating Nonrecurrence and ofNo Change Indicating Recurrence. LPFB: Left Posterior Fascicular Block

Number Number Positive NegativeLead of Changes of Recurrence Sensitivity Specificity Predictive Value Predictive Value

I 18 (15.5%) 1 15.7% 87.5% 94.4% 7.1%II 72 (62.1%) 0 66.7% 100% 100% 18.2%III 87 (75.0%) 2 78.7% 75% 97.7% 20.7%aVL 29 (25.0%) 1 25.9% 87.5% 96.6% 8.1%aVF 87 (75.0%) 1 79.6% 87.5% 98.9% 24.1%I + aVL 9 (7.8%) 1 7.4% 87.5% 88.9% 6.5%II + III + aVF 72 (62.1%) 0 66.7% 100% 100% 18.2%LPFB 11 (9.5%) 0 10.2% 100% 100% 7.6%No change 24 (20.7%) 5 62.5% 82.4% 20.8% 96.7%

In this study we found a significant correlation betweenchanges in leads II, III, and aVF and nonrecurrence of VT.The changes in lead II predicted nonrecurrence of VT with asensitivity of 66.7%, specificity of 100%, and nonrecurrencepredictive accuracy of 100%. For the same criterion, changesin lead III had a sensitivity of 78.7%, a specificity of 75%, andnonrecurrence predictive accuracy of 97.7% with two falsepredictions, and changes in aVF had a sensitivity of 79.6%, aspecificity of 87.5%, and nonrecurrence predictive accuracyof 98.9% with only one false prediction. When these criteriawere incorporated, we were able to make an accurate pre-diction of nonrecurrence in 100% without false prediction.Thus, based on the results in our patients, the combined mor-phology changes in inferior leads can be used as an endpointduring ablation of ILVT with RBBB and LAD.

In some patients, VT is not inducible or sustained at thetime of ablation procedures. Absence of inducible or sus-tained tachycardia often leads to aborted planned ablation orrecurrence after initial apparent success.8 Noncontact map-ping and a linear ablation fashion had been applied previ-ously by David et al.15 and Chen et al.16 In the present study,ablation was applied successfully in 16 patients with nonin-ducible or nonsustained tachycardia, and two of them expe-rienced recurrence during follow-up. No change in inferiorleads was found in these two patients, and all the 12 patientswith changes had no recurrence, which indicates that changesin inferior leads is also a simple definite endpoint during ab-lation of nonsustained or noninducible VT.

Conclusions

As a single center of study, the radiofrequency ablationapplied by five different physicians can lead to QRS mor-phology changes in limb leads, and the changes in all infe-rior leads can be used as an effective endpoint for ablation ofILVT with RBBB and LAD.

References

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