The Ventricular Myocardium Repolarization Process and its Pecu - … · 2001. 1. 29. · repolarization peculiarities in persistent WPW sy- n drome and to clear up whether repolarization

October 1999 519

Introduction

Although the preexcitation syndromes, especiallyWolff-Parkinson-White (WPW), are considered to be awell- known electrophysiological phenomenon [1,2]only a few authors mention that WPW syndrome isassociated with repolarization abnormalities [3,4].Previously, the ventricular myocardium repolarizationprocess and its features in WPW patients attracted lessattention than depolarization abnormalities caused byaccessory atrioventricular pathways (AAVP).Currently, "closed" methods, i.e. catheter treatmentmethods, are preferable among nonmedication WPW

treatment methods. As reported elsewhere [5], the opti-mized balance between patient safety and procedureefficiency could be achieved. Myocardium applicationis well localized and the risk of myocardial damage issmall due to small application power. Nevertheless, wehave paid attention to electrocardiographic features ofmyocardium repolarization abnormalities in WPWpatients after radiofrequency ablation (RFA) proce-dures. Several publications [4,6-9] point to the fact thatthese features appearing after catheter ablation aretemporary, disappear in 6 weeks and are not related to

Progress in Biomedical Research

The Ventricular Myocardium Repolarization Process and its Peculiaritiesin Wolff-Parkinson-White Syndrome

I.P. POLYAKOVA, A.SH. REVISHVILI, L.A. BOCKERIABakoulev Research Centre for Cardiovascular Surgery of Russian Academy of Medical Sciences, Moscow, Russia

Summary

Radiofrequency ablation (RFA) of accessory atrioventricular pathways (AAVP) seems to be the most preferabletherapeutic method in the treatment of Wolff-Parkinson-White syndrome (WPW). Correct identification of post-ablation ECG changes is possible only if depolarization and repolarization process features are established ininstances of WPW syndrome. The goal of our investigation was to clear up peculiarities of the ventricular repo-larization process in cases of WPW syndrome and whether repolarization disturbances are sustained after themyocardium excitation pattern changes. We analyzed the surface ECG mapping (SM) data of 112 patients with per-sistent and intermittent forms of WPW and different AAVP localization prior to and after the RFA of AAVP, as wellas patients undergoing RFA due to other forms of supraventricular arrhythmia. It has been shown that in persis-tent WPW syndrome, an anomaly of ventricle repolarization exists. Its degree depends on AAVP localization, andon the degree of pre-excitation for parietal AAVP. In paraseptal, anterior, and posterior AAVPs, the ventricularrepolarization process direction is opposite to the depolarization process direction; different values of appropriateelectric axes serve as an additional diagnostic feature to localize anomalous conduction paths and to discriminateparaseptal and parietal AAVP. Post-ablation repolarization anomalies are more evident in patients with persistentpre-excitation syndrome and are related mainly to the anomalous depolarization process. Localization of maximaland minimal STT integral over the surface ECG immediately after the RFA procedure coincides with the localiza-tion of, appropriately, maximal and minimal values of the delta wave prior to the RFA procedure in patients withany AAV, (except right).

Key Words

Wolff-Parkinson-White syndrome, ventricular myocardium repolarization, surface ECG mapping, radiofrequencyablation

520 October 1999

sive electrophysiological investigation (EPI). Leftlocalized AAVPs were in 46 pts, septal and posteriorparaseptal in 30 pts, right in 22 pts, anterior septal andanterior paraseptal in 14 pts.Intermittent WPW syndrome was registered by SM in10 pts (8 male and 2 female, mean age 24.4 ± 14.0years). Left localized AAVP was in 3 pts, septal andposterior paraseptal in 3 pts, right in 2 pts, anterior sep-tal in 2 pts.The SM was also performed in 39 pts after successfulRFA of persistent AAVP. Left AAVP localization wasin 15 pts, septal and posterior paraseptal in 7 pts, rightin 11 pts, anterior septal and anterior paraseptal in 6pts. Intermittent WPW was in 3 pts (anterior septalAAVP localization in one pt, right anterior AAVPlocalization in one pt, left posterior AAVP localizationin one pt).SM data prior to and after the RFA procedure have alsobeen studied in patients with other forms of supraven-tricular arrhythmias. Among them were 5 pts with hid-den forms of WPW syndrome and different AAV local-ization and 5 pts with AV-node tachycardia (mean age24.9 ± 13.4 years).The investigation was performed prior to the RFA pro-cedure, during the first 2 days after the RFA procedure(the mean time after procedure was 31.3 ± 8.2 hours)and in long-term follow-up (3-6 months).The control group was comprised of 20 healthy sub-jects (mean age 21.8 ± 4.6 years).

myocardial damage. The authors relate them to the"cardiac memory" phenomenon introduced byRosenbaum [10], assuming the cardiac muscle memo-rizing of repolarization abnormalities for some periodof time (up to several weeks)However, only a few works mention (along withpostablation myocardium changes) the relationship ofWPW syndrome with repolarization abnormalities.Correct identification of postablation myocardiumrepolarization changes is possible only if process pecu-liarities caused by the WPW syndrome are known.We have extensively studied ECG investigations orsurface ECG mapping (SM) data in patients with per-sistent and intermittent WPW syndrome prior and afterRFA, as well as in patients with other forms ofsupraventricular arrhythmia subjected to the RFA pro-cedure. The task was to reveal ventricular myocardiumrepolarization peculiarities in persistent WPW syn-drome and to clear up whether repolarization distur-bances are maintained during myocardium excitationpattern changes.

Materials and Methods

We analyzed the SM data of 112 persistent WPWpatients (pts) (63 male and 49 female, mean age 29.5 ±13.7 years) without associated cardiac pathology andwith different AAVP localization confirmed by inva-

Table 1. Peculiarities of QRS and ST-T vectors interposition along frontal plane in different AAVP localizations.

October 1999 521

Surface mappingDuring the SM procedure, signals were recorded in 12standard Frank orthogonal ECG leads and 80 chestunipolar leads ("Cardiag 128.1" specialized system)registered simultaneously. The electrodes were locatedin regular netting across the 1st to 6th ribs on the tho-racic surface. SM data were presented as simultaneousisopotential map sequences of the whole cardiac cycle,as a T-wave amplitude distribution map, and as isoin-tegral QRS, ST-T and QRST interval maps. Also dif-ferential maps were plotted, in which the so-called"departure index" (DI) or normal difference of patient-integrated characteristics and of corresponding mean"normal" characteristics were calculated. The absolutevalue deviations exceeding 2 (|DI| > 2) were signifi-cant. The repolarization process was evaluated by T-wave amplitude, by the area under the ST-T curve indifferent leads, and by localization of appropriateextremities. With differential maps on QRS, ST-T, andQRST intervals, the minimum negative – DI and max-

imum positive +DI deviations (from normal) of thesurface manifestations of the de- and repolarizationprocesses could be evaluated. Also their localization(of deviations) on the thoracic surface and mean vol-ume (–DI) in % or (+DI) in % (in surface percentageon the thoracic surface) might be evaluated. The ven-tricular myocardium repolarization direction was eval-uated from QRS and ST-T electrical vectors differ-ences in the frontal and horizontal planes

Radiofrequency ablationDuring invasive EPI, the EPI parameters, diagnosis,and utmost early excitation point were defined. Anablation catheter-electrode was introduced under X-raycontrol for RF power application. The applicationpower was set at gradual increments ranging from 5 to50 W, the duration was up to 1-1.5 min, the tempera-ture was controlled to be in the range of 50-60 °C, andthe number of applications was 1 to 25.In 13 pts (persistent WPW syndrome and differentAAVP localization in 7 pts; other supraventriculartachyarrhythmia forms in 6 pts) the control enzymeactivity measurements in blood plasma were per-formed: using general KFK and MB isoenzyme exact-ly prior to RFA, and were also measured within 24hours after the RFA procedure in 4 hour intervals.

Statistical analysisData bases using Excel tables have been created toprocess the SM data of patients and healthy subjects.Sampling characteristics are presented as M ± SD, withM-mean values, and SD-standard deviation. Statisticaldata processing was performed using Statistika pro-gram software for Windows 95.

Results

Control groupT wave amplitude distribution maps, QRS, ST-T andQRST interval isointegral maps were uniform in thecontrol group. They were dipolar, with maximum inthe precordial area and with minimum on the rightshoulder, in the case of T-wave map and ST-T andQRST isointegral maps. The minimum was observedin the upper middle part of the thoracic front wall forQRS isointegral map (Figure 1). QRS and ST-T elec-trical vector difference was +23.5 ± 10.9° (from 3 to44°) in the frontal plane, and – 47.4 ± 27.7° (from – 4to – 85°) - in the horizontal plane.


Figure 1. Ventricular myocardium repolarization analysisin patients with persistent WPW syndrome. Standard ECGleads, isointegral QRS, ST-T and QRST maps and differen-tial QRST maps. Angles below are EOSQRS - EOSST-T. Eachmap is presented on the thoracic surface scan which is cutalong the right posterior-axillary line. A) anterior parasep-tal AAVP localization; B) posterior paraseptal AAVP local-ization.

522 October 1999

observed, reflected also in the extreme shift on the ST-T isointegral map (Figure 1).The values of different angles between QRS and ST-Telectrical vectors in the frontal plane at different AAVPlocalization are demonstrated in Table 1. These dataproved that at ventricular myocardium preexcitation,the repolarization direction can be opposite to thedepolarization direction or can significantly deviatefrom it depending on the AAVP localization, in con-trast to the normal process (where both vectors deviateonly slightly). Asynchronous excitation of ventricularmyocardium paraseptal areas abruptly changes the sumrepolarization process, and the repolarization directionbecomes opposite to the depolarization direction.Different isointegral maps and DI negative values inpatients with persistent WPW and different AAVPlocalizations were studied to evaluate a possible rela-tionship between surface abnormalities in ventricularmyocardium repolarization and pre-excitation degree,which is expressed indirectly in QRS complex dura-tion. The results are shown in Figure 2. The increase ofrepolarization deviation from normal with pre-excita-tion increasing (Figure 2 above, r = 0.46) is most sig-nificant in the cumulative analysis of cases of earlyventricular myocardium preexcitation.Figure 2 shows the data divided into 2 groups accord-ing to AAVP localization. In parietal left and rightAAVP the dependence becomes more evident (r = 0.59and r = 0.49, respectively). However, the front andback paraseptal AAVP DIST-T dependence on QRSduration is less definite. In front paraseptal AAVP withQRS increasing, the DIST-T decreasing can be observed(r = 0.13 and r = – 0.18, respectively).While QRS duration values at different AAVP local-ization did not differ significantly, repolarization devi-ation was maximal in paraseptal AAVP and minimal inleft ones, 35 ± 6.2% and 14.24 ± 13.1% (p < 0.025),respectively.

Intermittent WPW syndromeIn all pre-excitation cases, all surface distribution char-acteristics and QRS and ST-T angle differences in thefrontal plane correspond to those AAVP localization.For example, on the QRS isointegral maps the mini-mum was located on that thoracic surface part wherenegative delta waves are registered; the QRS and ST-Tangle difference in the frontal surface was +202° and+187° in anterior septal AAVP localization, being– 148 ± 5° in posterior paraseptal.

Manifesting WPW syndromeIn all AAVP localizations the extreme shift (mostlynegative) in T-wave amplitude distribution was


Figure 2. Negative DI values vs. QRS_MS dependencederived from differential isointegral maps. Upper panel -general characteristic; lower panel - divided into groupsaccording to the AAVP localization.

October 1999 523

However, the differences from mean normal in surfacedistributions were also observed without pre-excita-tion. That could be noticed in the disposition of QRSand ST-T vectors on differential maps as well. In 9 outof 10 cases, the QRS vector direction, which charac-terizes the direction of the integral depolarizationprocess, was within normallimits. In 9 out of 10 casesthe abnormal QRS and ST-T vector disposition wasdetermined by direction of the anomalous repolariza-tion process. However, differential QRS and QRST-Tisointegral maps have revealed deviations of total de-and repolarization processes from normal.Figure 3 depicts the thoracic surface for patients withintermittent WPW syndrome and different AAVP. Alsoshown are QRSmin localization at ventricularmyocardium pre-excitation, i.e. leads with minimal

negative delta wave; and Tmin localization in theabsence of pre-excitation, i.e. leads with minimal neg-ative T wave amplitude. In the absence of pre-excita-tion, the negative T wave is localized in the "normal"area only in left AAVP, while registered beyond thisarea at other AAVP localization. Only in 1 out of 3 ptswith posterior paraseptal AAVP localization, the nega-tive T-wave without pre-excitation was registeredwithin the area where the negative delta wave was reg-istered at ventricular myocardium pre-excitation.

Surface mapping after RFA procedureTables 2 & 3 summarize peculiar features of ventricu-lar depolarization and repolarization processes prior toand after the RFA of persistent WPW syndrome andother supraventricular arrhythmia forms.


Figure 3. Localization (intercostal space number) of surface features of ventricular myocardium repolarization abnormalitiesin persistent and intermittent WPW syndrome without pre-excitation prior to and after RAF of AAVP of different localization.

524 October 1999

AAVP pts (53.3%), in 6 posterior paraseptal AAVP pts(54.5%), in 6 right AAVP pts (54.5%) and in 4 anteri-or paraseptal AAVP pts (80% of successfully eliminat-ed AAVPs)].No correlation was revealed between the deviations onthe post-ablation differential QRS map and the nega-tive T wave localization. Thus, in patients with "nor-mal" QRS mapping, the negative T wave was localizedin the "normal" area as well as in the area of the nega-tive delta wave prior to ablation.The following was observed in 3 RFA cases of inter-mittent WPW syndrome: in right and left AAVP local-ization patients, the Tmin after RFA and without pre-excitation coincided, although it was not the area of thenegative delta wave registration (Figure 3). In patientswith the anterior septal AAVP localization, the Tminafter RFA and without pre-excitation did not coincidewith each other, nor with the delta wave localization onthe ECG prior to RFA.Quantitative analysis of the deviation in the repolarizationprocess from the mean "normal" process according to dif-ferential ST-T and QRST maps reveals the deviationdepending on different AAVP localizations (Table 3).

Immediately following the RFA of persistent AAVP,the changes in QRS waveform corresponding to ven-tricular depolarization pattern changes are observed inordinary 12 lead ECGs. QRS vector direction withoutpre-excitation gets into normal values. The thoracicpart with vivid deviations of QRS complex configura-tion from normal is definitely reduced on the differen-tial maps (Table 2). In one patient with anterior septalAAVP, all surface distributions showed pre-excitationfeatures, because RFA of an abnormal path modifiedits electrophysiologic characteristics but did not divertit.The signs of repolarization process disturbances arenoticed simultaneously with these changes. Accordingto the 12-lead ECG, they are the following: the T low-ering or even its inversion in V1-V2 leads, or T inver-sion in I, III, F leads, or T increasing in precordial V2-V6 leads. T wave amplitude significantly increases inV1-V3 or V4 leads, fewer changes are observed in V5and V6.Figure 3 shows that after RFA, the negative T wavewas localized in the same area where the negative deltawave was localized prior to RFA [or QRSmin, in 8 left


Table 2. Ventricular myocardium depolarization features in persistent WPW and other SV arrhythmia patients prior to andafter RFA (differential isointegral QRS map parameters).

October 1999 525

The analyzed results of the possible influence of pre-excitation rate on post ablation repolarization distur-bances are depicted in Figure 4. They reveal a relative-ly weak correlation of these effects in left, r = 0.14 andposterior septal AAVP, r = – 0.23, and a little strongercorrelation in anterior septal AAVP, r = 0.35. In case ofright AAVP, the pre-excitation rate depends on postablation repolarization disturbances in the same way asin repolarization disturbances prior to ablation, r = 0.48(r = 0.49, Figure 2).Minimal-negative (–DIQRSTmin) values in left AAVP arelocalized mid dorsum from the 1st to the 6th ribs in allpatients, in 66.7% of patients on the 5th rib level alongthe paravertebral line, and in 60% of pts the(–DIQRSTmin) localization prior to and after RFA coin-cided. In posterior paraseptal AAVP, the (–DIQRSTmin)position was on the 5th rib level along the paraverte-bral line in 42% of cases, on the 6th rib in the rightaxillary zone in 42.9% of cases, coinciding with theposition prior to ablation in 42.9% of cases. In rightAAVP the (–DIQRSTmin) position was in the lower rightpart of the thoracic wall in 45.5% of cases, and, note,on the 5th rib level along the paravertebral line in 3

patients (27.2%), coinciding with the position prior tothe ablation procedure in 36.4% of pts. In anteriorparaseptal AAVP the position in the right part of thefront thoracic wall from the 1st to 6th ribs coincidedwith the position prior to ablation in 1 pt (16.7%).In patients with hidden WPW syndrome and A-Vnodal tachycardia, the differential isointegrated QRSand ST-T maps revealed the differences of the total de-and repolarization processes from normal, both prior toand after the RFA procedure of an AAVP or an acces-sory intra-nodal conduction path. However, statistical-ly significant differences in DIQRS and DIQRST valueswere not revealed. Therefore, we have combined thesepatients in 1 group according to a comparison of SMresults prior to and after RFA of arrhythmogenic zones.No difference was revealed in the differential mapparameters of these patients prior to and post RFA(Tables 2 and 3).The Tmin localization on the thoracic surface prior toRFA was in the normal range, after RFA in 4 pts (40%)was in the normal range, and in 5 patients (50%) on theright anterior thoracic part from the 2nd to 5th ribs.The comparison of maximum KFK-MB level increase


Table 3. Ventricular myocardium repolarization features in persistent WPW and other SV arrhythmia patients prior and afterRFA (differential isointegrated QRST map parameters).

526 October 1999

utions somewhat depend on ventricular activation pat-terns and reflect mostly distribution of repolarizationfeatures in myocardium and their disturbances. Thus,QRST differential maps and DIQRST parameters arewidely used in coronary artery disease diagnostics.There are very few studies concerning the electrocar-diographic peculiarities in ventricular repolarization inWPW patients in sinus rhythm. Nicolai et al. [3] dis-covered that repolarization abnormalities in normalexcitation conduction appeared in 87% of patients withpersistent WPW syndrome. The minimum localizationon the QRST maps differs from normal in 82% of leftAAVP cases and in 62% of right AAVP cases, i.e. repo-larization in persistent WPW syndrome is anomalousand DIQRSTmin is localized mostly according to theAAVP localization.While analyzing SM in parietal and septal persistentWPW patients, we have found that surface abnormali-ty features of the repolarization process are not onlylocalized according to the AAVP localization but showdifferent features in different AAVP localization. Table1 shows that in persistent WPW syndrome not only thedirection of the ventricular myocardium activationprocess changes with the AAVP localisation, but thedirection of the repolarization process as well. If theQRS vector bend can be directly related to the onset ofthe anomalous depolarization process, the ST-T vectorin the absence of organic heart disease should followthe QRS vector. However, the ventricular myocardiumrepolarization process in anterior and posteriorparaseptal AAVP is opposite to the depolarizationprocess.The influence of the localization of the initial asyn-chronous excitation zone on repolarization can benoticed from the fact that the correlation between thepre-excitation rate and repolarization deviations fromnormal, expressed by DI, so vivid in the parietalAAVP, is sharply reduced and even changes the sign inparaseptal AAVP (Figure 2).The specificity of repolarization process features cor-responding to different AAVP localization is evidencedalso by the specific areas of the thoracic surface wherethey occur. As can be seen from Figure 3, localization(–DIQRSmin), characterizing maximum deflection ofmyocardium activation from mean-"normal", coin-cides with the negative delta wave registration area inECG and is situated on the thoracic surface in the AVsulcus projection zone of the AAVP [13]. At the sametime, the (–DIQRSTmin) localization, characterizing, as

in patients with persistent WPW and in patients withthe hidden WPW form or nodal tachycardia revealedan anomalous increase up to 31.1% in 1 persistentWPW patient (12 RFA applications), and up to 34% in1 hidden WPW patient (5 RFA applications). On theaverage no statistically significant differences wererevealed for this parameter (17.3 ± 8.7 vs. 12.6 ± 11.8).

Discussion

Surface ECG mapping for the topical diagnosis of per-sistent WPW syndrome, i.e. anomalous early excita-tion zone localization, is well known [11-13].However, the detailed analysis of ventricularmyocardium repolarization happens to be more com-plicated than the ventricular activity study. It is oftenconsidered [4,14,15] that QRST integral deviationscould supply information on restoration processes. Ithas been theoretically proven that these QRST distrib-


Figure 4. Dependence of surface features of ventricularmyocardium repolarization abnormalities after persistentWPW RFA from the preexcitation rate in patients with dif-ferent AAVP localizations. X-axis: QRS interval duration(ms) prior to RFA of AAVP; Y-axis: –DIST-T, i.e. the amountof negative DI values on differential isointegral maps ST-T(in %).

October 1999 527

expected maximum deflection of myocardium activa-tion from mean-"normal", occurs in this area only in76% of left AAVP cases, and in 67% of right AAVPcases. But only in 16.7% of posterior paraseptal casesthe (–DIQRSTmin) localization coincides with the nega-tive delta wave zone, in 73.3% of cases coincidingwith that of the left AAVP. These results contradict theresults of the authors cited above.The analysis of repolarization process anomalies inpersistent WPW syndrome and different AAVP local-izations raises the question whether these anomaliesdecrease with activation process changes. The latter isachieved in clinical practice in WPW patients afterRFA and also in the intermittent pathology form.While the post-ablation repolarization features are dis-cussed frequently [4,7-9,15], repolarization featureswithout pre-excitation are treated only in a single study[15], based on SM in 13 intermittent WPW patients.SM data of our patients with intermittent WPW syn-drome showed that differential isointegrated ST-T andQRST maps for the pre-excitation period revealedanomalous differences in integral ventricularmyocardium repolarization, in accordance with thedata of Nirei et al. [15] in that aspect. Do these anom-alies show a relationship to AAVP localization?We compared our data with those in 13 intermittentWPW patients [15]. The differential QRST maps with-out pre-excitation revealed the coincidence of (–DIQRST)distribution in 1 right AAVP case, in 1 posterior septalcase, and in 1 left AAVP case. Notice that the(–DIQRSTmin) distribution coincidence with and withoutpreexcitation was observed only in 2 of our patientswith left AAVP. Here the anomalous negative T-wavedisposition without pre-excitation coincided with thenegative delta wave registration area on EGC in 30%of cases - in right and anterior/posterior septal AAVP(Figure 3).Perhaps the lack of a definite correlation between men-tioned anomalies of the ventricular repolarizationprocess and asynchronous activation zone in the pres-ence of pre-excitation was determined by deviations ofthe ventricular myocardium depolarization processwhich were not considered by Nirei et al. [15], butcould be seen on differential isointegratal QRS maps in70% of our cases. The integral depolarization processwas within the "normal" range only in 3 (30%) of ourpatients (one pt left, one pt posterior septal and one ptright AAVP).The achieved results could not be the basis for a statis-

tically significant conclusion due to the insufficientnumber of observed patients. However, they testify thepreservation of myocardium de- and repolarizationanomalies immediately after the depolarization patternchanges in young patients without organic heart dis-eases. The time interval for intermittent WPW syn-drome cases was 24 hours. The supposition that repo-larization abnormalities without preexcitation are dueto the "cardiac memory" phenomenon can not be con-sidered valid, in so far as retained ventricular depolar-ization disturbances can not be ruled out.ST-T segment changes on ECG maps after RFA of per-sistent WPW syndrome have been discussed in severalpublications [4,7-9,15]. It has been shown that ST-Tchanges after successful RFA appear mostly in persis-tent WPW and are practically not observed in hiddenAAVP. Moreover, these ST-T changes are temporaryand gradually disappear in 6 weeks to 3 months. Theauthors have discovered that temporary repolarizationabnormalities depend on delta wave polarity on ECGand the pre-excitation rate prior to RFA of AAVP.In addition, the authors have discovered [8] that thepost-ablation T-wave abnormality existed in 7 rightAAVP patients and did not exist in 12 left AAVPpatients. The majority of the authors believe that post-ablation ventricular repolarization changes are due tothe continuous influence of electrophysiologicalprocess disturbances existing prior to ablation, i.e. theyare due to the "cardiac memory" phenomenon.In our study, the anomalous negative T wave, localizedin the same thoracic area where the pre-ablation nega-tive delta wave was registered, was observed in 80% ofanterior paraseptal AAVP. And it was observed only in53.3% of left AAVP cases. Comparison of the (–Tmin)localization after the RFA of intermittent AAVP and inabsence of pre-excitation also does not establish adefinitive conclusion.The quantitative evaluation of different QRST mapscoincided in general with those of other authors: afterRFA of AAVP of all localizations, except the right one.The amplitude and (–DIQRST) deflection range areretained. In the right AAVP, these differential QRSTmap parameters were significantly reduced, althoughthe deflection range was greater in patients with non-persistent WPW. Note, patients with normal QRS andQRST maps after RFA were in each AAVP group(Table 3).However, the (–DIQRSTmin) localization analysis afterthe RFA of AAVP differs from that described in papers


528 October 1999

on AAVP localization exists in persistent WPW syn-drome. In parietal AAVP the anomaly depends onthe pre-excitation rate as well.

l The direction of the ventricular myocardium repo-larization process is opposite to the depolarizationdirection in paraseptal anterior and posterior AAVP.The difference of the QRS and ST-T electric axes(EOSQRS – EOSST-T) can serve as an additional diag-nostic feature to localize an anomalous conductionpath and to discriminate paraseptal and parietalAAVP.

l In patients with intermittent WPW syndrome fromthe pre-excitation period, the differential isointegralST-T and QRST maps reveal repolarization changesdeviating from normal; in the absence of the deltawave manifestations of these changes differ with theAAVP localization.

l If the effects on the myocardium are equal duringthe RFA of supraventricular arrhythmias, the post-ablation repolarization anomalies are more evidentin patients with persistent pre-excitation syndrome.

l Post-ablative abnormalities of the myocardiumrepolarization pattern are caused mostly by anom-alous characteristics of myocardium depolarization.Just after RFA the localization of maximum andminimum STT integral values over surface ECG inpatients with septal, anterior, and posterior parasep-tal and left AAVP localisation coincide, respective-ly, with the localization of maximum and minimumdelta wave values prior to RFA.

References

[1] Bockeria LA. Tachyarrhythmias. Diagnostics and surgicaltreatment. Meditsina 1989 (in Russian).

[2] Koushakovskii MS. Heart arrhythmias. St-Petersburg: Foliant1998 (in Russian).

[3] Mandela VG (ed). Heart arrhythmias. Meditsina 1996 (inRussian).

[4] Gallagher JJ. In: Zipes DP, Jalife J (eds). Variants of preexi-tation. in cardiac electrophysiology and arrhythmias.Orlando, 1985.

[5] Nicolai P, Medvedovsky JL, Delaage M, et al. Wolff-Parcinson-White syndrome: T wave abnormalities duringnormal pathway conduction. J of Electrocardiol. 1981; 14:295-300.

[6] Hirai M, Tsuboi N, Hayashi H, et al. Body surface distribu-tion of abnormally low QRST areas in patients with in Wolff-Parkinson-White syndrome. Evidence for continuation ofrepolarization abnormalities before and after catheter abla-tion. Circulation. 1993; 88(6): 2674-2684.

[4,9,15]. Pre- and post-ablation (–DIQRSTmin) localiza-tion coincided with 60% only in left AAVP patients, -for other localizations coincidence was in less than50% of cases.Is it possible to agree with the following statement: "themore the preexcitation rate prior to ablation, the moredistinct repolarization abnormalities after ablation?" Inpublications [4, 9], the mean QRS interval duration inright and left AAVP patients and differential map para-meters like (–DIQRSTmin) and (–DIQRST) in % were stud-ied. Higher QRS parameters in the right AAVP groupcorresponded to higher parameters of differential maps.Analyses of a possible correlation of post-ablative dif-ferential map parameters with the preexcitation rate ineach group of our patients have shown that in the rightAAVP localization, in contrast to other AAVP localiza-tion, the influence of the pre-excitation rate on repolar-isation deviations from "norm" is more probable bothprior to and after ablation.Thus, we have shown that isointegratal QRS mapsbecame practically "normal" only in some of thepatients, though the post-ablative surface distributions,corresponding to ventricular activation normalized,and their parameters significantly changed.The question still remains whether the post-ablativerepolarization disturbances refer to secondary T-wavedisturbances, i.e. they are caused by disturbances inventricular myocardium activation patterns.Our investigations have shown no statistically signifi-cant differences in KFK-MB level increase in persis-tent and in hidden WPW patients. However, the testwith structural protein troponin Tn I, that has a speci-ficity and sensitivity higher than those of the KFK-MBtest, reveals ablative myocardium distractions, as stat-ed in [16]. Therefore, we can surmise that in post abla-tive abnormalities of the repolarization process themyocardium distraction after RFA plays a definite role.Further investigations may prove this supposition.A repolarization anomaly after RFA of the manifestingAAVP becomes more evident in patients as the pre-excitation rate increases, but not completely. TheAAVP and other specific anatomic and electrophysio-logic characteristics of the anomalous pathway alsoplaya role.

Conclusion

l A ventricular repolarization abnormality expressedin the process of changing direction and dependent


October 1999 529

[7] Inaba-Sato F, Hirai M, Hayashi H, et al. Relationshipbetween QRS duration and repolarization abnormalities inpatients with Wolff-Parkinson-White syndrome. JElectrocardiol. 1996; 29(4): 301-308.

[8] Zipes D. Catheter ablation of arrhythmias. Armonk, NY:Futura Publ Comp Inc 1994.

[9] Kalbfleish SJ, Sousa J, El-Atassi R, et al. Repolarizationabnormalities after catheter ablation of accessory atrioven-tricular connections with radiofrequency current. J Am CollCardiol. 1991; 18: 1761-1766.

[10] Wood MA, Di Marco JP, Haines DE. Electrocardiographicabnormalities after radiofrequency catheter ablation of acces-sory bypass tracts in the Wolff-Parkinson-White syndrome.Am J Cardiol. 1992; (70): 200-204.

[11] Helguera ME, Pinski SL, Sterba R, et al. Memory T wavesafter radiofrequency catheter ablation of accessory atrioven-tricular connections in Wolff-Parkinson-White syndrome. JElectrocardiol 1994; 27(3): 243-249.

[12] Tomita Y, Hirai M, Yanagawa T, et al. Body surface distribu-tion of significant changes in QRST time-integral values afterradiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome. Am J Cardiol. 1996; 77(1): 59-63.

[13] Rosenbaum MB, Blanko HH, Elizari MV, et al. Electrotonicmodulation of the T wave and cardiac memory. Am J Cardiol.1982; 50: 213-232.

[14] Benson DW, Sterba R, Gallagher JJ, et al. Localization of thesite of ventricular preexcitation with body surface maps inpatients with Wolff-Parkinson-White syndrome. Circulation.1982; 65: 1259.

[15] Kamakura S, Shimomura K, Ohe T, et al. The role of initialminimum potentials on body sur-face maps in predicting thesite of anomalous pathway. Circulation. 1986; 74: 89-96.

[16] Bockeria LA, Revishvili ASh., Polyakova IP, et al. Newmethod of topical diagnostics of accessory conduction path-ways in patients with the Wolff-Parkinson-White syndrome.1989; 7: 49-53.

[17] Mirvis DM. Body surface mapping. Boston 1988.

[18] Abildskov JA, Lux RL. Distribution of QRST deflectionareas in relation to repolarization and arrhythmias. JElectrocardiol. 1991; 24: 197-203.

[19] Nirei T, Kasanuki H, Ohnishi S, et al. Cardiac memory inpatients with intermittent Wolff-Parkinson-White syndrome.J Electrocardiol. 1997; 30: 323-329.

[20] Madrid AH, del Rey JM, Rubi J, et al. Biochemical markersand cardiac troponin I release after radiofrequency catheterablation: approach to size of necrosis. Am Heart J. 1998; 136:948-955.


Documents

The Ventricular Myocardium Repolarization Process and its Pecu - … · 2001. 1. 29. · repolarization peculiarities in persistent WPW sy- n drome and to clear up whether repolarization