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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
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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.
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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.
Progress in Biomedical Research
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.
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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
Progress in Biomedical Research
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.
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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.
Progress in Biomedical Research
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.
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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
Progress in Biomedical Research
Table 2. Ventricular myocardium depolarization features in
persistent WPW and other SV arrhythmia patients prior to andafter
RFA (differential isointegral QRS map parameters).
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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
Progress in Biomedical Research
Table 3. Ventricular myocardium repolarization features in
persistent WPW and other SV arrhythmia patients prior and afterRFA
(differential isointegrated QRST map parameters).
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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-
Progress in Biomedical Research
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 %).
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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
Progress in Biomedical Research
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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.
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[5] Nicolai P, Medvedovsky JL, Delaage M, et al.
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[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
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Progress in Biomedical Research