(Circulation. 1996;93:982-991.)
© 1996 American Heart Association, Inc.
Articles |
Prediction of Successful Ablation Site of Concealed Posteroseptal Accessory Pathways by a Novel Algorithm Using Baseline Electrophysiological Parameters
Implication for an Abbreviated Ablation Procedure
From the Division of Cardiology, Department of Medicine, National Yang-Ming University, School of Medicine, and Veterans General Hospital-Taipei, Taiwan, ROC.
Correspondence to Shih-Ann Chen, MD, Director of Electrophysiology, Division of Cardiology, Veterans General Hospital-Taipei, 201 Sec 2, Shih-Pai Rd, Taipei, Taiwan, ROC.
 |
Abstract |
|---|
 Top Abstract IntroductionMethods Results Discussion References |
|---|
Background Radiofrequency catheter ablation of concealed posteroseptal accessory pathways (APs) has been a relatively difficult task for electrophysiologists. Without a detailed mapping procedure, the left versus the right posteroseptal AP could not be distinguished. We investigated the electrophysiological characteristics of concealed posteroseptal APs and defined criteria from baseline parameters to predict the successful ablation site. Validity of the criteria was prospectively verified.
Methods and Results Eighty-nine consecutive patients with a
single concealed posteroseptal AP underwent successful
radiofrequency catheter ablation. Of the initial 48 patients (group 1),
the right posteroseptal area was first mapped. If no ideal
electrogram could be obtained, or after several ineffective
radiofrequency pulses, the left posteroseptal area was then
mapped. Special attention was paid to the stability of the
coronary sinus catheter with the most proximal electrode
straddling the ostium, verified by coronary sinus venography,
in all patients. Six patients (12.5%) had the earliest retrograde
atrial activation at the middle electrode of the coronary sinus
catheter, and successful ablation could only be achieved at the left
posteroseptal area. For patients who presented with
the earliest atrial activation at the proximal electrode, the presence
of long RP' tachycardia suggested a right endocardial
approach, while the 
VA (defined as the difference in the VA
intervals between that recorded at the His bundle catheter and that
at one of the electrode groups recording the earliest atrial
activation) 
25 ms during tachycardia suggested a left
endocardial approach. The subsequent 41 patients (group 2) were
randomized into two subgroups. The initial mapping site was guided by
the algorithm in group 2B, while it was not in group 2A. The successful
ablation site could be predicted accurately in 18 (90%) of the 20
patients in group 2B. The radiofrequency pulses, ablation time, and
fluoroscopic time were markedly reduced in group 2B, mainly because of
the omission of unnecessary mapping procedure in the right
posteroseptal area in patients with "left
atrio–left ventricular" fibers.
Conclusions By the algorithm based on baseline electrophysiological parameters, the successful ablation site could be accurately predicted in a majority of patients with concealed posteroseptal APs. Radiofrequency pulses, ablation time, and fluoroscopic time were markedly reduced.
Key Words: catheter ablation • electrophysiology
|
Introduction |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
The posteroseptal area is a complex anatomic entity.1 Accessory pathways (APs) located in this area pose a relatively difficult task for cardiac surgeons2 3 4 5 and electrophysiologists.6 7 8 9 Initial results from surgical ablation of APs in this area were associated with a moderate success rate but a high incidence of complete AV block because of the close proximity of the AV node to this area.2 With the use of epicardial techniques, surgical results have been much improved.5 Catheter ablation has replaced surgical intervention in the treatment of patients with drug-refractory supraventricular tachycardia in recent years.7 8 9 10 Initially, DC delivered through an electrode catheter at the coronary sinus ostium achieved a high success rate in eliminating these APs11 12 but carried a potential risk of cardiac tamponade and complete AV block.12 Radiofrequency energy, with a more homogeneous lesion and devoid of barotrauma, has recently become a more favored energy source.
In some studies, radiofrequency catheter ablation of posteroseptal APs has been identified as being more difficult than for APs located in other areas.7 13 14 Schluter et al7 reported that more radiofrequency pulses, longer procedure time, and longer radiation exposure were needed to achieve successful results. In addition to the complex anatomic structure involved, difficulty in the discrimination of the successful ablation site on the right versus the left posteroseptal area before the ablation procedure was a major reason. Dhala et al15 demonstrated that posteroseptal APs were "right atrio–left ventricular" fibers and suggested that a right atrial approach would suffice; there was ample evidence to show that a left ventricular or left atrial approach was required for certain APs located in this particular area.6 7 10 16 The usual approach was that after baseline electrophysiological study, the posteroseptal tricuspid annulus including the coronary sinus ostium and its most proximal parts and the inferomedial right atrium were carefully mapped. If ablation at these areas failed or no appropriate ablation site could be obtained, the left posteroseptal area was then mapped with the use of a transaortic or transseptal approach. In the case that the appropriate electrogram was again unavailable at the left posteroseptal area, switch of the mapping procedure back to the right posteroseptal area was not uncommon. More radiofrequency pulses, prolonged procedure time, and radiation exposure were inevitable by these approaches.
There were already several ECG criteria to predict the successful ablation site for manifest APs in this area.13 17 18 However, without a delicate mapping procedure, it was impossible to predict the successful ablation site in patients with concealed posteroseptal APs. In the present study, the electrophysiological characteristics of concealed posteroseptal APs were investigated in detail to define criteria from the baseline parameters to discriminate the successful ablation site. The validity of these criteria was verified prospectively.
|
Methods |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
Patient Characteristics
The inclusion criteria were based on the successful ablation site by radiofrequency energy when it was within the caudal extremity of the septal tricuspid annulus either around the margin of the coronary sinus ostium or in the inferomedial right atrium or within 2 cm of the coronary sinus ostium along the posteroseptal mitral annulus.17 19 20 Of the 92 consecutive patients with a single concealed posteroseptal AP referred to this electrophysiological laboratory, 3 were excluded: 1 with unsuccessful ablation, and 2 with angulation of coronary sinus in whom coronary sinus catheter could not be properly placed. The remaining 89 patients formed the subjects of the study: there were 48 male subjects and 41 female subjects, with a mean age of 43 years (range, 13 to 82). All had had frequent attacks of documented supraventricular tachycardia. Three patients presented with permanent junctional reciprocating tachycardia.21 22 Associated cardiovascular diseases included hypertensive heart disease (8 patients), valvular heart disease (3 patients), and ostium primum-type atrial septal defect (1 patient). A mean of 2.1±0.8 antiarrhythmic drugs had either been ineffective or had not been tolerated before the patients' referral.
Electrophysiological Study
As described
previously,23 24
electrophysiological study was performed
while the patient was fasting and not sedated and all antiarrhythmic
medications had been discontinued for at least 5 half-lives before
study. Three 6F multipolar electrode catheters (Mansfield, Boston
Scientific) were inserted percutaneously into the right
or left femoral vein and positioned in the right atrium, the His bundle
area, and the right ventricle. A 6F catheter with three groups of four
circumferential electrodes arranged in an orthogonal configuration
(Jackman Catheter, Mansfield/Webster Catheter, Mansfield Scientific,
Inc) was positioned from the internal jugular vein into the
coronary sinus. The vascular sheath (Argon, Maxxim Medical) in
the internal jugular vein has a locking device that can secure the
catheter in place while the sheath itself is sutured to the skin for
stability. The coronary sinus ostium was demarcated by
coronary sinus venography or the venous phase of left
coronary arteriography, routinely performed in this laboratory
in patients with posteroseptal AP.25 The
position of the coronary sinus electrode catheter was adjusted
to make sure that the most proximal group of electrodes straddled the
ostium, and close bipolar electrograms were obtained by
recording between adjacent electrodes within a circumferential
group of electrodes. A bipolar electrogram from each of the three
groups of electrodes was recorded simultaneously.
The diagnostic portion of the electrophysiological study included (1) measurement of the conducting properties of the atrium, AV node, ventricle, and APs, (2) initiation of supraventricular tachycardia, and (3) determination of the mechanism of tachycardia. If tachycardia could not be induced in the baseline state, isoproterenol (1 to 4 µg/min) was used to facilitate the induction of tachycardia. In patients requiring isoproterenol, all electrophysiological parameters were measured again during isoproterenol infusion. Induction of functional left bundle-branch block was not routinely performed. Induced tachycardias were classified as AV reciprocating tachycardia involving an AP according to the classic criteria.26 Heparin was administered in a dose of 1000 U/h after a bolus of 5000 U when left heart catheterization was performed.
Mapping and Ablation Procedures
Informed consent was obtained
from all patients under an
investigational protocol approved by the Human Research Committee of
this Medical Center. Once the initial
electrophysiological assessment localized
the AP in the posteroseptal
region,26 27 28 that
is, when the earliest retrograde atrial activation was recorded at
the coronary sinus ostium or at the middle electrode of the
coronary sinus catheter, a 7F deflectable quadripolar catheter
with a 4-mm tip electrode (Mansfield, Boston Scientific) was introduced
via the right or left femoral vein for detailed mapping along the right
posteroseptal area. By the use of 30° right anterior
oblique and 60° left anterior oblique projections, which can
clearly delineate the interatrial and interventricular
septa and the mitral and tricuspid annuli,29 the location
of the successful ablation site was defined as the right
posteroseptal region when successful ablation could be
obtained within the caudal extremity of the septal tricuspid annulus
around the margin of the coronary sinus ostium and its most
proximal part (<1 cm from the ostium) or in the inferomedial right
atrium (Fig 1
). The left posteroseptal
region was defined when the successful ablation could be achieved
within 2 cm of the coronary sinus ostium along the
posteroseptal mitral annulus17 19 20 (Fig
1)
by transaortic or transseptal approaches. During orthodromic
tachycardia or ventricular pacing, appropriate
sites for ablation were identified fulfilling all of the following: the
presence of discrete atrial and ventricular electrograms,
fusion of local ventricular and atrial activation (except
in patients with long RP' tachycardia) with atrial
activation simultaneous with or earlier than that
recorded in the coronary sinus, and/or the presence of a
presumed AP activation potential. We did not specially look for the AP
activation potential (described by Jackman et al6 ), and no
attempts were made to validate suspected AP activation potential with
pacing maneuvers. Radiofrequency energy was not delivered into the
coronary sinus except to the most proximal part (<1 cm from
the ostium), neither into the middle cardiac vein nor on the
ventricular aspect beneath the tricuspid valve. If no ideal
electrogram could be obtained or if attempts at ablation were
unsuccessful by the femoral vein approach, the ablation catheter was
repositioned through the transaortic or transseptal approaches (if
necessary) to map the atrial and ventricular aspects of the
left posteroseptal area against the mitral annulus near the
coronary sinus ostium. Electrograms with the earliest
retrograde atrial activation obtained from the right side and the left
side were compared.
|
Radiofrequency current was delivered by a radiofrequency generator (Radionics-3C, Radionics, Inc) providing 500-kHz unmodulated sine wave energy, connected to the distal 4-mm tip of the ablation catheter via a switch box, and grounded to the posterior chest wall with a standard electrosurgical grounding pad. Applied voltage and measured current were displayed, and the impedance was monitored continuously. The energy was delivered in a power range from 30 to 45 W. When AP conduction was lost within 10 seconds, the application of energy was maintained for 30 to 60 seconds but was terminated immediately in the event of an increase in impedance or displacement of the ablation catheter. The radiofrequency pulses, the ablation time (defined as the duration spent in mapping and ablation procedures), and the fluoroscopic time for each patient were recorded.
Analysis of ECG and
Electrophysiological
Characteristics
The ECG characteristics of tachycardia and the
electrophysiological parameters
of APs ablated in right posteroseptal and left
posteroseptal areas were analyzed and compared
comprehensively. For patients who had a failed initial ablation
session, the ECG and electrophysiological
characteristics of the second successful session were included. The VA
interval, defined as the interval from the initiation of the QRS
complex on the surface ECG to the local atrial activation of
intracardiac recording of the proximal and the middle
circumferential groups of electrodes of the coronary sinus
catheter and of the His bundle catheter, was recorded during
ventricular pacing and supraventricular
tachycardia (Fig 2). The electrode that
recorded the earliest atrial activation during
ventricular pacing and tachycardia was also
recorded. The VA during ventricular pacing or
tachycardia was defined as the difference in VA intervals
between that recorded at the His bundle catheter and that at one of
the electrode groups of the coronary sinus catheter, which
recorded the earliest atrial activation. The HA interval was
defined as the interval from the His potential to the atrial activation
of the His bundle catheter during tachycardia. The
algorithm was constructed by recruiting the parameters that
could successfully discriminate the left versus a right
posteroseptal ablation site. The one with the highest
specificity (>95%) was recruited first, and the others were added in
the order of decreasing specificity.
|
Prospective Study
The second part of the study consisted of
the prospective
component. After baseline
electrophysiological study, patients who
had the earliest atrial activation at the coronary sinus ostium
or the middle electrode were randomized into two subgroups. In one
subgroup, the mapping procedure was the same as the usual one: the
right posteroseptal area was mapped first. In another
subgroup, the initial mapping site was guided by the algorithm. If no
ideal electrogram could be obtained at the initial site or after
several unsuccessful pulses of radiofrequency energy, the opposite site
would be mapped. The mean pulses of radiofrequency energy, the mean
ablation time, and fluoroscopic time delivered or distributed at either
side of the posteroseptal area for each patient were
recorded and compared.
Statistical Analysis
All data are expressed as
mean±SD. The ECG and
electrophysiological parameters
of APs in different groups were compared by Student's unpaired
t test. Univariate analysis of
nonparametric data was performed by contingency table
analysis. Multivariate analyses were
performed by use of the multiple logistic regression technique, with
the successful ablation site as the dependent variable and the ECG
and electrophysiological
parameters as the independent variables. The
radiofrequency pulses, ablation time, and fluoroscopic time of
different groups were compared by Student's unpaired t
test. A value of P<.05 was considered significant.
|
Results |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
Patient Categorization
All the 89 patients included had successful ablation. They were divided into two groups: group 1 consisted of the initial 48 patients whose ECGs and electrophysiological data were analyzed, and group 2 was composed of the following 41 patients who were prospectively evaluated. The group 1 patients were further divided into two subgroups: group 1A, in whom successful ablation could be obtained in right posteroseptal area, and group 1B, in whom successful ablation had to be achieved in the left posteroseptal area. The group 2 patients were also divided into two subgroups: group 2A, in whom the right posteroseptal area was first mapped as in group 1, and group 2B, in whom the initial mapping site was guided by the algorithm.
ECG Characteristics
The 12-lead ECGs from patients in both
subgroups of group 1 shared
the same characteristics: a positive retrograde P wave in lead
V1, a negative retrograde P wave in leads II, III,
and aVF, and a biphasic retrograde P wave in lead I. No ECG
characteristics could be used as discriminative criteria for
distinguishing a tachycardia using a left
posteroseptal AP from that using a right
posteroseptal AP.
Electrophysiological Characteristics and
Radiofrequency Ablation
Tachycardia could not be induced in 2 patients
in
group 1 despite administration of isoproterenol and atropine.
Functional right bundle-branch block developed in 8 patients, but
none had VA interval prolongation. Functional left bundle-branch
block was not observed. Various
electrophysiological parameters
of baseline electrophysiological study of
group 1A and group 1B were analyzed and compared. Seven
parameters were found to be significantly different between
the two subgroups (Table 1 and Fig 3). We
found it interesting that 6 of the 18 patients (33%) in group 1B had
the earliest retrograde atrial activation at the middle electrode of
the coronary sinus catheter during tachycardia,
while none of the 28 patients in group 1A had this phenomenon
(P<.01), so a left posteroseptal ablation site
for patients with posteroseptal APs could be identified
with a high specificity (100%) and positive predictive value (100%).
To find the predictors of the successful ablation site for patients
with earliest retrograde atrial activation at the coronary
sinus ostium (the proximal electrode), the baseline
electrophysiological parameters
for all the patients in group 1, excluding those from patients with
earliest atrial activation at the middle electrode, were
reanalyzed. One independent predictor was found: the VA
during tachycardia. A cutoff value of 25 ms for VA
could predict a successful ablation site at the left
posteroseptal area with a sensitivity of 92%, a
specificity of 89%, and a positive predictive value of 79% (Fig
3).
This, together with the other two parameters that have the
highest specificity in discrimination (the presence of long RP'
tachycardia [100% specificity for prediction of right
posteroseptal ablation site] and the earliest atrial
activation at the middle coronary sinus electrode), constituted
the algorithm (Fig 4). By this algorithm, a successful
ablation site could be predicted accurately in 42 of the 46 patients
(91%) in group 1 when they were retested. Isoproterenol had no effect
on the VA because the VA showed no significant difference for
patients who did or did not receive it (13.5±11.6 versus
14.4±9.4 ms,
P>.05) in group 1A and in group 1B (32.5±12.2 versus
33.8±14.4 ms, P>.05). The proportions of patients
receiving isoproterenol were also without significant difference in the
two subgroups (31% versus 26%, P>.05).
|
|
|
For all the patients
in group 1B in whom left-sided ablation was
necessary, local atrial activations recorded at the atrial aspect
of the left posteroseptal area and at the successful
ablation site beneath the mitral valve during tachycardia
were always earlier than those recorded from the right side. In
addition, successful ablation could be achieved at the
ventricular aspect beneath the mitral valve in all
patients. The above findings suggested that these APs were "left
atrio–left ventricular" fibers.3 5
None in group 1B received a transseptal approach. For the 22 patients
in group 1A who also received the mapping procedure in the left
posteroseptal area, the local atrial activation of the
successful ablation site around the coronary sinus ostium and
its most proximal part (<1 cm from the ostium) or at inferomedial
right atrium in the right posteroseptal area was always
earlier than that from the left side, and successful ablation could be
achieved on the endocardial surface of the right
posteroseptal area above the tricuspid annulus, suggesting
that their atrial insertion was on the right side of the interatrial
septum around the coronary sinus ostium or the inferomedial
right atrium above the posterior superior process of the left
ventricle. However, the ventricular insertion site could
not be definitely localized. For the remaining 7 patients in group 1A,
no comparison was made because the left posteroseptal area
was not mapped. Comparisons of other characteristics of the successful
electrograms in groups 1A and 1B are shown in Table 2.
For the whole patient population in group 1, the mean pulse number of
radiofrequency energy was 7.9±7.1 (range, 1 to 31). Mean ablation time
was 90.6±45.4 minutes (range, 10 to 230), and the mean fluoroscopy
time was 35.6±17.2 minutes (range, 10 to 82). No complication was
encountered. Average follow-up period was 33.5±12.9 months (range,
17 to 60). Only 1 patient had a recurrence of
tachycardia and then underwent successful ablation in the
second session on the same side of the posterior septum.
|
Prospective Study
Forty of the 41 patients in group 2, except
1 patient in whom
tachycardia could not be induced, entered the second part
of the study. There were 20 patients in each subgroup. The
electrophysiological characteristics and
results of radiofrequency ablation are shown in Table 3. The
algorithm accurately predicted
the successful ablation site in 18 (90%) of the 20 patients in group
2B. The sensitivity, specificity, and positive predictive value for
prediction of the right posteroseptal APs were 91%, 89%,
and 91%, respectively, and were 89%, 91%, and 89%, respectively,
for left posteroseptal APs. Ten patients of group 2A
required mapping procedures in both sides of the posteroseptum,
significantly more frequent than in group 2B (10 of 20 versus 2 of 20,
P<.01). Together with group 1 patients, 12 patients (13%)
had the earliest retrograde atrial activation at the middle electrode
in the coronary sinus during tachycardia, and all
could have successful ablation at the left posteroseptal
area beneath the mitral leaflet. None received a transseptal approach.
The radiofrequency pulses, ablation time, and fluoroscopic time were
significantly less in group 2B compared with group 2A (Fig 5).
Fig 5 also shows that for APs successfully ablated
in the right posteroseptal area in either subgroup, these
parameters were not different. The main reduction was
attributed to the marked decrease in APs successfully ablated in the
left posteroseptal area in group 2B. The dramatic reduction
of the radiofrequency pulses, ablation time, and fluoroscopic time
delivered on the right posteroseptal area further
contributed to the above findings. The efficacy of the algorithm in
cutting down the radiofrequency pulses and in abbreviating the ablation
procedures, by skipping the unnecessary mapping procedures in the right
posteroseptal area for left posteroseptal APs,
was confirmed.
|
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
This is the first study to demonstrate that successful ablation sites for concealed posteroseptal APs could be predicted from baseline electrophysiological parameters, based on the results of the largest patient group ever reported. Patients may have earliest retrograde atrial activation at the middle electrode of the coronary sinus catheter during tachycardia, and left endocardial approach will suffice. One of the major new findings is that for patients with earliest atrial activation at the coronary sinus ostium, some APs could be effectively ablated from the left side when the
VA was
25 ms during tachycardia, while a long RP'
tachycardia suggests a right endocardial approach.
Radiofrequency pulses, ablation time, and fluoroscopic time could be
reduced significantly by the application of the algorithm. This study
also demonstrated that without the use of an epicardial approach
through the major coronary veins, a vast majority of the
concealed posteroseptal APs could be successfully ablated
on the endocardial surface without complication.
Anatomic and Electrophysiological
Considerations
The posteroseptal area is a complex anatomic
entity. It corresponds to a region where the four cardiac chambers
reach their maximal proximity posteriorly.3 30 In
this
area, the interatrial sulcus is to the far left of the
interventricular sulcus, while the mitral annulus
usually inserts into the right fibrous trigone as much as 5 mm superior
to the insertion of the tricuspid annulus.3 Between the
mitral annulus and the tricuspid annulus lies the right atrio–left
ventricular sulcus, which was the junction between the
inferomedial right atrium and the posterior superior process of the
left ventricle.3 5 The undersurface of the
coronary sinus is about 1 cm above the mitral annulus, and its
ostium abuts the superior margin of the right atrio–left
ventricular sulcus.3 5 30
To know the true dimensions of the posterior septum is important because it may provide a basis for consensus among electrophysiologists and facilitate more accurate comparison of the outcome and risks of catheter ablation techniques in relation to the anatomic sites of the APs. Davis et al19 studied the dimensions of the posterior septum in 48 adult cadaver hearts. They found that the mean distance from the coronary sinus ostium to the left margin of the posterior septal space was 2.3±0.4 cm and that the junction of the posterior septum and the left free wall lies >1.75 cm to the left of the coronary sinus ostium in >75% of all but the smallest adults. Sealy and Mikat3 demonstrated that the distance from the central fibrous body to the left free wall ranged from 15 to 28 mm in 20 adult cadaver hearts and by intraoperative measurements. Jackman et al31 have shown that the AP activation potential could be recorded as far as 18 mm from the coronary sinus ostium distally for left posteroseptal APs. In the present study, we defined the margin of the left posteroseptal space as 2 cm from the coronary sinus ostium, which was reasonable and compatible with the previous reports.
From the surgical findings, most posteroseptal APs consist of "right atrio–left ventricular" fibers with the ventricular insertion attaching onto the posterior superior process of the left ventricle,3 but some posteroseptal APs were considered to be left posteroseptal, and a left atrial approach was needed for successful dissection.5 Furthermore, results from radiofrequency catheter ablation also suggested that the left-sided approach was indeed necessary for certain APs in the posteroseptum.6 7 8 9 10 16 For the APs described as group 1B in the present study, the earliest atrial activity recorded at the posteroseptal mitral annulus was always earlier than that recorded from the right posteroseptal area, suggesting that the atrial end might insert onto the posteroseptal mitral annulus, in contrast to the ordinary posteroseptal APs described by other investigators.3 15 Besides, these APs could be ablated successfully by radiofrequency energy delivered at the ventricular aspect of the posteroseptal mitral annulus, which implies that ventricular insertion was on the left ventricle. The above findings provided evidence that the APs described as group 1B in the present study were composed of "left atrio–left ventricular" fibers and comprised a subgroup of posteroseptal APs. Radiofrequency energy applied on the atrial aspect of the right posteroseptal area was unable to ablate these APs. Only radiofrequency energy delivered at the posteroseptal mitral annulus was expected to be effective.
For certain patients with concealed posteroseptal APs, the earliest retrograde atrial activation might be recorded at the middle electrode of the coronary sinus catheter instead of the proximal one. The distance between the neighboring electrode groups is 1 cm for the Jackman orthogonal coronary sinus catheter. With the proximal electrode straddling the ostium of the coronary sinus, it is possible for a "left atrio–left ventricular" AP to have the earliest atrial activation recorded at the middle electrode if the APs are at some distance from the ostium of the coronary sinus but still within the proximal 2 cm from the ostium. In other words, if the earliest atrial activation could be recorded on the middle electrode for a "left atrio–left ventricular" AP, there was hardly a chance for a right endocardial approach to be effective in ablation except by applying radiofrequency energy deep into the coronary sinus, an approach not undertaken in the present study.
One of the
major new findings in the present study was that some
APs that had the earliest retrograde atrial activation at the
coronary sinus ostium could be ablated successfully on the left
side and predicted in advance. VA approximately
represented the intra-atrial conduction time from the
atrial insertion of APs to the His bundle area. A value 25 ms
suggested a left endocardial approach. This criterion could not be
explained fully because throughout the literature, no previous reports
have been found that study the intra-atrial conduction time from
the posteroseptal tricuspid annulus to the His bundle area
versus that from the posteroseptal mitral annulus. More
electrophysiological studies may be needed
to answer this.
The presence of long RP' tachycardia predicts a right endocardial ablation site. Chien et al32 reported 6 patients with concealed posteroseptal APs with decremental properties presented as a permanent form of junctional reciprocating tachycardia. All the APs could be treated successfully by DC shock via a catheter positioned just outside the coronary sinus ostium. Haissaguerre et al33 also reported successful ablation with DC shock in all 8 patients with long RP' tachycardia, using a right endocardial approach. Gaita et al34 recently reported 32 patients with permanent junctional reciprocating tachycardia. Twenty-five of them had concealed posteroseptal APs, and all the APs could be successfully ablated with radiofrequency current delivered at the right posteroseptal area; this is in accordance with findings here that all 11 patients with long RP' tachycardia including 3 patients with permanent junctional reciprocating tachycardia could have successful ablation on the right endocardial surface. As far as is known, no one has ever reported a left endocardial approach achieving successful ablation of posteroseptal APs presenting as long RP' tachycardia. These findings suggested that in patients with posteroseptal APs presenting with long RP' tachycardia, the right endocardial approach should be tried first.
The surface ECG did not provide any clues for discrimination of a right versus a left endocardial ablation site. Waldo et al35 reported that when the atria were paced from a site anterior to the coronary sinus ostium, a negative P wave would appear in leads II, III, and aVF. (They did not pace the left posteroseptal area.) As far as is known, no ECG criteria have ever been reported as able to discriminate a successful ablation site for concealed posteroseptal APs. The difference in the intra-atrial activation may be too subtle to be detected by surface ECGs.
Verification of the Coronary Sinus Ostium
Coronary sinus
venography or the venous phase of left
coronary arteriography can clearly delineate the
coronary sinus morphology and its ostium. The importance of the
stability of the orthogonal catheter in the vascular sheath should be
addressed. The catheter was locked to the vascular sheath, which was
then sutured to the skin. Any dislodgment or displacement of the
proximal electrode group away from the coronary sinus ostium
might compromise the accuracy of the algorithm.
Comparison With Previous Studies
All the authors in the
previous reports used the right endocardial
approach first.15 16 18 If attempts at
the right
posteroseptal area failed, the left
posteroseptal area was then mapped. Schluter et
al7 reported a series of 92 patients with APs receiving
radiofrequency catheter ablation. Of the 21 patients with
posteroseptal APs, only 8 had concealed APs. A great effort
has been devoted to the search for AP activation potential. The mean
pulse was comparable to that of group 1 in the present study (7
versus 7.9, P>.05) but higher than that of our group 2 (7
versus 3.1, P<.05). Among the 10 patients in whom ablation
was attempted from the coronary sinus, 7 failures were
encountered, while the ablation was successful in all 4 patients in
whom the left ventricular approach was used. Calkins et
al16 reported the results of radiofrequency ablation in
250 patients with APs. The actual number of patients with concealed
posteroseptal APs was not provided. Twenty-two percent
of patients needed the left endocardial approach. The success rate for
the overall 44 patients with posteroseptal APs was 93% (41
of 44). The mean pulse number (8), mean ablation time (93 minutes), and
mean fluoroscopic time (47 minutes) were comparable to those of group 1
but more than those of group 2 in the present study. Wang et
al18 also reported a series of 74 patients with
posteroseptal APs. The actual number of patients with
concealed AP was not available. They emphasized the importance of
demonstrating AP activation potential for successful ablation; 8 of the
74 (11%) patients had detectable AP activation potential in the
coronary sinus (>1.5 cm from the ostium) or middle cardiac
vein. Of the 7 patients who received radiofrequency energy in the
middle cardiac vein, acute tamponade developed in 1 patient, and
occlusion of the middle cardiac vein was found in 3
patients.36 Dhala et al15 reported their
experience with 50 patients with posteroseptal APs. Only 14
patients had concealed APs. They highlighted the importance of
induction of a functional left bundle- branch block and suggested that
a VA interval prolongation accompanying left bundle-branch block
implied a left ventricular insertion; however, they did not
map the left ventricular endocardial surface to prove it.
Neither did the results justify their methods because 48 patients
(96%) could have successful ablation on the right endocardial surface,
irrespective of VA interval prolongation with left bundle-branch block,
while only 2 patients needed a left endocardial approach. Such a low
requirement for left-sided ablation might be related to a different
definition of posteroseptal APs in their series compared
with the present one and those of
others.7 16 18 They
defined posteroseptal APs as that in which the earliest
atrial or ventricular activation was recorded <1 cm
from the coronary sinus ostium, much narrower than the actual
dimensions.3 19 31 Thus, some of the
posteroseptal APs might have been classified by Dhala et
al15 as left posterior free wall pathways for which
left-sided ablation was indeed necessary. In this way, the
requirement for a left endocardial approach may be minimized for
posteroseptal APs.
The present study consisted of results from 93 consecutive patients with concealed posteroseptal APs, the largest patient group ever reported. The position of the coronary sinus ostium was verified by angiography, and the coronary sinus catheter was fixed on the vascular sheath with the proximal electrode straddling the ostium. The "left atrio–left ventricular" fibers could be predicted by the algorithm from the baseline electrophysiological study without the induction of functional bundle-branch block or the search for AP activation potential. The radiofrequency energy pulses, ablation time, and fluoroscopic time were therefore markedly reduced, as proved in the prospective study. Almost all APs (98.9%) could be successfully ablated on the endocardial surface without complications.
Study Limitations
This study was based on the results from
patients with
concealed posteroseptal APs. The conclusions could not be
properly applied to patients with manifest APs. The fact that some
patients were excluded from the study and that some patients did not
have inducible tachycardia might impair the validity of the
algorithm. However, its impact should be negligible because the
majority of the patients were eligible to enter the study. Some APs may
have a slanting course, so that ablation from either side may be
successful, and some APs successfully ablated on the left side may be
eliminated from the right side when the electrophysiologist spends
extended time or delivers energy deeply into the coronary
sinus, avoiding the potential risks of transaortic or transseptal
catheterization. We used bipolar recordings
from the circumferential electrodes of the orthogonal coronary
sinus catheter in the present study. The findings might not be
applicable to bipolar mapping using standard catheters with
interelectrode space of 1 cm. Finally, coronary sinus
diverticulum was not encountered in this study, an unusual finding
compared with others.37 In a series of 408 patients with
supraventricular tachycardia receiving
coronary angiography to demonstrate the coronary sinus
anomalies in this laboratory,25 none had coronary
sinus diverticulum, a discrepancy that could not be adequately
explained.
Conclusions
This study demonstrated that without the need for
delicate
mapping procedures, the successful ablation site could be predicted to
be on the right or left endocardial surface, simply based on the
baseline electrophysiological
parameters. All the pathways in which the earliest
retrograde atrial activation could be recorded from the left side
(the middle electrodes of the orthogonal coronary sinus
catheter) could be ablated from the left side. For the pathways
presented with the earliest atrial activation at the
coronary sinus ostium, a long RP' tachycardia
suggests a right endocardial approach, while the VA 25 ms during
tachycardia suggests a left endocardial approach. Although
the right endocardial approach has several potential advantages over
the left endocardial approach, for "left atrio–left
ventricular" fibers, the correct prediction of the
successful ablation site to the left posteroseptal
endocardial surface by the algorithm can markedly reduce the pulse
number, ablation time, and fluoroscopic time. This study also
demonstrated that the endocardial approach is feasible for the vast
majority of patients with concealed posteroseptal APs and
has a high success rate and negligible complications.
|
|
Acknowledgments |
|---|
This study was supported in part by grants from the National Science Council (NSC-84-2331-B-075-004, NSC-84-2331-B-010-018) and the Academia Sinica, Taipei, Taiwan, ROC.
Received August 14, 1995; revision received October 5, 1995; accepted October 10, 1995.
|
References |
|---|
|
TopAbstractIntroductionMethods Results Discussion References |
|---|
1. Dean JW, Ho SY, Rowland E, Mann J, Anderson RH. Clinical anatomy of the atrioventricular junctions. J Am Coll Cardiol. 1994;24:1725-1731. [Abstract]
2. Sealy WC, Gallagher JJ. The surgical approach to the septal area of the heart based on the experiences with forty-five patients with Kent bundles. J Thorac Cardiovasc Surg. 1980;79:542-551. [Abstract]
3. Sealy WC, Mikat EM. Anatomical problems with identification and interruption of posterior septal Kent bundles. Ann Thorac Surg. 1983;36:584-595. [Abstract]
4. Cox JL, Gallagher JJ, Cain ME. Experience with 118 consecutive patients undergoing surgery for Wolff-Parkinson-White syndrome. J Thorac Cardiovasc Surg. 1985;90:490-501. [Abstract]
5. Guiraudon GM, Klein GJ, Sharma AD, Jones DL, Mclellan DG. Surgical ablation of posterior septal accessory pathways in the Wolff-Parkinson-White syndrome by a closed heart technique. J Thorac Cardiovasc Surg. 1986;92:406-413. [Abstract]
6. Jackman WM, Wang X, Friday KJ, Roman CA, Moulton KP, Beckman KJ, McClelland JH, Twidale N, Hazlitt HA, Prior MI, Margolis PD, Calame JD, Overholt ED, Lazzara R. Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current. N Engl J Med. 1991;324:1605-1611. [Abstract]
7.
Schluter M, Geiger M, Siebels J, Duckeck W, Kuck KH.
Catheter ablation using radiofrequency current to cure
symptomatic patients with tachyarrhythmias
related to an accessory atrioventricular
pathway. Circulation. 1991;84:1644-1661.
8. Lesh MD, Van Hare GF, Schamp DJ, Chien W, Lee MA, Griffin JC, Langberg JJ, Cohen TJ, Lurie KG, Scheinman MM. Curative percutaneous catheter ablation using radiofrequency energy for accessory pathways in all locations: results in 100 consecutive patients. J Am Coll Cardiol. 1992;19:1303-1309. [Abstract]
9. Leather RA, Leitch JW, Klein GJ, Guiraudon GM, Yee R, Kim YH. Radiofrequency catheter ablation of accessory pathways: a learning experience. Am J Cardiol. 1991;68:1651-1655. [Medline] [Order article via Infotrieve]
10. Calkins H, Sousa J, El-Atassi R, Rosenheck S, De Buitleir M, Kou WH, Kadish AH, Langberg JJ, Morady F. Diagnosis and cure of the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardias during a single electrophysiological test. N Engl J Med. 1991;324:1612-1618. [Abstract]
11. Morady F, Scheinman MM. Transvenous catheter ablation of posteroseptal accessory pathway in a patient with the Wolff-Parkinson-White syndrome. N Engl J Med. 1984;310:705-707. [Medline] [Order article via Infotrieve]
12.
Morady F, Scheinman MM, Kou WH, Griffin JC, Dick M,
Herre J, Kadish AH, Langberg J. Long-term results of
catheter ablation of a posteroseptal accessory
atrioventricular connection in 48 patients.
Circulation. 1989;79:1160-1170.
13. Haissaguerre M, Gaita F, Marcus FI, Clementy J. Radiofrequency catheter ablation of accessory pathways: a contemporary review. J Cardiovasc Electrophysiol. 1994;5:533-552.
14. Moulton KP. Ablation of posteroseptal accessory atrioventricular pathways. In: Huang SKS, ed. Radiofrequency Catheter Ablation of Cardiac Arrhythmias. Armonk, NY: Futura Publishing Co; 1995:289-309.
15.
Dhala AA, Deshpande SS, Bremner S, Hempe S, Sra JS,
Blanck Z, Akhtar M, Jazayeri MR. Transcatheter
ablation of posteroseptal accessory pathways using a venous
approach and radiofrequency energy.
Circulation. 1994;90:1799-1810.
16.
Calkins H, Langberg J, Sousa J, El-Atassi R, Leon A,
Kou WH, Kalbfleisch S, Moraday F. Radiofrequency catheter
ablation of accessory atrioventricular connections in
250 patients: abbreviated therapeutic approach to
Wolff-Parkinson-White syndrome.
Circulation. 1992;85:1337-1346.
17. Chiang CE, Chen SA, Teo WS, Tsai DS, Wu TJ, Cheng CC, Chiou CW, Tai CT, Lee SH, Chen CY, Wang SP, Chiang BN, Tan A, Chang MS. An accurate stepwise electrocardiographic algorithm for localization of accessory pathways in patients with Wolff-Parkinson-White syndrome from a comprehensive analysis of delta waves and R/S ratio during sinus rhythm. Am J Cardiol. 1995;76:40-46. [Medline] [Order article via Infotrieve]
18. Wang X, Jackman WM, McClelland J, Beckman K, Roman C, Oren J, Santora IH, Arruda M, Nakagawa H, Hirao K, Lazzara R. Sites of successful radiofrequency ablation of posteroseptal accessory pathways. PACE. 1992;15:535. Abstract.
19. Davis LM, Byth K, Ellis P, McGuire MA, Uther JB, Richards DAB, Ross DL. Dimensions of the human posterior septal space and coronary sinus. Am J Cardiol. 1991;68:621-625. [Medline] [Order article via Infotrieve]
20. Hood MA, Cox JL, Lindsay BD, Ferguson TB, Schechtman KB, Cain ME. Improved detection of accessory pathways that bridge posterior septal and left posterior regions in the Wolff-Parkinson-White syndrome. Am J Cardiol. 1992;70:205-210. [Medline] [Order article via Infotrieve]
21. Coumel P, Cabrol C, Fabiato A, Gourgon R, Slama R. Tachycardie permanente par rythme reciprozue. I-Preuves du diagnostic par stimulation auriculaire et ventriculaire. Arch Mal Coeur. 1967;60:1830-1864.
22. Gallagher JJ, Sealy WC. The permanent form of junctional reciprocating tachycardia: further elucidation of the underlying mechanism. Eur J Cardiol. 1978;8:413-430. [Medline] [Order article via Infotrieve]
23. Chen SA, Tsang WP, Hsia CP, Wang DC, Chiang CE, Yeh HI, Chen JW, Chiou CW, Ting CT, Kong CW, Wang SP, Chiang BN, Chang MS. Comparison of direct-current and radiofrequency ablation of free wall accessory atrioventricular pathways in the Wolff-Parkinson-White syndrome. Am J Cardiol. 1992;70:321-326. [Medline] [Order article via Infotrieve]
24.
Chen SA, Chiang CE, Yang CJ, Cheng CC, Wu TJ, Wang SP,
Chiang BN, Chang MS. Sustained atrial tachycardia in
adult patients: electrophysiological
characteristics, pharmacological response, possible mechanisms, and
effects of radiofrequency ablation.
Circulation. 1994;90:1262-1278.
25. Chiang CE, Chen SA, Yang CR, Cheng CC, Wu TJ, Tsai DS, Chiou CW, Chen CY, Wang SP, Chiang BN, Chang MS. Major coronary sinus abnormalities: identification of occurrence and significance in radiofrequency ablation of supraventricular tachycardia. Am Heart J. 1994;127:1279-1289. [Medline] [Order article via Infotrieve]
26. Leitch J, Klein GJ, Yee R, Murdock C. Invasive electrophysiologic evaluation of patients with supraventricular tachycardia. Cardiol Clin. 1990;8:465-477. [Medline] [Order article via Infotrieve]
27.
Miller JM, Rosenthal ME, Gottlieb CD, Vassallo JA,
Josephson ME. Usefulness of the HA interval to accurately
distinguish atrioventricular nodal reentry from
orthodromic septal bypass tract tachycardias.
Am J Cardiol. 1991;68:1037-1044. [Medline]
[Order article via Infotrieve]
28.
Martinez-Alday JD, Almendral J, Arenal A, Ormaetxe JM,
Pastor A, Villacasatin JP, Medina O, Peinado R, Delcan JL.
Identification of concealed posteroseptal Kent
pathways by comparison of ventriculoatrial intervals from apical and
posterobasal right ventricular sites.
Circulation. 1994;89:1060-1067.
29. Cain ME, Lindsay BD. The preoperative electrophysiology study. In: Cox JL, ed. Cardiac Arrhythmia Surgery. Philadelphia, Pa: Hanley and Belfus; 1990:53-91.
30. McAlpine WA. Heart and Coronary Arteries: An Anatomical Atlas for Clinical and Surgical Treatment. New York, NY: Springer-Verlag; 1975.
31. Jackman WM, Friday KJ, Fitzgerald DM, Bowman AJ, Yeung-Lai-Wai JA, Lazzara R. Localization of left free-wall and posteroseptal accessory atrioventricular pathways by direct recording of accessory pathway activation. PACE. 1989;12:204-214.
32.
Chien WW, Cohen TJ, Lee MA, Lesh MD, Griffin JC,
Schiller NB, Scheinman MM.
Electrophysiological findings and
long-term follow-up of patients with the permanent form of
junctional reciprocating tachycardia treated by catheter
ablation. Circulation. 1992;85:1329-1336.
33. Haissaguerre M, Montserrat P, Warin JF, Donzeau JP, Metayer PL, Massiere JP. Catheter ablation of left posteroseptal accessory pathways and of long RP' tachycardias with a right endocardial approach. Eur Heart J. 1991;12:845-859.
34. Gaita F, Haissaguerre M, Giustetto C, Fischer B, Riccardi R, Richiardi E, Scaglione M, Lamberti F, Warin JF. Catheter ablation of permanent junctional reciprocating tachycardia with radiofrequency current. J Am Coll Cardiol. 1995;25:648-654. [Abstract]
35.
Waldo AL, Maclean WAH, Karp RB, Kouchoukos NT, James
TN. Sequence of retrograde atrial activation of the human heart:
correlation with p wave polarity. Br Heart J. 1977;39:634-640.
36. Oren J, McClelland J, Beckman K, Wang X, Santoro I, Roman C, Arruda M, Nakagawa H, Hirao K, Lazzara R, Jackman W. Epicardial posteroseptal accessory pathways requiring ablation from the middle cardiac vein. PACE. 1992;15:535. Abstract.
37. Weiss C, Cappato R, Schluter M, Hebe J, Kuck KH. Anomalies of the coronary venous system in patients with and without accessory pathways. J Am Coll Cardiol. 1995;25:18A. Abstract.
This article has been cited by other articles:
 |
|
 |
|
  W.-C. Yu, S.-A. Chen, C.-T. Tai, A.-N. Feng, and M.-S. Chang Effects of Different Atrial Pacing Modes on Atrial Electrophysiology : Implicating the Mechanism of Biatrial Pacing in Prevention of Atrial Fibrillation Circulation, November 4, 1997; 96(9): 2992 - 2996. [Abstract] [Full Text]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||