576
lACC Vol. 10. No.3
September 1987:576--82
High Frequency Alternating Current Ablation of an Accessory
Pathway in Humans
MARTIN BORGGREFE, MD, THOMAS BUDDE, MD, ANDREA PODCZECK, MD,
GUNTER BREITHARDT, MD
Dusseldorf, West Germany
High frequency alternating current ablation of an accessory pathway was performed in a patient with incessant circus movement tachycardia using a right-sided,
free walI accessory pathway. Antiarrhythmic drugs, antitachycardia pacing and transvenous catheter ablation
using high energy direct current shocks could not control
the supraventricular tachycardia. A 7F bipolar electrode
catheter with an interelectrode distance of 1.2 em was
positioned at the site of earliest retrograde activation
during circus movement tachycardia. At this area, two
alternating current high frequency impulses were delivered with an energy output of 50 W through the distal
tip of the bipolar catheter, while the patient was awake.
After the first shock supraventricular tachycardia ter-
Catheter ablation or fulguration of structures involved in the
genes is of tachycardias using high energy direct current
through electrode catheters has become a therapeutic tool
for selected patients. Since the initial reports of Scheinman
et al. (I) and Gallagher et al . (2) , catheter ablation of the
atrioventricular (AV) junction has been performed in a substanti al number of patients, resulting in good arrhythmia
control in a high percentage of patient s (3). Catheter ablation
of accessory pathways has also been attempted, but with
less overall success (4-14). Catheter ablation of a left-sided
accessory pathway by shocks delivered within the coronary
sinus has resulted in perforation of the coronary sinus (5).
Few attempts of ablation of a right free wall accessory
pathwa y have been reported. However, the overall success
From the Hospital of the University of DUsseldorf. Department of
Ca rdiology. Pneumology and Angiology. DUsseldorf. West German y. Thi s
study was supported by a grant fro m the Sonderforschun gsberei ch SFB
242 (Koronare Herzkrankhe it-Therapie und Proph ylaxe akuter Kompli kationen ) o f the Deutsche Forschun gsgemeinschaft. Bonn-Bad God esberg ,
West Germany.
Addre ss for reprints: Martin Borggrefe , MD . Medi zinische Klinik und
Poliklinik , Abte ilung fur Kardi ologie , Pneurnologie und Angiologie, Universitat DUsseldorf, Moorenstrasse 5 . D-4000 DUsseldorf. West German y.
Manuscript received September 15. 1986; revised manuscript received
Feb ruary 18 .1987. accepted March 12. 1987 .
© 1987 by the American College of Cardiology
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minated and accessory pathway conduction was absent
without altering anterograde conduction in the normal
atrioventricular (AV) conduction system. No reports of
pain or other complications were noted. In short-term
folIow-up of 5 months, the patient had been free of arrhythmias without antiarrhythmic medication.
Thus, high frequency alternating current ablation was
performed for the first time in the treatment of an arrhythmia incorporating an accessory pathway in a human. This technique may be an attractive alternative to
the available transcatheter ablation techniques and to
antitachycardia surgery.
o Am Call Cardiol 1987;10:576-82)
rate seems to be low . In contrast to free wall accessory
pathways, posteroseptal pathways may be eligible for this
technique with a success rate of about 75 to 80% (II).
One of the major problems of high energy direct current
ablation techniques has been the transient nature of the antiarrhythmic effect due to recov ery of the arrhythmogenic
tissue (3,5,11,14). Therefore, there is a need for ablation
techniques that produce more persi stent tissue damage . In
a recent experimental study (15 ), we evaluated the usefulness of alternating high frequen cy current ablation techniques; the results indicated that there was an energydose-related tissue response resulting in well delineated
necrosis. The purpose of the present study is to present the
first clinical application of high frequenc y alternating current
for ablation of a right-sided acce ssory pathway in human s
after previou sly unsucce ssful high energy direct current
ablation .
Case Report
Previous history. A 40 year old man with Wolff-Parkinson- White syndrome presented with a history of incessant supraventricular tachycardia incorporating a right-sided
accessory pathway. The arrhythmia had been present for 14
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JACC Vol. 10, No.3
September 1987:576-82
II
III
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BORGGREFE ET AL.
HIGH FREQUENCY ALTERNATING CURRENT ABLATION
I?
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r>
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~~ /'
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--------v---
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--------r-
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---y--
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Figure 1. Left panel, 12 lead electrocardiogram (ECG) before ablation showing sinus rhythm
with pre-excitation; delta waves are positive in
leads I, II, aVL and V2 to V6 and negative in
lead III, suggesting a right-sided accessory pathway. Right panel, ECG showing permanent
normalization of the QRS complex after high
frequency ablation.
aVF ~v---
after ablation
V6 --J '"--'
before
ablation
days. The diagnosis of Wolff-Parkinson-White syndrome
had been made 4 months before referral to our hospital when
the patient reported short episodes of palpitation. At that
time, the 12 lead electrocardiogram (ECG) revealed normal
sinus rhythm with pre-excitation. Delta wave polarity suggested the presence of a right-sided accessory pathway
(Fig. I).
On admission to our hospital, the patient presented with
supraventricular reentrant tachycardia with a cycle length
of 445 ms and narrow QRS complexes (Fig. 2). A retrograde
P wave was visible. Administration of verapamil, ajmaline,
sotalol, propafenone, f1ecainide and digitalis proved ineffective in permanently terminating the tachycardia. A drug
trial using amiodarone was refused by the patient because
of possible side effects. Physical examination and echocardiographic evaluation revealed no cardiovascular abnormality. The supraventricular tachycardia was hemodynamically well tolerated when the patient was supine.
Electrophysiologic study. The study was performed 16
hours after the last dose of propafenone. A 6F quadripolar
catheter (USCI) was advanced to the coronary sinus using
the left cephalic vein. Three additional catheters were inserted through the right femoral vein: a 6F quadripolar catheter (USCI) to the high right atrium, one bipolar catheter
to the His bundle area and another bipolar catheter to the
right ventricular apex. Additionally, a 6F quadripolar mapping catheter (Josephson catheter, USC)) was inserted by
way of the left femoral vein for atrial mapping. The study
confirmed the diagnosis of a circus movement tachycardia
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using a right free wall accessory pathway. Atrial or ventricular pacing resulted in only transient termination of the
supraventricular tachycardia; after a single sinus beat, the
tachycardia immediately resumed. At the time of electrophysiologic study, no anterograde conduction through the
Figure 2. Electrocardiogram during supraventricular tachycardia
with narrow QRS complexes with a cycle length of 455 ms and
visible retrograde P waves.
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V3 -4, r r
V
/
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~ ~VV\ r
aVL ~
578
BORGGREFE ET AL.
HIGH FREQUENCY ALTERNATING CURRENTABLATION
accessory pathway could be demonstrated. The anterograde
effective refractory period of the AV node during incremental atrial pacing was 400 ms. The effective refractory
period of the accessory pathway in retrograde direction was
215 ms.
Detailed right atrial mapping was performed during circus movement tachycardia and during pacing from the right
ventricular apex. The earliest retrograde activation occurred
at the right atrial free wall. At this site, AV bypass tract
deflections were recorded. Because the supraventricular
tachycardia persisted despite antiarrhythmic treatment and
antitachycardia pacing, the patient was offered the option
of either surgical or catheter ablation of the accessory pathway. He chose the latter and gave his informed consent.
High energy direct current ablation procedure. The
ablation procedure was performed the next day. Surgical
standby was available. A quadripolar 6F catheter was inserted through the left femoral vein for stimulation of the
right ventricular apex as well as for recording ventricular
activity. Additionally, one quadripolar catheter (USC}, Josephson) was inserted and atrial mapping was repeated.
After endotrachial intubation and anesthesia, an initial 100
J discharge was delivered through the tip electrode (the
anode) directed to a back paddle (the cathode) using a standard defibrillator (Hellige) at the site of earliest retrograde
atrial activation at the right atrial free wall. At this site,
bypass tract deflections were also recorded. This first shock
resulted in only transient termination of the supraventricular
tachycardia. Four additional shocks were also ineffective.
However. after the sixth shock, permanent termination of
the supraventricular tachycardia was observed. Thereafter,
two additional shocks (100 J each) were delivered to the
same location. Complete retrograde block was noted but
anterograde conduction over the AV node remained intact.
An angiogram of the right coronary artery revealed no structural abnormality before and after application of the shocks
to the right-sided AV groove. However, after 8 hours supraventricular tachycardia with a cycle length of 440 ms resumed. Under the assumption that catheter ablation may
have altered the properties of the accessory pathway, antiarrhythmic treatment with propafenone was started again
and proved ineffective. Therefore, the patient was offered
two alternatives: I) the possibility of high frequency alternating current ablation of the accessory pathway as a new
approach or 2) a surgical procedure.
High frequency catheter ablation. High frequency
catheter ablation was performed 3 days later without the use
of anesthesia. Because trans venous catheter ablation technique using high energy direct current had been unsuccessful, this experimental mode of treatment was chosen. Surgical standby was available. Blood pressure was monitored
with a 6F pigtail catheter inserted into the right femoral
artery. A 6F quadripolar catheter was inserted through the
left femoral vein for stimulation of and recording from the
right ventricular apex. A 7F bipolar catheter (Lumelec, CorDownloaded From: http://content.onlinejacc.org/ on 10/01/2016
lACC Vol. 10. No.3
September 1987:576-82
dis) with an interelectrode distance of 1.2 cm was inserted
into the right femoral vein and used for right atrial mapping
and ablation. This catheter possesses a central lumen with
a diameter of I mrrr', which allows for continuous rinse
with saline solution during the ablation procedure to prevent
both blood coagulation and overheating at the catheter tip.
Continuous rinsing of the catheter lumen was performed
during application of high frequency current using a O. 19%
saline solution at 50 mllmin. High frequency alternating
current was administered through the distal electrode using
a back paddle as neutral electrode. A specially designed
energy source for high frequency coagulation (HAT 100;
Dr. Osypka GmbH, Grenzach-Wyhlen, West Germany) was
used. With this unit, energy can be varied in 10 steps from
2.5 W (step I) up to 50 W (step 10). Alternating current
frequency varies between 500 and 1,000 kHz. The unit was
designed to switch off automatically as soon as the impedance of the tissue increases during the coagulation procedure.
During the ablation procedure, the earliest site of retrograde atrial activation during circus movement tachycardia
was found at the identical site as during the first ablation
procedure. Again, electrograms with three distinct deflections were recorded (Fig. 3). The first broad electrogram is
probably due to local ventricular activation (V), the second
deflection most likely represents accessory pathway depolarization (K) and the third deflection represents atrial activity (A).
The following points are suggested to support the idea
that the deflections named K may represent electrical activity from the accessory pathway: I) These three simultaneous deflections were only recorded at the earliest site of
retrograde activation during reciprocating tachycardia, indicating a close proximity to the accessory pathway; 2) all
recordings were made at low gain; 3) during ventricular
pacing with varying cycle lengths the VK and KA intervals
were nearly identical, thus excluding that K represents far
field ventricular activity (if K was far field ventricular activity, the K deflections should have become more fragmented and delayed with shorter cycle lengths and closer
premature ventricuiar stimuli); 4) after successful ablation
of the accessory pathway the deflection K could no longer
be recorded during sinus rhythm or ventricular pacing, even
when pacing at the same cycle length as before ablation the
catheter remained at the same recording site; and 5) during
incremental atrial pacing only A and V electrograms were
recorded as the impulse traveled only through the normal
AV node conduction system. In contrast tothefirst electrophysiologic study, the effective refractory period of the
accessory pathway in retrograde direction had increased from
215 to 370 ms as a result of the previous transcatheter
ablation. During incremental ventricular pacing, block between the accessory pathway potential and the atrium was
observed (Fig. 4). Although the exact site of retrograde
block cannot be determined, this finding supports the con-
BORGGREFE ET AL.
HIGH FREQUENCY ALTERNATING CURRENT ABLATION
lACC Vol. 10, No.3
September 1987:576-82
579
500
--------"--...._------------------[
[[
--.. . . . -.- - - - - - - - - - ..... ....- - - - - - - - - - ......
' --""
-"\
'---
V
RA
- _.
c-:
~'
-----
1\•
,
(unipolar)
.
--J
460
RVA
-
_~ -
-
..-.0-_-,\ I
K A
~~--
V
_
K A
/'. ~---...._.I\./'·...,.:\A..- r...- .-'..- - -- --
Figure 3. Recording during incessant supraventricular tachycardia. From top to bottom, electrocardiographic leads I, II and VI ,
and intracardiac leads from the right ventricular apex (RVA) and
right atrial (RA) free wall. At the site of earliest right atrial retrograde activation, simultaneous recordings of ventricular (V),
accessory pathway (K)and atrial (A)activity were obtained during
circus movement tachycardia with a cycle length of 460 ms.
cept that the distal junction of the accessory pathway may
be the most vulnerable to block.
At this site. high frequency alternating current ablation
was performed. An energy of 50 W was applied for 10
seconds during circus movement tachycardia (Fig. 5). After
10 seconds, the device automatically switched off because
"-- - -- -
,
·· ../ .. _. ' '-
'vv"'-"" - '
of increasing tissue impedance due to the coagulation process. During the application of high frequency current, the
patient was awake and did not report any pain. Tachycardia
terminated at the time when the device automatically switched
off. The PR interval during sinus rhythm was 230 ms without evidence of pre-excitation (Fig. I) . Five minutes after
ablation, ventricular stimulation revealed complete retrograde block. Despite this apparent success, a second high
frequency alternating impulse was applied using the same
energy at the identical site. This time the device switched
off automatically after 15 seconds.
At the immediate electrophysiologic control study. the
anterograde effective refractory period of the AV node was
1000
\
- - - - _\...._----------'------[
370
[[
-- '--\,--~.~ ~V\.rr--'r'~
---..........,~
RA
(bipolar)
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~
Figure 4. Recordings during incremental right
ventricular pacing at a cycle length of 370 rns,
which produced 2:I retrograde block in the accessory pathway . After the first stimulated beat,
activity from the accessory pathway (K)andthe
atrium (A)were recorded, whereas afterthesecond stimulated beat, block occurs between the
Kent potential and the atrial signal . RA = right
atrium.
580
lACC Vol. 10, No.3
September 1987:576-82
BORGGREFE ET AL.
HIGH FREQUENCY ALTERNATING CURRENT ABLATION
TOOO
\
I
1
- \ . , . - '''''''''-- ' L
460
Jstart
-<v----- v-''j' -
HF
ablation
- 10 seconds
Figure S. Recordings of leads I, II and VI during
the high frequency ablation procedure. During incessant supraventricular reentrant tachycardia (SVT)
with a cycle length of 460 ms high frequency (HF)
alternating current ablation was started (arrow).
After 10seconds,the deviceautomatically switched
off and normal sinus rhythm (NSR) with a cycle
length of 850 ms resumed. See text for further explanations.
incessanf SVT
\
\
I
efc
stop HF ablation
1 ,
NSR
390 ms as determined during incremental atrial pacing. There
was no evidence of pre-excitation. Ventricular pacing revealed complete retrograde block. Coronary angiography of
the right coronary artery was performed before and after
high frequency ablation, without evidence of any deleterious
side effect. The patient was effectively heparinized and
monitored for 6 days without any evidence of pre-excitation
or any reappearing arrhythmias. A lung perfusion scan performed 24 hours after the ablation procedure was normal.
Serial echocardiographic evaluation revealed no intracardiac
thrombus formation. The maximal serum creatine kinase
level was 60 Uzliter, and the creatine kinase, MB fraction
levels were also normal.
A control electrophysiologic study carried out 10 days
after the ablation procedure revealed absence of accessory
pathway conduction. The refractory period of the AV node
during incremental atrial pacing was 460 ms. During a treadmill exercise test, the patient was exercised up to 150 W
without evidence of arrhythmias or pre-excitation. During
a follow-up period of 5 months, during which time the
patient has taken no cardioactive medication, his clinical
course has been uneventful without arrhythmias or any ECG
evidence of pre-excitation.
Discussion
Previous experience with catheter ablation techniques
in the WoltT·Parkinson-White syndrome. After the initial
reports by Morady and Scheinman (4) and Gallagher et al.
(2), several groups (5-14) have reported that transvenous
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catheter ablation of accessory pathway can be used in selected patients with refractory arrhythmias. However, the
number of patients studied so far is small and the success
rate is difficult to determine. Fisher et al. (5) were the first
to attempt catheter ablation of left free wall accessory pathways through the coronary sinus. However, this approach
seldom resulted in permanent interruption of accessory pathway conduction. Ward and Camm (9) studied three such
patients, only two of whom were free of pre-excitation during follow-up. Morady et al. (12) studied eight patients with
a posteroseptal pathway, in whom trans venous high energy
direct current catheter ablation was performed, with an overall success rate of 75%. Similar results have been reported
by Kunze and Kuck (7). Thus, transvenous catheter ablation
for accessory pathways may be effective in some patients;
however, the overall success rate seems to be only about
60 to 80%. Reasons for failures are difficult to interpret.
One possible explanation may be problems in correctly identifying the site of the accessory pathway. Furthermore, the
local injury produced by high energy transvenous catheter
shocks may be insufficient to produce block. Therefore, the
new technique applied in the present case may be a promising alternative.
Catheter electroshocks may result in thermal electrocoagulation of tissue, concussive shock waves or membrane
damage due to the intense electric field. The histologic changes
produced by the shocks are lesions I to 2 em in diameter
(16,17). However, these injuries may be only transient in
nature because of a recovery process of the tissue possibly
due to local recovery from edema or to only minor histologic
JACC Vol. 10. No.3
September 1987:57&-82
lesions. Because of these limitations of catheter ablation
techniques, there is a need for alternative techniques to
produce delineated and more controlled focal tissue necrosis.
High frequency ablation. Recently, high frequency alternating current coagulation has been introduced as an alternative to conventional ablation techniques in the experimental animal (15,18,19). Previous extensive animal
experiments in our laboratory (15) demonstrated that high
frequency catheter ablation may be a promising technique
for ablation of myocardial structures resulting in local necrosis. Our results as well as those of previous studies (18)
showed a relation between applied energy and tissue response. Coagulation zones or tissue necrosis could be induced in a size-correlated relation to the applied energy.
Furthermore, deleterious effects of thermal injury induced
by ablation procedures such as thrombus formation at the
tip of the electrode catheter may be prevented by continuously rinsing the catheter at the tip using a specialelectrode
catheter (Lumelec , Cordis). The energy source used (HAT
100, Dr. Osypka GmbH, Grenzach-Wyhlen) is designed to
automatically terminate the energy delivery as soon as the
impedance of the ablated tissue increases.
In our patient, a right-sided free wall accessory pathway
could be ablated by the delivery of transvenous high energy
alternating current impulses. The procedure was effective
and safe and the patient did not require general anesthesia.
High energy direct current shock had been ineffective in
this patient; however, it might already have damaged the
accessory pathway before the attempt at high frequency
alternating current ablation . This new catheterablation technique, performed in a human for the first time, appears to
be an attractive alternative to conventional ablation procedures. High frequency ablation techniques obviate the need
for general anesthesia and may be associated with less expense, less discomfort and a shorter convalescence period
than are associated with high energy transvenous ablation
techniques.
Role of intracardiac electrocatheter recordings of an
atrioventricular bypass tract. Since the initial reports
(20,21) on intracardiac electrocatheter recordings of accessory pathways, several studies (22,23) have demonstrated
that potentials originating from accessory bypass tracts may
be recorded using electrode catheters in humans. Although
many methodologic problems exist to validate the accessory
pathwayelectrogram, recording of the signal may be helpful
in defining the site of application of transvenous catheter
shocks. In our present case the ablation procedure was also
guided by endocardial recordings of the accessory pathway.
Interestingly, during ventricular pacing retrograde blockoccurred at the accessory pathway-atrial junction, suggesting
that the proximal junction of the pathway is the most vulnerableto block. Application of transvenous alternating current shock to this site resulted in a permanent abolition of
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BORGGREFE ET AL.
HIGH FREQUENCY ALTERNATING CURRENT ABLATION
581
accessory pathway conduction. This finding in our patient
is consistent with the concept of "impedance mismatch,"
elegantly demonstrated in a series of experiments carried
out by de la Fuente et al. (24).
Clinical implications. Our results suggest that high frequency catheter ablation of an accessory pathway may be
an alternative to "conventional" catheter ablation procedures and to surgical intervention; however, further studies
are needed to ascertain the efficacy and safety of this procedure. Whether other myocardial structures such as ventricular myocardium in patients suffering from ventricular
tachycardia or a left-sided accessory pathway are also suitable for this technique has to be further demonstrated.
References
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