Download two groups were present in 45 hearts (90%). In the last 5 cases (10

E UROPACE
two groups were present in 45 hearts (90%). In the last 5 cases (10%) there
was also a middle group. Neither a single initial group nor any case without
any initial groups were found. In the examined sections, in 27 hearts (54%) the
superior group appeared as the first, in 23 cases (46%) the inferior group. The
length of each group was measured from the first appearence to the first solid
contact with the second part. The length of the superiorpart oscillated from 0,15
to 2,91 m m (an 0,90&0,6 mm), inferior from 0,ll to 2,41 m m (am. 0,88&0,6
mm)(table 2) and the middle from 0,67 to 2,21 m m (am 1,04&0,7 mm).
Based on OUTstudy we could conclude that the prevalence of at least two
initial zones of the node: superior and inferior one, is constant and occurs in
each examined heart. Our data suggest that the middle group is additional one.
I
P 352
THE SPECIFIC BIMODAL DISTRIBUTION PATTERN IN
RR INTERVAL HISTOGRAM PREDICTS EARLY
RECURRENCE OF ATRIAL FIBRILLATION
FOLLOWING EXTERNAL ELECTRICAL
CARDIOVERSION
X.H. Guo, J.M. Bland, M.M. Gallagher, A.J. Camm. St George’sHospita2
Medical
School,
UK
Background: W e hypothesize that abnormal AV nodal electrophysiological
behaviour as assessed by the presence of a bimodal RR histogram in atria1
fibrillation (AF) may contribute to vulnerability to recurrent AF postexternal
electrical cardioversion (ECV).
Methods: RR interval histograms were constructed from 24hour ECGs
recorded before ECVon 98 patients (68 men, age 65.3&10.3 years) with persistent AF. A 48.hour recording was obtained from each of 20 patients for
evaluating the reproducibility of RR histograms. RR histograms were classified as either unimodal or bimodal, including multi-modal RR histograms, by
3 observers according to predefined criteria. All patients were prospectively
followed-up during ECV, one-week and one-month later.
Results: Out of total 98 patients, 13 (13.2%) patients failed ECV and a total
of 52 (53%) patients were in AF at one-week and 66 (67%) at one-month post
ECV A bimodal RR interval distribution during AF was found in 17 (18%) of
the 98 patients and 8 (47%) of these 17 patients exhibited a speciiicbimodal RR
histogram. Inter- observed identification of bimodality was excellent (k= 0.966,
p<O.OOOl). The reproducibility of bimodality on consecutive days was good
(k= 0.56, p=O.O04). Compared to the patients with non- specific bimodality,
patients with the specific bimodal RR histogram were more likely to have recurrent AF within one-week and one-month (88 vs. 33%, 100 vs. 33%, p=O.Ol,
p=O.O09,respectively) with sensitivity: 78.73%; specificity: 88.100%; positive
predictive accuracy: 88.100% respectively.
Conclusion: A specific bimodal RR histogram is associated with low probability of maintaining sinus rhythm following ECV.
I P 353
P W A V E PARAMETERS IN PACEMAKERBIOTRONIK
AXIOS D ELECTROPHYSIOLOGY
TEST - STUDY IN
BRADYCARDIA-TACHYCARDIA
SYNDROME PATIENTS
M. Rosiak, M. Chudzik, K. Bartuak, .I. Kawinski, H. Bolinska, .I. Ruta.
Institute
of Cardiology,
Medical
of Lodz,
University
Poland
Atria1 fibrillation (AF) is the common arrhythmia observed in patients with
bradycardia-tachycardia syndrome (BTS). Inter&al conduction disturbances
represented by P-wave duration prolongation, and effective refractory period
shortening are proposed as the electrophysiologic substrate for AF. It has
been demonstrated that AAI/DDD pacing reduce supraventricular arrhythmia
(AFISVT) incidence in BTS patients.
Aim: The aim of the study was to document the changes of the P-wave
parameters in BTS patients (pts) after DDD pacemaker @cm) implantation.
Methods: Study population: 7 patients (4 women and 4 men aged 66,8&12,3)
with BTS (AF vs. sinus bradycardia) who hadBiotronikAxiosD
pcm implanted.
All pts were in DDD 60 bpm pacing mode. Pts had measured on l-day (l-d), 2
weeks (2-w) and 3 months (3-m) after implantation the following parameters: 1.
Measured by BiotronikAxios
D pcm electrophysiology program: Paced P-wave
duration (pP), sinus P-wave duration (sP), atria1 effective refractory period
(ERPA); 2. P-wave duration (PWD) from SAECG.
Results (p<O,O5):
Friedman
test
Pd
sPd
ERM
PWD
l-d vs. Z-w
NS
NS
NS
NS
l-d vs. 3-m
0,015s
NS
0,036
NS
Conclusion: In the group of OUTpts treated by DDD 60 bpm pacing we
observed the shortening of pPd and lengthening of ERPA (l-d vs. 3-m) mea-
2003
ERPA
ERR43-m I
P
sued by pcm electrophysiology program. These tendency should be beneficial
in lowering the number of AF episodes. Further studies with larger group and
different pacing rates are necessary to evaluate pacing rate optimal for P-wave
shortening and ERPA lengthening.
IP
354
CHRONAXIE TIMES ARE THE SAME FOR INDUCTION
OF VENTRICULAR FIBRILLATION
AND
DEFIBRILLATION
BUT DIFFERENT FOR STIMULATION
T. Lawo, B. Wenzel, S.M. Wagner, M. Buddensiek, J.H. Fischer, M. Bose,
A. Muegge, B. Lemke. University Hospital Bergmanmheil,
Bochum,
Germany;
University
of Cologne,
Germany;
Biohmik,
Erlangq
Germany
The strength-duration curve for cardiac stimulation is described by the hyperbolic chronaxie-rheobase relationship. Studies on the strength-duration relation
for the defibrillation threshold (DFT) are limited and show conflicting results.
In addition, no such data are available regarding the induction of ventricular
fibrillation (VF) by a T-wave shock. W e therefore assessedthe hypothesis that
the strength-duration curve for VF induction follows a hyperbolic relation with
a chronaxie (&) different from the t, for stimulation but identical to the t, for
defibrillation.
Twelve pigs were implanted with an ICD lead in the right ventricle. Three
single-coil leads served as the common anode. Fairly rectangular monophasic
shocks were applied by a custom made external defibrillator. Pacing thresholds
(via shock coil) were determined at stimulus durations of 0.02-20 ms. The lower
and upper VF induction threshold (LVr, UVT) and the DFT were determined
for different shock durations (0.1-100 ms). Chronaxies were derived from the
strength-duration curves of each single experiment.
The strength-duration curves for the LVT and the UVT followed a hyperbolic
function (r=O.96 for LVT and r=0.78 for UVT. The mean k for stimulation
was 0.22 ms (&0.12 ms, n=12) and was signiiicantly (p<O.OOl, t-test) shorter
than the k for the LVT (2.4&1.7 ms, n=lO), the UVT (2.5&1.3 ms, n=7) and
the DFT (2.2&1.3 ms, n=ll), respectively.
W e conclude, that not only the time constants but also the underlying cellular mechanisms are identical for T-wave induction and defibrillation (“graded
response”) but different from stimulation (“all-or-nothing response”).
I P 355
ORGANIZATION
OF MULTIPLE REENTRANT W A V E
FRONTS DURING ATRIAL FIBRILLATION
BY A PURE
IKR CHANNEL BLOCKER IN CANINE ATRIA
T. Ikeda, A. Kawase, K. Nakazawa, T. Ashihara, T. Namba, T. Yao, S. Yusu,
H. Yoshino. Kyorin University Mitaka, Japan and Japanese Working Group
On Cardiac
Simulation
and Mapping,
To&w, Japan
Background: Effects of II+ channel blocker on wave front dynamics during
atria1 fibrillation (AF) is unknown. This study aimed to assess the effects of
nifekalant, a pure II+ channel blocker on the characteristics of activation waves
during AF using mapping technique.
Methods: W e used an isolated, coronary perfused canine biatrial model
(n=7). The endocardium was mapped using computerized mapping system
(2.mm resolution). AF was induced by an extrastimulus method in the presence
of 5 u M acetylcholine. After coniirming sustained AF, 5 u M nifekalant was
added to the perfusing Tyrode’s solution. Effective refractory period (ERP),
conduction velocity (Cv), and excitable gap (EG) were determined during
AF.
Results: At baseline, multiple nonstationary wave fronts were observed
leading to meandering, breakups, and the generation of new wave fronts. After
perfusing the drug, multiple wave fronts were completely organized into a
single stationary reentrant wave front in all 7 preparations, anchoring to a large
pectinate muscle (5 preparations), to or&x of inferior vena cava (1 preparaEuropace Supplements,
Vol. 4, December 2003
B149
E UROPACE
tion), or to crista terminalis (1 preparation). In these all episodes, periodic and
uniform activities were recorded in local bipolar electrograms after the drug.
The cycle length of AF increased from 98&12 to 160&14 ms (P<O.Ol). ERP
prolonged from 75&9 to 85&12 ms (P<O.Ol). CV was not changed (55&10
vs. 58&S cm/s). EG was markedly widened (15&6 ms to 75&15 ms; P<O.Ol).
Although no episode was terminated by this drug, a single stimulus applied
through EG area on the map could terminate AF easily.
Conclusion: Nifekalant organizes multiple wave fronts and converts an
irregular “fibrillation-like” activity to a regular “flutter-like” activity, widening
an EG of the reentrant wave front. These findings may suggest an alternative
strategy for AF treatment such as hybrid therapy of a&rhythmic
agents and
atria1 pacing.
I
P 356
P W A V E DISPERSION PREDICTS PAROXSYMAL ATRIAL
FIBRILLATION
IN PATIENTS WITH CONGESTIVE
HEART FAILURE
G. Abali, L. Sahiner, K. Aytemir, 0. On&n, L. Tokgozoglu, G. Kabak&
H. Ozkutlu, N. N&i, A. Oto. Hacettepe Universty Faculty of Medicine Ankara
Background: P wave dispersion calculated from 12.lead standard ECG has
been shown to be used for predicting of patients with lone paroxysmal atria1
fibrillation (PAF). However the role of P wave dispersion for detecting of
paroxysmal atrial fibrillation has not been evaluated in patients with congestive
heart failure who had history of PAF.
Methods: Twelve lead surface ECG electrocardiogram was recorded in 21
patients (13 men and 8 women; mean age 58&11 years, group A) with congestive heart failure (CHF) who had paroxysmal atria1 fibrillation (PAF) and
in 26 CHF patients without history of PAF (16 men and 10 women; mean
age 57&13, group B). All patients were in sinus rhythm on study day. The
maximum P wave duration (P max), the minimum P wave duration (P min) and
P wave dispersion (P dispersion= P max -P min) were calculated. All patients
were also evaluated using echocardiography to measure left ventricular ejection
fraction (LVEF) and left atria1 diameter.
Results: There was no significant difference between two groups in age and
sex. P dispersion (56&10 ms vs 41&12 ms, p=O.OOl) was found to be significantly higher in group A than in Group B, whereas P minimum (74&13 ms
vs 86&12 ms, p=O.OOl), LVEF ejection fraction (28&4% vs 34&4%, p=O.O2)
were significantly lower in group A than group B. P maximum (131&15 ms vs
127&16 ms, p=O.64) and left atria1 diameter (46.3&3.2 m m vs 44X&2.4 mm,
p=O.42) were higher in group A than group B. There was a correlation between
P dispersion and age (r=O.38, p<O.O5). In univariate analysis, P minimum (p
=O.Ol), P dispersion @= 0.001) and LVEF (p=O.OOZ)were significant predictors
of paroxysmal AF in patients with CHF but not age @=O.OS)and P maximum
(p=O.6). In multivariate analysis revealed only P dispersion to be a significant
independent predictor of paroxysmal AF @<O.OOl). A P wave dispersion cut
off value of 48 ms separated CHF patients with PAF from CHF patients without
PAF a with a sensitivity of 86% and specificity of 69%.
Conclusion: Measurement of P wave dispersion in sinus rhythm may be a
useful noninvasive clinical tool to identify patients with congestive heart failure
at risk of developing atria1 electrical instability and atria1 fibrillation.
I
P 358
SUDDEN CARDIAC DEATH RISK IN PATIENTS AFTER
MYOCARDIAL
INFARCTION TREATED WITH
CORONARY ARTERY BYPASS GRAFTING
D. Mroczek-Czemecka, A. Pietmcha, M. Wegrzynowska, W. Piwowarska.
Department
of Cardiology.
Paul II Hospital,
Cracow
Medical
School
of Jagiellonian
University
John
Aim of study: SCD risk assessmentin patients after myocardial infarction (MI)
treated with CABG.
W e observed 131 pts. aged 40-75 years after MI treated with CABG. All pts
were divided into 2 groups. Group I-52 pts with left ventricle ejection fraction
(LVEF) < 40%, with late ventricular potentials &VP) present and ventricular
arrhythmias (VA) no treatment needed. Group II - 79 pts. with LVEF>40%
without both LVP and VA-related symptoms.
Echocardiography study, 24.hour ECG Halter monitoring and high resolution ECG were done every 3 months in all pts. After 1 year follow-up pts.
with abnormal results of mentioned examinations suggesting the manifestation
Table 1. Results
“A
[W] of pts
act. Lawn
Scale
LVEF
LvP(+)
11
1”
IV*
IVB
1A
17,5
45
22,5
37,l
100
1lA
28,6
7,5%
21,4%
17,9%
27,l
54,l
30
B150
Europace Supplements,
Vol. 4, December 2003
2003
of substrate for VA were exposed. There were 40 pts from group I (subgroup
IA) and 28 pts from group II (subgroup IIA). Coronary bypass angiography,
trmsoesophageal electrophysiological study (TES) and programmed electrical
stimulation (PES) were conducted in these selected patients.
Results: Results are shown in Table 1.
Progression of coronary atherosclerosis was revealed in 10% of IA pts and
in 21,4% of IL4 pts
Table 2
Subgroup
15
15
30
30
10
32,l
2,5
14,2
10
17,s
2,5
14,2
Conclusions: 1. Patients after MI and CABG without nsVT revealed in
24.hours ECG, but with presented LVP and symptoms of arrhythmia, depressed
LVEF (~40%) and in whom sustained monomorphic VT was inducted by
PES, were at high risk of SCD 2. Impulse generating - conducting system
dysfunction was responsible for arrhythmia related symptoms in 25% of pts
after MI and CABG.
I P 359
INCREASED P-WAVE DURATION AND DISPERSION IN
PATIENT WITH IDIOPATHIC DILATED
CARDIOMYOPATHY
H. Turhan, K. Senen, E. Yetkin, N. Basar, A.R. Erbay, R. Atak, H. Sasmaz,
E. Ku&. Turkiye Yuksek Ihtisas Hospital, Department of Cardiology Ankara,
Turkey
Background: P-wave dispersion (PWD), defined as the difference between
maximum and minimum P-wave duration, is a new electrocardiographic marker
that has been associated with inhomogeneous and discontinuous propagation of
sinus impulses. The correlation between the presence of inter&al and intraatrial conduction abnormalities and the induction of paroxysmal atria1 fibrillation
(AF) has been well documented. Dilated cardiomyopathy (DC) imposed the
greatest risk for the development of AF with a 4.to-6 fold increased risk. The
aim of the present study was to investigate P W D in patients with DC and
compare with healthy control subjects.
Methods: The study population consisted of 72 patients with idiopathic
DC (group I, 55 men, 17 women; aged 63&S years) and 72 healthy control subjects (group II, 55 men, 17 women; aged 62&9 years) without any
clinically apparent cardiovascular disease. Patients who had coronary artery
disease, diabetes mellitus, uncontrolled hypertension, valvular heart disease,
hyperthyroid@ chronic obstructive pulmonary disease, ventricular preexcitation, atrioventricular conduction abnormalities, or abnormal serum electrolytes
were excluded from the study. Maximum and minimum P wave durations were
calculated from 12.lead surface electrocardiogram. P W D was determined as
the difference between maximum and minimum P-wave durations.
Results: There was no statistically significant difference between 2 groups
in respect to age and gender. Maximum P-wave duration and P W D of group I
were found to be signiiicantly higher than those of group II (Maximum P-wave:
126&12 ms vs 116&10 ms, PWD: 47&6 ms vs 38&7 ms respectively, p<O.OOl
for all). However, there was no statistically signiiicant difference between group
I and group II regarding minimum P-wave duration (79&7 ms vs 78&6 ms
respectively, p=O.27). Left atria1 diameter was significantly higher in group I
patients compared to control subjects (4.51&0.62 cm vs 3.60&0.43 cm respectively, p<O.OOl) and positively correlated with P W D (r=0.488, p<O.OOl). Left
ventricular ejection fraction was found to be signiiicantly lower in group I patients compared to control subjects (33&5% vs 63&7% respectively, p<O.OOl)
and negatively correlated with P W D (I=-0.573, p<O.OOl)
Conclusion: W e have shown that PWD, indicating increased risk for paroxysmal AF, is significantly higher in patients with idiopathic DC than in healthy
control subjects. Further assessmentof the clinical utility of P W D for the prediction of paroxysmal AF in patients with DC will require longer prospective
studies including larger series.
I
P 360
THE EFFECT OF ISCHEMIC PRECONDITIONING
ON
THE VENTRICULAR
FIBRILLATION
AND
DEFIBRILLATION
THRESHOLD, IN A PORCINE MODEL
E. Tsagalou, M. Mponios, S. Stav&is, G. Karmastasis, P. Glentis,
S. Charitos, G. Voidonikolas, D. Koudoumas, C. Charitos,
M. Anastasiou-Nma. University ofAthens, Athens, Greece
Background: Conflicting data exist on how ischemic preconditioning affects
the vulnerability to ventricular fibrillation during the early phase of subsequent