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ABSTRACT: Focused high-density atrial endocardial mapping was performed with a three-dimensional electroanatomical mapping system or a multielectrode basket catheter in six men and two women (mean age = 54 years) with atypical atrial flutter (AFL) to characterize its reentry circuit and identify its isthmus of critically slow conduction (ICSC). Activation mapping revealed figure-8 reentry with ICSC between a surgical atrial scars in three atypical AFLs following atriotomy, and between the crista terminalis (CT) and the inferior (IVC) or superior (SVC) vena cavae in atypical right atrial (RA) AFL in absence of prior atriotomy. Figure-8 double loop reentry was documented in one RA atypical AFL. ICSC was characterized by concealed entrainment with a post-pacing interval identical to the AFL cycle length, and a mid-diastolic fractionated electrogram, 129 +/- 23 ms in duration, spanning the isoelectric line between double potentials on adjacent area of conduction block. All AFLs were successfully ablated with 4.9 +/- 4.3 RF pulses applied at ICSC. A possible mechanism of atypical AFL consists of figure-8 reentry with ICSC between surgical scars in postoperative AFL, and between the CT and the IVC/SVC in RA AFL not preceded by cardiac surgery. Late and partial regeneration of conduction across the atriotomy scar can create an ICSC. Nonlinear ablation targeting ICSC can cure atypical AFL, whether it follows surgery or not.
Pacing and Clinical Electrophysiology 12/2000; 23(11 Pt 2):1911-5. · 1.35 Impact Factor
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ABSTRACT: A 55-year-old man was referred because of congestive heart failure and atrial flutter. A 12-lead electrocardiogram (ECG) showed positive P waves in leads II, III, and aVF with a continuously undulating pattern that lacked an isoelectric baseline. Tachycardia was diagnosed as atypical atrial flutter based on classical criteria. An electrophysiological study and catheter ablation using an electroanatomical system revealed the mechanism of the tachycardia to be focal atrial tachycardia originating from the left atrial roof. This case indicates that focal atrial tachycardia may present as atypical atrial flutter on the surface ECG.
Japanese Circulation Journal 12/2000; 64(11):886-9.
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ABSTRACT: The purpose of this study was to evaluate the clinical significance of residual slow cavotricuspid isthmus (IT) conduction on the ablation line after typical atrial flutter (AF) ablation, undetected by analysis of right atrial (RA) activation. Seventy patients with AF underwent IT ablation. In the first 35 patients (group I), IT block was verified only by the RA activation sequence. In the subsequent 35 patients (group II), IT block was verified by the presence of parallel double potentials with an isoelectric interval through the entire ablation line (in addition to RA activation sequence criteria) during pacing from the low lateral RA and the coronary sinus ostium. In group I patients, residual IT conduction was retrospectively analyzed at the ablation site immediately after the last radiofrequency (RF) application. Six of 33 group I patients (18%) with IT block had residual IT conduction represented by fractionated or multicomponent potentials immediately after the final RF application. Four of these 6 patients (67%) had recurrences of AF, 3 +/- 1.4 months after ablation. Four (12%) of 33 group II patients with IT block had residual IT conduction in the ablation line after creation of IT block confirmed by RA activation sequence. This conduction was eliminated by 1.6 +/- 0.9 further RF applications in all 4 patients. No AF recurrence was observed in group II patients. Up to 18% of patients with apparent IT ablation had residual slow IT conduction on the ablation line. This conduction was associated with AF recurrences and must be eliminated to achieve complete cure of AF.
Pacing and Clinical Electrophysiology 12/2000; 23(11 Pt 2):1902-7. · 1.35 Impact Factor
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Y Iesaka,
T Yamane,
M Goya, A Takahashi,
H Fujiwara,
Y Okamoto,
Y Soejima,
J Nitta,
A Nogami,
K Aonuma,
M Hiroe,
F Marumo,
M Hiraoka
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ABSTRACT: In orthodromic common atrial flutter (AFL), details of intraseptal propagation of the flutter (FL) wave exiting from the isthmus between the inferior vena cava and tricuspid annulus (IVC-TA isthmus) remain unknown. We hypothesized the existence of dual septal exits of the FL wave from the IVC-TA isthmus to both the anterior, coronary sinus ostium (CSO-TA) isthmus, and the posterior septal (IVC-CSO) isthmus, and that the IVC-TA isthmus might consist of dual muscle bundles directed to both septal isthmuses over the eustachian ridge; therefore, segmental ablation of the IVC-TA isthmus could change intraseptal FL wave propagation.
To test the hypothesis, we investigated the influence of segmental ablation of the IVC-TA isthmus on intraseptal FL wave propagation. In seven of 40 (18%) consecutive patients, segmental ablation of the ventricular side of the IVC-TA isthmus during orthodromic common AFL led to sudden prolongation of the flutter cycle length (FCL) (from 266 +/- 33 ms to 291 +/- 45 ms) associated with changes in intraseptal activation sequences. They consisted of prolongation of the interval between the IVC-TA isthmus and the CSO (from 38 +/- 13 ms to 86 +/- 25 ms), shortening of the interval between the CSO and His (from 31 +/- 15 ms to 9 +/- 15 ms), and atrial electrogram polarity change at the His-bundle recording site. Morphological change in the FL wave was also seen on the 12-lead ECG.
In some patients, segmental ablation of the IVC-TA isthmus can lead to a jump in FCL and changes in intraseptal activation sequences of FL waves due to anterior-to-posterior shifting of the septal exit. This indicates that the IVC-TA isthmus may contain dual circumferential muscle bundles as conduction pathways directed to dual septal exits both anterior and posterior to the CSO.
Europace 05/2000; 2(2):163-71. · 1.98 Impact Factor
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ABSTRACT: A 12-year-old girl was referred to our institution because of frequent episodes of AV reciprocating tachycardia. Ventriculoatrial and AV intervals were relatively long along the tricuspid annulus. Earliest retrograde atrial activation was recorded at the mid-portion of the right atrial appendage, 7 mm from the tricuspid annulus. The CARTO electroanatomic mapping system was very useful for providing accurate spatial orientation of the accessory connection. Complete ablation of this connection required multiple radiofrequency energy applications over an extensive area because of the multicomponent structure of the connection.
Journal of Cardiovascular Electrophysiology 09/1999; 10(8):1112-8. · 3.06 Impact Factor
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ABSTRACT: Although a variety of ablation techniques have been developed in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT), there have been few reports discussing the location of the optimal target site. Based on our early experiences, we hypothesized that radiofrequency (RF) current applied around the upper margin of the coronary sinus ostium (UCSO) results in the most effective and safe treatment of AVNRT.
To confirm our hypothesis, the efficacy of RF currents applied around the UCSO guided by local electrograms in 59 patients (group B: predetermined focal mapping approach) were compared with the outcomes in 60 other patients previously treated with the standard electrogram-guided mapping method starting around the lower margin of the coronary sinus ostium (group A). The precise location of ablation catheters at successful sites (S) was also evaluated. All the patients were successfully treated without complications. Significantly fewer RF pulses and lower energies were needed in group B patients (mean RF applications: 4.3 vs 1.4 applications, mean total energy delivered: 4,699 vs 2,236 J in groups A and B, respectively, P < 0.01). Detailed analyses of the anatomical locations of S using CS venography in group B patients who received only a single RF application (46 patients) revealed that the distance between His and S varied according to the length of Koch's triangle, while that between S and UCSO was relatively constant. In 85 % of these 46 patients, S was located within 5 mm above and below the level of the UCSO.
RF applications around the UCSO guided by local electrograms yielded excellent outcomes in AVNRT patients with wide varieties in the size of Koch's triangle. The optimal target site was located within 5 mm above and below the level of UCSO along the tricuspid annulus.
Journal of Cardiovascular Electrophysiology 05/1999; 10(4):529-37. · 3.06 Impact Factor
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M Goya,
Y Iesaka, A Takahashi,
T Mitsuhashi,
T Yamane,
Y Soejima,
Y Okamoto,
M Gotoh,
K Tanaka,
J Nitta,
A Nogami,
H Amemiya,
K Aonuma,
H Fujiwara,
M Hiroe,
F Marumo
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ABSTRACT: The aim of this study was to investigate catheter ablation of sino-atrial reentrant tachycardia (SART) and the electrophysiologic characteristics of the ablation sites. From January 1990 to October 1997, 651 patients with supraventricular tachycardia were referred and 11 patients were found to have SART. Ablation was successful in all cases with a mean number of 3.3 radiofrequency (RF) current pulses. SART terminated during 22 of 36 RF pulses. In spite of prompt termination, tachycardia could be re-induced in 3 of 11 patients with its earliest activation site shifted. At effective ablation sites, the electrograms during tachycardia were characterized as fractionated (75+/-17 ms), and 38+/-16 ms prior to surface P wave, and 42+/-18 ms prior to the high right atrium. Unipolar electrograms revealed a sharp negative unipolar deflection, so called QS pattern, in 15 of 20 sites during SART and 15 of 15 sites during sinus rhythm. During effective applications, atrial premature beats (APB) with activation sequences identical to sinus rhythm appeared in 14 of 22 cases. Effective ablation sites of SART showed fractionated electrograms during tachycardia and sinus rhythm. Unipolar electrogram with a QS pattern and APB during energy application could be an indicator of the optimal ablation sites.
Japanese Circulation Journal 04/1999; 63(3):177-83.
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Y Iesaka, A Takahashi,
M Goya,
T Yamane,
T Tokunaga,
H Amemiya,
H Fujiwara,
J Nitta,
A Nogami,
K Aonuma,
M Hiroe,
F Marumo,
M Hiraoka
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ABSTRACT: There have been controversies concerning the optimal target sites and approaches in radiofrequency catheter ablation of common atrial flutter. We attempted high energy radiofrequency catheter ablation targeting the isthmus between the inferior vena cava and tricuspid valve annulus (IVC-TV isthmus) with a super long (8 mm) tip electrode, and compared the efficacy of this anatomical approach with the electrophysiological approach targeting the posteroseptal right atrium posterior to the coronary sinus using a standard 4-mm tip electrode. Atrial flutter was successfully ablated in 12 of 12 patients (100%) without recurrence with the anatomical approach, while, in 7 of 9 patients (64%) with 2 recurrences with the electrophysiological approach. In comparison of ablation data between the anatomical and electrophysiological approaches, there were significant differences in the mean number of application pulses (anatomical vs electrophysiological: 2.3 +/- 0.8 vs 9.9 +/- 6.4, P < 0.01), applied wattage (39 +/- 12 W vs 24 +/- 6 W, P < 0.01), applied energy per application (1,986 +/- 426 J vs 659 +/- 323 J, P < 0.01), fluoroscopic time (26 +/- 11 min vs 74 +/- 30 minutes, P < 0.01), and procedure time (59 +/- 8 min vs 181 +/- 53 min, P < 0.01). In conclusion, the anatomical approach is superior to the electrophysiological one with respect to procedure and radiation time, and linear ablation at the IVC-TV isthmus with an 8-mm tip electrode and high energy application is highly effective and safe.
Pacing and Clinical Electrophysiology 02/1998; 21(2):401-9. · 1.35 Impact Factor
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Y Iesaka,
T Yamane, A Takahashi,
M Goya,
S Kojima,
Y Soejima,
Y Okamoto,
H Fujiwara,
K Aonuma,
A Nogami,
M Hiroe,
F Marumo,
M Hiraoka
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ABSTRACT: The determinants of susceptibility to atrial fibrillation (AF) and the existence of accessory pathway conduction have remained unidentified in the Wolff-Parkinson-White (WPW) syndrome. We tested the hypothesis that excitation inputs into the atrium over a retrograde multiple or multifiber accessory pathway during AV reentrant tachycardia (AVRT) could precipitate initiation of AF.
Two hundred fifty consecutive patients with WPW syndrome underwent electrophysiologic study and radiofrequency catheter ablation. The patients were classified into two groups according to the study results: 29 with retrograde multiple or multifiber accessory pathway (MP) and 221 with retrograde single accessory pathway (SP). Compared with the SP patients, the MP patients showed a significantly higher incidence of clinical AF (MP vs SP: 19/29 vs 51/221, P < 0.01), induced AF (12/29 vs 32/221, P < 0.01), and initiated AF during ventricular pacing and AVRT (10/12 vs 17/32, P < 0.05). There were no differences between the two groups in incidence of clinical and induced AVRT (24/29 vs 200/221 and 25/29 vs 206/221, respectively), mean cycle length of induced AVRT, or electrophysiologic parameters of the accessory pathway. AF inducibility during AVRT or ventricular pacing was eliminated by partial ablation in 7 of 10 patients with MP. After total ablation, the incidence of induced AF was similar between the two groups (MP vs SP: 1/29 vs 11/221).
The existence of a retrograde multiple or multifiber accessory pathway in patients with WPW syndrome is associated with a higher incidence of clinical and induced AF. Successful ablation of the retrograde multiple or multifiber accessory pathway can eliminate the induction of both AVRT and AF.
Journal of Cardiovascular Electrophysiology 02/1998; 9(2):141-51. · 3.06 Impact Factor
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Y Iesaka, A Takahashi,
M Goya,
Y Soejima,
Y Okamoto,
H Fujiwara,
K Aonuma,
A Nogami,
M Hiroe,
F Marumo,
M Hiraoka
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ABSTRACT: Atrial tachycardia shows wide variations in its electrophysiologic properties and sites of origin. We report an atrial tachycardia with ECG manifestations and electrophysiologic characteristics similar to an atypical form of AV nodal reentrant tachycardia (AVNRT).
This supraventricular tachycardia was observed in 11 patients. It was initiated by atrial extrastimulation with an inverse relationship between the coupling interval of an extrastimulus and the postextrastimulus interval. Its induction was not related to a jump in the AH interval, and its perpetuation was independent of conduction block in AV node. Ventricular pacing during tachycardia demonstrated AV dissociation without affecting the atrial cycle length. A very small dose of adenosine triphosphate (mean 3.9 +/- 1.2 mg) could terminate the tachycardia. The earliest atrial activation during tachycardia was recorded at the low anteroseptal right atrium with a different intra-atrial activation sequence from that recorded during ventricular pacing, where the tachycardia was successfully ablated in 9 of 10 attempted patients. Bidirectional AV nodal conduction remained unaffected after successful ablation.
There may be an entity of adenosine-sensitive atrial tachycardia probably due to focal reentry within the AV node or its transitional tissues without involvement of the AV nodal pathways. This tachycardia can be ablated without disturbing AV nodal conduction from the right atrial septum.
Journal of Cardiovascular Electrophysiology 09/1997; 8(8):854-64. · 3.06 Impact Factor
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Y Soejima,
Y Iesaka, A Takahashi,
M Goya,
T Tokunaga,
H Amemiya,
H Fujiwara,
J Nitta,
A Nogami,
K Aonuma,
M Hiroe,
F Marumo,
M Hiraoka
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ABSTRACT: The electrographic features of successful sites of radiofrequency catheter ablation were analyzed in 33 cases of posteroseptal accessory pathways and compared with those from 155 cases of free wall accessory pathways. The atrioventricular intervals in the posteroseptal cases were significantly longer than in the free wall cases (posteroseptal vs left and right free wall; 38 vs 33 and 26 msec, respectively; p < 0.05), and the incidences of continuous electrograms (42 vs 63 and 79%; p < 0.01) and PQS-pattern unipolar electrograms (50 vs 76 and 78%; p < 0.05) were significantly lower in the posteroseptal cases. The V-delta intervals in the posteroseptal cases were significantly longer than in the left free wall cases (17 vs 13 msec; p < 0.05), but shorter than in the right free wall cases (17 vs 23 msec; p < 0.05). No statistically significant difference in the incidence of Kent potentials among the 3 groups was observed. In radiofrequency ablation of posteroseptal pathways, the length of the atrioventricular interval and the incidences of continuous electrograms and PQS-pattern unipolar electrograms may be unsatisfactory even at the appropriate target site, but the V-delta interval and Kent potential are good indicators of suitable target sites.
Japanese Circulation Journal 02/1997; 61(1):46-54.
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ABSTRACT: The mechanism of cure in AV nodal reentrant tachycardia (AVNRT) by catheter ablation has not been fully clarified. We hypothesized that disruption of a shortcut link between the fast and slow pathways is responsible for the elimination of tachycardia. RESULTS: AVNRT was eliminated in 20 patients by catheter ablation. In five patients (25%; group I) slow pathway conduction disappeared 1 week after ablation. In six patients (30%; group II), the effective refractory period of the slow pathway was prolonged by more than 50 ms (212 +/- 81 ms vs 340 +/- 81 ms; P < 0.05). In the remaining nine patients (45%; group III), there was no change in the refractory period (270 +/- 65 ms vs 273 +/- 74 ms), although tachycardia was not inducible. A shortcut link between the fast and slow pathways was examined by comparing the A-H intervals over the slow pathway during the tachycardia and during atrial pacing at the tachycardia cycle length. Prior to ablation, a shortcut link was assumed in 1 of group I patients, 2 of group II patients, and 8 of group III patients. Of the 9 patients in whom the slow pathway was not impaired after ablation (group III), 8 patients were found to have a shortcut link, while 8 of 11 patients with impairment of the slow pathway after ablation (groups I and II) had no shortcut link between the fast and slow pathways (P < 0.05). CONCLUSION: In patients with a shortcut link between the fast and slow pathways, slow pathway conduction itself does not need to be impaired to eliminate the AVNRT, whereas in patients without this shortcut link, slow pathway conduction must be impaired.
Pacing and Clinical Electrophysiology 11/1996; 19(11 Pt 2):1972-7. · 1.35 Impact Factor
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Y Iesaka, A Takahashi,
M Goya,
T Yamane,
S Kojima,
H Fujiwara,
J Nitta,
A Nogami,
K Aonuma,
M Hiroe,
F Marumo,
M Hiraoka
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ABSTRACT: The utility of selective radiofrequency catheter ablation of the slow pathway for the treatment of common and uncommon atrioventricular nodal reentrant tachycardia (AVNRT) was studied in 110 consecutive patients, 94 with slow-fast form common AVNRT, and 11 and 5, respectively, with the fast-slow and slow-slow forms of uncommon AVNRT. Ablation sites were determined by mapping a late and spiky "slow pathway potential" in the posterior right atrial septum in common AVNRT, and also the earliest retrograde atrial activation over the retrograde slow pathway in uncommon AVNRT. AVNRT was successfully eliminated in all patients with a mean number of radiofrequency pulses of 2.9 +/- 3.0 and a mean total energy applied of 3536 +/- 2996 joules. There were no early or late complications, except for transient AV block for 15 sec immediately after energy application in one common AVNRT patient, and no recurrence of AVNRT in a mean follow-up period of 24 +/- 13 months. There were no significant differences between common and uncommon AVNRT in success rate, mean application number and total energy applied. However, the AVN physiology post-ablation was different. Slow pathway conduction was eliminated in only 32% of the patients post-ablation in common AVNRT, while it was elininated in 100% in uncommon AVNRT. Selective radiofrequency catheter ablation of the slow pathway can cure common and uncommon AVNRT effectively and safely. Common AVNRT can be eliminated irrespective of the persistence of slow pathway conduction, while uncommon AVNRT can be eliminated by the eradication of slow pathway conduction.
Japanese Heart Journal 10/1996; 37(5):759-70. · 0.40 Impact Factor
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ABSTRACT: To determine whether time- and frequency-domain analyses differ in their ability to predict sustained ventricular tachycardia (VT) induced by programmed ventricular stimulation, 60 consecutive patients with myocardial infarction and 30 healthy control subjects were evaluated. Programmed ventricular stimulation using three extrastimuli and signal-averaged ECG recordings were performed in patients with myocardial infarction. Of the 60 patients, sustained monomorphic VT (SMVT) with cycle length (CL) > or = 250 ms (slow SMVT) was inducible in 9, and SMVT with CL < 250 ms (fast SMVT) was inducible in 9. The durations of the filtered QRS (f-QRS) at each high-pass filter (25, 40, and 80 Hz) and the low amplitude signal (LAS) at 25-Hz high-pass filtering were significantly longer in the slow SMVT group than in the fast SMVT, no VT, or normal control group. The root-mean-square voltages at 25-Hz and 80-Hz high-pass filters in the slow SMVT group were significantly lower than in the fast SMVT, no VT, or normal control group. There was no significant difference in time-domain variables among fast SMVT, no VT, and normal control groups. The CL of the induced sustained VT was significantly correlated with the durations of f-QRS and LAS. Concerning frequency-domain variables (area ratio and factor of normality), there was no significant difference between slow and fast SMVT groups. Both the slow and fast SMVT groups had a significantly higher area ratio and a significantly lower factor of normality than the group with no VT or the normal control subjects. In conclusion, there were significant correlations between time-domain variables and CL of SMVT, while there was no correlation when using frequency-domain parameters.
Pacing and Clinical Electrophysiology 03/1996; 19(3):314-24. · 1.35 Impact Factor
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Ryōikibetsu shōkōgun shirīzu. 02/1996;
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ABSTRACT: The AV nodal physiology before and 1 week after "slow pathway potential" guided catheter ablation was examined in 32 patients with AV nodal reentrant tachycardia. A mean of 4.9 applications of radiofrequency energy eliminated AV nodal reentrant tachycardia in all patients. There were no significant differences in sinus cycle length (815 +/- 159 msec vs 813 +/- 162 msec; P = NS) and fast pathway conduction properties before and 1 week after ablation. Slow pathway conduction was completely eliminated in 10 (31%) (group I) of 32 patients after ablation. In the remaining 22 patients residual slow pathway conduction associated with one AV node echo was observed. In 15 patients (47%) (group II), the effective refractory period of the slow pathway showed a change of < 30 msec (265 +/- 51 vs 266 +/- 51 msec; P = NS), and in 7 patients (22%) (group III), a prolongation of more than 80 msec (247 +/- 56 vs 340 +/- 42 msec; P = 0.0001) before and 1 week after ablation. Minimal and maximal A2-H2 interval over the slow pathway in group II was not significantly changed (Min A2-H2: 241 +/- 37 vs 247 +/- 40 msec; P = NS, Max A2-H2: 346 +/- 79 vs 350 +/- 60 msec; P = NS), while a significant prolongation was measured in group III (Min A2-H2: 261 +/- 53 vs 373 +/- 107 msec; P < 0.01, Max A2-H2: 359 +/- 41 vs 427 +/- 63 msec; P < 0.05) before and after ablation.(ABSTRACT TRUNCATED AT 250 WORDS)
Pacing and Clinical Electrophysiology 12/1994; 17(11 Pt 2):2137-42. · 1.35 Impact Factor
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ABSTRACT: Radiofrequency catheter ablation of atrioventricular accessory pathways was performed in 125 cases of the Wolff-Parkinson-White syndrome (type-A:54, type-B: 29, concealed: 42) complicated with drug-refractory and symptomatic atrioventricular reentrant tachycardia and/or paroxysmal atrial fibrillation. A total of 135 accessory pathways were identified: 50 left free-wall manifest, 34 left free-wall concealed, 21 right free-wall manifest, 2 right free-wall concealed, 15 posteroseptal manifest, 10 posteroseptal concealed, 2 right anteroseptal manifest and 1 right anteroseptal concealed. Accessory pathway conduction was successfully eliminated in 133 of these 135 accessory pathways (99%). Two right posteroseptal pathways were eventually ablated with direct current. Successful ablation required a mean 5.2 applications of radiofrequency current, a mean total energy of 2615 J and a mean fluoroscopic time of 52 min. The mean number of applications, applied energy and fluoroscopic time were greater in the right free-wall pathways than in the left free-wall pathways, and in the concealed pathways than in the manifest pathways. None of the procedures produced complications. During a mean follow-up period of 11.5 months, 1 right free-wall accessory pathway recurred and was ablated successfully in a repeat session. These results suggest that radiofrequency catheter ablation of accessory pathways is highly effective and safe irrespective of the accessory pathway location and properties, although these factors can affect the difficulty of this procedure. This technique may be an alternative to surgical therapy for Wolff-Parkinson-White syndrome with drug-refractory and symptomatic supraventricular tachyarrhythmias.
Japanese Circulation Journal 11/1994; 58(10):767-77.
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ABSTRACT: Time and frequency domain analyses of signal-averaged ECG (SAECG) have several individual limitations, and the results of the two methods sometimes vary considerably. The purpose of this study was to determine whether the combined use of time and frequency domain variables facilitates identification of patients who will have ventricular tachycardia (VT) induced during programmed ventricular stimulation (PVS).
Nine myocardial infarction (MI) patients with clinically documented sustained monomorphic VT (SMVT), 40 MI patients without clinical VT, and 30 normal healthy control subjects were evaluated. PVS using three extrastimuli and SAECG recording were performed in the MI patients on day 36 +/- 4 after infarction. Of 40 MI patients, SMVT was inducible in 14, sustained polymorphic VT in three, nonsustained monomorphic VT in three, nonsustained polymorphic VT in two, and no inducible arrhythmia was obtained in 18. There were significant differences between MI patients with inducible SMVT and without inducible SMVT in the following SAECG variables: filtered QRS durations (high-pass filter setting, 25, 40, and 80 Hz); low-amplitude signal durations (LAS) under 10, 20, 30, and 40 microV (high-pass filter setting, 40 and 80 Hz); root-mean-square voltages (RMS) of the terminal 20, 30, 40, 50, and 60 msec (high-pass filter setting, 40 and 80 Hz); area ratio (area 20-50 Hz/area 0-20 Hz x 10(5)) of a 120-msec sampling interval starting 20 msec before QRS offset; factor of normality on lead X; and minimum value of the variables on lead X, Y, or Z. Stepwise logistic regression analysis selected only LAS under 30 microV (high-pass filter setting, 80 Hz) and area ratio as independent predictors of inducible SMVT. With these two variables, the predicted probability of inducible SMVT [p(VT)] was expressed as p(VT) = 1/[1+exp (6.2-0.11 LAS-0.01 area ratio)]. This function had 93% sensitivity, 81% specificity, 72% positive predictive value, 95% negative predictive value, and 85% predictive accuracy with greater than or equal to 0.3 as the criterion of a positive test.
The combined use of time and frequency domain analysis of SAECG can enhance the accuracy of this technique as a screening test for results of PVS in MI patients without clinical VT.
Circulation 10/1992; 86(3):780-9. · 14.74 Impact Factor
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ABSTRACT: To determine the optimal configuration for the subcutaneous placement of electrodes for the performance of ventricular defibrillation without thoracotomy, internal defibrillation using four different subcutaneous electrodes was performed in 13 anesthetized dogs (7-12 Kg, mean +/- SD: 9.2 +/- 1.5 Kg). An electrode (7 cm2) was positioned transvenously in the superior vena cava with the following electrodes randomly implanted subcutaneously on the left chest: small mesh electrode (14 cm2), large mesh electrode (28 cm2), small titanium plate electrode (14 cm2), and large plate electrode (28 cm2). Ventricular fibrillation was induced by applying alternating current; a monophasic defibrillation wave was administered between the superior vena cava and the subcutaneous electrodes 10 seconds later. The energy level associated with a 50% successful defibrillation, as predicted by logistic regression analysis, was defined as the ED50. After the completion of the defibrillation protocol using the four subcutaneous electrodes, the small mesh electrode was sutured to the epicardium and the ED50 measurements were repeated. Energy ED50s were lower when the superior vena cava electrode was used as the cathode rather than as the anode. Of the subcutaneous electrodes, the large plate electrode showed the lowest energy ED50 (3.3 +/- 0.9 joules). The plate electrodes had lower energy ED50s than the mesh electrodes, and the large electrode had a lower energy ED50 than the small electrodes. Using the epicardium electrode, transient arrhythmias and ST elevation were observed following successful defibrillation; however, no arrhythmias or ST-T changes were observed following defibrillation using the subcutaneous electrodes.(ABSTRACT TRUNCATED AT 250 WORDS)
Pacing and Clinical Electrophysiology 10/1991; 14(9):1402-10. · 1.35 Impact Factor
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ABSTRACT: To determine the influence of timing on the prognostic value of programmed ventricular stimulation after acute myocardial infarction (AMI), 32 patients were studied on day 19 (early study) and again on day 36 (late study) after AMI using up to 3 extrastimuli. At the early study, sustained monomorphic ventricular tachycardia (VT) was induced in 12 patients (38%), sustained polymorphic VT in 8 (25%), nonsustained monomorphic VT in 1 (3%), nonsustained polymorphic VT in 1 (3%) and no inducible arrhythmia in 10 (31%). At the late study, sustained monomorphic VT, nonsustained monomorphic VT and nonsustained polymorphic VT were induced in 8 patients (25%) each, and no inducible arrhythmia in 8 (25%). Of the 12 patients who had inducible sustained monomorphic VT at the early study, 7 had noninducibility of sustained monomorphic VT at the late study. Of the 20 patients who had noninducibility of sustained monomorphic VT at the early study, 3 had inducible sustained monomorphic VT at the late study. During the follow-up period (mean +/- standard deviation 21 +/- 8 months), there were 2 sudden cardiac deaths and 3 occurrences of sustained VT. Univariate analysis revealed both inducibilities of sustained monomorphic VT at the early study (p = 0.045) and at the late study (p less than 0.001) to be predictive of sudden cardiac death or clinical occurrence of sustained VT. However, inducibility of sustained monomorphic VT at the late study had a higher sensitivity (100%), specificity (89%), positive predictive value (63%) and negative predictive value (100%) than at the early study (80, 70, 33 and 95%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
The American Journal of Cardiology 08/1991; 68(1):13-20. · 3.37 Impact Factor
