The delivery of single His-refractory ventricular extra-stimulus during supraventricular tachycardia is useful to identify the mechanism of the tachycardia. We present the different responses based on the ventricular extra-stimulus site. Our findings demonstrate that the atrial activation via an accessory pathway was not advanced based on the ventricular pacing site. Therefore, atrioventricular tachycardia could masquerade as atrioventricular nodal reentrant tachycardia.
Tachycardia ; Tachycardia, Atrioventricular Nodal Reentry ; Tachycardia, Supraventricular*

Anterograde and retrograde conduction properties of dual AV nodal pathways were analyzed in 15 patients having no accessory pathway and showing dual AV nodal pathways during extrastimulation. Four patients in whom the supraventricular tachycardia of common type (common type SVT) was induced during electrophysiological study were classified into group A. The remained 11 patients in whom the common type SVT was not induced were classified into group B. There was a history of paroxysmal supraventricular tachycardia(PSVT) in all of group A but none of group B. Among the properties of dual AV nodal pathways, effective refractory period (ERP) of anterograde fast pathway (FP) and retrograde FP were not different in both group. Maximal AH interval of anterograde slow pathway (SP) was significantly shorter in group A than in group B (P<0.01). In group A, all patients had intact ventriculoatrial (VA) conduction, but in group B, 5 patients had no VA conduction. The paced atrial cycle length producing Wenckebach block (WBCL) and the paced ventricular cycle length producing retrograde VA block (VABCL) were significantly shorter in group A the in group B (p<0.05). There were two patients showing retrograde dual AV nodal pathways. The common type SVT was not induced in both of them probably due to long ERP of retrograde FP. In conclusion, in patients with anterograde dual AV nodal pathways, the occurrence of common type SVT is highly related to anterograde slow pathway refractoriness (WBCL) and retrograde fast patway refactoriness (VABCL).
Humans ; Tachycardia, Atrioventricular Nodal Reentry* ; Tachycardia, Supraventricular

OBJECTIVES: Although a subtle balance between conduction time of the antgrade slow pathway and refractory period of the retrograde fast pathway is known to play the most critical role in the induction of AV nodal reentrant tachycardia(AVNRT), other electrophysiologic factors such as concealed conduction in to the fast pathway have been suggested to be responsible. The present study was performed to determine the electrophysiologic factors responsible for the induction of AVNRT. METHODS: Total 34 subjects undergoing electrophysiologic study(EPS) including 9 normal subjects(SAVNP), 7 subjects with dual AV nodal pathways(DAVNP) but no inducible AVNBT, and 18 inducible AVNRT patients were included in this study. EPS was performed using the conventional technique. To evaluate the presence of concealed conduction into the fast AV nodal pathway(FP) and its effects on the effective refractory period(ERP) of the FP (FP-ERP) to a subsequent impulse, single(A2) and double atrial extrastimuli(A2A3) were given. FP-ERP of conducted A2 [FP-ERP-A2(+)] was measured with a second atrial extrastimulus(A3) following a first atrial extrastimulus(A2), which was delivered at a coupling interval 20-30ms longer than FP-ERP. ERPs of non-conducted A2 [FP-ERP-A(-)] was measured with A3 following A2 at coupling intervals 20 ms shorter than FP-ERP. Concealed conduction was considered to be present when A1A3 interval of A3 blocked at the FP with a longest A2A3 interval was longer than FP-ERP. Concealment index(CI)-1 and CI-2 were calculated by dividing FP-ERP-A2(-) by FP-ERP-A2(+) and FP-ERP, respectively. In addition, relationship between antegrade slow pathway conduction time(A2H2) and retrograde fast pathway conduction time(HA), retrograde AV conduction system block cycle length(VA-BCL), and retrograde AV conduction system EBP(VA-ERP) was evaluated by a regression analysis. RESULTS: Concealed conduction was present in all the subjects. CI-1 was 0.63 +/- 0.04 and CI-2, 0.79 +/- 0.04 in SAVNP and 0.67 +/- 0.11, 0.68 +/- 0.07 respectively, in AVNRT patients in whom the antegrade slow pathway(SP) was ablated with catheter ablation, showing no significant difference in CI between 2 groups. At the time of induction of AVNRT with A2, A2H2. was significantly correlated with FP-ERP and FP-CT(r=OA43, p=0.04; r=0.507, p=0,02, respectively). By multivariate regression analysis, it was derived that A2H2 should be greater than "0.79 FP-ERP+1.57 FP-CT-0.44 HA-190(ms)" (r=0.71, p<0.05). CONCLUSION: Induction of typical AVNRT with A2 is determined by conduction time of the slow pathway, refractory period and conduction velocity of the fast pathway, and concealed conduction into the fast pathway.
Catheter Ablation ; Humans ; Tachycardia, Atrioventricular Nodal Reentry*

OBJECTIVES: Refractory period and conduction time of the slow and fast pathways in the atrioven-tricular node are known to be the most important determinant of the inducibility of atrioventricular nodal reentrant tachycardia (AUNRT) but their relationship has not been determined in Korean. METHODS: Two hundred and ten patients under-gone electrophysioiogic study. One hundred twenty two patients with dual AV nodal pathways were divided into two groups (group I, 77 patients with no inducible AVNRT; group II, 45 patients with inducible AVNRT). RESULTS: Antegrade dual AV nodal pathways were documented in 77 patients (47%) out of 165 patients on whom AVNRT was not induced, Antegrade ERP of slow pathway in paced rhythm (600 msec) was shorter in group II than in group I (331 +/- 14 msec vs 269 +/- 47 msec, p<0.05). Ventriculoatrial block cycle length (VABCL) and retrograde ERP of the AV conduction system were significantly shorter in group 2 than in group 1 (p<0.001). Maximum slow pathway conduction times in sinus rhythm and paced rhythm (600msec) in group 2 were significantly longer than in group 1 (sinus rhythm: 332 +/- 68msec vs. 379 +/- 88msec, p<0.005; paced rhythm: 332 +/- 69msec vs. 392 +/- 85msec, p<0.005). The ERP gaps of two AV nodal pathways of group 2 in sinus rhythm and in paced rhythm were also significantly longer than those of group 1 (sinus rhythm 41 +/- 3msec vs. 78 +/- 50msec, p<0.001; paced rhythm 36 +/- 32 msec vs. 72 +/- 19msec, p<0.005). The incidence of intact ventriculoatrial conduction was significantly higher in group 2 than in group 1 (p<0.05). Antegrade slow pathway conduction time (A2H2 interval) at the time of AVNRT induction with single atrial premature depolarization (APD) with a coupling interval over 10 msec less than that of an APD producing AH jump were not correlated with VABCL (r=0.193, p<0.05). CONCLUSION: Dual AV nodal pathways were observed in 47% of patients with no-inducible AVNRT group. The inducibility of AVNRT appears to be closely ralated to the some conduction characteristics of the dual pathways and the refractoriness, i.e. maximum slow pathway conduction time, the ERP gap of two pathways, retrograde fast pathway ERP, VABCL.
Humans ; Incidence* ; Tachycardia, Atrioventricular Nodal Reentry*

Atrioventricular nodal reentrant tachycardia is the most common type of supraventricular tachycardia. The initiation and maintenance of tachycardia is caused by the characteristic anatomic and electrophysiologic properties of the atrioverntricular node. Acute management for the termination of tachycardia includes pharmacologic and non-pharmacologic management. There are several options for preventing recurrence of tachycardia, and radiofrequency ablation for modulation of tachycardia circuit can be considered as a primary strategy. A thorough understanding of the unique electrophysiologic features is very essential for optimal management and best possible outcome in cases of invasive management.
Catheter Ablation ; Recurrence ; Tachycardia ; Tachycardia, Atrioventricular Nodal Reentry* ; Tachycardia, Supraventricular

BACKGROUND: Retrograde P wave can be found not only in atrioventricular reentrant tachycardia (AVRT) but also in atrioventricular nodal reentrant tachycardia (AVNRT), especially of posterior-type. This study evaluated the usefulness of retrograde P wave for differentiating AVNRT from concealed AVRT and for localization of accessory pathway(AP). METHODS: Twelve lead ECGs were analyzed in patients with AVNRT (n=41) and concealed AVRT (n=53) who have taken successful ablation. Presence of pseudo r' in V1, pseudo S in II, III, aVF, and configuration and polarity of presumed retrograde P waves were evaluated. RP was obtained by subtracting RP interval in III from that in V1. RESULTS: In anterior-type AVNRTs (n=38), there were no retrograde P wave in 53% and the pseudo r' and/or S in 47%. Retrograde P waves in V1 were positive in 67% (2/3 cases) of posterior-type AVNRTs and 97.4% (37/38 cases) of AVRTs with left free wall AP, but negative in 83.3% (5/6 cases) of AVRTs with right free wall AP. Retrograde P waves in II, III, aVF were negative in all of posterior-type AVNRTs, all with left and right posteroseptal AP, right posterior AP, and 90% (9/10 cases) with left posterior AP. All with left anterior and right anteroseptal AP showed positive P wave in III. RP of posterior-type AVNRT was significantly larger than those with left posteroseptal or left posterior AP (p<0.01). Sensitivity of newly developed stepwise algorithm was 50-100%. CONCLUSION: Retrograde P wave during tachycardia on standard ECG is very useful for differentiation of AVNRT from concealed AVRT and also for localization of APs.
Electrocardiography ; Humans ; Tachycardia ; Tachycardia, Atrioventricular Nodal Reentry ; Tachycardia, Supraventricular*

Catheter Ablation ; Child ; Humans ; Male ; Tachycardia, Atrioventricular Nodal Reentry ; surgery

BACKGROUND: Second degree AV block is occasionally induced during AV nodal reentrant tachycardia by programmed electrical stimulation. This study was performed to determine the incidence, the block site, and the mechanism of AV block during AV nodal reentrant tachycardia. METHODS AND RESULTS: The study population was 67 consecutive patients with AV nodal reentrant tachycardia studied by programmed electrical stimulation. Among these patients, common types(slow pathway for anterograde and fast pathway for retrograde conduction) were 64 patients and uncommon types(fast pathway for anterograde and slow pathway for retrograde conduction) were 3 patients. Among 67 patients with AV nodal reentrant tachycardia 10 patients developed 2:1 AV block during tachycardia. The block site of AV block was infrai bundle in 9 patients and supraHis bundle in patient. There were intermittent aberrancies of RBBB and/or LBBB form during tachycardia in 5 patients with infraHis AV block. CONCLUSION: The occurrence of AV block during AV nodal reentrant tachycardia is not rare and might be related to the prematurity of atrial extrastimulation. The block sites of AV block were infraHis bundle in most cases and this finding suggests that distal common pathway of the reentry circuit is present in the AV node.
Atrioventricular Block* ; Atrioventricular Node ; Electric Stimulation ; Humans ; Incidence ; Tachycardia ; Tachycardia, Atrioventricular Nodal Reentry*

A 41-year-old male was presented with drug-resistant supraventricular tachycardia. Electrophysiological study confirmed that the supraventricular tachycardia was caused by dual atrioventricular nodal pathways and a left lateral accessory pathway (AP). The left lateral AP was resistant to traditional endocardial ablation, but was successfully eliminated by radiofrequency ablation via the intracoronary sinus approach.
Accessory Atrioventricular Bundle ; Catheter Ablation ; Humans ; Male ; Tachycardia, Atrioventricular Nodal Reentry ; Tachycardia, Supraventricular

BACKGROUND: Paroxysmal supraventricular tachycardia(PSVT) is frequently associated with ST segment depression or T-wave inversion. However, the mechanism of ST-T changes in the context of various mechanisms of PSVT is not clear. The purpose of this study was to evaluate the prevalence of ST depression or T-wave inversion during PSVT and determine whether these changes are related to the mechanism of PSVT or the rate of the tachycardia. METHODS: Twelve-lead electrocardiograms were recorded during sinus rhythm and during PSVT in 163 patients who underwent an electrophysiologic study for ablation. Tachycardia cycle length, presence of ST depression or T-wave inversion during PSVT and the mechanism of tachycardia were evaluated. Significant ST depression was defined as at least 1mm horizontal or downsloping depression, measured 80ms after the J point and T-wave inversion as inversion of T-wave which was positive in the same lead during sinus rhythm. RESULTS: 1) The mechanism of PSVT analysed for ST segment depression was atrioventricular nodal reentry tachycardia in 60 cases and atrioventricular reentry tachycardia in 111 cases. The mean tachycardia cycle length was 373.8+/-68.0 msec. 2) ST depression and T-wave inversion was observed during PSVT in 56%(96/171) and 45%(77/171) of cases, respectively. 3) Tachycardia cycle length, degree of ST depression and number of leads with ST depression are not different according to the mechanism of PSVT. 4) ST depression and tachycardia cycle length had significant correlation, especially in atrioventricular reentry tachycardia. 5) Leads with T-wave inversion during tachycardia was observed more frequently in atrioventricular reentry tachycardia than atrioventricular nodal reentry tachycardia(p<0.05), but no difference between manifest and concealed bypass tract. CONCLUSIONS: ST segment depression is rate-related phenomenon and not different according to the mechanism of PSVT. Leads with T-wave inversion during tachycardia was observed more frequently in atrioventricular reentry tachycardia.
Depression* ; Electrocardiography ; Humans ; Prevalence ; Tachycardia* ; Tachycardia, Atrioventricular Nodal Reentry ; Tachycardia, Supraventricular