Mio Tamura

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a "Superior" Slow Pathway: A Distinct Supraventricular Tachyarrhythmia

Background— The existence of an atypical fast-slow (F/S) atrioventricular nodal reentrant tachycardia (AVNRT) including a superior (sup) pathway with slow conductive properties and an atrial exit near the His bundle has not been confirmed. Methods and Results— We studied 6 women and 2 men (age, 74±7 years) with sup-F/S-AVNRT who underwent successful radiofrequency ablation near the His bundle. Programmed ventricular stimulation induced retrograde conduction over a superior SP with an earliest atrial activation near the His bundle, a mean shortest spike-atrial interval of 378±119 milliseconds, and decremental properties in all patients. sup-F/S-AVNRT was characterized by a long-RP interval; a retrograde atrial activation sequence during tachycardia identical to that over a sup-SP during ventricular pacing; ventriculoatrial dissociation during ventricular overdrive pacing of the tachycardia in 5 patients or atrioventricular block occurring during tachycardia in 3 patients, excluding atrioventricular reentrant tachycardia; termination of the tachycardia by ATP; and a V-A-V activation sequence immediately after ventricular induction or entrainment of the tachycardia, including dual atrial responses in 2 patients. Elimination or modification of retrograde conduction over the sup-SP by ablation near the right perinodal region or from the noncoronary cusp of Valsalva eliminated and confirmed the diagnosis of AVNRT in 4 patients each. Conclusions— sup-F/S-AVNRT is a distinct supraventricular tachycardia, incorporating an SP located above the Koch triangle as the retrograde limb, that can be eliminated by radiofrequency ablation.

Differential Diagnosis of Supraventricular Tachycardia with Ventriculoatrial Dissociation during Ventricular Overdrive Pacing

Case Presentation A 72-year-old man with a history of multiple episodes of paroxysmal supraventricular tachycardia underwent electrophysiologic studies and a catheter ablation procedure. The 12-lead electrocardiogram during tachycardia showed long RP’ tachycardia with negative P waves in leads II, III, and aVF. Ventriculoatrial (VA) conduction with a shortest 1:1 pacing cycle length of 780 ms and earliest atrial activation at the ostium of coronary sinus was observed during ventricular overdrive pacing. A narrow QRS tachycardia documented previously was reproducibly induced by programmed atrial, though not ventricular, stimulation. During tachycardia, the His-atrial (HA) and atrial-His (AH) intervals were 381 and 156 ms, respectively. The atrial activation sequence during tachycardia seemed identical to that during ventricular pacing. A 2-mg bolus injection of adenosine triphosphate reproducibly terminated the tachycardia after a last ventricular event, following progressive prolongation of the atrial cycle length. Overdrive ventricular pacing for >30 seconds during tachycardia, at a cycle length 10‐30 ms shorter than the tachycardia cycle length, invariably caused VA dissociation without atrial capture or termination of the tachycardia (Fig. 1). What is the tachycardia mechanism? Comment

Electroanatomically estimated length of slow pathway in atrioventricular nodal reentrant tachycardia

The length of the slow pathway (SP-L) in atrioventricular (AV) nodal reentrant tachycardia (NRT) has never been measured clinically. We studied the relationship among (a) SP-L, i.e., the distance between the most proximal His bundle (H) recording and the most posterior site of radiofrequency (RF) delivery associated with a junctional rhythm, (b) the length of Koch’s triangle (Koch-L), (c) the conduction time over the slow pathway (SP-T), measured by the AH interval during AVNRT at baseline, and (d) the distance between H and the site of successful ablation (SucABL-L) in 26 women and 20 men (mean age 64.6 ± 11.6 years), using a stepwise approach and an electroanatomic mapping system (EAMS). SP-L (15.0 ± 5.8 mm) was correlated with Koch-L (18.6 ± 5.6 mm; R2 = 0.1665, P < 0.005), SP-T (415 ± 100 ms; R2 = 0.3425, P = 0.036), and SucABL-L (11.6 ± 4.7 mm; R2 = 0.5243, P < 0.0001). The site of successful ablation was located within 10 mm of the posterior end of the SP in 38 patients (82.6 %). EAMS-guided RF ablation, using a stepwise approach, revealed individual variations in SP-L related to the size of Koch’s triangle and AH interval during AVNRT. Since the site of successful ablation was also correlated with SP-L and was usually located near the posterior end of the SP, ablating anteriorly, away from the posterior end, is not a prerequisite for the success of ablation procedures.

Pseudo-postpacing interval of diastolic potential after entrainment pacing of remote bystander pathway in reentrant ventricular tachycardia

Abstract After entrainment pacing, the postpacing interval of a diastolic potential may be misinterpreted if the distal tip of the ablation catheter captures a remote bystander pathway adjacent to the critical isthmus of a complex reentrant circuit in a structurally diseased heart. We discuss this possible pitfall of entrainment mapping of reentrant ventricular tachycardia, observed after a healed myocardial infarction.

Regular Atrial Tachyarrhythmia with Double Coronary Sinus Potentials: What Is the Diagnosis?

A 63-year-old woman underwent electrophysiologicalstudies and radiofrequency catheter ablation of a persistent,drug-refractoryatrialtachyarrhythmia(ATA).Shehadnohis-tory of left atrial (LA) surgery or catheter ablation. Positivewaves were present in leads II, III, aVF, and V1–V6 of the12-lead electrocardiogram, inconsistent with typical atrialflutter (AFL). A 7F Inquiry

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a “Superior” Slow PathwayCLINICAL PERSPECTIVE: A Distinct Supraventricular Tachyarrhythmia

Background— The existence of an atypical fast-slow (F/S) atrioventricular nodal reentrant tachycardia (AVNRT) including a superior (sup) pathway with slow conductive properties and an atrial exit near the His bundle has not been confirmed. Methods and Results— We studied 6 women and 2 men (age, 74±7 years) with sup-F/S-AVNRT who underwent successful radiofrequency ablation near the His bundle. Programmed ventricular stimulation induced retrograde conduction over a superior SP with an earliest atrial activation near the His bundle, a mean shortest spike-atrial interval of 378±119 milliseconds, and decremental properties in all patients. sup-F/S-AVNRT was characterized by a long-RP interval; a retrograde atrial activation sequence during tachycardia identical to that over a sup-SP during ventricular pacing; ventriculoatrial dissociation during ventricular overdrive pacing of the tachycardia in 5 patients or atrioventricular block occurring during tachycardia in 3 patients, excluding atrioventricular reentrant tachycardia; termination of the tachycardia by ATP; and a V-A-V activation sequence immediately after ventricular induction or entrainment of the tachycardia, including dual atrial responses in 2 patients. Elimination or modification of retrograde conduction over the sup-SP by ablation near the right perinodal region or from the noncoronary cusp of Valsalva eliminated and confirmed the diagnosis of AVNRT in 4 patients each. Conclusions— sup-F/S-AVNRT is a distinct supraventricular tachycardia, incorporating an SP located above the Koch triangle as the retrograde limb, that can be eliminated by radiofrequency ablation.

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a “Superior” Slow PathwayCLINICAL PERSPECTIVE

Background— The existence of an atypical fast-slow (F/S) atrioventricular nodal reentrant tachycardia (AVNRT) including a superior (sup) pathway with slow conductive properties and an atrial exit near the His bundle has not been confirmed. Methods and Results— We studied 6 women and 2 men (age, 74±7 years) with sup-F/S-AVNRT who underwent successful radiofrequency ablation near the His bundle. Programmed ventricular stimulation induced retrograde conduction over a superior SP with an earliest atrial activation near the His bundle, a mean shortest spike-atrial interval of 378±119 milliseconds, and decremental properties in all patients. sup-F/S-AVNRT was characterized by a long-RP interval; a retrograde atrial activation sequence during tachycardia identical to that over a sup-SP during ventricular pacing; ventriculoatrial dissociation during ventricular overdrive pacing of the tachycardia in 5 patients or atrioventricular block occurring during tachycardia in 3 patients, excluding atrioventricular reentrant tachycardia; termination of the tachycardia by ATP; and a V-A-V activation sequence immediately after ventricular induction or entrainment of the tachycardia, including dual atrial responses in 2 patients. Elimination or modification of retrograde conduction over the sup-SP by ablation near the right perinodal region or from the noncoronary cusp of Valsalva eliminated and confirmed the diagnosis of AVNRT in 4 patients each. Conclusions— sup-F/S-AVNRT is a distinct supraventricular tachycardia, incorporating an SP located above the Koch triangle as the retrograde limb, that can be eliminated by radiofrequency ablation.

Mechanism of Shorter Postpacing Interval Than the Tachycardia Cycle After High‐Output Entrainment Pacing of Atrial Flutter

A 77-year-old woman with a history of repaired atrial septal defect underwent electrophysiological studies and radiofrequency catheter ablation of drug-refractory paroxysmal atrial flutter (AFl). The 12-lead electrocardiogram showed positive flutter waves in leads II, III, aVF, V5, and V6 and negative flutter waves in leads V1 and V2, consistent with typical clockwise (CW) AFl. A Halo deflectable duodecapolar catheter (Fig. 1) was positioned along the posterior wall of the right atrium (RA), away from the tricuspid annulus (TA). An electroanatomical activation map of the RA combined with entrainment mapping along the TA confirmed the diagnosis as typical CWAFL. Double potentials during ongoing AFl were recorded longitudinally along the RA incisional line (Fig. 1C and D). Activation mapping of AFL with the Halo catheter located posterior to the incisional line revealed that the wavefronts traveling in a cranial-to-caudal and caudal-to-cranial direction collided in the middle of the RA free wall (Fig. 2), suggesting that the RA free wall posterior to the incisional line was a bystander pathway in the reentry circuit (Figure 3A), and that the first and second of the double potentials along the RA incisional line represented wavefronts traveling in a caudal-to-cranial direction in the essential pathway and in a cranial-to-caudal direction in the bystander pathway, respectively (Figs. 1C and 3A). When entrainment pacing was performed at an output of 4.4 V just behind the incisional line, the postpacing interval (PPI) between the last pacing stimulus (S) and the next atrial electrogram after cessation of entrainment pacing was longer than the tachycardia cycle length (TCL), consistent with pacing from a bystander pathway (Fig. 2A). However, when we increased the output to 9.9 V and repeated entrainment pacing and recording from that same site, the PPI was

Mechanism of alternans of diastolic potential cycles during overdrive pacing of ventricular tachycardia

A 77-year-old man with a history of healed inferior myocardial infarction underwent radiofrequency catheter ablation for drugrefractory ventricular tachycardia (VT) with right bundle branch block and superior axis. VT was reproducibly induced by programmed ventricular stimulation. Pacing during VT at the basal edge of the low voltage zone, where a low-amplitude diastolic potential (DP) was recorded, showed concealed entrainment, in which the pacing stimulus-QRS was nearly equal to the DP-QRS interval, and the post-pacing interval (PPI) of the DP was equal to the tachycardia cycle length (TCL), consistent with pacing on the essential pathway of the reentrant circuit (Fig. 1). The delivery of radiofrequency energy at that site terminated and eliminated the induction of VT. Before ablation, overdrive pacing with identical output and a cycle length slightly shorter than that of the VT near the successful ablation site caused alternans of the DP to DP intervals (Fig. 2). What is the mechanism of this DP alternans?

A case of atrial tachycardia originating from pulmonary vein invaded by lung cancer

A 59-year-old man during chemotherapy for squamous cell carcinoma of the lung, underwent catheter ablation of drug-refractory atrial tachycardia. Pulmonary venography and chest computed tomography revealed presence of stenotic, carcinomatous lesion of the left superior pulmonary vein. Excellent pace map and elimination of inducibility of atrial tachyarrhythmias after left pulmonary isolation suggested that the atrial tachycardia originated from the metastatic region.