Toshimitsu Kato

Putative Mechanism of a Postpacing Interval Paradoxically Shorter Than the Tachycardia Cycle Length

A 79-year-old man without structural heart disease underwent electrophysiological studies and radiofrequency catheter ablation of drug-refractory paroxysmal atrial flutter (AFl). The 12-lead electrocardiogram showed negative flutter waves in leads II, III, aVF, and V5 and V6, and positive flutter waves in lead V1 and V2, consistent with typical counterclockwise AFl. A 7F InquiryTM eicosapolar electrode catheter (St. Jude Medical, AF Division, Minnetonka, MN, USA) with 2-mm interelectrode spacing was advanced into the coronary sinus (CS) from the right subclavian vein, with its middle electrodes (9–10) placed at the ostium and proximal electrodes (20–11) along the Eustachian ridge (ER). Counterclockwise AFl was confirmed by entrainment pacing at multiple sites along the tricuspid annulus. Double potentials were recorded along the ER during ongoing AFl, with the first potential (DP1) in a proximal-to-distal and the second (DP2) in a distal-to-proximal direction, with fusion of the 2 potentials at the CS ostium (Fig. 1A). Two different postpacing intervals were reproducibly observed after the cessation of entrainment pacing near the ER (Figs. 1B and C). In Figure 1B, the interval between the last pacing stimulus (S) and the first atrial electrogram is equal to, whereas in Figure 1C, the interval is shorter than, the tachycardia cycle length (TCL). What are the (a) mechanism and (b) implications of this observation?

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

Is the Targeted Accessory Pathway Alive or Dead

J Cardiovasc Electrophysiol, Vol. 22, pp. 478-480, April 2011.No disclosures.Addressforcorrespondence:YoshiakiKaneko,M.D.,Ph.D.,DepartmentofMedicine and Biological Science, Gunma University Graduate School ofMedicine, 3-39-22 Showa, Maebashi, Gunma 371-8511, Japan. Fax: +81-27-220-8158; E-mail:kanekoy@gunma-u.ac.jpdoi: 10.1111/j.1540-8167.2010.01935.x

Long RP′ Tachycardia with an Initial A‐A‐V Activation Sequence: What Is the Mechanism?

A 79-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 a long RP′ tachycardia with negative P waves in leads II, III, and aVF. No dual anterograde atrioventricular (AV) nodal conduction was elicited by atrial extrastimulation. A narrow QRS tachycardia documented previously was reproducibly induced by atrial extrastimulation (Fig. 1A). During tachycardia, the HA and AH intervals measured 136 and 252 ms, respectively, and the earliest atrial activation was recorded at the ostium of the coronary sinus. Atrial extrastimuli delivered during the tachycardia did not reset the atrial cycle. Atrial overdrive pacing induced a second tachycardia with a similar atrial activation sequence and cycle length, and 2:1AV conduction (Fig. 1B). Ventricular overdrive pacing was delivered at a slightly shorter cycle length than the tachycardia (Fig. 2). Based upon these observations, what is the mechanism of tachycardia?

Atrial flutter after cavotricuspid isthmus ablation: what is the mechanism?

A 56-year-old man free from structural heart diseaseunderwent radiofrequency (RF) catheter ablation of drug-refractory paroxysmal atrial flutter (AFL). A decapolarcatheterwasadvancedwithitsproximal9and10polesplacedin the proximal coronary sinus (CS), and a Halo deflectableduodecapolarcatheterwaspositionedparalleltothetricuspidannulus (TA), across the inferior vena cava (IVC)-TA isth-mus, with its tip at the CS ostium. During electrophysiolog-

Discrimination between His‐bundle and the Right Bundle Branch during Electrophysiologic Studies

Background: The purpose of this study was to identify the His‐bundle (HB) versus right bundle branch (RBB) during electrophysiologic studies, using the V3 phenomenon, and to compare the timing of HB versus RBB potentials of sinus cycles (His‐ventricular [H‐V] interval).

Improvement of Oxygen Saturation Levels is Associated with Response to Adaptive Servo-Ventilation Therapy in Heart Failure Patients

Background: Although adaptive servo-ventilation (ASV) therapy is considered clinically beneficial to patients with heart failure (HF), a large proportion of patients fail to show improvement in HF. We aimed to identify reliable markers indicative of a favorable response to ASV. Methods: We evaluated 103 consecutive patients with New York Heart Association (NYHA) class II–IV HF who were scheduled for ASV therapy for 3 months. Patients were classified as responders if their brain natriuretic peptide levels were decreased after 3 months. Results: Twenty-one patients (20.3%) failed to respond to ASV. No significant differences were observed between responders and nonresponders with regard to NYHA classification, age, gender, body mass index, drug therapy, and cardiovascular risk factors. Polysomnography showed no significant baseline differences between the 2 groups in the apnea–hypopnea index (AHI) and percent sleep time of oxygen saturation level below 90% (responders, 4.7% ± 9.2%; nonresponders, 3.7% ± 6.0%; P=0.68). The percent sleep time of oxygen saturation level below 90% is similar parameter as cumulative percentage of time at a pulse-oximetry oxygen saturation below 90% (CT90%) which is measured by in-home screening. We named it “Modified CT90%”. After ASV therapy for 3 months, NYHA classification remarkably improved in responder group. Logistic regression analysis revealed that improvement of modified CT90%<1 was independent factor for the responder group. The adjusted odds ratio was 0.685 (95% confident interval 0.485 – 0.967, P=0.03). Conclusions: Our study suggests that improvement of modified CT90%<1 at 3 months is associated with a favorable response to ASV therapy.Background: Although adaptive servo-ventilation (ASV) therapy is considered clinically beneficial to patients with heart failure (HF), a large proportion of patients fail to show improvement in HF. We aimed to identify reliable markers indicative of a favorable response to ASV. Methods: We evaluated 103 consecutive patients with New York Heart Association (NYHA) class II–IV HF who were scheduled for ASV therapy for 3 months. Patients were classified as responders if their brain natriuretic peptide levels were decreased after 3 months. Results: Twenty-one patients (20.3%) failed to respond to ASV. No significant differences were observed between responders and nonresponders with regard to NYHA classification, age, gender, body mass index, drug therapy, and cardiovascular risk factors. Polysomnography showed no significant baseline differences between the 2 groups in the apnea–hypopnea index (AHI) and percent sleep time of oxygen saturation level below 90% (responders, 4.7% ± 9.2%; nonresponders, 3.7% ± 6.0%; P=0.68). The percent sleep time of oxygen saturation level below 90% is similar parameter as cumulative percentage of time at a pulse-oximetry oxygen saturation below 90% (CT90%) which is measured by in-home screening. We named it “Modified CT90%”. After ASV therapy for 3 months, NYHA classification remarkably improved in responder group. Logistic regression analysis revealed that improvement of modified CT90%<1 was independent factor for the responder group. The adjusted odds ratio was 0.685 (95% confident interval 0.485 – 0.967, P=0.03). Conclusions: Our study suggests that improvement of modified CT90%<1 at 3 months is associated with a favorable response to ASV therapy.

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?

Inappropriate Therapy Delivered by a CRT-D for Tachycardia with Simultaneous Atrial and Ventricular Activation: What Is the Tachycardia?

A 69-year-old woman was admitted to our hospital after she had received several shocks without warning from a model C154DWK ConcertoTM cardiac resynchronization therapy + defibrillation (CRT-D; Medtronic Inc., Minneapolis, MN, USA), implanted 2 years earlier for management of sustained ventricular tachycardia (VT) and congestive heart failure due to dilated cardiomyopathy. At the time of device implantation, the sensing and pacing characteristics of a tined atrial lead placed in the right atrial appendage were within normal limits. Interrogation of the device retrieved several episodes of tachycardia, unsuccessfully treated by antitachycardia pacing (Fig. 1A), followed by a successful direct cardioversion shock. Recordings stored in the device memory during VT revealed regular, nearly simultaneous ventricular and atrial electrograms (Fig. 1A). The 12-lead electrocardiogram during AAI pacing by the device revealed a marked latency between the pacing spike and the P-wave and a normal PQ interval (Fig. 1B). What is the mechanism of this tachycardia?

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.