Hidezou Sugimura

Cooled-tip ablation results in increased radiofrequency power delivery and lesion size in the canine heart: importance of catheter-tip temperature monitoring for prevention of popping and impedance rise.

AbstractSince myocardial lesion size during radio-frequency (RF) ablation is limited at high power by impedance rise when electrode tip temperature exceed 100 °C, controlling tip temperature by continuous intraelectrode saline infusion could permit generation of larger lesion. (1) Two dogs randomly received either standard or cooled tip RF ablation at 4 to 6 separate LV sites. Power output of 30 W was delivered via modified 7 Fr deflectable catheter with 4 mm tip for up to 120 sec or until impedance rise occurred. (2) Six dogs randomly received cooled tip RF ablation at power output of 20, 30, 40 W for 120 sec. (3) Three dogs randomly received cooled tip RF ablation using room temperature saline (21–25 °C) or chilled saline (1–4 °C) infusion. Results: Overall, peak tip temperature was lower for cooled vs standard RF deliveries (97±17 °C vs. 42±8 °C). Lesion depth and volume were significantly larger for cooled burns. Lesion depth and volume and the incidence of abrupt impedance rise/popping did not differ between room temperature saline and chilled saline infusion. The catheter-tip temperature at the onset of popping and abrupt impedance rise was 54±5 °C(48–60 °C) and 59±10 °C(50–75 °C). Conclusion: Cooled tip RF current delivery at high power is associated with increased myocardial lesion size which may facilitate successful ablation of ventricular tachycardia associated with acquired structural heart disease. Catheter-tip temperature should be maintained below 45 °C to prevent popping and abrupt impedance rise during RF energy delivery.

Prediction of the efficacy of pulmonary vein isolation for the treatment of atrial fibrillation by the signal-averaged P-wave duration

Background: The noninvasive methods for predicting a successful pulmonary vein isolation (PVI) have not been well described. The aim of this study was to assess the usefulness of the P‐wave signal‐averaged electrocardiogram (P‐SAECG) in predicting the chance of a successful PVI in patients with atrial fibrillation (AF).

Relationship between Polarity of the Flutter Wave in the Surface ECG and Endocardial Atrial Activation Sequence in Patients with Typical Counterclockwise and Clockwise Atrial Flutter

AbstractBackground: The relation between ECG and activation patterns within atria in typical atrial flutter (AFL) patients (pts) has not been defined due to the lack of simultaneous multisite right and left atrial mapping. Methods: In 13 pts with AFL, a Halo catheter was positioned along tricuspid annulus and multipolar catheters were placed in right atrial appendage, His bundle region, coronary sinus (CS), proximal portion of right pulmonary artery (Bachmanns bundle region, BB) and esophagus (Eso) to record right and left atrial activation simultaneously. Results: In counterclockwise (CCW) AFL (11 pts), 9 showed negative flutter wave (F) and 2 positive F in the inferior leads. CCW/negative F; CS electrograms (EGs) were proximal to distal, Eso EGs were inferior to superior and BB activation was later than CS and Eso. positive F; BB activation was earlier than CS. Eso EGs were superior to inferior or simultaneous. In clockwise (CW) AFL (7 pts), 5 showed positive F and 2 negative F. CW/positive F; BB activation preceded Eso and CS. Eso EGs were superior to inferior. CS EGs were proximal to distal (1), middle to proximal, distal (3) or proximal, distal to middle (1). negative F; CS EGs were proximal to distal. CS activation was earlier than BB or CS and BB activation were simultaneous. Eso EGs were inferior to superior. Conclusion: Impulse conduction to the left atrial free wall through either lower or upper interatrial connection is a major determinant of ECG morphology in AFL.

Differential Pacing for Distinguishing Slow Conduction from Complete Conduction Block of the Tricuspid-Inferior Vena Cava Isthmus after Radiofrequency Ablation for Atrial Flutter—Role of Transverse Conduction through the Crista Terminalis

Background: Partial conduction block has been suggested a predictor of recurrence of atrial flutter (AFL).Aim: The aim of this study was to assess transverse conduction by the crista terminalis (CT) as a problem in evaluating isthmus block and the usefulness of differential pacing for distinguishing slow conduction (SC) and complete conduction block (CB) across the ablation line.Methods: We assessed 14 patients who underwent radiofrequency catheter ablation of the eustachian valve/ridge–tricuspid valve isthmus for typical AFL. Activation patterns along the tricuspid annulus (TA) suggested incomplete CB across the isthmus. In these patients, atrial pacing was performed from the low posteroseptal (PS) and anteroseptal (AS) right atrium (RA) while the ablation catheter was placed at the ablation line where double potentials (DPs) could be recorded. The pattern of activation of the RA free wall was assessed by a 20-pole catheter positioned along the CT during pacing from the coronary sinus (CS) ostium (CSos) and low lateral RA (LLRA).Results: Faster transverse conduction across the CT resulted in simultaneous or earlier activation of the distal halo electrodes than of the more proximal electrodes, suggesting incomplete conduction block across the isthmus. CB (13) and SC (1) were detected as changes in the activation times of the first and second components of DPs (DP1, DP2) during PS RA pacing and AS RA. Similar changes in the activation times DP1 and DP2 during AS RA pacing as compared to PS RA reflected SC through the isthmus, whereas increased DP1 activation time and decreased of DP2 activation time reflected complete conduction block across the isthmus.Conclusions: Transverse conduction across the CT influences the sequence of activation along the TA after isthmus ablation. Differential pacing can distinguish SC from complete conduction block across the ablation line in the isthmus.

Anatomic and Electrophysiologic Differences between Chronic and Paroxysmal Atrial Flutter: Intracardiac Echocardiographic Analysis

Background : It remains unknown why atrial flutter (AFL) occurs as either a chronic or paroxysmal arrhythmia.

Usefulness of the polarity in high-density wide range-filtered bipolar mapping to detect isthmus block during radiofrequency ablation of typical atrial flutter.

Background: The atrial activation sequence around the tricuspid annulus (TA) cannot always be used to establish whether complete block has been achieved across the cavotricuspid isthmus (CTI) during radiofrequency ablation (RFCA) for typical counterclockwise atrial flutter (CCW-AFL).Aim: We examined whether a change in the polarity of the atrial high-density wide range-filtered bipolar electrograms recorded near the ablation line is an accurate indicator of complete CTI block.Methods: Nineteen patients with CCW-AFL underwent RFCA. Electrograms were recorded around the TA with duodecapolar conventional (2mm × 8mm × 2mm spacing) and high-density (2-mm spacing) Halo catheters. The bipolar electrograms on the high-density Halo catheter recorded from a series of adjacent electrode pairs positioned just lateral to the ablation line were filtered at a bandpass setting of 0.05–500 Hz. The activation sequence on the conventional Halo catheter during coronary sinus pacing (CSp) and inferolateral TA pacing, and the bipolar electrograms on the high-density Halo catheter during CSp were determined before and after RFCA. The final complete CTI block was verified by the presence of widely split double electrograms ≥100 msec along the ablation line.Results: The final complete CTI block was achieved in all the 19 patients. Before RFCA, the polarity of bipolar electrograms was predominantly negative during CCW-AFL and positive during CSp. In 18 of the 19 patients, the bipolar electrograms exhibited the CCW activation and a negative polarity during CSp only after complete CTI block. In one of those 18 patients, additional applications of RFCA changed the polarity of bipolar electrograms positive to negative although the conventional Halo electrogram activation sequence suggested complete CTI block during CSp. In seven patients, who had transverse conduction across the crista terminalis during CSp, the conventional Halo electrogram activation sequence suggested an incomplete CTI block. However, in six of those seven patients, the CCW activation had a predominantly negative polarity of the bipolar electrograms. In one of those seven patients, complete CTI block was unable to be detected even using the high-density Halo catheter.Conclusions: These data demonstrate that the high-density wide range-filtered mapping can identify the CTI block in undetectable cases of complete CTI block or incomplete CTI block by the conventional method. The polarity of the bipolar electrograms recorded just lateral to the ablation line during CSp after RFCA of AFL may be used as a simple and an accurate indicator of complete CTI block.

Full-motion two- and three-dimensional pulmonary vein imaging by intracardiac echocardiography after pulmonary vein isolation.

Background: The pulmonary veins (PVs) are topographically complex and motile, so angiographic visualization of the PVs anatomy is limited. An imaging technique that accurately portrays the pulmonary vein (PV) anatomy would be valuable during and after catheter ablation procedures.

Ectopic Atrial Rhythm with Exit Block Following Catheter Ablation for Focal Atrial Tachycardias in a Patient with Prior Surgery for Atrial Septal Defect

OHKUBO, K., et al.: Ectopic Atrial Rhythm with Exit Block Following Catheter Ablation for Focal Atrial Tachycardias in a Patient with Prior Surgery for Atrial Septal Defect. The patient was a 40‐year‐old woman with a history of surgery for atrial septal defect and catheter ablation for typical atrial flutter. An electrophysiological study was performed because she had palpitation and syncope. She had ectopic atrial rhythm originating from low lateral RA. Two focal atrial tachycardias ([1] superior vena cava‐RA junction and [2] a low posteroseptal RA) were successfully ablated. Following catheter ablation for the second atrial tachycardia, she developed junctional rhythm because ectopic atrial rhythm showed exit block. However, atrial activation of junctional rhythm could conduct into the ectopic atrial rhythm focus and reset the rhythm when atrial activation of junctional rhythm reached the blocked line after atrial refractoriness by preceding ectopic atrial rhythm.

Catheter Ablation for Three Focal Atrial Tachycardias in a Patient with Prior Fontan Surgery for Tricuspid Atresia

A 28‐year‐old woman who had undergone Fontan surgery for tricuspid atresia at 6 years of age was admitted to Nihon University Hospital due to syncope. Supraventricular tachycardia at 141 beats/min was induced with isoproterenol infusion during a tilt table test. The patient showed atresia of the right atrial orifice of the coronary sinus with persistent drainage into the left superior vena cava. Electrophysiological study was performed. Atrial tachycardia (AT) was induced by rapid atrial pacing. The AT originated in the lower lateral right atrium and electroanatomical mapping showed a focal origin. After successful ablation of the AT, two additional ATs were induced. These ATs were also shown to be of focal origin and were successfully ablated without recurrence during follow‐up.

Identifying the Origin of Right and Left Ectopic Atrial Beats Triggering Atrial Fibrillation before Atrial Transseptal Procedure

Atrial premature depolarizations (APDs) triggering atrial fibrillation (AF) originate from mainly the pulmonary veins (PVs), but, in some cases, atrial ectopic beats (AEBs) triggering AF originate from the right atrium (RA) or the superior vena cava. Accurate identification of the origin of APDs in the PVs by means of RA and coronary sinus mapping is difficult. Purpose: The aim of this study was to identify the origin of AEBs triggering AF before transseptal catheterization. Electrode catheters were placed in the posteroseptal RA (PSRA), right pulmonary artery (RPA), left pulmonary artery (LPA), and esophagus in 10 patients with paroxysmal AF. We analyzed endocardial electrograms from the PSRA, RPA and LPA, and epicardial electrograms from the esophagus. The origin of the AEBs in the PVs was determined before PV ablation by mapping 4 PVs simultaneously. Four AEBs originated from the left superior PV (LSPV), 2 from the left inferior PV (LIPV), 4 from the right superior PV (RSPV), 2 from the RA or superior vena cava. In AEBs originating from the RA, the PSRA activation was the earliest and it proceeded in a cranial to caudal direction. In AEBs originating from the RUPV, RPA was the earliest. The esophageal activation sequence was in a cranial to caudal direction. In AEBs from the LSPV, LPA was the earliest and the esophageal activation sequence proceeded in a cranial to caudal direction. In AEDs from LIPV, LPA was the earliest, and the esophageal activation sequence was nearly simultaneous. Atrial activation sequences from the PSRA, RPA, LPA, and esophageal catheters can accurately identify the location of the initiating foci of AF before a transseptal procedure.