Masamitsu Adachi

Histopathologic Background for Resistance to Conventional Catheter Ablation of Common Atrial Flutter

Histopathologic examination of the cavotricuspid isthmus in which a large‐tip catheter was necessary to achieve conduction block is presented. No thickened myocardium or prominent trabeculation was observed on the ablation line. A small cardiac vein extending through the isthmus across the ablation scar was detected. The remaining myocardial cells were distributed along the small cardiac vein. It is possible that the luminal blood flow of the small cardiac vein protects the surrounding atrial muscle from effective delivery of radiofrequency energy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 829‐832, July 2004)

Electrophysiologic and histopathologic findings of the ablation sites for ventricular fibrillation in a patient with ischemic cardiomyopathy

We examined autopsy specimens from a patient with ischemic cardiomyopathy who underwent radiofrequency catheter ablation of ventricular fibrillation. There was site specific arrhythmogenesis of the trigger ventricular premature contractions (VPCs) and Purkinje potentials were recorded before the onset of the QRS. In postmortem examination, fibromuscular bands connecting the posterior papillary muscle and ventricular septum were recognized at the successful ablation sites of the trigger VPCs and the microscopic examinations revealed Purkinje cells in the center of that fibromuscular band.

Long-term reliability of AAI mode pacing in patients with sinus node dysfunction and low Wenckebach block rate.

AIMS To compare the risk of atrioventricular (AV) conduction disturbance between patients with sinus node dysfunction on AAI pacing who had a low or high Wenckebach block rate (WBR). METHODS AND RESULTS Patients with sinus node dysfunction and normal AV conduction those underwent an electrophysiological study were studied. The patients were classified into two groups: Group L was with the patients with a WBR of 100 to 129 per minute and Group H was with the patients with a WBR > or = 130 per minute. All patients followed up every 3-6 months after an AAI pacemaker implantation. A total of 102 patients, including 35 Group L and 67 Group H, were followed for 90 +/- 44 months. Six patients died from non-cardiac cause and five patients required a new atrial lead implantation due to lead failure during follow-up. Symptomatic bradycardia requiring a new ventricular lead implantation developed in four patients (annual incidence 0.5%). In Group L, two patients developed AV block (annual incidence 0.7%). In Group H, two patients developed bradycardic atrial fibrillation (annual incidence 0.4%). Kaplan-Meier analysis revealed no significant difference between the two groups (P = 0.2983). CONCLUSION These results suggest that a long-term risk of developing AV conduction disturbance is low even in patients with a WBR of 100 to 129 per minute.

Left atrial branches of coronary arteries; clinical implications related to linear catheter ablation for atrial fibrillation.

BackgroundCoronary artery damage has been reported during catheter ablation procedures. Recently, linear ablation of thin left atrial tissue has been performed for atrial fibrillation.Objective and MethodsBecause we have little information about the arteries in the left atrium, this study was performed to evaluate the anatomy of these arteries, and to compare them with previously reported ablation lines. Coronary angiography was performed in 262 patients. Atrial coronary arteries between the left atrial appendage and the left superior pulmonary vein (LAA-LSPV region), as well as between the left inferior pulmonary vein and the mitral annulus (“mitral isthmus” region) were examined.ResultsAtrial coronary arteries extending to the LAA-LSPV region were found in 92 subjects (35%), while arteries crossing the mitral isthmus region were found in 119 subjects (46%). Atrial coronary arteries crossed the ablation line in about 69% of subjects overall.ConclusionThese results might suggest a risk of acute complications due to left atrial ablation. Alternatively, recurrence of atrial fibrillation might be caused by protected myocardium around the atrial arteries. We should note that atrial coronary arteries cross the ablation line in many patients.

QRS complex widening due to loss of left bundle branch capture: pitfall of para-Hisian pacing

During para-Hisian pacing, widening of the paced QRS complex usually indicates loss of His bundle capture. We describe a patient without any accessory pathways in whom widening of the paced QRS complex occurred due to loss of left bundle branch capture during para-Hisian pacing. After initial widening of the QRS complex, further widening was observed due to loss of His bundle capture. With the initial QRS widening, the stimulus-atrial interval and retrograde atrial activation sequence were almost unchanged, so the findings mimicked retrograde conduction over an accessory pathway. This may be a pitfall of the para-Hisian pacing technique.

IDIOPATHIC LEFT VENTRICULAR TACHYCARDIA WITH BLOCK BETWEEN PURKINJE POTENTIAL AND VENTRICULAR MYOCARDIUM

We performed radiofrequency current catheter ablation in a patient with idiopathic LV. While mapping the inferoapical LV septum during tachycardia, spontaneous termination of tachycardia was observed with block between Purkinje (P) potential and ventricular electrogram (P‐V block). The cycle length of the tachycardia was associated with prolongation of P‐P interval and P‐V interval. P potential recording at this site was earliest and at very low amplitude during tachycardia. The radiofrequency current at this site was successful. These findings indicated that Purkinje fiber was a critical part of the tachycardia circuit. Ablation was successful at a site where both an earliest and low amplitude P potential was recorded during tachycardia, and where P‐V block that was induced by catheter manipulation was observed during tachycardia.

Exact Location of the Branching Bundle in the Living Heart

Aims: The His bundle electrogram is believed to reflect the exact location of the His bundle. However, the distinction between distal His bundle potential and proximal right bundle branch potential is challenging. The aim of this study was to pinpoint the location of the branching point of the His bundle, and to compare that site with the site of recording of the largest His bundle electrogram (LH) during sinus rhythm.

Macroreentrant atrial tachycardia with an isolated pathway mimicking focal activation on three-dimensional electroanatomical mapping

A 76-year-old man with two different sustained atrial arrhythmias that occurred after coronary artery bypass grafting underwent electrophysiological studies. Macroreentrant atrial tachycardias were detected with an isolated slow pathway mimicking focal activation on three-dimensional electroanatomical mapping. The slow conduction pathway in the right atrial free wall was assumed to represent tissue damaged by right atrial cannulation during previous coronary artery bypass grafting.

Removal of coronary sinus intima by a guidewire during cardiac resynchronization therapy.

Previously, complications associated with the placement of the left ventricular pacing lead were reported in 1.9–6% of cases. We describe a case with a stripping of venous intima from the coronary sinus by a guidewire during a left ventricular lead implantation. Judging from this case, the firm guidewire and coronary catheter should not be used within the coronary sinus.