Kouji Azegami

Electrophysiologic effects of ischemic preconditioning on QT dispersion during coronary angioplasty

OBJECTIVES The aim of this study was to examine the effect of ischemic preconditioning on the manner of ventricular repolarization by assessing the change in QT dispersion during coronary angioplasty. BACKGROUND QT interval dispersion reflects regional variations in ventricular repolarization and cardiac electrical instability. Previous studies have suggested that increased QT dispersion is associated with an increased incidence of malignant ventricular arrhythmias, whereas brief episodes of myocardial ischemia can render the heart more resistant to subsequent ischemic episodes, a phenomenon called ischemic preconditioning. METHODS To assess the effects of ischemic preconditioning on myocardial repolarization by examining the change in QT dispersion during coronary angioplasty, we studied 47 consecutive patients (39 men and 8 women; mean age 57 +/- 16 years). QT dispersion was measured after each balloon inflation during coronary angioplasty. Statistical analysis was performed by using repeated measurement of analysis of variance. RESULTS There were significant differences in QT dispersion as the number of balloon inflations increased (mean +/- SD 52 +/- 14, 42 +/- 11, 36 +/- 9, 31 +/- 10 and 29 +/- 11 ms, respectively [p < 0.01], for the first, second, third, fourth and fifth balloon inflations). The magnitude of decrease in QT dispersion was significant in the first and second balloon inflations, then became insignificant with later inflations. CONCLUSIONS These data indicate that the gradual decrease in QT dispersion provoked by coronary artery occlusion and reperfusion during coronary angioplasty may be associated with electrophysiologic effects of ischemic preconditioning on myocardium in the human heart.

Radiofrequency Catheter Ablation for AV Nodal Reentrant Tachycardia Associated with Persistent Left Superior Vena Cava

Slow A V nodal pathway ablation using RF is highly effective for patients with refractory A V nodal reentrant tachycardia (AVNRT). We report three catheter ablation cases using RF current in patients associated with persistent left superior vena cava (PLSVC). Three patients with drug refractory AVNHT of common variety were involved in this study. An electrode catheter introduced through the left subclavian vein inserted directly into the coronary sinus, a typical anatomical finding of PLSVC. The ablation procedure was initially performed at the posteroinferior region of Kochs triangle. A slow pathway potential could not be found from that area; nonsustained junctional tachycardia (NSJT) did not occur during the delivery of RF current; there was failure to eliminate slow AV nodal pathway conduction. The catheter then was moved into the bed of the proximal portion of the markedly enlarged coronary sinus. A slow AV nodal pathway potential was recorded through the ablation catheter, and the delivery of RF current caused NSJT in two patients. Complete elimination of slow AV nodal pathway conduction was accomplished in these two patients by this method. No adverse effects were provoked by this procedure. Catheter ablation of the slow A V nodal pathway guided by a slow pathway potential and the appearance of NSJT was feasible and safe in the area of the coronary sinus ostium in patients associated with PLSVC.

Radiofrequency ablation of tachyarrhythmias in patients with Ebstein's anomaly

We performed radiofrequency catheter ablation in five patients associated with Ebsteins anomaly to cure their refractory tachyarrhythmias. The presenting arrhythmias were four cases of orthodromic circus movement tachycardia using accessory pathways as a requisite limb, including one case of a Mahaim fiber and one of atrial flutter of common variety. All accessory pathways, including the Mahaim fiber, were ablated by RF energy delivered through the catheter placed at the AV annulus rather than the displaced anatomical AV groove. Interestingly, the antegrade or retrograde conduction interval over these accessory pathways was relatively longer than that of usual accessory pathways, and the accessory pathway potential was fractionated in some cases. The location of the atrioventricular node was displaced from the usual position to the postero-inferior area of Kochs triangle in one case. The configuration of the flutter wave was larger than usual in height as well as in width. All tachyarrhythmias were cured by RF catheter ablation. In the case of RF catheter ablation for patients with Ebsteins anomaly, close attention is indispensable in order to accomplish it safely and successfully, because of the anatomical and functional differences peculiar to Ebsteins anomaly.

Ventricular tachycardia with narrow QRS duration, a right bundle branch block pattern, and right axis deviation abolished by catheter manipulation.

A 25-year-old women underwent electrophysiologic evaluation for sustained normal QRS complex tachycardia with a pattern of right bundle branch block and right axis deviation. Ventricular tachycardia was diagnosed by demonstrating fusion beats, atrioventricular dissociation, and bundle of His potential activation, which began before the onset of each QRS complex. A single ventricular extrastimulus was capable of easily provoking the tachycardia. There was an inverse relationship between the coupling interval of the first extrastimulus and the interval of the first tachycardia beat, suggesting reentry as the mechanism. The tachycardia was unexpectedly abolished during catheter manipulation in the left ventricle and has never recurred during 1 year of follow-up evaluation. The tachycardia was thought to be an unusual form of interfascicular tachycardia or microreentrant fascicular tachycardia.

Radiofrequency Catheter Ablation from the Epicardial Sites for Ventricular Arrhythmias Originating from the Left Ventricular Summit—Two Case-Reports—

Introduction: We report 2 cases of ventricular arrhythmias (VAs) originating from the left ventricular summit (LVS) which required radiofrequency energy (RF) application in the great cardiac vein (GCV) and/or the epicardium for treating VAs. Case 1: Sixty-five year-old female with idiopathic VAs underwent RF-catheter ablation (CA). The earliest activation site of VAs was observed in GCV, to which left descending coronary artery (LAD) run close. Sufficient RF delivery could not be performed due to the concerns about the injury to LAD, and the procedure resulted in a transient therapeutic effect. Case 2: Fifty-one year-old male suffering from VAs associated with non-ischemic cardiomyopathy underwent RF-CA. In 1st session, the earliest activation site of VAs was recognized in GCV, however, RF-CA application in GCV failed to abolish VAs. In 2nd session with the subxiphoidal pericardial approach, the earliest site was located at LVS extremely close to LAD. Despite the multiple RF applications in the vicinity sites of that portion, we were unable to abolish VAs. Conclusion: In sporadic cases, epicardial approach is required to eliminate VAs. However, the discretion and attention have to be paid in order to avoid the serious complications for treating VAs originating from LVS.