Notes: TAKAGI, M., et al.: Change in Morphology of Reentrant Atrial Arrhythmias Without Termination Following Radiofrequency Catheter Ablation. A 60-year-old woman who had previously undergone an atrial septal defect repair and had type I atrial flutter underwent electrophysiological study. After radiofrequency (RF) ablation to the isthmus between the inferior vena cava and the tricuspid annulus, type I atrial flutter was changed to atrial tachycardia following atriotomy without termination. This atrial tachycardia was eliminated by single-site RF ablation of a small lesion below the caudal end of the atriotomy scar, where continuous and fragmented potentials were recorded during tachycardia. We experienced a rare case in which RF energy changed tachycardia circuits.

Notes: This case report describes two distinct morphological ventricular tachycardias (VTs) associated with bidirectional reentrant circuit around the tricuspid annulus in a 32-year-old patient with arrhythmogenic right ventricular dysplasia. Multiple radiofrequency linear ablation could abolish both VTs, and this patient has been clinically free from symptoms of VTs at 1-year follow-up. (PACE 2003; 26:2050–2051)

Notes: Ogawa, M., et al.: Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single site and Biabrial Pacing. It has been reported that atrial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS–d), or biatrial (simultaneous RAA and CS–d) pacing. In the AF group, AF inducibility was significantly higher with RAA extrastimulus during RAA (12/20; P 〈 0.0001) or biatrial paced drive (7/20; P 〈 0.01) than during CS–d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS–d paced drive. The atrial recovery time (ART) at RAA and CS–d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS–d was calculated as the ART difference (ARTD). The ARTD was significantly longer during RAA pacing in the AF group than in control group (155.0 ± 32.8 vs 128.8 ± 32.9 ms, P 〈 0.05). In the AF group, ARTDs during biatrial (52.0 ± 24.2 ms) and CS–d pacing (51.7 ± 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS–d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS–d and biatrial pacing significantly reduced ARTD compared with RAA pacing.

Notes: This case report describes VT with figure eight pattern originating from the right ventricle in a 33-year-old patient with cardiac sarcoidosis. Multiple radiofrequency linear ablation could abolish the VT, and this patient has been clinically free from symptoms of VT during a 6-month follow-up. (PACE 2004; 27:561–562)

Notes: AIBA, T., et al.: The Role of Purkinje and Pre-Purkinje Potentials in the Reentrant Circuit of Verapamil-Sensitive Idiopathic LV Tachycardia. Although the mechanism of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT) is usually reentry, the actual reentrant circuit is not clearly understood. This study examined the relationship between the Purkinje potential (PP) and a dull potential preceding PP (pre-PP) during ILVT to elucidate the roles of these potentials in the reentrant circuit of ILVT. Electrophysiological studies and radiofrequency catheter ablation were performed in ten patients (7 men, 3 women, mean age 29 years) who had an ILVT with a right bundle branch block configuration and left-axis deviation. Left ventricular endocardial mapping using an octapolar catheter and entrainment and resetting studies during VT was performed by pacing from the right ventricular outflow tract (RVOT) and each site of the left ventricular mapping catheter. PP and pre-PP were recorded simultaneously during VT in all patients. The earliest PP during VT was recorded at the inferoposterior septum, and PP was activated bidirectionally toward the proximal (basal) and distal (apical) sites along the left posterior fascicle. In contrast, pre-PP was recorded at sites slightly proximal to the earliest PP recording site, and was activated toward the earliest PP site. Pacing from RVOT confirmed manifest entrainment, and the stimulus to pre-PP interval was prolonged with a shorter pacing cycle length. Concealed entrainment was demonstrated by capture of the PPs of the left ventricular mapping catheter in six patients, and the postpacing interval at each PP site was equal to the tachycardia cycle length. The pre-PP was orthodromically activated from the proximal to the distal site during pacing. More rapid pacing also produced delay in activation from PP to pre-PP, indicating slow conduction in ILVT. Catheter ablation was performed at the pre-PP recording site during VT, and was successful in all patients. The reentrant circuit of ILVT could be constructed based on the pre-PP, PP, and slow conduction between the PP and pre-PP. Catheter ablation of ILVT was successful at the pre-PP recording site.