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Ventricular tachycardia originating within the PA has different electrocardiographic and electrophysiologic characteristics from that originating from the RV-end-OT. When mapping the RVOT area, the catheter may be located within the PA if a low-voltage atrial or local ventricular potential of <1-mV amplitude is recorded. Heightened attention must be paid if RFCA is required within the PA.

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ignificant tricuspid regurgitation (TR) has been reported in patients with a permanent pacemaker (PPM), [1][2][3][4][5] and the leads of such a device or those of an implantable cardioverter defibrillator (ICD) can be the primary cause of symptomatic TR. 6,7 However, in the clinical setting, the diagnosis of lead-induced TR can be challenging because conventional 2-dimensional echocardiography (2-DE) has limitations in identifying the anatomical relationship between the lead and the tricuspid leaflets. 7 The 3-dimensional echocardiography (3-DE) has been recently developed for assessing tricuspid valve morphology and pathology, including TR, [8][9][10][11] and case reports on its utility in the diagnosis of PPM-and ICD-lead-related TR have been published. 12,13 However, the ability of 3-DE to identify both the anatomical lead route through the tricuspid valve and lead-induced valve malfunction has not been studied systematically. Methods Patient PopulationIn 87 patients with PPM, ICD or cardiac resynchroniza- Circulation Journal Vol.72, September 2008tion therapy device, 3-DE studies were performed to evaluate the route of the leads and the presence of lead-related TR (Table 1). The underlying cardiac disease for which PPM implantation was required was complete or advanced atrioventricular block in 28 patients and sick sinus syndrome, including slow atrial fibrillation, in 22 patients, and for ICD implantation it was primary or secondary prevention of fatal cardiac arrhythmias in 17 patients. Cardiac resynchronization therapy devices with or without ICD were implanted in 20 patients with advanced heart failure. The study was approved by the local research ethics committee, and all patients gave written informed consent. Clinical Utility of 3-Dimensional Echocardiography in the Evaluation of Tricuspid Regurgitation Caused by Pacemaker LeadsYoshihiro Seo, MD; Tomoko Ishizu, MD; Hideki Nakajima, RDCS*; Yukio Sekiguchi, MD; Shigeyuki Watanabe, MD; Kazutaka Aonuma, MD Background This study evaluated the usefulness of 3-dimensional echocardiography (3-DE) for identifying permanent pacemaker (PPM) or implantable cardioverter defibrillator (ICD) lead-related symptomatic tricuspid regurgitation (TR). Methods and ResultsEighty-seven patients underwent 3-DE examination: 50 patients with PPM, 17 with ICD, and 20 with cardiac resynchronization therapy devices. TR severity was classified as trivial/mild, moderate, or severe according to the ratio of TR area to right atrium area. The 3-DE identified the lead route and position at the tricuspid valve in 82 patients (94.2%). In 5 patients, images without lead-induced artifacts could not be obtained. TR severity was trivial/mild in 50 patients, moderate in 20 patients, and severe in 12 patients. In all patients with trivial/mild TR and all but 1 patient with moderate TR, leads were positioned on the annulus side between leaflets. Lead-induced obstruction to tricuspid valve closing was identified in 1 patient with moderate TR and in 7 of 12 patients with severe TR: 4 patients had...

NOGAMI A et al.(5) View the monitor during imaging During imaging, the heart rate must be continuously monitored using a pulse oximeter or an ECG monitor. (6) Prepare for unexpected situations It should be ensured that the room is equipped with an electrical defibrillator to be used in an emergency, if necessary. A hospital manual for handling unexpected situations should be established. In addition, it should be kept in mind that the threshold and lead resistance need to be re-measured after imaging and the mode needs to be returned to the original setting.Recommendations are shown in Table 6. Electrophysiology StudiesThe clinical significance of induced arrhythmia depends on the underlying heart disease, type of arrhythmia, and induction protocol. Electrophysiology studies are considered less useful in patients with frequent premature ventricular contraction (PVCs) without structural heart disease.