Subtle variations in QRS morphology occurs during idiopathic outflow tract ventricular tachycardia (OTVT), but no studies have clarified the prevalence and characteristics of the OTVT with altered QRS morphology following radiofrequency catheter ablation (RFA), which then require an additional RF application at a different portion of the outflow tract to abolish OTVT. Of 202 patients with a monomorphic VT or premature ventricular contraction (PVC) originating from the outflow tract, 6 (3%) showed changes in QRS morphology in the OTVT following RFA, requiring an additional RF application to the outflow tract at a different portion. In all six patients, RFA was applied for the first or second OTVT to a right or left ventricular endocardial site, with the other site being the left sinus of Valsalva. In each patient, OTVT before or after the changes in QRS morphology had characteristic ECG findings originating from a particular portion of the outflow tract. Changes in QRS morphology consistently included an increase or decrease in R wave amplitude in all inferior leads. Detailed continuous observation of QRS morphology in OTVT, especially R wave amplitude in inferior leads, is important for identifying changes of QRS morphology during catheter ablation. Mapping and ablation at a different portion of the outflow tract is then needed for cure.

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he coronary venous system (CVS) is increasingly being used for different electrophysiologic purposes; for example, cardiac resynchronization therapy incorporating a left ventricular (LV) coronary vein lead may improve the condition of patients with severe heart failure. [1][2][3] The CVS has also been used for radiofrequency catheter ablation, 4 mapping, 5 and defibrillation. 6,7 Visualization of the CVS has been attempted by angiography, 8,9 echocardiography 10,11 and electron-beam computed tomography (CT), 12,13 and recently contrast-enhanced multidetector row spiral computed tomography (MDCT) has been used to noninvasively visualize coronary artery stenosis by creating high-quality 3-dimensional (3-D) images, [14][15][16][17][18][19] However, there has not been a study to date that has attempted to analyze the CVS using MDCT, so the aim of the present study was to investigate the applicability and image quality of contrast-enhanced visualization of the CVS by MDCT using retrospective ECG gating. Attention was also focused on the presence and number of coronary veins on the lateral aspect of the left ventricle (LV), which are the optimal sites for placing pacing leads for LV pacing in patients with advanced heart failure. Circulation Journal Vol.69, February 2005 Methods Study PopulationThis study included 70 patients who underwent MDCT as well as radiofrequency catheter ablation (51 men, 19 women; mean age, 58±9 years [range: 25-74 years]). Sixtyfive patients had paroxysmal atrial fibrillation, and 5 had left atrial tachycardia. All patients underwent MDCT to determine the morphology and size of the left atrium and pulmonary veins prior to the ablation procedure. 20 All patients had a normal ECG during sinus rhythm, and no structural abnormalities were found by physical examination and echocardiography. MDCTAfter informed written consent was obtained, MDCT was performed using a LightSpeed Ultra™ (GE Medical System, Milwaukee, WI, USA). All patients were in normal sinus rhythm at the time of MDCT image acquisition. Patients were examined while supine and all images were acquired during an inspiratory breath-hold. After determining the contrast agent transit time, we acquired MDCT data during an intravenous injection of 100 ml of the iodinated contrast agent iopromid (Ultravist 370; Schering, Berlin, Germany) at a rate of 4 ml/s. The following scanning protocol was used: 8-detector; beam collimation, 1.25 mm; pitch factor, 0.275-0.35; scan time, 0.5 or 0.6 s/rotation; ECG gate, and half-or multi-sector reconstruction. 17 The tube current was 150 mA at 140 kV to keep the radiation dose within a reasonable range. On the basis of the results of the preliminary study, the data acquisition was started 25 s after the initiation of the contrast agent. The breath-hold Circ J 2005; 69: 165 -170 (Received August 12, 2004; revised manuscript received November 17, 2004; accepted November 25, 2004 Background This study was undertaken to investigate the applicability and image quality of contrast-enhanced visualization of...

The aim of this study was to identify the characteristics of electrograms that may be helpful in predicting successful ablation of idiopathic ventricular tachycardia from the aortic sinus of Valsalva. Data were obtained from 23 patients with symptomatic ventricular tachycardia or premature ventricular contractions (LV-VT) who underwent RF catheter ablation from the left sinus of Valsalva. Electrograms before and after application of RF energy during sinus rhythm and during LV-VT were analyzed. Complete elimination of LV-VT was finally achieved in 21 (91%) patients. The incidence of presystolic potentials preceding the QRS complex of LV-VT (P1 potential) was 90% for the 21 successful ablation sites, which did not differ from the incidence for the 24 unsuccessful sites (79%; P = 0.5). During sinus rhythm, a potential following the QRS complex (P2 potential) was more often recorded at the successful ablation site than at an unsuccessful ablation site before and after application of RF energy (before, P < 0.05; after, P < 0.001). The appearance of the P2 potential or a delay in the preexisting P2 potential after application of RF energy was observed only at the successful ablation sites (P < 0.001). In 18 control individuals who had no LV-VT, no P2 potential was recorded within the left sinus of Valsalva. Although the P1 potential may be useful for identifying the successful ablation site, its sensitivity is low. The appearance of the P2 potential or an increasingly delayed P2 potential after application of RF energy may be more useful than the P1 potential for predicting successful ablation.

adiofrequency (RF) catheter ablation is an established curative therapy for ventricular tachycardias (VT) or symptomatic premature ventricular contractions (PVCs) originating from the outflow tract (OT-VT/PVCs) in structurally normal hearts. [1][2][3][4][5][6][7][8][9][10][11][12][13] Although most of these arrhythmias have their origin in the septal aspect of the right ventricular outflow tract (RVOT), [1][2][3][4][5][6][7][8][9]14 some originate from the free wall of the RVOT. 3,4,14 However, the prevalence and electrocardiographic (ECG) characteristics of idiopathic VT or PVC originating in the free wall of the RVOT have not been sufficiently clarified and the present study was undertaken to determine these. Methods Patient GroupThe study included 110 patients with symptomatic VT or PVCs who underwent successful RF catheter ablation at the RVOT: 41 men and 69 women, with a mean age of 50±16 years (± SD; range, 21-81 years). During the clinical arrhythmia, the surface ECG showed a left bundle branch block morphology with an inferior axis in all patients. Thirty-four patients had monomorphic VT, defined as 3 or Circulation Journal Vol. 68, October 2004 more consecutive PVCs; 76 had monomorphic PVCs. All patients had a normal ECG during sinus rhythm, and no structural abnormalities were found by physical examination or echocardiography. None had electrolyte abnormalities, metabolic disorders or advanced systemic disease. The selection criteria of the patients with a PVC included: (1) severe symptoms (including palpitations, asthenia and vertigo) for a period of months or years that were clearly related to frequent PVCs; and (2) inability of the patient to tolerate, or unsuccessful treatment with, at least one antiarrhythmic drug or the patient did not wish to take long-term antiarrhythmic medications because of special reasons (eg, young women who want to become pregnant). To determine the precise origin of the OT-VT/PVC and to evaluate the short-term effects of RF ablation, patients were enrolled in this study provided that the clinical arrhythmia occurred spontaneously or could be induced during the ablation procedure. These criteria excluded 8 patients prior to initiation of the study. In 1 patient, nearly identical ventricular activations were recorded from both the RVOT and left sinus of Valsalva, and RF applications at both sites could not ablate the OT-VT/PVC. In the remaining 7 excluded patients, the OT-VT/PVC could not be induced during the procedure. Mapping and RF AblationAfter informed consent was obtained and anti-arrhythmic drugs had been withdrawn, electrophysiologic evaluation and catheter ablation were performed as previously described. Under fluoroscopic guidance, catheters were introduced into the high right atrium, right ventricular (RV) Circ J 2004; 68: 909 -914