We describe a new ECG algorithm having a high sensitivity and specificity to identify the optimal ablation site for idiopathic ventricular outflow tachycardia or premature ventricular contractions.

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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...