Thrombolytic therapy can reduce the arrhythmogenic substrate after acute myocardial infarction: a study using the signal-averaged electrocardiogram, endocardial catheter mapping and programmed ventricular stimulation.
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Thrombolytic therapy improves survival after acute myocardial infarction (AMI) primarily by preserving left ventricular function. Its influence on the arrhythmogenic substrate remains uncertain. To investigate the electrophysiologic effects of thrombolytic therapy, signal-averaged electrocardiography, endocardial catheter mapping and programmed stimulation were performed in 93 consecutive patients with their first AMI who underwent thrombolytic therapy. Early reperfusion was achieved in 75 patients (group 1), but not in 18 patients (group 2). The incidence of the signal-averaged electrocardiogram abnormality was 11% in group 1 (8 of 75 patients) and 33% in group 2 (6 of 18 patients) (p<0.02). Catheter mapping detected delayed endocardial electrograms in 30 group 1 patients and 10 group 2 patients (p=NS). The spatial distribution of these electrograms was smaller, and the longest duration of endocardial electrograms was shorter in group 1 than in group 2 (p<0.01). Sustained monomorphic ventricular tachycardia was induced less commonly in group 1 (20%) than in group 2 (44%) (p<0.05). In conclusion, thrombolytic therapy can reduce the arrhythmogenic substrate and improve electrical stability after AMI. This antiarrhythmic effect may contribute, in part, to the improved survival of patients treated with thrombolytic drugs. (+info)
Incidence and clinical significance of junctional rhythm remaining after termination of radiofrequency current delivery in patients with atrioventricular nodal reentrant tachycardia.
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The aim of this study was to elucidate the electrophysiologic characteristics and clinical significance of the accelerated junctional rhythm (JR) that remains after termination of radiofrequency (RF) current delivery during catheter ablation (CA) for atrioventricular nodal reentrant tachycardia (AVNRT). Fifty consecutive patients with AVNRT (21M, 29F, age 48 years) underwent RF-CA targeting the slow pathway. JR occurred at 124 out of a total of 236 ablation sites (53%) during the RF delivery. With 15 RF deliveries (6.4%, n=10), JR remained after termination of the RF delivery (Post-JR). The mean cycle length of the Post-JR immediately after termination of the RF delivery was 639+/-124 ms and its duration was widely distributed from 3 s to more than 1 h. The Post-JR exhibited a spontaneous rate deceleration and overdrive suppression by rapid atrial pacing. The JR during the RF delivery followed by Post-JR had a greater time span in which the JR appeared, compared with that without Post-JR. The Post-JR had less sensitivity(18 vs 96%), but greater specificity (97 vs 59%) and a positive predictive value (60 vs 39%) in predicting successful ablation compared with JR seen only during the RF delivery. It is concluded that the presence of Post-JR might be a reflection of the intense effect of RF energy on the nodal or peri-nodal tissue. (+info)
Characteristic findings of body surface potential map during ventricular repolarization in patients with coronary heart disease.
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The objective of the present study was to investigate the characteristics of body surface potential map (BSPM) findings during ventricular repolarization in patients with coronary artery disease (CAD). A total of 108 consecutive patients, 99 men and 9 women with angina pectoris and positive treadmill exercise test results as well as angiographically documented CAD underwent BSPM study in a fasting state. Their ages ranged from 30 to 70 years. There were 13 patients with right coronary artery (RCA) lesions, 37 with left anterior descending artery (LAD) lesions, 5 with left circumflex artery (LCX) lesions, 17 with both RCA and LAD lesions, 12 with both LCX and LAD lesions, and 24 with 3-vessel disease. The BSPMs were obtained by using the heart potential map system designed by Toyama et al. There were 59 lead points on the anterior chest wall and 28 on the back. The BSPMs in isopotential distribution were made every one msec throughout the ventricular activation period. The distribution of positive and negative potentials, potential maximum and potential minimum, polarity of potential distribution, and the reversal of potential distribution during ventricular repolarization were analyzed. The following information on BSPMs was obtained: (1) In early ventricular repolarization, the negative potential and the potential minimum appeared abnormally on the anterior thorax. The potential abnormality displayed on the right portion or the inferior portion in patients with RCA lesions, on the middle portion or the left portion in patients with LAD lesions, and on the left-superior portion or the left-middle portion in patients with LCX lesions. In patients with multi-vessel disease, the abnormal potential distribution showed a combined pattern of individual vessel lesions. (2) In some cases, the multipolar potential distribution appeared abnormally during the initial stage and the peak of the T wave. (3) The reversal of potential distribution was observed in about half of the patients. The characteristic findings of the BSPM during ventricular repolarization, including abnormal potential distribution, multipolar potential distribution and reversal of potential distribution, will be of clinical value in patients with CAD. (+info)
Prediction of accessory pathway locations in Wolff-Parkinson-White syndrome with body surface potential Laplacian maps . A simulation study.
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An electrocardiographic computer simulation was conducted to study the feasibility of predicting accessory pathway locations in Wolff-Parkinson-White (WPW) syndrome with body surface potential Laplacian maps. Three-dimensional, realistically-shaped heart and torso models were used. Ten accessory pathways (APs) around the atrioventricular ring corresponding to Gallagher et al. were set in the heart model, and body surface Lapacian and potential maps of WPW syndrome with single or multiple APs were simulated and compared to each other. In simulations with a single AP in the anterior walls, the maximum-minimum pairs in Laplacian maps appeared to be similar to those in potential maps with respect to their locations and orientations, but the maximum-minimum pairs in Laplacian maps were sharper and more localized than in potential maps. In simulations with a posterior AP or multiple APs, the maximum-minimum pairs in the Laplacian maps showed features correlative to the AP locations, but no such features were found in potential maps. These results suggest the possibility of using Laplacian maps, as a non-invasive method for predicting accessory pathways locations in WPW syndrome. (+info)
Diastolic potentials observed in idiopathic left ventricular tachycardia.
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Radiofrequency catheter ablation (RF-CA) has demonstrated a high success rate in eliminating idiopathic left ventricular tachycardia (ILVT), and the target site is determined by the score of pace mapping or the Purkinje potential (PP) preceding the onset of the ventricular activation, which is considered to indicate the exit site of the reentrant circuit. However, only a few reports have described the potential obtained from the slow conduction zone. RF-CA was successfully performed in 8 patients with ILVT. Careful mapping of the left ventricle during tachycardia was carried out to find the diastolic potential (DP). A DP was obtained in 4 patients (group 1), but not in 4 others (group 2). The local electrogram was recorded from the distal tip of the ablation catheter during the RF current application in order to investigate the pattern of termination of ILVT. A DP was recorded at the point where the catheter was slightly pulled back to a site proximal to the exit site of the reentrant circuit at the left interventricular basal septum. In group 1, conduction block between the DP and PP eliminated ILVT in 3 out of 4 cases, and 1 case showed conduction block between the DP and ventricular potential. In 2 out of 4 patients in group 2, the local electrogram showed conduction block between PP and the ventricular potential when VT terminated. The ablation site in group 1 was located relatively more basal than that in group 2 in anatomy. A DP was obtained in a half of the cases with ILVT and RF-CA at this site could eliminate ILVT. A DP was obtained at a site relatively basal to the exit of the reentrant circuit and it is considered that this is a useful marker in terms of the successful ablation of ILVT. (+info)
Atypical atrial flutter originating in the right atrial free wall.
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BACKGROUND: Data from experimental models of atrial flutter indicate that macro-reentrant circuits may be confined by anatomic and functional barriers remote from the tricuspid annulus-eustachian ridge atrial isthmus. Data characterizing the various forms of atypical atrial flutter in humans are limited. METHODS AND RESULTS: In 6 of 160 consecutive patients referred for ablation of counterclockwise and/or clockwise typical atrial flutter, an additional atypical atrial flutter was mapped to the right atrial free wall. Five patients had no prior cardiac surgery. Incisional atrial tachycardia was excluded in the remaining patient. High-density electroanatomic maps of the reentrant circuit were obtained in 3 patients. Radiofrequency energy application from a discrete midlateral right atrial central line of conduction block to the inferior vena cava terminated and prevented the reinduction of atypical atrial flutter in each patient. Atrial flutter has not recurred in any patient (follow-up, 18+/-17 months; range, 3 to 40 months). CONCLUSIONS: Atrial flutter can arise in the right atrial free wall. This form of atypical atrial flutter could account for spontaneous or inducible atrial flutter observed in patients referred for ablation and is eliminated with linear ablation directed at the inferolateral right atrium. (+info)
Mapping and ablation of ventricular tachycardia guided by virtual electrograms using a noncontact, computerized mapping system.
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OBJECTIVES: The purpose of this study was to describe a computerized mapping system that utilizes a noncontact, 64 electrode balloon catheter to compute virtual electrograms simultaneously at 3,360 left ventricular (LV) sites and to assess the clinical utility of this system for mapping and ablating ventricular tachycardia (VT). BACKGROUND: Mapping VT in the electrophysiology laboratory conventionally is achieved by sequentially positioning an electrode catheter at multiple endocardial sites. METHODS: Fifteen patients with VT underwent 18 electrophysiology procedures using the noncontact, computerized mapping system. A 9F 64 electrode balloon catheter and a conventional 7F electrode catheter for mapping and ablation were positioned in the LV using a retrograde aortic approach. Using a boundary element inverse solution, 3,360 virtual endocardial electrograms were computed and used to derive isopotential maps. An incorporated locator system was used in conjunction with or instead of fluoroscopy to position the conventional electrode catheter. RESULTS: A total of 21 VTs, 12 of which were hemodynamically-tolerated and 9 of which were not, were mapped. Isolated diastolic potentials, presystolic areas, zones of slow conduction and exit sites during VT were identified using virtual electrograms and isopotential maps. Among 19 targeted VTs, radiofrequency ablation guided by the computerized mapping system and the locator signal was successful in 15. CONCLUSIONS: The computerized mapping system described in this study computes accurate isopotential maps that are a useful guide for ablation of hemodynamically stable or unstable VT. (+info)
Mechanism, localization and cure of atrial arrhythmias occurring after a new intraoperative endocardial radiofrequency ablation procedure for atrial fibrillation.
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OBJECTIVES: The purpose of this study was to test a new pattern of radiofrequency ablation for atrial fibrillation (AFib) intended to optimize atrial activation, and to demonstrate the usefulness of catheter techniques for mapping and ablation of postoperative atrial arrhythmias. BACKGROUND: Linear radiofrequency lesions have been used to cure AFib, but the optimal pattern of lesions is unknown and postoperative tachyarrhythmias are common. METHODS: A radial pattern of linear radiofrequency lesions (Star) was made using an endocardial open surgical approach in 25 patients. Postoperative arrhythmias were induced and characterized during electrophysiological studies in 15 patients. RESULTS: The AFib was abolished in most patients (91%), but atrial flutter (AFlut) occurred in 96% of patients postoperatively. At postoperative electrophysiological studies, 37 flutter morphologies were studied in 15 patients (46% spontaneous, cycle length [CL] 223 +/- 25 ms). Seven mechanisms (lesions discontinuity, n = 6; focal mechanism, n = 1) of AFlut were characterized in six patients. In these cases, flutter was abolished using further catheter radiofrequency ablation. In the remaining cases, flutter was usually localized to an area involving the interatrial septum, but no critical isthmus was identified for ablation. After 16 +/-10 months, 15 patients (65%) were asymptomatic with (n = 3) or without (n = 12) antiarrhythmic medications. Eight (35%) patients had persistent arrhythmias. Postoperative atrial electrical activation was near physiological. CONCLUSIONS: The AFib maybe abolished using a radial pattern of linear endocardial radiofrequency lesions, but postoperative AFlut is common even when lesions are made under optimal conditions. Endocardial mapping techniques can be used to characterize the flutter mechanisms, thus enabling subsequent successful catheter ablation. (+info)