Radiofrequency catheter ablation of inappropriate sinus tachycardia guided by activation mapping.
(17/507)
OBJECTIVE: The purpose of this study was to evaluate the value of activation mapping for radiofrequency modification of the sinus node and the long-term success rate of the procedure in a series of patients with inappropriate sinus tachycardia. BACKGROUND: The results of radiofrequency ablation of inappropriate sinus tachycardia have been reported in only a small number of patients. METHODS: The subjects of this study were 29 consecutive drug-refractory patients who underwent catheter ablation of inappropriate sinus tachycardia. Target sites were selected by activation mapping during sinus tachycardia. RESULTS: The ablation procedure was successful acutely in reducing the baseline sinus rate to <90/min and the sinus rate during isoproterenol infusion by >20% in 22 of 29 patients (76%). In 13 of 22 patients (59%) with a successful acute outcome, successive applications of radiofrequency energy at the site of earliest endocardial activation resulted in a cranial-caudal migration of earliest endocardial activation from the high lateral right atrium, along with a step-wise reduction in heart rate. In the other nine patients (41%) with a successful acute outcome, the reduction in sinus rate occurred abruptly, unaccompanied by migration of the site of earliest activation. Symptoms due to inappropriate sinus tachycardia recurred at a mean of 4.4+/-; 3 months after the ablation procedure in 6 of 22 patients (27%). After additional procedures in three patients, symptoms of inappropriate sinus tachycardia ultimately were successfully eliminated over the long-term in 19 of 29 patients (66%). CONCLUSIONS: In conclusion, radiofrequency ablation is at best only modestly effective for managing patients with inappropriate sinus tachycardia. The two different responses of heart rate to radiofrequency ablation may reflect differences in the number and/or multicentricity of subsidiary sites of impulse generation within the sinus node and/or atrium in patients with inappropriate sinus tachycardia. (+info)
New body surface isopotential map evaluation method to detect minor potential losses in non-Q-wave myocardial infarction.
(18/507)
BACKGROUND: Potential losses caused by stable non-Q-wave myocardial infarction (MI) are too small to diagnose with the use of standard ECG. The aim of the present study was to obtain accurate diagnostic criteria for this prognostically important disease with the help of body surface mapping. METHODS AND RESULTS: Body surface potentials were recorded with the use of 63 unipolar leads in 45 patients with a non-Q-wave MI (41 to 75 years old); 24 healthy adults, 42 patients with unstable angina, and 70 patients with Q-wave MI served as reference groups. Qualitative pathological features of the isopotential maps, such as onset time and site and magnitude of the first right-anterior/anterior minimum, as well as pathological negativities at that time, were defined in non-Q-wave MI cases. These features, which account for the activation sequence and the body surface projections of specific cardiac regions (Selvester classification), showed a 91% sensitivity and an 88% specificity for the detection of non-Q-wave MI. In comparison, the different departure maps (first third QRS, QRS, and QRST isoarea) resulted in less favorable specificities (50% to 58%). Concordance between the isopotential maps and the acute-phase ECG (90%), hypokinesis (64%), fixed perfusion defects (59%), and significant stenosis of the infarct-related coronary artery (87%) supported the concept that these isopotential map changes correspond to the supposed sites of MI. There were pathological features in 69% of patients with unstable angina, with similar concordances as in non-Q-wave MI. CONCLUSIONS: Isopotential maps revealed characteristic features that were suitable for the detection and localization of non-Q-wave MI in the clinical setting of unstable coronary artery disease. (+info)
Ventricular arrhythmias induced by endothelin-1 or by acute ischemia: a comparative analysis using three-dimensional mapping.
(19/507)
OBJECTIVES: To analyze three-dimensional activation patterns of ventricular arrhythmias induced by endothelin-1 in comparison with ischemia-induced tachycardias. METHODS: Following AV node ablation, sixty pin electrodes containing four bipoles each were inserted into both ventricles of ten foxhounds. Using a computerized mapping system, this would allow to simultaneously record 240 endo-, epi- and midmyocardial electrograms for reconstruction of the three-dimensional activation pattern. In five dogs, endothelin-1 was infused into the LAD at 60 pmol/min. In another five animals, the LAD was ligated. During the following 40 min, all ventricular arrhythmias were recorded for subsequent analysis. Furthermore, left ventricular conduction times during constant pacing and local effective refractory periods at eight left ventricular sites were determined before and after either intervention. RESULTS: Endothelin-1 had no significant effect on conduction time and refractoriness, whereas ligation prolonged both parameters significantly. Endothelin-1 as well as ligation induced multiple mono- and polymorphic nonsustained ventricular tachycardias. Endothelin-1-induced arrhythmias were exclusively based on focal mechanisms, whereas during ligation, macroreentrant mechanisms were involved in the maintenance of tachycardias in 29% of episodes. CONCLUSION: The differences in the effects of endothelin-1 and LAD ligation on electrophysiologic properties and the difference in the mechanism of induced ventricular tachycardias support the hypothesis that, apart from vasoconstrictive properties, endothelin-1 exerts an intrinsic arrhythmogenic effect. (+info)
Electromagnetic guidance for catheter-based transendocardial injection: a platform for intramyocardial angiogenesis therapy. Results in normal and ischemic porcine models.
(20/507)
OBJECTIVES: To test the feasibility of myocardial angiogenic gene expression using a novel catheter-based transendocardial injection system. BACKGROUND: Angiogenesis has been induced by direct injection of growth factors into ischemic myocardium during open-heart surgery. Catheter-based transendocardial injection of angiogenic factors may provide equivalent benefit without need of surgery. METHODS: A new guidance system for intramyocardial therapy utilizes magnetic fields and catheter-tip sensors to locate a position in space and reconstruct three-dimensional left ventricular (LV) electromechanical maps without using fluoroscopy. A retractable 27G needle was coupled with the guidance system for LV transendocardial injection. In 12 pigs, the catheter was used to inject 0.1 ml of methylene-blue (MB) dye and 8 pigs had myocardial injections of adenoviral vector (1 x 10(10) particles per site) containing the LacZ transgene. Ten pigs underwent catheter-based transendocardial injection and six pigs were injected using transepicardial approach with the gene encoding adenovirus vascular endothelial growth factor-121 (Ad.VEGF121; 1 x 10(10) viral particles x 6 sites) and sacrificed at 24 h. Injection sites were identified with ultraviolet light by coinjection of fluorescent beads. RESULTS: Overall, 138 of 152 attempted injection MB tracks (91%) were found after sacrifice. Tissue staining was 7.1+/-2.1 mm in depth and 2.3+/-1.8 mm in width. No animal had pericardial effusion or tamponade. In Ad.LacZ injected animals, gross pathology showed positive staining in injected zones, and histology confirmed positive myocyte staining. Adenovirus vascular endothelial growth factor-121 injected sites showed high levels of VEGF121 production that was of similar magnitude whether injected using the transendocardial (880.4+/-412.2 pg VEGF121/mg protein) or transepicardial (838.3+/-270 pg VEGF121/mg protein) delivery approach (p = 0.62). CONCLUSIONS: Using this magnetic guidance catheter-based navigational system, transgenes can effectively be transfected into designated myocardial sites. Thus, if it is determined that direct intramyocardial injection of angiogenic factors enhances collateral function in patients, this less invasive catheter-based system offers a similar gene delivery efficiency and, thus, may have clear advantages compared with the surgically-based transepicardial injection approach. (+info)
Body surface mapping of counterclockwise and clockwise typical atrial flutter: a comparative analysis with endocardial activation sequence mapping.
(21/507)
OBJECTIVES: This study was directed at developing spatial 62-lead electrocardiogram (ECG) criteria for classification of counterclockwise (CCW) and clockwise (CW) typical atrial flutter (Fl) in patients with and without structural heart disease. BACKGROUND: Electrocardiographic classification of CCW and CW typical atrial Fl is frequently hampered by inaccurate and inconclusive scalar waveform analysis of the 12-lead ECG. METHODS: Electrocardiogram signals from 62 torso sites and multisite endocardial recordings were obtained during CCW typical atrial Fl (12 patients), CW typical Fl (3 patients), both forms of typical Fl (4 patients) and CCW typical and atypical atrial Fl (1 patient). All the Fl wave episodes were divided into two or three successive time periods showing stable potential distributions from which integral maps were computed. RESULTS: The initial, intermediate and terminal CCW Fl wave map patterns coincided with: 1) caudocranial activation of the right atrial septum and proximal-to-distal coronary sinus activation, 2) craniocaudal activation of the right atrial free wall, and 3) activation of the lateral part of the subeustachian isthmus, respectively. The initial, intermediate and terminal CW Fl wave map patterns corresponded with : 1) craniocaudal right atrial septal activation, 2) activation of the subeustachian isthmus and proximal-to-distal coronary sinus activation, and 3) caudocranial right atrial free wall activation, respectively. A reference set of typical CCW and CW mean integral maps of the three successive Fl wave periods was computed after establishing a high degree of quantitative interpatient integral map pattern correspondence irrespective of the presence or absence of organic heart disease. CONCLUSIONS: The 62-lead ECG of CCW and CW typical atrial Fl in man is characterized by a stereotypical spatial voltage distribution that can be directly related to the underlying activation sequence and is highly specific to the direction of Fl wave rotation. The mean CCW and CW Fl wave integral maps present a unique reference set for improved clinical detection and classification of typical atrial Fl. (+info)
Endocardial mapping of atrial fibrillation in the human right atrium using a non-contact catheter.
(22/507)
BACKGROUND: Endocardial mapping of atrial fibrillation in humans is limited by its low resolution and by complexities in the arrhythmia and atrial anatomy. METHODS AND RESULTS: A catheter mounted non-contact multielectrode was deployed in the right atrium of 11 patients with atrial fibrillation and used to reconstruct 3360 electrograms, superimposed onto a computer-simulated model of the endocardium, using inverse solution mathematics. This allows construction of isopotential maps of the right atrium. Patients had either sustained atrial fibrillation (n=3) for >6 months or developed atrial fibrillation during the study (n=8). Spontaneous initiation of atrial fibrillation was recorded in one patient and was demonstrated by the non-contact system to arise from two successive atrial ectopic beats from the site of a roving contact catheter. Reconstruction of electrograms recorded during atrial fibrillation was validated by comparison with contact electrograms with cross-correlation. During established atrial fibrillation, four patients predominantly had a single right atrial wave front, two had two wave fronts and five patients had three to five wave fronts for most of the time. Periods of electrical silence were seen in the right atrium in eight patients, after which, activity emerged from consistent septal sites alone, suggesting a left atrial origin. During intravenous administration of flecainide, atrial fibrillation in two patients terminated spontaneously or following pacing manoeuvres, while in the remaining patient sinus rhythm was restored via atrial tachycardia. CONCLUSION: Non-contact mapping of the right atrium has demonstrated modes of initiation and termination of atrial fibrillation, characterized different patterns of right atrial activation in atrial fibrillation and suggests that the left atrium may sustain atrial fibrillation in some patients. Simultaneous mapping of the right and left atrium is required to further elucidate the mechanisms of human atrial fibrillation. (+info)
Estimates of repolarization dispersion from electrocardiographic measurements.
(23/507)
BACKGROUND: Repolarization dispersion (Rd) is frequently mentioned as a predictor of cardiac abnormalities. We present a new measure of Rd based on the root-mean-square (RMS) curve of an ECG lead set and compare its performance with that of the commonly used QT dispersion (QTd) measure with the use of recovery times measured from directly recorded canine electrograms. METHODS AND RESULTS: Using isolated, perfused canine hearts suspended in a torso-shaped electrolytic tank, we simultaneously recorded electrograms from 64 epicardial sites and ECGs from 192 "body surface" sites. RMS curves were derived from 4 lead sets: epicardial, body surface, precordial, and a 6-lead optimal set. Repolarization was altered by changing cycle length, temperature, and activation sequence. Rd, calculated directly from recovery times of the 64 epicardial potentials, was then compared with the width of the T wave of the RMS curve and with QTd for each of these 4 lead sets. The correlation between T-wave width and Rd for each lead set, respectively, was epicardium, 0.91; body surface, 0.84; precordial, 0.72; and optimal leads, 0.81. The correlation between QTd and Rd for each lead set was epicardium, 0.46; body surface, 0.47; precordial, 0.17; and optimal leads, 0.11. CONCLUSIONS: RMS curve analysis provides an accurate method of estimating Rd from the body surface. In contrast, QTd analysis provides a poor estimate of Rd. (+info)
Short- and intermediate-term clinical outcomes from direct myocardial laser revascularization guided by biosense left ventricular electromechanical mapping.
(24/507)
BACKGROUND: Direct myocardial revascularization (DMR) has been examined as an alternative treatment for patients with chronic refractory myocardial ischemic syndromes who are not candidates for conventional coronary revascularization. Methods and Results-We used left ventricular electromagnetic guidance in 77 patients with chronic refractory angina (56 men, mean age 61+/-11 years, ejection fraction 0.48+/-0.11) to perform percutaneous DMR with an Ho:YAG laser at 2 J/pulse. Procedural success (laser channels placed in prespecified target zones) was achieved in 76 of 77 patients with an average of 26+/-10 channels (range 11 to 50 channels). The rate of major in-hospital cardiac adverse events was 2.6%, with no deaths or emergency operations, 1 patient with postprocedural pericardiocentesis, and 1 patient with minor embolic stroke. The rate of out-of-hospital adverse cardiac events (up to 6 months) was 2.6%, with 1 patient with myocardial infarction and 1 patient with stroke. Exercise duration after DMR increased from 387+/-179 to 454+/-166 seconds at 1 month and to 479+/-161 seconds at 6 months (P=0.0001). The time to onset of angina increased from 293+/-167 to 377+/-176 seconds at 1 month and to 414+/-169 seconds at 6 months (P=0.0001). Importantly, the time to ST-segment depression (>/=1 mm) also increased from 327+/-178 to 400+/-172 seconds at 1 month and to 436+/-175 seconds at 6 months (P=0.001). Angina (Canadian Cardiovascular Society classification) improved from 3.3+/-0.5 to 2.0+/-1.2 at 6 months (P<0.001). Nuclear perfusion imaging studies with a dual-isotope technique, however, showed no significant improvements at 1 or 6 months. CONCLUSIONS: Percutaneous DMR guided by left ventricular mapping is feasible and safe and reveals improved angina and prolonged exercise duration for up to a 6-month follow-up. (+info)