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Mean Cycle Length (mean + cycle_length)
Selected AbstractsElectrophysiologic and electrocardiographic characteristics of focal atrial tachycardia arising from superior tricuspid annulusINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 7 2008J. X. Yin Summary Objectives:, This study describes the electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia (AT) arising from superior tricuspid annulus in six (1.9%) patients of a consecutive series of 320 patients. Methods:, Six patients (mean age 42 ± 22 years) with a mean cycle length of 326 ms of a consecutive series of 320 patients undergoing radiofrequency ablation for focal AT were mapped. Results:, During electrophysiologic study, tachycardia could be induced in five patients with programmed atrial extrastimuli while a spontaneous onset and offset with ,warm-up and cool-down' phenomenon was seen in the other patient. During tachycardia, P-wave morphology in Lead I, II, III and aVF was upright in all the six patients. The precordial leads were dominantly negative or isoelectric in V1,V2 and positive in V5,V6 with a transition at V3 or V4. Moreover, the tachycardia was sensitive to intravenous administration of adenosine triphosphate in five of six patients. Conclusions:, Radiofrequency ablation was performed successfully in all patients (mean 4.5 ± 1.2 applications). No recurrence of AT was observed after a mean follow-up of 8 ± 6 months. Thus, AT arising from superior tricuspid annulus is rare. Radiofrequency ablation of this kind of AT is safe and effective. [source] Incidence and Clinical Significance of Inducible Atrial Tachycardia in Patients with Atrioventricular Nodal Reentrant TachycardiaJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2001CHRISTIAN STICHERLING M.D. Significance of Atrial Tachycardia.Introduction: The purpose of this prospective study was to determine the prevalence and clinical significance of inducible atrial tachycardia in patients undergoing slow pathway ablation for AV nodal reentrant tachycardia who did not have clinically documented episodes of atrial tachycardia. Methods and Results: Twenty-seven (15%) of 176 consecutive patients who underwent slow pathway ablation for AV nodal reentrant tachycardia were found to have inducible atrial tachycardia with a mean cycle length of 351 ± 95 msec. The atrial tachycardia was sustained in 7 (26%) of 27 patients and was isoproterenol dependent in 20 patients (74%). The atrial tachycardia was not ablated or treated with medications, and the patients were followed for 9.7 ± 5.8 months. Six (22%) of the 27 patients experienced recurrent palpitations during follow-up. In one patient each, the palpitations were found to be due to sustained atrial tachycardia, nonsustained atrial tachycardia, recurrence of AV nodal reentrant tachycardia, paroxysmal atrial fibrillation, sinus tachycardia, and frequent atrial premature depolarizations. Thus, only 2 (7%) of 27 patients with inducible atrial tachycardia later developed symptoms attributable to atrial tachycardia. Conclusion: Atrial tachycardia may be induced by atrial pacing in 15% of patients with AV nodal reentrant tachycardia. Because the vast majority of patients do not experience symptomatic atrial tachycardia during follow-up, treatment for atrial tachycardia should be deferred and limited to the occasional patient who later develops symptomatic atrial tachycardia. [source] Focal Ablation versus Single Vein Isolation for Atrial Tachycardia Originating from a Pulmonary VeinPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 7 2010BRYAN BARANOWSKI M.D. Background: Rapid, disorganized firing from a pulmonary vein (PV) focus may initiate atrial fibrillation. The natural history of PV atrial tachycardia (AT), resulting in a slower, more organized form of firing, is less clear. Furthermore, the optimal therapeutic approach to a PV AT is poorly defined. Objective: This study assessed the characteristics and long-term outcomes of focal ablation versus PV isolation for ATs arising from a single PV. Methods: We reviewed 886 consecutive patients who underwent an AT radiofrequency ablation at our institution from January 1997 through August 2008. Results: Twenty-six patients had focal AT with a mean cycle length of 364 ± 90 ms that arose from within a single PV. Ten patients underwent focal ablation of their AT and 16 patients underwent PV isolation of the culprit vein. All procedures were acutely successful. The average follow-up was 25 months (range 2,90 months). There were three recurrences of AT in patients who underwent a focal ablation. There were no recurrences in patients who underwent targeted PV isolation (P = 0.046). No patients developed atrial fibrillation or AT from another focus during the follow-up period. Conclusion: PV AT can be successfully treated with single vein isolation or focal ablation with a low risk of recurrence or the development of atrial fibrillation. PV isolation may be the preferred approach when the AT focus arises from a site distal to the ostium where targeted ablation could result in phrenic nerve injury or occlusion of a pulmonary venous branch. (PACE 2010; 776,783) [source] High Density Endocardial Mapping of Shifts in the Site of Earliest Depolarization During Sinus Rhythm and Sinus TachycardiaPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4p1 2003TIM R. BETTS BETTS, T.R., et al.: High Density Endocardial Mapping of Shifts in the Site of Earliest Depolarization During Sinus Rhythm and Sinus Tachycardia.Previous mapping studies of sinus rhythm suggest faster rates arise from more cranial sites within the lateral right atrium. In the intact, beating heart, mapping has been limited to epicardial plaques or single endocardial catheters. The present study was designed to examine shifts in the site of the earliest endocardial depolarization during sinus rhythm and sinus tachycardia using high density activation mapping. Noncontact mapping of the right atrium during sinus rhythm was performed on ten anesthetized swine. Recordings were made during sinus rhythm, phenylephrine infusion, and isoproterenol infusion. The hearts were then excised and the histological sinus node identified. The mean minimum and maximum cycle lengths recorded were355 ± 43and717 ± 108 ms. A median of three (range two to five) sites of earliest endocardial depolarization were documented in each animal. With increasing heart rate the site of earliest endocardial depolarization remained stationary until a sudden shift in a cranial or caudal direction, often to sites beyond the histological sinoatrial node. The endocardial shift was unpredictable with considerable variation between animals; however, faster rates arose from more cranial sites(r = 0.46, P = 0.023). There was no difference in the mean cycle length of sinus rhythm originating from specific positions on the terminal crest(r = 0.44, P = 0.17). Cranial sites displayed a more diffuse pattern of early depolarization than caudal sites. In the porcine heart the relationship between heart rate and site of earliest endocardial depolarization shows considerable variation between individual animals. These findings may have implications for clinical mapping and ablation procedures. (PACE 2003; 26[Pt. I]:874,882) [source] Cytologic, hormonal, and ultrasonographic correlates of the menstrual cycle of the New World monkey Cebus apellaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2005R.E. Ortiz Abstract Few reports on the reproductive physiology of Cebus apella have been published. In this study we characterized menstrual cycle events by means of vaginal cytology, ultrasonography (US), and hormonal measurements in serum during three consecutive cycles in 10 females, and assessed the probability that ovulation would occur in the same ovary in consecutive cycles in 18 females. The lengths and phases of the cycles were determined according to vaginal cytology. Taking the first day of endometrial bleeding as the first day of the cycle, the mean cycle length ± SEM was 19.5±0.4 days, with follicular and luteal phases lasting 8.2±0.2 and 11.3±0.4 days, respectively. The follicular phase included menstruation and the periovulatory period, which was characterized by the presence of a large number of superficial eosinophilic cells in the vaginal smear. The myometrium, endometrium, and ovaries were clearly distinguished on US examination. During each menstrual cycle a single follicle was recruited at random from either ovary. The follicle grew from 3 mm to a maximum diameter of 8,9 mm over the course of 8 days, in association with increasing estradiol (E2) serum levels (from 489±41 to 1600±92 pmol/L). At ovulation, the mean diameter of the dominant follicle usually decreased by >20%, 1 day after the maximum E2 level was reached. Ovulation was associated with an abrupt fall in E2, a decreased number of eosinophilic cells, the presence of leukocytes and intermediate cells in the vaginal smear, and a progressive increase in progesterone (P) levels that reached a maximum of 892±65 nmol/L on days 3,6 of the luteal phase. The menstrual cycle of Cebus apella differs in several temporal and quantitative aspects from that in humans and Old World primates, but it exhibits the same correlations between ovarian endocrine and morphologic parameters. Am. J. Primatol. 66:233,244, 2005. © 2005 Wiley-Liss, Inc. [source] Implantable Cardioverter-Defibrillator Shock: Appropriate or Inappropriate?ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2010F.R.C.P.C., Michael A. Nault M.D. A 76-year-old female with a single chamber implantable cardioverter-defibrillator implanted for secondary prevention was referred due to multiple discharges. The device was programmed for ventricular tachycardia (VT) detection at 400 ms, fast VT detection at 280 ms, and ventricular fibrillation detection at 320 ms. Antitachycardia pacing (ATP) during charge was enabled. Interrogation revealed a VT episode with a mean cycle length of 270 ms, which was successfully terminated with ATP during charge. Seconds later, the device delivered a shock. This case illustrates the importance of understanding programming algorithms as part of troubleshooting when facing a scenario of device discharge. Ann Noninvasive Electrocardiol 2010;15(2):181,183 [source] | ||||||||||