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Wave Morphology (wave + morphology)
Selected AbstractsDeterioration of Organization in the First Minutes of Atrial Fibrillation: A Beat-to-Beat Analysis of Cycle Length and Wave SimilarityJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2007FLAVIA RAVELLI Ph.D. Introduction: It has been recently suggested that many episodes of atrial fibrillation (AF) may be partially organized at the onset and thus more suitable for antitachycardia pacing therapy. Nevertheless, the time course of organization in the first minutes of AF has not been quantified yet. Methods and Results: Twenty episodes of paroxysmal AF were studied. Electrograms were recorded from the right atrium (RA), distal (CSd), and proximal coronary sinus (CSp). The time course of AF cycle length (AFCL) and the regularity of wave morphology (similarity index S) were beat-to-beat measured at each recording site during the first 7 minutes of AF. AFCL and S showed a decreasing trend after the onset of AF. AFCL decreased from 208 ± 31 to 171 ± 21 msec (P < 0.001), from 206 ± 40 to 169 ± 23 msec (P < 0.001) and from 190 ± 42 to 152 ± 18 msec (P < 0.05), respectively, in RA, CSd, and CSp. Similarly, the similarity index decreased in CSd from 0.37 ± 0.27 to 0.12 ± 0.09 (P < 0.01) and in RA from 0.40 ± 0.18 to 0.17 ± 0.16 (P < 0.001). The 80% of the decrease occurred during the first 3 minutes of the arrhythmia, while after this time both cycle length and similarity index did not change significantly anymore. Conversely, the electrical activity in CSp was highly disorganized (S = 0.05 ± 0.03) even in the first minute of AF, and no decreasing temporal trend was observed. Conclusion: Higher levels of organization and longer fibrillation intervals exist at the onset of AF. The degree of organization of the electrical activity decays within less than 3 minutes. Since antitachycardia pacing success rate increases with high levels of organization, these results suggest an early delivery of pacing treatment. [source] A Single Pulmonary Vein as Electrophysiological Substrate of Paroxysmal Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2006HE HUANG M.D. Introduction: It has been demonstrated that pulmonary veins (PVs) play an important role in initiation and maintenance of paroxysmal atrial fibrillation (AF). However, it is not clearly known whether a single PV acts as electrophysiological substrate for paroxysmal AF. Methods and Results: This study included five patients with paroxysmal AF. All patients underwent complete PV isolation with continuous circular lesions (CCLs) around the ipsilateral PVs guided by a three-dimensional mapping system. Irrigated radiofrequency (RF) delivery was performed during AF on the right-sided CCLs in two patients and on the left-sided CCLs in three patients. The incomplete CCLs resulted in a change from AF to atrial tachycardia (AT), which presented with an identical atrial activation sequence and P wave morphology. Complete CCLs resulted in AF termination with persistent PV tachyarrhythmias within the isolated PV in all five patients. PV tachyarrhythmia within the isolated PV was PV fibrillation from the left common PV (LCPV) in two patients, PV tachycardia from the right superior PV (RSPV) in two patients, and from the left superior PV in one patient. All sustained PV tachyarrhythmias persisted for more than 30 minutes, needed external cardioversion for termination in four patients and a focal ablation in one patient. After the initial procedure, an AT from the RSPV occurred in a patient with PV fibrillation within the LCPV, and was successfully ablated. Conclusion: In patients with paroxysmal AF, sustained PV tachyarrhythmias from a single PV can perpetuate AF. Complete isolation of all PV may provide good clinical outcome during long-term follow-up. [source] Arrhythmogenesis of T Wave Alternans Associated with Surface QRS Complex Alternans and the Role of Ventricular Prematurity: Observations from a Canine Model of LQT3 SyndromeJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2002MASAOMI CHINUSHI M.D. Intramural TWA and Its Arrhythmogenesis.Introduction: T wave alternans (TWA) is characterized by cycle-to-cycle changes in the QT interval and/or T wave morphology. It is believed to amplify the underlying dispersion of ventricular repolarization. The aim of this study was to examine the mechanisms and arrhythmogenesis of TWA accompanied by QRS complex and/or blood pressure (BP) waveform alternans, using transmural ventricular electrogram recordings in an anthopleurin-A model of long QT syndrome. Methods and Results: The cardiac cycle length was gradually shortened by interruption of vagal stimulation, and TWA was induced in six canine hearts. Transmural unipolar electrograms were recorded with plunge needle electrodes from endocardial (Endo), mid-myocardial (Mid), and epicardial (Epi) sites, along with the surface ECG and BP. The activation-recovery interval (ARI) was measured to estimate local refractoriness. During TWA, ARI alternans was greater at the Mid than the Epi/Endo sites, and it was associated with the development of marked spatial dispersion of ventricular repolarization. As TWA increased, ventricular activation of the cycles associated with shorter QT intervals displayed delayed conduction at the Mid sites as a result of a critically longer ARI of the preceding cycle and longer QT interval, while normal conduction was preserved at the Epi site. Delayed conduction at the Mid sites manifested as surface ECG QRS and BP waveform alternans, and spontaneous ventricular tachyarrhythmias developed in absence of ventricular prematurity. In other instances, in absence of delayed conduction during TWA, ventricular premature complexes infringed on a prominent spatial dispersion of ventricular repolarization of cycles with long QT intervals and initiated ventricular tachyarrhythmia. Conclusion: TWA accompanied by QRS alternans may signal a greater ventricular electrical instability, since it is associated with intramural delayed conduction, which can initiate ventricular tachyarrhythmia without ventricular premature complexes. [source] P Wave Duration and Morphology Predict Atrial Fibrillation Recurrence in Patients with Sinus Node Dysfunction and Atrial-Based PacemakerPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2002ANTONIO DE SISTI DE SISTI, A., et al.: P Wave Duration and Morphology Predict Atrial Fibrillation Recurrence in Patients with Sinus Node Dysfunction and Atrial-Based Pacemaker. P wave duration and morphology have never been systematically evaluated as markers of AF in patients with a conventional indication to pacing. This study correlated sinus P wave duration and morphology and the incidence of AF in patients with sinus node dysfunction (SND), previous history of AF before implant, and atrial-based pacemaker. Included were 140 patients (86 men, 54 women; mean age 71.8 ± 10.4 years) with recurrent paroxysmal AF and who received a DDD (128 patients) or AAI (12 patients) pacemaker for SND. Forty-nine patients had structural heart disease. Sinus P wave duration and morphology was evaluated in leads II, III. Twenty-two patients had an abnormal P wave morphology, diphasic (+/-) in 5 and notched (+/+) in 17. The basic pacemaker rate was programmed between 60 and 70 beats/min. Rate responsive function was activated in 65 patients. During a follow-up of 27.6 ± 17.8 months, AF was documented in 87 patients. Forty-four patients developed permanent AF, following at least one episode of paroxysmal AF in 26 cases. Statistical analysis used Cox model regression. Univariate predictors of AF (P < 0.10) were drugs (mean: 2 ± 1.4) and DC shock before pacing (16/140 patients), P wave duration (mean 112.5 ± 24.6 ms), basic pacemaker rate (mean 68 ± 5 beats/min), and drugs in the follow-up (mean 1.2 ± 0.94). Multivariate analysis showed that P wave duration (b = 0.013, s.e. = 0.004; P = 0.003), and drugs before pacing (b = 0.2; s.e.= 0.08; P < 0.01) resulted in a significant independent predictor of AF. Actuarial incidence of patients free of AF at 30 months was 35%: 56% in patients with a P wave < 120 ms, and 13% in those with P wave , 120 ms (P < 0.01 by Score test). Univariate predictors of permanent AF were drugs and DC shock before pacing, left atrial size (mean 39 ± 6 mm), P wave duration, abnormal P wave morphology (22/140 patients), and drugs in the follow-up. Multivariate analysis showed that P wave morphology was the most important predictor of permanent AF (b = - 0.56, s.e.= 0.2; P = 0.008). Incidence of patients free of permanent AF at 30 months was 69%: 74% in patients with normal P wave, compared to 28% in the case of abnormal P wave morphology (P < 0.01). P wave duration and morphology are good markers of postpacing AF recurrence in patients with SND and an atrial-based pacemaker. This observation suggests that intra- and interatrial conduction disturbances be extensively evaluated before implantation, and the indication for atrial resynchronization procedures be reevaluated. [source] | ||||||||||