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Electrophysiological Substrate (electrophysiological + substrate)

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Medical Sciences	100%

Selected Abstracts

A Single Pulmonary Vein as Electrophysiological Substrate of Paroxysmal Atrial Fibrillation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2006
HE 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]

Perioperative Ventricular Arrhythmias in Patients Undergoing Partial Left Ventriculectomy

JOURNAL OF CARDIAC SURGERY, Issue 2 2001
Toshimi Ujiie M.D.
Background: Although incidence of ventricular arrhythmias after partial left ventriculectomy (PLV) has been reported, there are no studies comparing incidence before and after PLV. Although operative scars may give rise to arrhythmias, improved energetic efficiency after PLV may decrease their incidence. Methods: Pre- and postoperative ventricular arrhythmias were monitored by Holter ECG and analyzed in 17 patients undergoing PLV in Curitiba, Brazil. Results: Although total 24-hour heart beat (THB) increased significantly (p = 0.018), ventricular premature contractions (VPCs) decreased markedly (p = 0.036), excluding one patient dying in low cardiac output (LOS) who had terminal arrhythmias increased multifold. In the remaining 16 patients, VPC pairs were also reduced significantly on the average (p = 0.038). In contrast, ventricular tachycardia (VT; more than three consecutive VPCs) disappeared in five patients, decreased in two patients, and newly occurred in four patients, with five patients showing no change; one of them developed a prolonged VT, successfully reversed by external cardioversion. Conclusions: Despite notable significant increase in THB immediately after PLV, PVC and PVC pairs were significantly decreased in contrast to VT, which disappeared in some patients and newly occurred in other patients, remaining constant on the average. Sustained VT occurring in a patient with all other arrhythmias suppressed may suggest a unique electrophysiological substrate, may justify prophylactic use of amiodarone or an implantable cardioverter-defibrillator, and may underscore the importance of further and extended studies. [source]

A Single Pulmonary Vein as Electrophysiological Substrate of Paroxysmal Atrial Fibrillation

Mechanisms of Right Atrial Tachycardia Occurring Late After Surgical Closure of Atrial Septal Defects

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2005
ISABELLE MAGNIN-POULL M.D.
Introduction: In patients without structural heart disease, the most frequently occurring AT is the common atrial flutter. In patients with repaired congenital heart disease other mechanisms of AT may occur, due to the presence of an atriotomy that can provide a substrate for reentry. The aim of the present study was to identify the mechanisms of atrial tachycardia (AT) occurring late after atrial septum defect (ASD) repair, with the help of a three-dimensional electroanatomical mapping system. Methods and Results: Twenty-two consecutive patients presenting with AT underwent complete electroanatomic mapping (CARTO®, Biosense Webster, Diamond Bar, CA) of spontaneously occurring and inducible right ATs. Complete maps of 26 ATs were obtained. Three tachycardia mechanisms were identified: single-loop macroreentrant atrial tachycardia (MAT) (n = 7), double-loop MAT (n = 18), and focal AT (n = 1). In all MATs, protected isthmuses were identified as the electrophysiological substrate of the arrhythmia, most frequently the cavotricuspid isthmus (CTI) (n = 24), and a gap between the inferior vena cava and a line of double potentials (n = 11). A mean number of 13.5 ± 2.1 radiofrequency applications were delivered to transect these critical parts of the circuit. During a follow-up of 25 ± 16 months the RF ablation was acutely successful in all patients. Thirteen patients (59%) had an early recurrence of MAT and needed an additional ablation procedure. One of those patients needed two additional ablation procedures. Conclusions: Three-dimensional electroanatomic mapping is useful to identify postsurgical AT mechanisms; the CTI isthmus is involved in 92% MAT, and if the right atrial free wall (RAFW) abnormal tissue related to surgical scar is present this substrate contributes to the MAT circuit [source]