Ole Kongstad Rasmussen

Gender Differences in the Electrophysiological Characteristics of Atrioventricular Conduction System and their Clinical Implications

Objective - The underlying mechanisms of the differences in sex distribution of patients with atrioventricular (AV) nodal re-entrant tachycardia and Wolff-Parkinson-White syndrome are poorly understood. The objective of this study was to determine potential gender differences in the electrophysiological properties of the normal AV conduction system that may be attributable to differences in sex distribution. Design - The AV conduction properties were studied in 96 patients (52 men and 44 women) who underwent electrophysiological testing, 32 patients with atrial tachycardia, 39 with idiopathic ventricular tachycardia and 25 with unexplained palpitations or syncope. Results - The AH (83 - 15 ms) and His-ventricular intervals in men (42 - 6 ms) were significantly longer than in women (78 - 14, 38 - 6 ms, p < 0.05, respectively), as was the PR interval (160 - 17 vs 152 - 13 ms, p = 0.02). The effective refractory period of AV node in men (349 - 75 ms) was longer than in women (297 - 45 ms, p = 0.03). However, no significant difference was observed between men and women with respect to the incidence of AV nodal dual pathway and the maximum AH interval achieved during premature stimulation or incremental pacing. The AV block cycle length was significantly longer in men (371 - 76 ms) than in women (330 - 52 ms, p = 0.02). A longer ventriculoatrial block cycle length was also found in men than in women although not at a significant level (436 - 107 vs 384 - 90 ms, p = 0.08). In addition, men (23%) were twice as likely to have ventriculoatrial dissociation during ventricular pacing as women were (11%, p = 0.2). Conclusion - The data show that gender-related differences in AV conduction properties may be responsible for the differences in sex distribution observed in patients with AV nodal re-entrant tachycardia and those with ventricular pre-excitation.OBJECTIVE The underlying mechanisms of the differences in sex distribution of patients with atrioventricular (AV) nodal re-entrant tachycardia and Wolff-Parkinson-White syndrome are poorly understood. The objective of this study was to determine potential gender differences in the electrophysiological properties of the normal AV conduction system that may be attributable to differences in sex distribution. DESIGN The AV conduction properties were studied in 96 patients (52 men and 44 women) who underwent electrophysiological testing, 32 patients with atrial tachycardia, 39 with idiopathic ventricular tachycardia and 25 with unexplained palpitations or syncope. RESULTS The AH (83 +/- 15 ms) and His-ventricular intervals in men (42 +/- 6 ms) were significantly longer than in women (78 +/- 14, 38 +/- 6 ms, p < 0.05, respectively), as was the PR interval (160 +/- 17 vs 152 +/- 13 ms, p = 0.02). The effective refractory period of AV node in men (349 +/- 75 ms) was longer than in women (297 +/- 45 ms, p = 0.03). However, no significant difference was observed between men and women with respect to the incidence of AV nodal dual pathway and the maximum AH interval achieved during premature stimulation or incremental pacing. The AV block cycle length was significantly longer in men (371 +/- 76 ms) than in women (330 +/- 52 ms, p = 0.02). A longer ventriculoatrial block cycle length was also found in men than in women although not at a significant level (436 +/- 107 vs 384 +/- 90 ms. p = 0.08). In addition, men (23%) were twice as likely to have ventriculoatrial dissociation during ventricular pacing as women were (11%, p = 0.2). CONCLUSION The data show that gender-related differences in AV conduction properties may be responsible for the differences in sex distribution observed in patients with AV nodal re-entrant tachycardia and those with ventricular pre-excitation.

Left atrial conduction along the coronary sinus during ectopic atrial tachycardia and atrial fibrillation: a study using correlation function analysis.

Introduction: Correlation function analysis was applied to endocardial electrograms to investigate conduction patterns along the coronary sinus (CS) during sinus rhythm (SR) and atrial tachycardias.

Global dispersion of right atrial repolarization in healthy pigs and patients.

Objective—To investigate the feasibility of monophasic action potential (MAP) mapping using an electroanatomical mapping system (CARTO) in obtaining information on global dispersion of atrial repolarization and to evaluate the role of dispersion of repolarization in the genesis of paroxysmal atrial fibrillation (PAF). Methods and results—Right atrial MAPs were recorded from 53 ± 18 sites in 10 healthy pigs and 33 ± 21 sites in 6 patients with and 4 patients without history of PAF. In pigs, the global dispersions of activation time (AT), MAP duration and end of repolarization time (EOR), 70 ± 8, 95 ± 18 and 121 ± 28 ms, respectively, were significantly greater than those among 10, 20 and 30 sites. In patients with PAF, the global dispersions of MAP duration and EOR (128 ± 10 and 149 ± 31 ms) were significantly greater than those in patients without PAF (84 ± 10 and 91 ± 17 ms). Conclusion—MAP mapping using the CARTO system was feasible in experimental and clinical settings in obtaining information on global dispersion of atrial repolarization. The number of recording sites could significantly affect repolarization parameters. The dispersions of atrial repolarization were significantly greater in patients with PAF than those without, suggesting the involvement of an increased dispersion of repolarization in the genesis of PAF.

Endocavitary treatment of atrial fibrillation.

A cardiac arrhythmia may be permanently cured if the electrophysiological function of any anatomical structure mandatory for the initiation or perpetuation of the arrhythmia is abolished. This easy principle has prompted a rapid development of curative techniques for several different types of cardiac arrhythmias over the last decades. Initially, this principle was thus the prerequisite for the development of arrhythmia surgery, a treatment modality that during recent years almost completely has been replaced by the catheter ablation technique. The mechanisms responsible for initiation and maintenance of atrial ~brillation (AF) are increasingly better understood, although still far from being completely understood. Today’s knowledge does, however, allow catheter ablations aimed at interfering with several different mechanism that have been veri~ed to initiate or perpetuate the arrhythmia. AF may thus develop from several different primary arrhythmias, including atrial _utter, AV-nodal tachycardia, the atrioventricular reciprocating tachycardias of the WPW syndrome, as well as from ectopic atrial tachycardias [1,2]. The perpetuation of AF is pursued by multiple, parallel, interfering re-entering wavelets, a mechanism that was proposed a long time ago and that during the last decade has been veri~ed not only in animal experiments [3], but also in experimentally induced AF in humans [4], as well as during chronic AF in humans [5]. It should be emphasized, however, that chronic AF seems more “deteriorated” than recent-onset AF, a difference that, at least in part, may be explained by several weeks of long-lasting structural and electrophysiological remodeling of the atrial myocardium following the onset of the arrhythmia [6]. Although current knowledge of the mechanisms of initiation and maintenance of AF is far from complete, several different endocardial ablation techniques have been developed aiming at symptom limitation or cure. The main purpose of the present article is to review these endocardial catheter–based methods. An alternative endocardial catheter technique for the prevention of AF is the use of endocardial stimulation by pacemaker. Recent studies have veri~ed the possible use of this principle, and therefore a short description of the different endocardial pacing approaches is also included. His Bundle Ablation