Franz Xaver Roithinger

Use of Electroanatomic Mapping to Delineate Transseptal Atrial Conduction in Humans

BACKGROUND Interaction between wave fronts in the right and left atrium may be important for maintenance of atrial fibrillation, but little is known about electrophysiological properties and preferential routes of transseptal conduction. METHODS AND RESULTS Eighteen patients (age 44+/-12 years) without structural heart disease underwent right atrial electroanatomic mapping during pacing from the distal coronary sinus (CS) or the posterior left atrium. During distal CS pacing, 9 patients demonstrated a single transseptal breakthrough near the CS os, 1 patient in the high right atrium near the presumed insertion of Bachmanns bundle and 1 patient near the fossa ovalis. The mean activation time from stimulus to CS os was 48+/-15 ms compared with 86+/-15 ms to Bachmanns bundle insertion (P<0.01) and 59+/-23 ms to the fossa ovalis (P=NS and P<0.01, respectively). During left atrial pacing, the earliest right atrial activation was near Bachmanns bundle in 5 and near the fossa ovalis in 4 patients. The activation time from stimulus to CS os was 70+/-15 ms compared with 47+/-16 ms to Bachmanns bundle (P<0.01) and 59+/-25 ms to the fossa ovalis (P=NS). Whereas the total septal activation time was not significantly different during CS pacing compared with left atrial pacing (41+/-16 versus 33+/-17 ms), the total right atrial activation time was longer during CS pacing (117+/-49 versus 79+/-15 ms; P<0.05). CONCLUSIONS Three distinct sites of early right atrial activation may be demonstrated during left atrial pacing. These sites are in accord with anatomic muscle bundles and may have relevance for maintenance of atrial flutter or fibrillation.

Organized activation during atrial fibrillation in man: endocardial and electrocardiographic manifestations.

Atrial Fibrillation Organization. Introduction: Atrial fibrillation is not entirely random, but little is known about the spatiotemporal endocardial organization and its surface ECG manifestations.

Body surface mapping of counterclockwise and clockwise typical atrial flutter: a comparative analysis with endocardial activation sequence mapping.

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.

The Effect of the Atrial Pacing Site on the Total Atrial Activation Time

ROITHINGER, F.X., et al.: The Effect of the Atrial Pacing Site on the Total Atrial Activation Time. The effect of dual site pacing for prevention of atrial fibrillation may be due to synchronization of right and left atrial activation. Little is known, however, about the effect of pacing from single right atrial sites on differences in interatrial conduction. Twenty‐eight patients without structural heart disease were studied following radiofrequency catheter ablation of supraventricular arrhythmias. Pacing was performed using standard multipolar catheters from the presumed insertion site of Bachmanns bundle, the coronary sinus ostium, the high lateral right atrium, and the right atrial appendage (n = 8 patients). Bipolar recording was performed from the distal coronary sinus, the high and low lateral right atrium, and the posterolateral left atrium (n = 13 patients). The longest conduction time from each pacing to each recording site was considered the total atrial activation time for the respective pacing site. During high right atrial pacing, the total atrial activation time was determined by the conduction to the distal coronary sinus (118 ± 18 ms), during coronary sinus ostium pacing by the conduction to the high right atrium (94 ± 18 ms), and during Bachmanns bundle pacing by the conduction to the distal coronary sinus (74 ± 18 ms). The total atrial activation time was signifiantly shorter during pacing from Bachmanns bundle, as compared to pacing from other right atrial sites. Thus, in normal atria, pacing from the insertion of Bachmanns bundle causes a shorter total atrial activation time and less interatrial conduction delay, as compared to pacing from other right atrial sites. These findings may have implications for alternative pacing sites for prevention of atrial fibrillation.

Electrophysiologic Effects of Selective Right versus Left Atrial Linear Lesions in a Canine Model of Chronic Atrial Fibrillation

Mapping of Atrial Fibrillation. Introduction: Long linear lesions have been shown to eliminate atrial fibrillation in animal models, but little is known about the electrophysiologic response in one atrium to lesions in the contralateral atrium.

The Influence of High Versus Normal Impedance Ventricular Leads on Pacemaker Generator Longevity

As pacemaker generator longevity is dependent on current consumption and resistance of the pacing lead, the use of a high impedance pacing lead theoretically results in an extension of battery longevity. Therefore, the effect of high versus standard impedance ventricular leads on generator longevity was studied. In 40 patients (21 women, age 73 ± 13 years) with a standard dual chamber pacemaker indication, a bipolar standard impedance ventricular lead was implanted in 20 patients, the remaining patients received a bipolar high impedance lead in a randomized fashion. All patients received identical pacemaker generators and atrial leads. The estimated longevity of the generator was calculated automatically by a programmed pacemaker algorithm. After a mean follow‐up of 39 ± 4.8 months, no significant differences were observed with respect to mean pacing and sensing thresholds of the atrial and ventricular leads in both groups. However, the high impedance leads displayed a significantly higher impedance and a significantly lower current drain as compared to standard impedance leads (1,044 ± 139 vs 585 ± 90 Ω, and 2.2 ± 0.4 vs 4.3 ± 1.1 mA). The extrapolated generator longevity was significantly longer in the high impedance lead group, as compared to the standard impedance lead group (107.3 ± 8.5 vs 97.6 ± 9.0 months; P = 0.02). In conclusion, implantation of a high impedance lead for ventricular pacing results in a clinically relevant extension of generator longevity. (PACE 2003; 26:2116–2120)

The spatial dispersion of atrial refractoriness and atrial fibrillation vulnerability

The local dispersion of conduction and refractoriness has been considered essential for induction of atrial arrhythmias. This study sought to determine whether a difference of refractoriness and vulnerability for induction of atrial fibrillation between trabeculated and smooth as well as high and low right atrium may contribute to initiation of atrial fibrillation in dogs.In 14 healthy mongrel dogs weighing 22.4 ± 1 kg, closed-chest endocardial programmed stimulation was performed from four distinct right atrial sites. Atrial refractory periods and vulnerability for induction of atrial fibrillation or premature atrial complexes were determined during a basic cycle length of 400 and 300 ms and an increasing pacing current strength.For a pacing cycle length of 300ms, atrial refractory periods were longer on the smooth, as compared to the trabeculated right atrium (102 ± 25 vs. 97 ± 17ms, p < 0.05), whereas for a pacing cycle length of 400ms, there was no significant difference. The duration of the vulnerability zone for induction of atrial fibrillation was longer on the smooth right atrium, for a cycle length of both 400 ms (40 ± 30 vs. 31 ± 22 ms; p < 0.05) and 300 ms (33 ± 25 vs. 23 ± 21 ms; p < 0.01). When comparing high and low right atrium, refractory periods were longer on the the low right atrium, for a cycle length of both 400 ms (111 ± 23 vs. 94 ± 24ms; p < 0.01) and 300 ms (104 ± 20 vs. 96 ± 23ms; p < 0.01). For a pacing cycle length of 300 ms, the duration of the atrial fibrillation vulnerability zone was longer for the high, as compared to the low right atrium (34 ± 22 vs. 22 ± 22, p < 0.01). Seven dogs with easily inducible episodes of atrial fibrillation demonstrated significantly shorter refractory periods as compared to 7 non-vulnerable dogs, regardless of pacing site and current strength.In conclusion, significant differences in refractoriness and vulnerability for induction of atrial fibrillation can be observed in the area of the crista terminalis in healthy dogs. Thus, local anatomic factors may play a role in the initiation of atrial fibrillation.

Novel Catheter Technology for Ablative Cure of Atrial Fibrillation

Atrial ~brillation (AF) is the most common sustained arrhythmia in clinical practice. It affects approximately 2,000,000 Americans with 160,000 new cases per year. Drug therapy can be associated with a number of untoward effects such as proarrhythmia, long term inef~cacy and even an increase in mortality, especially in those with impaired ventricular function [1,2]. Catheter ablation of the atrioventricular node with pacemaker implantation [3,4], or modi~cation of the AV node without pacer implantation [5,6] can be useful to facilitate ventricular rate control, but thromboembolic risk is unchanged and atrial systole is not restored. Given the limitations of medical therapy, repeated cardioversions and atrioventricular conduction ablation, an approach that cures atrial ~brillation would be highly desirable. At the present time, catheter-based cure of atrial ~brillation must be considered highly investigational. Nevertheless, because the clinical need for better therapy of atrial ~brillation is so vast, there are a number of on-going efforts to develop devices and techniques for atrial ablation in order to effectively restore sinus rhythm and atrial mechanical contraction. Do we need a cure for atrial ~brillation? Certainly, given the problems with drug treatment and the impact on quality of life, a cure would be highly desirable, and efforts to create such a cure well rewarded. In the history of electrophysiologic intervention, there are many examples in which a cycle of clinical science and new interventional techniques has been demonstrated. That is, we start with a given hypothesis of arrhythmia mechanism or substrate, we intervene to alter what we believe to be the substrate (with surgery, or with catheter-based techniques), in the process of intervention we have an opportunity to garner further, more accurate insights into mechanism and substrate and to develop subsets of what we has thought was a single disorder, and this in turn allows us to develop better interventional tools and techniques. For example, all regular narrow complex tachycardias used to go by the moniker of “PAT.” First with surgery, and then with catheter-based techniques, we came to be able to discern that “PAT” may actually be one of several speci~c arrhythmia substrates such as WPW, AV nodal reentry, etc. In the era of catheter ablation, we can now even describe three or more types of AV nodal reentry. So, too, our ability to intervene on patients with atrial ~brillation has just begun to allow us to develop more detailed descriptions of mechanism. “Atrial ~brillation” as such may come to be recognized as the common surface manifestation of multiple potential mechanisms. This will allow us to develop tools and techniques that are more directly targeted to a given mechanism. In the case of atrial ~brillation this will be particularly important, since if one considers the current “gold standard” for curative intervention to be the extensive lesions produced during the Cox surgical maze operation, then recognition of AF mechanisms that require a less extensive lesion set would be highly desirable. Recently, it has come to be understood that the initiating event in many cases of AF is a “focal trigger” arising in the vast majority of cases from within one of the pulmonary veins [7]. The purpose of the present paper is to brie_y describe early progress towards the development of a novel technology addressing this particular class of AF mechanism.

Electrocardiographic Analysis of Ectopic Atrial Activity Obscured by Ventricular Repolarization: P Wave Isolation Using an Automatic 62-Lead QRST Subtraction Algorithm

62‐Lead QRST Subtraction Algorithm. Introduction: Atrial activity on the surface ECG during premature beats and supraventricular arrhythmias frequently is obscured by the superimposed QRST complex of the previous cardiac cycle. This study examines the performance of a newly developed automatic QRST subtraction algorithm to isolate ectopic P waves from the preceding T‐U wave.

What is the Relationship of Atrial Flutter and Fibrillation

Animal models and human studies of atrial activation mapping and entrainment have considerably enhanced our understanding of the anatomical substrate for atrial flutter and created the basis for a definite cure with radiofrequency catheter ablation. As atrial flutter has now become a curable arrhythmia, emphasis is shifting to understand the most common arrhythmia: atrial fibrillation. Furthermore, from clinical observation, it is apparent that there is a relationship between atrial fibrillation and atrial flutter in patients with atrial arrhythmias. Techniques that have informed our understanding of the anatomical basis of atrial flutter may also be useful in understanding the relationship between atrial fibrillation and flutter, including animal models, clinical endocardial mapping, and intracardiac anatomical imaging. Thus, atrial anatomy and its relationship to electrophysiological findings, and the role of partial or complete conduction barriers around which reentry can and cannot occur, may be of importance for atrial fibrillation as well. Ultimately, the relationship between atrial fibrillation and atrial flutter may inform our understanding of the mechanisms of atrial fibrillation itself, and help to develop new approaches to device, catheter‐based, and pharmacological therapy for atrial fibrillation.