Arne SippensGroenewegen

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.

Clinical and electrophysiologic characteristics of left septal atrial tachycardia.

OBJECTIVES It was the purpose of this study to define the electrophysiologic (EP) identity of left septal atrial tachycardia (AT). BACKGROUND The clinical and EP characteristics of this particular type of arrhythmia have not been fully described. METHODS A total of 120 patients with AT underwent invasive EP evaluation. Five patients (two men and three women; mean age 49 +/- 15 years) with left septal AT were identified. Mapping of the right and left atrium was performed using conventional electrode catheters (five patients) and a three-dimensional electroanatomic mapping system (three patients) followed by radiofrequency (RF) ablation at the earliest site of local endocardial activation. RESULTS Five tachycardias with a mean cycle length of 320 +/- 94 ms were mapped, and the earliest endocardial electrogram occurred 22 +/- 10 ms before the onset of the surface P-wave. Three left septal ATs were found to be originating from the left inferoposterior atrial septum and two from the left midseptum. During tachycardia, positive (three patients), biphasic negative-positive deflection (one patient), or isoelectric (one patient) P waves were recorded in lead V(1). The inferior leads demonstrated a positive or biphasic P-wave morphology in four of five patients (80%). Four patients were given both adenosine and verapamil during AT. In three of four patients, verapamil successfully terminated AT after adenosine had failed. Adenosine successfully terminated AT in one of four patients. Successful RF ablation was performed in all patients (mean 2.2 +/- 1.7 RF applications) without affecting atrioventricular conduction properties. No recurrence of AT was observed after a mean follow-up of 14 +/- 8 months. CONCLUSION Left septal AT ablation is safe and effective. There was no consistent P-wave morphology associated with this particular type of AT. This arrhythmia appears to be resistant to adenosine and moderately responsive to calcium antagonists.

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.

Association of Left Ventricular Remodeling and Nonuniform Electrical Recovery Expressed by Nondipolar QRST Integral Map Patterns in Survivors of a First Anterior Myocardial Infarction

BACKGROUND Progressive left ventricular dilatation after myocardial infarction is associated with a high mortality rate, the majority of which is arrhythmogenic in origin. The underlying mechanism of this relation remains unknown. It has been suggested, however, that left ventricular dilatation is accompanied by changes in repolarization characteristics that may facilitate the occurrence of life-threatening ventricular arrhythmias. METHODS AND RESULTS We examined 62-lead body surface QRST integral maps during sinus rhythm in 78 patients at 349 +/- 141 days after thrombolysis for a first anterior myocardial infarction. Visual map analysis was directed at discriminating dipolar (uniform repolarization) from nondipolar (nonuniform repolarization) patterns. In addition, the nondipolar content of each map was assessed quantitatively with the use of eigenvector analysis. Nondipolar map patterns were present in almost one third of the patients (32%). Left ventricular end-systolic and end-diastolic volumes were assessed echocardiographically before discharge and after 3 and 12 months with the use of the modified biplane Simpson rule. The increase in left ventricular end-systolic volume 1 year after myocardial infarction was more pronounced in patients with nondipolar QRST integral map patterns (14.47 +/- 14.10 versus 4.22 +/- 8.44 mL/m2, P = .017). In patients with an increase in end-systolic volume of more than 16 mL/m2 (upper quartile), the prevalence of nondipolar maps was 89% compared with 29% in patients with dilatation of less than 16 mL/m2. In addition, the nondipolar content of maps in patients in the upper quartile was significantly increased compared with the lower quartiles (49 +/- 14% versus 37 +/- 12%, P = .013). Logistic regression analysis revealed that an end-systolic volume of more than 42 mL/m2 after 1 year contributed independently to the appearance of nondipolar maps. Patients with high-grade ventricular arrhythmias showed a higher nondipolar content (49 +/- 17% versus 39 +/- 10%, P = .013). QTc dispersion did not discriminate between patients with and those without high-grade ventricular arrhythmias. Also, the association between left ventricular remodeling and nondipolar map patterns was confirmed prospectively in an additional group of 15 patients. CONCLUSIONS Nondipolar map patterns are present in 32% of patients after thrombolysis for a first anterior myocardial infarction and are associated with increased left ventricular dilatation. These data support the hypothesis that left ventricular dilatation after myocardial infarction leads to changes in repolarization characteristics that may facilitate the occurrence of life-threatening ventricular arrhythmias.

Automatic QRS onset and offset detection for body surface QRS integral mapping of ventricular tachycardia

A QRS onset and offset detection algorithm has been developed for use in body surface QRS integral mapping of ventricular tachycardia. To determine QRS intervals, the algorithm uses two computed signals: the sum of the absolute values of the first derivatives of all leads and the sum of the absolute values of all leads. The second order derivative of the latter parameter is used to detect the time instants of QRS onset and offset. Using the algorithm, QRS integral maps are subsequently computed, which are correlated with a database of QRS integral maps in order to localize the site of origin of ventricular tachycardia. Comparison of the performance of the algorithm with visual evaluation by a human expert in this procedure revealed, in 95% of the cases, an identical or adjacent localization of the site of origin.<<ETX>>

Electrocardiographic identification of abnormal ventricular depolarization and repolarization in patients with idiopathic ventricular fibrillation

OBJECTIVES We sought to gain more insight into the arrhythmogenic etiology of idiopathic ventricular fibrillation (VF) by assessing ventricular depolarization and repolarization properties by means of various electrocardiographic (ECG) techniques. BACKGROUND Idiopathic VF occurs in the absence of demonstrable structural heart disease. Abnormalities in ventricular depolarization or repolarization have been related to increased vulnerability to VF in various cardiac disorders and are possibly also present in patients with idiopathic VF. METHODS In 17 patients with a first episode of idiopathic VF, 62-lead body surface QRST integral maps, QT dispersion on the 12-lead ECG and XYZ-lead signal-averaged ECGs were computed. RESULTS All subjects of a healthy control group had a normal dipolar QRST integral map. In patients with idiopathic VF, either a normal dipolar map (29%,), a dipolar map with an abnormally large negative area on the right side of the thorax (24%) or a nondipolar map (47%) were recorded. Only four patients (24%) had increased QT dispersion on the 12-lead ECG and late potentials could be recorded in 6 (38%) of 16 patients. During a median follow-up duration of 56 months (range 9 to 136), a recurrent arrhythmic event occurred in 7 patients (41%), all of whom had an abnormal QRST integral map. Five of these patients had late potentials, and three showed increased QT dispersion on the 12-lead ECG. CONCLUSIONS In patients with idiopathic VF, ventricular areas of slow conduction, regionally delayed repolarization or dispersion in repolarization can be identified. Therefore, various electrophysiologic conditions, alone or in combination, may be responsible for the occurrence of idiopathic VF. Body surface QRST integral mapping may be a promising method to identify those patients who do not show a recurrent episode of VF.

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.

Continuous localization of cardiac activation sites using a database of multichannel ECG recordings

Monomorphic ventricular tachycardia and ventricular extrasystoles have a specific exit site that can be localized using the multichannel surface electrocardiogram (EGG) and a database of paced ECG recordings. An algorithm is presented that improves on previous methods by providing a continuous estimate of the coordinates of the exit site instead of selecting one out of 25 predetermined segments. The accuracy improvement is greatest, and most useful, when adjacent pacing sites in individual patients are localized relative to each other. Important advantages of the new method are the objectivity and reproducibility of the localization results.

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.

Body surface mapping of atrial arrhythmias: Atlas of paced p wave integral maps to localize the focal origin of right atrial tachycardia☆

Abstract Successful curative treatment of right atrial tachycardia (AT) can be obtained provided detailed catheter activation mapping of the target site for radiofrequency energy application has been accomplished. However, right AT mapping may be difficult with a single roving catheter due to infrequent presence or noninducibility of the arrhythmia. The present report describes the preliminary clinical use of body surface mapping as an adjunctive noninvasive method to identify the region of AT origin prior to catheter ablation. This technique has been previously applied to develop a reference data base of 17 different paced P wave integral map patterns. The data base was designed by performing right atrial pace mapping in patients without structural heart disease. Each P wave integral map pattern in the data base is unique to ectopic activation onset in a circumscribed right atrial endocardial segment. Localization of the segment of AT origin is accomplished by matching the P wave integral map of a single AT beat with the data base of paced P wave integral maps. The use of body surface mapping as an integral part of the mapping protocol during radiofrequency catheter ablation of right AT offers the possibility to: (1) noninvasively determine the arrhythmogenic target area for ablation using a single beat analysis approach; (2) confine detailed catheter activation mapping to a limited area; and (3) accelerate the overall procedure and limit fluoroscopic exposure by reducing the time required for mapping.