Three‐Dimensional Noncontact Mapping Defines Two Zones of Slow Conduction in the Circuit of Typical Atrial Flutter

Abstract

The cavotricuspid isthmus (CTI) is a slow conduction area in the circuit of typical atrial flutter. However, conventional methods are limited by the inaccuracy of measurements of distance on the surface of the heart. The aim of the study was to define the conduction properties of the atrial flutter circuit along the tricuspid annulus by using a three-dimensional noncontact mapping system. In 34 atrial flutter patients (30 men, 4 women; mean age 54 +/- 14; 27 counter-clockwise, 4 clockwise, and 3 both), a noncontact multielectrode array was used to reconstruct electrograms in the right atrium. Isochronal and isopotential propagation mapping was performed during atrial flutter. The conduction velocity was calculated by dividing conduction time by surface distance. The right atrium along the tricuspid annulus was divided into five regions: lateral wall, superior right atrium, septum, septal CTI, and lateral CTI. Conduction velocities were 0.99 +/- 0.85, 1.67 +/- 1.21, 1.58 +/- 1.05, 0.82 +/- 0.72, and 1.68 +/- 1.00 m/s in counter-clockwise and 0.81 +/- 0.71, 2.61 +/- 1.90, 1.52 +/- 0.91, 0.91 +/- 0.80 and 1.91 +/- 0.83 m/s in clockwise, respectively. Conduction velocities were significantly slower in the septal CTI and lateral wall than in the lateral CTI, the septum, and the superior right atrium (P < 0.05). No significant difference was found between the septal CTI and the lateral wall. Conduction within the septal CTI was slower in patients treated with antiarrhythmic agents than in untreated patients (P < 0.05). The septal part of the CTI (but not the lateral CTI) and the lateral wall are slow conduction zones in the atrial flutter circuit, and both may, therefore, be mechanically important for the development of atrial flutter.

Electrophysiological Properties of the Right Atrial Septum in Patients with Atrial Tachyarrhythmias

“…However, the septal isthmus between the IVC and TA and lateral wall have been reported to be the slow conduction zones in the atrial flutter circuit using the non-contact mapping system (Chen et al 2003b). In the present study, we noted that the conduction velocity during AFL was significantly lower in the septum, and that there were both transverse and longitudinal conduction delays in addition to the low voltage in the septum in the patients with AFL as compared with those without AFL.…”

Alterations in Electrophysiology and Tissue Structure of the Left Atrial Posterior Wall in a Canine Model of Atrial Fibrillation Caused by Chronic Atrial Dilatation

“…The conduction velocities (CV) at the LAPW, LA anterior wall (LAAW) and LAA were measured as the difference in the activation times over a measurable distance perpendicular to the activation wavefront on the LA geometry, at the center of the regions indicated. 3,11,15 The CV at the RAFW and in the CS was measured as the difference in the activation times over the distance from the distal tip to the proximal end of the lead. The CV was also calculated during atrial premature pacing in the RAA, using an 8-beat pacing train with a basic CL (BCL) of 300 ms followed by 1 premature beat with a pacing interval that was 10 ms longer than the atrial effective refractory period (ERP).…”

“…Noncontact mapping technology can simultaneously record the endocardial activation of the entire chamber in which it is positioned, and has been demonstrated to be ideal for the study of atrial arrhythmias. [10][11][12] The aim of the present study was to use the noncontact mapping system to delineate the electrophysiological (EP) characteristics of the LAPW in a model of AF in dogs with CDLA.…”

Is Isolation of Arrhythmogenic Pulmonary Veins sufficient for The Long-term Efficacy of Atrial Fibrillation Ablation?

“…[20][21][22][23] Anisotropy which, can be defined as lack of shared regional directionality amongst muscle fibers, is commonly observed in the right atrium along the crista terminalis, in the cavo-tricuspid isthmus region, near the coronary sinus ostium / eustachian ridge area, and these locations have frequently been identified as sites of atrial premature complexes and / or atrial tachycardias. [24][25][26] Data from autopsied human hearts has also shown marked tissue anisotropy in the form of complex looping posterior LA musculature encircling individual PV ostia and extending distally along the PV walls where it interdigitates with thevein musculature. 27 Such anisotropy may result in variable conduction velocities and unidirectional blocks that could potentiate wave front fractionation and AF initiation.…”