Radiofrequency catheter ablation within the coronary sinus eliminates a macro-reentrant atrial tachycardia: importance of mapping in the coronary sinus

Anomalies of the Coronary Sinus and Its Tributaries: Evaluation on Multidetector Computed Tomography Angiography

Imaging of the coronary sinus and its tributaries has gained increasing significance consequent to the development of an array of electrophysiological and interventional procedures using the cardiac venous system, including ablation for arrhythmias, left ventricular pacing, and in the administration of retrograde cardioplegia. Knowledge of the normal anatomy and the possible anomalies and their clinical significance is imperative to circumvent possible complications. A number of coronary sinus (CS) anomalies, both symptomatic and asymptomatic, have been observed with the widespread use of noninvasive cross-sectional imaging for the imaging of the heart. However, it should be kept in mind that even clinically occult lesions of the CS can cause disastrous complications in specific interventions. Hence, a thorough knowledge of the expected anatomy and the possible anomalies involving the CS along with their clinical significance is imperative for the reporting radiologists and the concerned physicians. In this review, we briefly describe the relevant anatomy and embryology and describe the gamut of anomalies pertaining to the CS and its draining veins on multidetector computed tomography angiography along with their clinical importance.

Association of Rate-Dependent Conduction Block Between Eccentric Coronary Sinus to Left Atrial Connections With Inducible Atrial Fibrillation and Flutter

BACKGROUND

We sought to describe the prevalence and variability of coronary sinus (CS) and left atrial (LA) myocardium connections, their susceptibility to rate-dependent conduction block, and association with atrial fibrillation (AF) and flutter induction.

METHODS AND RESULTS

The study cohort included 30 consecutive AF patients (age 63.3±10.5 years, 63% male). Multipolar catheters were positioned in the CS, high right atrium (HRA), and LA parallel to and near the CS. Trains of 10 pacing stimuli were delivered during sinus rhythm from each of the following sites: CS proximal (CSp), CS distal (CSd), LA septum (LAs), lateral LA (LAl), and HRA, at the following cycle lengths: 1000, 500, 400, 300, and 250 ms, while recording from the other catheters. With the CS 9 to 10 bipole just inside the CS ostium, CS-LA connections were observed in 100% at CS 9 to 10, 30% at CS 7 to 8, 23% at CS 5 to 6, 23% at CS 3 to 4, and 97% at CS 1 to 2. Eighteen patients (60%) had AF/atrial flutter induced. Rate-dependent conduction block of a CS-LA connection at cycle length of ≥250 ms was present in 17 (94%) of those with versus none of those without AF/atrial flutter induction (P<0.001).

CONCLUSIONS

Rate-dependent eccentric CS-LA conduction block is associated with AF/atrial flutter induction in patients with drug-refractory AF undergoing ablation. The presence of dual muscular CS-LA connections, coupled with unidirectional block in one limb, seems to serve as a substrate for single or multiple reentry beats, and arrhythmia induction.

The role of coronary sinus musculature in the induction of atrial fibrillation

BACKGROUND

Coronary sinus (CS) musculature connects the right atria (RA) and the left atria (LA). However, the functional significance of the electrical junctions between the atria and the CS musculature is still unclear.

OBJECTIVE

We investigated electrophysiological properties of the CS-atrial connections and their role in atrial fibrillation.

METHODS

By using an optical mapping system, we mapped action potentials at 256 sites on the epicardial surface of 16 isolated and arterial-perfused canine atrial tissues containing the entire musculature of the CS, lower RA, posterior LA, left inferior pulmonary vein, and vein of Marshal. We paced from each of the above regions to measure electrophysiological properties and inducibility of atrial tachyarrhythmias.

RESULTS

The CS musculature connected to the RA at the ostium of the CS and to the LA at proximal and distal CS sites. Electrical conduction across each of these CS-atrial junctions was slow (P < .01), but not decremental. Rapid pacing often induced entrance block at the CS-atrial junctions and resulted in sequential changes of activation sequence in the CS. Macroreentrant circuit involving the CS musculature and the CS-atrial junctions occurred in association with conduction block at these junctions. The reentrant circuit was usually unstable and resulted in atrial fibrillation-like electrocardiographic activity.

CONCLUSIONS

The anatomical and electrical connections between the CS musculature and the RA and the LA caused conduction slowing and block in the CS musculature and its atrial junctions, which frequently initiated unstable macroreentry and atrial fibrillation.

Centrifugal gradients of rate and organization in human atrial fibrillation

INTRODUCTION

Animal studies show that atrial fibrillation (AF) may emanate from sites of high rate and regularity, with fibrillatory conduction to adjacent areas. We used simultaneous mapping to find evidence for potential drivers in human AF defined as sites with higher rate and regularity than surrounding tissue.

MATERIALS AND METHODS

In 24 patients (age 61+/-10 years; 12 persistent), we recorded AF simultaneously from 32 left atrial bipolar basket electrodes in addition to pulmonary veins (PV), coronary sinus, and right atrial electrodes. We measured AF cycle length (CL) by Fourier transform and electrogram regularity at each electrode, referenced to patient-specific atrial anatomy.

RESULTS

We analyzed 10,298 electrode-periods. Evidence for potential AF drivers was found in 11 patients (five persistent). In persistent AF, these sites lay at the coronary sinus and left atrial roof but not PVs, while in paroxysmal AF six of nine sites lay at PVs (P<0.05). During ablation, a subset of patients experienced AF CL prolongation or termination with a focal lesion; in each case this lesion mapped to potential driver sites on blinded analysis. Conversely, sequential mapping failed to reveal these sites, possibly due to fluctuations in dominant frequency at driver locations in the context of migratory AF.

CONCLUSIONS

Simultaneous multisite recordings in human AF reveal evidence for drivers that lie near PVs in paroxysmal but not persistent AF, and were sites where ablation slowed or terminated AF in a subset of patients. The future work should determine if real-time ablation of AF-maintaining regions defined in this fashion eliminates AF.