• Tommie Benjamin posted an update 4 months, 1 week ago

    The exact location of the APs within the cusps is difficult to determine. The majority of studies used coronary angiography, and less commonly electroanatomical mapping. The morphology of local atrial and ventricular electrograms may be additionally used [1,2]. Mapping within the RCC typically shows a large ventricular electrogram, while the atrial electrogram is small and often absent. The largest atrial electrograms are recorded in the NCC. A ventricular signal may or may not be present. Electrograms obtained from the LCC are the most variable of the aortic cusps [19,20]. Intracardiac echocardiography may add important information on this topic. sigma 1 receptor of cardiac computed tomography or magnetic resonance imaging with 3-D electroanatomical mapping may also provide useful anatomical information during catheter ablation.In previous studies, there were no embolic events following RF ablation within the cusps [3–18]. However, based on the clinical experience during ablation of other left sided arrhythmias, a more prudent strategy is to use cooled RF ablation or cryoablation within the aortic cusps in order to minimize the risk of thrombus formation [27].ConclusionConflict of interestIntroductionThe coronary sinus (CS) musculature (CSM), which is electrically connected to both atria, [1,2] plays the important role of synchronizing their activation during sinus rhythm, [3] as well as perpetuating some atrial tachyarrhythmias [4–6]. Since the direction of wavefront propagation across the CSM varies among atrial tachyarrhythmias, its analysis and elucidation is a critical step toward an accurate interpretation of their mechanisms. For example, during atrioventricular (AV) reentrant tachycardia (RT) utilizing a left-sided AV accessory pathway (AP), the wavefront propagates via a left atrial (LA) connection into and through the CSM toward the right atrium, whereas during typical counterclockwise (CCW) atrial flutter (AFL), the wavefront propagates into and through the CSM in a right atrial (RA) → LA direction (Fig. 1).A multipolar electrode catheter is usually needed during electrophysiological studies and ablation procedures in order to record the activation sequence from inside the CS. Because of the multiple muscle bundles connecting the CSM and LA, [2] the activation of the CSM and adjacent LA myocardium appears simultaneously. However, we previously found that, in patients whose LA-CSM connections are particularly weak, the far-field LA activation during retrograde conduction over a left-sided AP only, was separated from the near-field activation of the CSM on the CS recordings [7]. If the activation sequence of LA and CSM could be analyzed on the CS recordings of the general population, regardless of differences in conductive properties between LA and CSM, it could be used as an electrophysiological marker of the wavefront propagating across the CSM. Therefore, the present study was conducted to verify our hypothesis that (1) the far-field LA potential recorded in the CS is universally visible in the general population, and (2) the activation sequence of the LA and CSM potentials reflects the direction of impulse propagation over the CSM.Material and methodsWe studied 19 patients (51±18 years old, 12 men) presenting with AVRT utilizing a left-sided AP, and 21 patients (67±11 years old, 18 men) presenting with CCW AFL, who all underwent successful catheter ablation. All of ablation procedures were performed from a submitral approach, confirming the presence of an AP. As briefly mentioned earlier, during AVRT utilizing a left-sided AP, the wavefront, after retrograde conduction over the AP, propagates via LA → CSM connections into and through the CSM in a LA → RA direction, and reaches the RA via the ostium of the CS. During typical CCW AFL, the wavefront rotating around the tricuspid annulus propagates via the ostium of the CS into and through the CSM in a RA → LA direction and reaches the LA via CSM → LA connections. Thus, the wavefront across the interatrial connection at the CS propagates in a left → right direction during ongoing AVRT and in a right → left direction during typical AFL (Fig. 1).

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