Sinus of Valsalva Origin of Atrial Tachycardia
Abstract & Commentary
By John P. DiMarco, MD, PhD
Source: Liu X, et al. Atrial tachycardia arising from the noncoronary aortic sinus. Distinctive atrial activation patterns and anatomic insights. J Am Coll Cardiol. 2010; 56:796-804.
In this report, Liu and colleagues describe the electrophysiologic characteristics of atrial tachycardias (AT) that arise from the noncoronary aortic sinus (NCAS). The authors performed atrial 3D electroanatomic mapping in 13 patients with NCAS-AT and compared the results with those from a reference group of patients undergoing pulmonary vein isolation for paroxysmal atrial fibrillation (PAF). Detailed imaging of the NCAS was performed in the PAF patients, and selected autopsy specimens were examined to determine the anatomy of the region. In the NCAS-AT patients, electroanatomic mapping of both right and left atria and the aortic root were performed and the earliest activation sites during AT determined. The activation sequence through the atria was then compared to that seen during unipolar pacing in the reference group. Anatomic imaging was performed with a dual-source CT scanner after contrast injection.
During NCAS-AT, the P wave in lead 1 was isoelectric in 10/13 patients. It was slightly positive, or isoelectric in lead aVL, in 13/13 patients. In lead V1, the P wave was biphasic (negative to positive) in 11 patients and positive in the remaining two patients. Sustained NCAS-AT could be initiated and terminated with programmed atrial stimulation in all patients. In the right atrium, the earliest atrial activation was seen in the para-Hisian region during tachycardia. In the left atrium, the earliest activation was in the anteroseptal region. Right-atrial and left-atrial activation could precede the surface P wave by 23 + 3 m/sec and 20 + 2 m/sec in the right and left atria, respectively. However, atrial electrograms in the NCAS were 37 + 3 m/sec earlier than the P wave in the NCAS and were 6-22 m/sec ahead of right or left atrial activity in the same patient. Initial activation during NCAS-AT spread in a diffuse pattern in the atria. Once the earliest site of atrial activation in the NCAS was identified, radiofrequency (RF) ablation was uniformly successful. The initial RF application was successful in 12/13 patients.
CT images showed that the NCAS was adjacent to the paraseptal wall of both atria but in slightly closer proximity to the right atrium. Histological sections through the NCAS did not show atrial cells, with the NCAS itself suggesting that the tachycardia foci were in the adjacent atrial wall. The authors conclude that NCAS-AT is a distinct entity with characteristic electrophysiologic features explained by its anatomic site of origin.
Commentary
It has only recently been recognized that some atrial tachycardias can be mapped to, and ablated from, the noncoronary aortic sinus. This entity is particularly important to recognize. If one persists in mapping and ablation in the right atrium only, there are significantly increased risks for either damage to the AV conduction system and AV block or perforation. We have now taken the approach of placing a recording catheter in the NCAS early in the case whenever a tachycardia appears to be arising from the superior right para-Hisian region. We do this often before any ablation lesions are placed. If early activation in the NCAS is demonstrated, we can avoid placing unnecessary lesions in a high-risk area. If the activation in the NCAS is late, we then usually proceed with cryoablation rather than RF. Although this approach requires arterial access, the added step can often reduce procedure time and the risk for complications.
In this report, Liu and colleagues describe the electrophysiologic characteristics of atrial tachycardias (AT) that arise from the noncoronary aortic sinus (NCAS).You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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