Magnetic Electroanatomic Mapping of an Atrial Tachycardia Requiring Ablation Within the Coronary Sinus

Abstract

We describe a focal atrial tachycardia (AT) originating from the region of the inferoposterior mitral annulus in which ablation at the site of earliest endocardial activation during AT was unsuccessful. Three-dimensional electroanatomic mapping identified the earliest atrial activation within the coronary sinus. Radiofrequency energy delivered at this site within the CS terminated this tachycardia without any complications, suggesting an origin within the CS. To our knowledge, this is the first time a three-dimensional, high-density activation map of such a tachycardia has been reported.

Atrial Tachycardia Arising From the Coronary Sinus Musculature

“…First, the LA endocardial maps showed a broad activation pattern compatible with a source emanating from a contiguous structure. This finding was found in two previous case reports (3,5). A unique finding in our study was the observation of dissociation of CS (P) and LA activation in one patient.…”

“…The P-wave in avL in all patients showed an initial positive component followed either by a negative or isoelectric component. These characteristic findings were also noted in the previous case reports (1)(2)(3)(4)(5). In summary, the finding of positive P waves in V 1 and avR associated with negative P waves in inferior leads and a positive P-wave in avL is highly suggestive of AT arising from the CS musculature.…”

“…This observation proves that the potential is independent of the LA and hence localized to the CS muscle. Successful ablation from CS muscle and not from the earliest LA site in three of our patients and in four patients from the literature (1,(3)(4)(5) also supports the notion that the tachycardia originated from the CS musculature. Propagation maps.…”

“…The value of using advanced imaging techniques for these patients is emphasized by the frequency of tachycardia termination with mechanical trauma. The ability to mark early areas allowed for ablation in sinus rhythm in three patients in our series and in two patients (3,5) in the literature. P-wave morphology.…”

“…Radiofrequency catheter ablation (RFCA) of focal AT is achieved by targeting sites of earliest atrial activation that precede the "P-wave" during tachycardia. In the prior case reports of AT requiring RFCA within the CS (1)(2)(3)(4)(5), there is no definitive evidence that the origin of the tachycardia is from CS muscle itself or from atrial muscle bundles in the ligament of Marshall (LOM) or from a part of the LA contiguous to the site of ablation. In addition, there is no data relative to tachycardia mechanism.…”