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Updated: Jun 19, 2026

Non-fluoroscopic Catheter Tracking for Fluoroscopy Reduction in Interventional Electrophysiology
Published on: May 26, 2015
Electrophysiological anatomy of typical atrial flutter: the posterior boundary and causes for difficulty with
Apoor S Gami1, William D Edwards, Nirusha Lachman
1Midwest Heart Specialists, Elmhurst, Illinois, USA.
Background:
The electrophysiological anatomy of cavotricuspid isthmus-dependent atrial flutter (CVTI-AFL) has not been fully elucidated.
Methods:
We studied 602 autopsied human hearts from individuals aged 0 to 103 years. We measured morphological features of the right atrium, including the crista terminalis (CT), pectinate muscles, sub-Eustachian pouch, Thebesian valve (TV), and the coronary sinus (CS) ostium.
Results:
In adults, the mean right atrium dimensions were 4.7 cm x 4.5 cm x 4.4 cm. Pectinate muscles extended medial to the CT in 54% of hearts. In 19% of hearts, these ended in another ridge termed the second CT. Pectinate muscles extended into the CVTI in 70% of hearts. A sub-Eustachian pouch was present in 16% of hearts, was always located on the septal CVTI, and was more likely when a prominent TV was also present. A TV, present in 62% of all hearts, covered the inferior quadrant of the CS ostium in 9% of these hearts.
Conclusion:
The posterior boundary of the reentrant circuit of CVTI-AFL comprises the Eustachian ridge and CT, but in some patients may also include a second CT. Sub-Eustachian pouches on the septal CVTI are strongly associated with a prominent TV. The lateral CVTI can have prominent pectinate muscles. This comprehensive characterization of the electrophysiological anatomy of the reentrant circuit of CVTI-AFL may provide guidance and improve success during difficult ablations.
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