Necropsy study of right atrial appendage: Morphology and quantitative measurements

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Abstract
The right atrial appendage (RAA) of 23 randomly selected autopsied patients was examined at necropsy, and data related to orifice size and appendicular depth measurements and features of the endocardial surface were recorded. The study included 21 men and 2 women aged 71 ± 15 years (range, 32‐91); underlying coronary artery disease was present in 16 patients. The orifice size of the RAA measured 2.0± 1.0 cm (range, 0‐5 cm). The orifice size was slightly, but not significantly, smaller in patients over age 70 years compared with those younger than 70. In hearts weighing more than 450 g, the orifice was significantly larger (2.6 cm) than in hearts weighing less (1.4 cm). The appendicular depth averaged 1.2 ±0.7 cm (range, 0‐2.5 cm), and a significant difference was noted in patients older and younger than 70 years (depth of 0.9 cm vs. 1.5 cm; p<0.05). The RAA depth was 0.5 cm or less in 8 patients (35%), 6 of whom represented patients older than 70 years. Antemortem mural thrombi within the RAA were found in three hearts and completely filled the lumen in one. The suitability of the RAA as a site for atrial pacing and secure electrode implantation, particularly when anatomical deficiencies are identified, was also considered. Atrial lead displacement, a relatively common postoperative complication, may be related more to implantation within a shallow appendicular fossa and/or one with larger orifice than to faulty technique. Because these anatomical deficiencies threaten stable electrode implantation more prevalently in patients older than 70 years and in those with markedly enlarged hearts, we support the use of the grasping (screw‐in) atrial electrode in these circumstances for a more effective active lead fixation.