Macroscopic morphology of right atrial appendage in humans

Atrial fibrillation (AF) is a common arrhythmia in elderly people, and in many cases it is responsible for stroke or pulmonary embolism. One of the factors facilitating atrial thrombus formation is anatomical morphology of the atria, and especially the appendages. The pharmacological treatment of arrhythmia is generally focused on ventricular rate control. Electrical cardioversion is the preferred treatment method in the majority of clinics but it can occasionally produce the potentially dangerous complication of AF.

A macroscopic study was carried out on 40 (25 male [M], 15 female [F]) human hearts, 18-72 years of age, and a microscopic study in a group of 20 human right atrial appendages (RAA) (M 10, F 10), 18-72 years of age. Only hearts without anomalies were included in the study. Classical anatomical studies and statistic analyses were applied.

RAA is triangle shaped with a mean area of 2.73 cm2. Muscle fascicules build the wall of RAA and compose a dense net inside a chamber. Sagittal bundle connecting terminal crest with an apex of RAA was observed in all examined hearts. In microscopic specimens longitudinal and perpendicular fascicles were described.