Morphology of the left atrial appendage

Abstract

Background: When examining the left atrial appendage by transesophageal echocardiography, differences in size and shape of the left atrial appendage are to be observed. The study was carried out with the aim of investigating the morphology of the left atrial appendage and to find associations with pathologic cardiac findings. Methods and results: In 220 cases (106 female, 114 male, mean age 72 ± 13 years) a cast of the left atrial appendage was made after the post mortem examination by using synthetic resin. In 198 cases an ECG was available (sinus rhythm n = 143, atrial fibrillation n = 55). The casts were described in respect to course and ramifications of the principal axis. The casts were measured concerning orifice diameters, outline, and volume. Most frequently (42%) the course of the principal axis was angulated below 100°. More than five ramifications of the principal axis were found in 56% of the casts. The volume ranged from 770–19,270 mm³ (mean 5,220 ± 3,041). When comparing the clinical and autopsy‐data of the patients with the morphology of the casts, associations could be found between the volume of the casts and atrial fibrillation (7,060 mm³ as compared to 4,645 mm³ in sinus rhythm, P < 0.01), left ventricular hypertrophy (5,740 mm³ as compared to 4,639 mm³ without hypertrophy, P < 0.01), myocardial scars (5,923 mm³ as compared to 4,891 mm³ without scars, P < 0.05), closed foramen ovale (5,515 mm³ as compared to 4,037 mm³ with patent foramen ovale, P < 0.01), and left atrial appendage thrombi (8,566 mm³ as compared to 5,027 mm³ without thrombi, P < 0.01). Conclusion: Left atrial appendages are formations greatly varying in volume and shape. This variability should be considered when interpreting images of the left atrial appendage, and in particular when diagnosing thrombi.