A Study on Variations in Size and Shape of Left Atrial Appendage from Formalin-fixed Cadavers

Abstract

Introduction: Atrial appendages were once considered vestigial structures with no significant role in atrial function. However, they are now recognized as significantly impacting various pathophysiological conditions, including cardiac thromboembolism and arrhythmias. The left atrial appendage (LAA), in particular, has been found to have significant variations in shape and size, and its relationship with nearby structures, such as the pulmonary veins (PVs), is crucial in planning interventional and surgical procedures in and around the LAA. Although most studies examining variations in the LAA are image-based, few have focused on anatomical studies. Materials and Methods: In this study, we examined heart specimens from 54 cadavers for anatomical dissection at a tertiary care teaching hospital. After removing the heart from the pericardial cavity, we opened the left atrium and examined its interior. Observations were made regarding the LAA orifice and PV orifices, and measurements were taken. Subsequently, we removed the LAA along with a portion of the left atrial wall, observed its shape and number of lobes, and took measurements. To classify the shape, we used a system proposed by Wang et al. based on resemblance to familiar objects. Categorical variables were expressed as percentages and continuous as mean and standard deviation. The institutional research committee and the institutional ethics committee approved the study. Results: The most common shape variant observed was the Chicken Wing type, followed closely by the Windsock type. Specimens with Cauliflower or Cactus morphology were rare, with the Cactus variant being the least common. The LAA orifice was round or oval shaped in most cases. In most cases, the LAA orifice was at the same or lower level as the left superior PV orifice, with a prominent ridge between the two orifices in most patients. We observed most of the appendages to be trilobed, with considerable variations in length and diameter. We found two specimens with unusual morphologies but no specimens with accessory appendages. Conclusions: Based on our study, there are significant differences in findings compared to some of the previous studies reporting the shape variations of LAA. However, our findings are matching with those of some other earlier studies. The variations in the shape and size of LAA orifices and their relationship to PV orifices are similar to those reported in earlier studies. The distribution of variations in the size of LAA was also similar to those reported in earlier studies. Conducting larger studies to explore these variations could aid in designing and developing therapeutic interventions in the LAA.