Checking the shape and lobation of the right atrial appendage in view of their clinical relevance.

Clinically, anatomy of the appendage of the atrium is associated with atrial fibrillation, with the shape and lobation of the appendage having been used to stratify the risk of thromboembolic events. The aim of this study was to examine the age-dependent change in the shape and lobation of the right atrial appendage. A cross-sectional evaluation of the heart of 172 adults and 61 children, fixed in 4% formalin solution was performed. The morphology of the atrial appendage was assessed based on its shape and number of lobes. The following shapes of the appendage were identified: horse head, parrot beak, anvil, sailboat, and undefined. Using the horse head shape as a reference, the risk for a thromboembolic event was higher for anvil, sailboat and undefined shapes of the appendage (p < 0.001). The number of lobes ranged between 1 and 6 in adults, and 1 and 5 in children. The number of lobes for each shape was equivalent between adults and children (p > 0.05). Our analysis indicated that the number of lobes and the distribution of shapes of the atrial appendage remained unchanged throughout life. The risk for a thromboembolic event increased with the morphological complexity of the appendage (anvil, sailboat, and undefined), with 21% of adult hearts being prone to intra-atrial thrombosis in cases of fibrillation.