Thoracic aortic dimensions in a Sri Lankan cohort; a computerized tomography-based study

Introduction: In adults the Thoracic aorta (TA) begins from the ascending aorta at the level of the manubrio sternal joint and arches backward and to the left over the left main bronchus and ends at the level of 4th thoracic vertebra. From this level it continues as descending thoracic aorta (DTA). The TA diameter decreases progressively from the ascending aorta (ASA) to the DTA. In addition the diameter of the TA also varies according to the age, gender and race. It is believed that diameters of the arteries including the thoracic aorta may be smaller in Sri Lankan population. Therefore this study was done on the diameters of the thoracic aorta because accurate knowledge of these diameters are essential to define abnormalities, and to plan interventions.Methodology: The patients who underwent contrast-enhanced computerised tomographic scans (CECT) of chest for non-aorta-related diseases at the National Hospital of Sri Lanka in Colombo were included. The imaging was done using a Toshiba Aquilion scanner with 3D reconstructions. Omnipaque 300 (Iohexol) intravenous contrast agent. Data on age, gender, and ascending (D1) and descending aortic (D2) diameters were collected. Aortas with variations, unclear images and images with artefacts were excluded. Statistical significance was regarded as a p-value of less than 0.05.Results: Total of 50 CECT were evaluated. 28 images were analysed. Mean age was 56.0 years (20-81). 16 (57.1%) were males. The mean diameter at the mid ascending aorta (D1) was 27.6mm (21.0 - 34.0). The mean diameter at mid DTA (D2) was 21.9 mm (15.6 – 33.0). This difference was statistically significant (P < 0.0001) compared to values reported from other races in literature. Similarly the D2 in the present study was 21.9 mm (15.6- 33.0). This difference was also statistically significant (P < 0.0001).Conclusion: This study findings indicate that the diameters of the thoracic aorta in the study population is smaller than the western population. This is likely to be the case with the all Sri Lankan population. Therefore country wide study is needed to confirm the above findings. Further, the aortic aneurysm size definition and the size threshold for aortic aneurysm repair have to be redefined in the Sri Lankan population.