The Parasternal Long Axis Ultrasound View Does Not Allow The Maximum Diameter Of The Aortic Root To Be Measured In Atypical Bav

Abstract Background Following guidelines, maximal aortic root diameter have to be measured in parasternal long axis view (PLA TTE) in trans-thoracic echocardiography (TTE). However, asymmetry of the aortic root is common in BAV and the larger diameter might be missed when using PLA TTE, depending on the asymmetric root orientation. Purpose Assess whether the maximum aortic diameter measured with PLA TTE and CT differs according to the type of BAV. Methods 86 patients with BAV without significant valvulopathy (aortic regurgitation <2 and no more than mild stenosis with mean gradient <10mmHg) referred for aortic aneurysm assessment and who had benefited from TTE and CT were studied. Definition: Typical BAVs have a horizontal valve opening (type I L-R and type 0 anteroposterior) while atypical BAVs have a vertical valve opening (type I N-R and type 0 lateral). (Figure) We compared: – using CT, the orientation of the largest diameter of the aortic root in typical and atypical BAVs using the sagittal plane as a reference (Figure). – the difference of the maximal aortic root diameter measured with PLA TTE and CT in typical and atypical BAVs. Results Patients with typical and atypical BAVs were comparable for age, sex, weight, height, aortic root surface area and maximum diameter of the aoric root. When comparing maximal aortic root diameter measured in PLA TTE and CT: – in the whole cohort, PLA TTE underestimates the maximal aortic root diameter with a mean difference of 3 mm. – in atypical BAVs, the difference between CT and PLA TTE is 6,0 mm significantly different from the 2,3 mm found in typical BAVs p=0.0008 (Figure) The orientation of the maximal aortic diameter is correlated with the type of BAV: Using the sagittal plan as a reference, this angle is 64.3° for the typical BAV and 143,1° for the atypical BAV p<0.0001 (Figure). The use of a blue arrow (figure) to show the ultrasound beam direction in PLA ETT helps to understand that, in typical BAVs, the maximal aortic root diameter has the same direction that ultrasound beam while in atypical BAVs, the ultrasound beam direction is perpendicular to the direction of the maximum aortic diameter. Figure 1 Conclusion The difference in maximal diameter of the aortic root measured with CT and PLA TTE is significantly greater in atypical BAVs than in typical BAVs (6.0 mm vs 2.3mm). This difference can be explained by the fact that in the atypical BAV, the orientation of the maximal diameter of the aortic root differs from the typical BAV: using the sagittal plane as a reference, in the atypical BAV, the mean angle is around 140° and this orientation is perpendicular to the direction of the ultrasonic beam, explaining the inability to measure the maximum aortic diameter in PLA TTE for the atypical BAVs.