The parasternal long axis ultrasound view does not allow the maximum diameter of the aortic root to be measured in atypical BAV

Background Following guidelines, maximal aortic root diameter has to be measured in parasternal long axis (PLA TTE) view in trans-thoracic echocardiography (TTE). However, asymmetry of the aortic root is common in BAV and the largest diameter might be missed when using PLA TTE. Purpose Assess whether the maximum aortic diameter measured with PLA TTE and CT differs according to the type of BAV. Methods Eighty-six patients with BAV without significant valvulopathy referred for aortic aneurysm assessment and who had benefited from TTE and CT were studied. Definitions 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) ( Fig. 1 ). We compared: – In CT, using the sagittal plane as a reference, the orientation of the largest diameter of the aortic root in typical and atypical BAVs ( Fig. 1 ); – the difference of the maximal aortic root diameter measured with PLA TTE and CT in typical and atypical BAVs. Results 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 ( Fig. 1 ). 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  Fig. 1 ). In typical BAVs, the maximal root diameter has the same direction that ultrasound beam (red arrow) while in atypical BAVs, the ultrasound beam is perpendicular to the maximum aortic diameter. Conclusion The different orientation of the maximal diameter of the aortic root in atypical vs. typical BAVs explains the inability to measure the maximum aortic diameter in PLA TTE for the atypical BAVs.