Clinical Investigations
Echocardiographic Assessment of the Aortic Root
Aortic Root Anatomy Is Related to the Bicuspid Aortic Valve Phenotype

https://doi.org/10.1016/j.echo.2021.11.012Get rights and content

Highlights

  • BAV aortic root is asymmetric (not circular), resulting in unequal root diameters.

  • Orientation in the thorax of the largest root diameter depends on BAV phenotype.

  • When BAV is present, the largest root diameter is perpendicular to the opening.

  • When N-R BAV is present, on TTE, the aortic valve opening is vertical.

  • In N-R BAV, the transthoracic PLAX view underestimates maximal root diameter.

Background

Bicuspid aortic valve (BAV) is associated with an asymmetric (not circular) aortic root, resulting in variability in the aortic root diameter measurements obtained using different techniques. The objective of this study was to describe aortic root asymmetry, including its orientation in the thorax, in relation to the various phenotypes of BAV and its impact on aortic root diameter measurements obtained using transthoracic echocardiography.

Methods

Aortic root asymmetry, orientation of the largest root diameter, and orientation of the valve opening were studied using computed tomographic scans of patients with BAV without significant aortic valve dysfunction referred for evaluation of a thoracic aortic aneurysm. Eighty-five patients with BAV were evaluated; BAV with fusion of the left and the right coronary cusps (L-R BAV), with or without raphe (n = 63), was compared with BAV with fusion of the right coronary and noncoronary cusps (N-R BAV), with or without raphe (n = 22).

Results

Asymmetry of the aortic root and its orientation in the thorax can be predicted from BAV phenotype: orientation of the valve opening differed from orientation of the largest root diameter by nearly 75° in both groups. The angle of the largest root diameter with the reference sagittal plane was 64.3° in the L-R BAV group versus 143.1° in the N-R BAV group (P < .0001). Therefore, using the parasternal long-axis view on transthoracic echocardiography, in N-R BAV, the ultrasound beam is roughly parallel to the valve opening orientation and almost orthogonal to the maximum diameter of the root. On the contrary, in L-R BAV, the ultrasound beam is roughly perpendicular to the valve opening orientation and almost parallel to the maximum diameter of the root. Consequently, the parasternal long-axis view on transthoracic echocardiography significantly underestimates maximal aortic root diameter in N-R BAV and modestly underestimates root diameter in L-R BAV (−6.1 ± 0.96 vs −2.3 ± 0.47 mm, P = .0008).

Conclusions

Aortic root morphology in patients with BAV can be predicted by BAV phenotype: the largest root diameter is roughly perpendicular to the orientation of the valve opening. Therefore, echocardiographic measurements according to present recommendations (parasternal long-axis view) underestimate maximal diameter in patients with N-R BAV.

Section snippets

Population

Consecutive patients referred to two tertiary centers (Centre de Référence pour le Syndrome de Marfan et syndromes apparentés, Hopital Bichat, Paris, France, and Institut Mutualiste Montsouris, Paris, France) for evaluation of thoracic aortic aneurysms, in whom Marfan syndrome (MFS) diagnosis has been excluded, who had BAV and underwent both TTE and electrocardiographically gated computed tomography (CT) for ascending aortic assessment, were included. Patients with significant aortic

Population

Eighty-four patients with BAV and without significant valvulopathy were included in the study. Characteristics of patients are summarized in Table 1. Patients were mostly men (74%), with a mean age of 43.7 ± 15.4 years. Sixty-three patients (74%) were found to have L-R BAV, and 22 (26%) had N-R BAV. The L-R BAV group included 52 patients with raphe and 11 patients without raphe, while the N-R BAV group included 12 patients with raphe and 10 patients without raphe. Approximately half of the

Discussion

Aortic root asymmetry in patients with BAV is already known,7,8 and it has led to difficulties in interpreting aortic root diameters in these patients, so that a recent panel of experts called for research and consensus on the phenotyping of BAV to help in resolving the gaps of knowledge in this field.9 In the present study, we show that there is a close relationship between the orientation of aortic valve opening (BAV phenotype) and the orientation of the maximal aortic root diameter in the

Conclusion

The aortic root is asymmetric in patients with BAV, and aortic root phenotype can be predicted from the valve opening orientation. Indeed, the largest root diameter is roughly perpendicular to the valve opening orientation. As a result, the largest aortic root diameter cannot be adequately measured in the PLAX view on TTE, as presently recommended in guidelines, when valve opening orientation is vertical. A simple BAV classification based on the valve opening orientation (i.e., horizontal vs

Acknowledgment

We wish to thank Natasha Barr for editing the manuscript.

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Conflicts of interest: None.

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