Echocardiogram for Aortic Valve Stenosis, the Complex Interplay between Flow and Gradient and Insight into Stress Echocardiography and Transoesophageal Echo for Transcatheter Aortic Valve Implantation (TAVI)

Abstract

Aortic valve stenosis (AS) is a relatively frequent pathology in the elderly and management is mainly dependent on the degree of stenosis and the potential presence of comorbidities. Transthoracic echocardiography (TTE) is the basic initial test for aortic valve imaging, yielding valuable measurements of aortic valve area, peak velocity, mean and peak gradients and dimensionless velocity index. TTE allows to classify the type of AS, as high gradient/normal flow (HG/NF), low gradient/normal flow (LG/NF), high gradient/low flow (HG/LF) and low gradient/low flow (LG/LF); the latter is also subdivided into regular or paradoxical LG/LF according to the value of the ejection fraction (EF). Transoesophageal echocardiography (TOE) has an added value compared to TTE for detailed anatomical visualization of the aortic valve and adjacent structures, also it is particularly useful as a perprocedural test during transcatheter aortic valve implantation (TAVI). Moreover, stress echocardiography (SE) is useful in cases where accurate assessment of the degree of stenosis is challenging, especially in LF/LG AS. In summary, appropriate assessment of AS is essential in order to guide decision making and echocardiography is the gold standard test for this purpose.

Stress Echocardiography: Concept and Criteria, Structure and Steps, Obstacles and Outcomes, Focused Update and Review

“…The classical views where data are acquired are A3C or A5C view, and stroke volume is better measured using the left ventricle outflow tract (LVOT) velocity time integral (VTI) and LVOT area. At every stage of the test, AV/VTI, LVOT/ During DSE, if the mean gradient rises to more than 40 mm Hg while the aortic valve area remains < 1.0 cm 2 , DSE indicates true severe AS, whereas if the aortic valve area increases to more than 1.0 cm 2 , DSE implies pseudo-severe AS even if gradients may increase [12,13] (Table 3). Similarly, DSE may help to assess AS severity in patients with paradoxical LF/LG AS.…”