From the Guidelines
To assess aortic regurgitation (AR) using transthoracic echocardiography (TTE), begin with a comprehensive evaluation of the aortic valve morphology, followed by color Doppler assessment of the AR jet, and integration of multiple parameters to accurately grade AR severity. According to the most recent guidelines 1, a comprehensive TTE evaluation is essential for confirming the presence, severity, and etiology of AR. The assessment should include:
- Evaluation of the aortic valve morphology, looking for leaflet abnormalities, calcification, or congenital anomalies
- Use of color Doppler to identify the AR jet, assessing its width at the origin (vena contracta) and the extent of the jet in the left ventricular outflow tract
- Measurement of the vena contracta width, with values >0.6 cm suggesting severe AR
- Calculation of the regurgitant volume and fraction using the PISA method or by comparing stroke volumes across different valves
- Assessment of the pressure half-time of the AR jet with continuous-wave Doppler, where values <200 ms indicate severe AR
- Evaluation for diastolic flow reversal in the descending aorta using pulsed-wave Doppler
- Assessment of left ventricular size and function, as chronic severe AR leads to LV dilation
- Evaluation of the aortic root and ascending aorta dimensions, as dilation can be both a cause and consequence of AR. The European Association of Cardiovascular Imaging also recommends the use of TTE as the first-line imaging modality in valvular regurgitation, with TOE advocated when TTE is of non-diagnostic value or when further diagnostic refinement is required 1.
From the Research
Assessment of Aortic Regurgitation with TTE
According to the ASE guidelines, the following steps can be used to assess aortic regurgitation with TTE:
- Quantification of left ventricular end-diastolic diameter and volume and left ventricular ejection fraction, which are key elements in the clinical decision making regarding the timing of valve surgery 2
- Qualitative echocardiographic features contributing to the AR severity grading, including:
- Fluttering of the anterior mitral valve leaflet
- Density and shape of the continuous wave Doppler signal of the AR jet
- Colour flow imaging of the AR jet width
- Holodiastolic flow reversal in the descending thoracic aorta and abdominal aorta 2
- Volumetric assessment of the AR by measuring the velocity time integral of the left ventricular outflow tract (LVOT) and transmitral valve (MV) plane, and diameters of LVOT and MV 2
- Calculation of the regurgitant fraction and effective regurgitant orifice area (EROA) 2
- Use of the proximal isovelocity surface area to determine the EROA 2
- Assessment of AR severity using pressure half time and vena contracta width 2, 3, 4
Comparison with Other Imaging Modalities
Comparison of TTE with other imaging modalities, such as cardiovascular magnetic resonance (CMR) and transesophageal echocardiography (TEE), has shown that:
- CMR provides more prognostic relevant information than TTE in assessing AR severity 5
- TEE can be used to measure the vena contracta area (VCA) of AR, which has high diagnostic accuracy and reproducibility 4
- Live three-dimensional TTE color Doppler measurements of VCA can be used for accurate assessment of AR and are comparable to assessment by aortography 3