Aortic Regurgitation
Aortic regurgitation can arise from either pathological abnormality of
the aortic valve leaflets (congenital, degenerative, or infectious) or
primary dilatation of the aortic root and ascending thoracic aorta.
Identifying the etiology and severity of aortic regurgitation is crucial
for decision making regarding the choice and the timing of aortic valve
intervention. Therefore, it is important to assess the aortic valve
apparatus, ascending aorta, and left ventricle to decide on the type of
intervention needed. Similar to aortic stenosis, transthoracic
echocardiography is usually sufficient to diagnosis and assess the
severity of aortic regurgitation. Once a significant aortic
regurgitation is identified by Doppler echocardiography assessing the
aortic regurgitation severity, etiology, aortic root dimensions, and
left ventricular size and function is essential for comprehensive
evaluation. However, both qualitative and quantitative Doppler
assessment of aortic regurgitation including pressure half time, vena
contracta width, proximal isovelocity surface area, regurgitant volume
and fraction suffer several limitations due hemodynamic changes,
eccentric jets and inherited geometric assumption that the regurgitant
orifice is circular, which is not the case in most cases. Adding TEE and
3D echocardiography can provide more detailed assessment of the aortic
regurgitation and aortic valve morphology and function. 3D
echocardiography can reliably identify the mechanism of aortic
regurgitation and with the complementary use of 3D color mode provides
important diagnostic information about the regurgitant jets size,
location, and severity. In addition, full-volume 3D mode can be very
useful for accurate quantification of the left ventricular size and
function, an important echocardiographic criterion for surgical referral
in patients with severe chronic aortic regurgitation.
The recent advances in 3D technology allows for volumetric assessment of
the regurgitant volume by measuring the left and right ventricular
stroke volumes with strong correlation with other cardiac imaging
modalities.In the setting of good 2D image quality, the use of 3D stroke
volume measurements eliminate the interobserver variation, geometric
assumption of the LVOT size and ventricular foreshortening.
Another unique advantage of 3D over standard 2D echocardiography is the
ability to measure the vena contracta area (VCA). Adding 3D color
Doppler to live 3D of the aortic valve allows visualization of the
regurgitant jet. In a multiplanar reconstruction model, 3D color dataset
can be cropped from either the aortic or left ventricular perspective to
the level of the narrowest regurgitant jet (vena contracta) in a
perpendicular plane to measure the VCA in early diastole (Figure 4,
Movie 3).24 The VCA can be multiplied by the velocity
time integral of the aortic regurgitant jet to calculate the regurgitant
volume. 3D measurement of VCA is simple and correlates very well with
MRI method.25 Noteworthy, the incremental value of 3D
echocardiography is invaluable in the evaluation of patients with
prosthetic aortic valve regurgitation. The use of color 3D TEE allows
for accurate assessment of paravalvular regurgitation site, size, and
severity. In addition, live 3D TEE is used to guide percutaneous
paravalvular leak closure (Figure 5, Movie 4).