Clinical Case
This case is from Dr Jorge Parras. A 60 year old man presents with acute pulmonary oedema, new murmur and is found to have gram positive cocci in his blood cultures.
Key findings
- Severe aortic regurgitation
- Co-existing aortic stenosis
- Destruction of aortic valve leaflets & presence of vegetations.
- Sinus of valsalva abcess
Evaluating Severity of AR
Classification & Mechanism
Several classifications are available
Functional classification base on Capentier's classification for MV can be used
TYPE I - NORMAL LEAFLET MOTION & MORPHOLOGY
Type Ia - STJ and ascending aorta dilatation
Type Ib - SOV & STJ dilatation
Type Ic - Annular dilatation
Type Id - Leaflet perforation
TYPE II - Leaflet prolapse
TYPE III - Restricted leaflet motion
Qualitative & Quantitative Evaluation
2D imaging
Evaluation of aortic regurgitation begins with 2D imaging to determine the mechanism of aortic regurgitation and continues with the evaluation of hemodynamics and cardiac adaptation to AR. The cardiac adaptive responses to acute and chronic AR are different.
Features of acute SEVERE aortic regurgitation:
- Early mitral valve closure
- Small AR jet or not visible in all views
- Normal LV dimensions
- EF likely reduced
- LV dilated & globular
- AR jet is visble in all views
- Reduced LVEF is a late finding
Evaluate the following:
- Aortic valve, aortic root & ascending aorta anatomy
- LV size, geometry & function
Colour Dopper
- Flow convergence
- Vena contracta
- Jet area
The width of the AR jet compared with the LVOT diameter in centrally directed jets can be used to semi quantitatively assess the severity of regurgitation. This ratio is obtained in the ME LAX view, just proximal to the aortic valve.
A ratio <25% generally indicates mild, 25%-64% indicates moderate, and >65% indicates severe AR.
VC is best visualized and measured in a zoomed, ME AV LAX view. Since it is the narrowest area of the jet, it is smaller than the jet width in the LVOT. It can be measured in most patients with good echocardiographic images. A VC < 0.3 cm indicates mild, 0.3-0.6 cm indicates moderate, and > 0.6 cm indicates severe AR. If optimized, VC can still be measured in most eccentric jets.
Flow convergence can be used qualitatively and quantitatively for evaluation of AR severity. Zooming on the LVOT in te ME AV LAX view is the best approach to record the proximal flow convergence area, with a baseline shift of the Nyquist limit to measure the flow convergence radius. Measurement of the AR peak velocity and VTI by CWD allows calculation of the EROA and RVol. The threshold for severe AR is an EROA > 0.30 cm2 and an RVol greater than 60 mL
Pulse Wave Doppler
PWD Descending Aorta
Continuous Wave Doppler
The best windows for evaluating the AR jet with CWD are the transgastric views. These are qualitative doppler assessments.
- Signal Density of CWD Envelope. A faint or incomplete jet indicates mild or trace regurgitation,while a dense jet may be compatible with more significant regurgitation but cannot differentiate between moderate and severe AR.
- Pressure half-time: The pressure half-time of the AR spectral Doppler slope can be a parameter of severity. A pressure half-time > 500msec suggests mildAR, and < 200msec suggests severe AR. (see image below)
- Decel slope. A decel slope >300cm/sec indicates severe AR, whilst a decel slope <200cm/sec indicates mild AR.
CWD AR Jet
The images above show CWD tracings of AR. The tracing above the baseline indicates AR, as blood flow is towards the transducer head. In the bottom image, there is co-existing aortic stenosis present, as evidenced by a CWD trace below the baseline with a peak velocity close to 4.0m/s
References:
- Zoghbi et al. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. JASE 2017.