Indirect Signs of AR Severity Flashcards
What are the five indirect clues to significant AR?
- Forward flow velocities
- Intensity of AR CW signal
- Shape of AR CW signal
- Flow reversal in descending/abdominal aorta
- Colour Doppler imaging (CDI)
AR: Significance of Increased Forward Flow Velocities (PW LVOT)
- Increased forward flow velocities seen on PW Doppler at LVOT with AR
- SV LVOT = forward SV + regurgitant volume
AR: Significance of Increased Forward Flow Velocities - Limitations
- Increased LVOT velocities are also elevated in 1) high cardiac output states and 2) HOCM
AR: Significance of Intensity of AR Signal
- CW Doppler signal intensity directly proportional to the number of red blood cells moving within Doppler beam
- Intensity of regurgitant signal increases as severity of regurgitation increases
AR: Significance of Intensity of AR Signal - Limitations
- AR intensity can be underestimated when Doppler beam is not parallel with AR jet
AR: Significance of Shape of AR CW Signal in Severe AR
- Pressure half time reflect pressure gradient between the aorta and LV during diastole
- In chronic severe AR, aortic pressure falls rapidly = short p1/2t
- P1/2t < 200ms = severe AR
AR: Significance of Shape of AR CW Signal - Limitations
- P½t is highly dependent on chamber compliance and systemic vascular resistance
- P½t can be short in absence of severe AR when there is poor LV complicance
- P½t can be prolonged in chronic severe AR when there is a compliant LV (LV can accept large volume of blood without significant increase in LVEDP)
What signs indicate restrictive filling?
- Transmitral inflow; big E-wave and little or no A-wave
- E/A > 2
- DT < 160ms
- Elevated LVEDP
What is meant by restrictive filling?
- Marked reduction in LV compliance i.e. the LV is very stiff and non-compliant
What does short P½t without severe AR suggest?
Reduced LV compliance (increased LVEDP)
What does prolonged P½t with severe AR suggest?
Compensated/compliant LV; able to accept a large volume of blood without significant increase in LVEDP
AR: Significance of Diastolic Flow Reversal in Descending Aorta
- Pan diastolic flow reversal in descending aorta = significant AR
- CFI shows red flow towards Tx in diastole from suprasternal notch
- If end-diastolic velocity > 1.8m/s = moderate to severe AR
AR: Significance Diastolic Flow Reversal in Abdominal Aorta
- Pan diastolic flow reversal
- CFI shows blue flow away from Tx in diastole (subcostal abdonimal aorta)
- Sign of severe AR
AR: Significance of Flow Reversal - Limitations
- False positive when there is a diastolic pressure gradient between the aorta and another low pressure chamber
- E.g. aorta-LA fistula (communication between aorta and LA)
- E.g. PDA
AR: Significance of Colour Flow Imaging (Jet Height)
- Origin of regurgitant jet height is compared to LVOTd during diastole
- Fills < 25% of LVOTd = mild
- AR fills entire LVOTd during diastole = severe AR
What is the Vena Contracta?
- Vena contracta is the narrowest neck of flow region at the level of the aortic valve immediately below the flow convergence region
AR: Significance of Colour Flow Imaging - Limitations: Technical Factors
- Gain and filter settings
- Tx frequency
- PRF
- Incident angle
- Frame rate
- Attenuation
- Suboptimal images
AR: Significance of Colour Flow Imaging - Limitations: Physiological Factors
- Driving pressure
- Eccentric jets
- Size and shape of orifice
- Chamber compliance
- Regurgitant volume
- Coexistent jets
AR: Significance of Colour Flow Imaging - Limitations: Other Limitations
- Effect of angle: need to pan through valve
2. Billiard ball phenomenon: over-estimation of regurgitation
Other signs of severe AR?
- Reduced mitral deceleration time
- Diastolic mitral regurgitation
- Premature mitral valve closure
- Premature aortic valve opening
What is considered the best indirect clue of significant AR?
Flow reversals
Other signs of AR: Reduced Mitral Deceleration Time
- Rapid and sharp rise of LVEDP => shortened p½t and reduced DT
- In the absence of other causes, increased LVEDP, DT < 160ms and E/A > 2 = severe AR
Other signs of AR: Diastolic mitral regurgitation
- Normally, MR occurs during systole
- If diastolic MR seen = severe AR
Other signs of AR: Premature mitral valve closure
- Marked increase in LVEDP such that LV pressure during diastole exceeds LAP = early MV closure
Other signs of AR: Premature aortic valve opening
- Really marked increase in LVEDP such that LVEDP rises to a pressure greater than diastolic aortic pressure = AV opens early
