TEE Quantification of Aortic Stenosis and

Aortic RegurgitationDr PK Neema

Normal Aortic valve

ME Sax view transducer at 40o

Normal flow-dynamics

V1 = V2

P1 = P2V1

V2

P2

P1

Aortic velocity Vmax 1-1.2m/sec

LVOT max velocity 0.9-1.1 m/sec

AS and its effect on Flow-dynamic

P1 > P2

V2 > V1

Doppler principle

Effect of interrogation angle on frequency shift

Ultrasound beam should be parallel to the flow under study

The ultrasound should intercept the center of the flow not the periphery

The interrogation angle should be < 15o

The view optimal for the imaging may not be the optimal view for the Doppler study

Essentials during Doppler study

Transgastric Lax view (Transducer at 130o)

TEE Views for Doppler study

Deep Transgastric Lax view

TEE Views for Doppler study

Simplified Bernoulli equation Continuity equation

Methods to quantify AS

Simplified Bernoulli equation

P = 4V2 2

Severe AS = P > 75 mmHg

P – Pressure gradient

Deep Transgastric Lx View

Peak velocity Mean velocity Peak gradient 4V2

Mean gradient Velocity time

integral (VTI) or TVI

Measurements

Continuity equation

Continuity equation

Blood flow through LVOT = Blood flow through AoV

Blood flow through LVOT = CSA LVOT X TVI LVOT

Blood flow through AoV = CSA AoV X TVI AoV

CSA LVOT X TVI LVOT = CSA AoV X TVI AoV

CSA AoV = LVOT flow/TVI AoV

The LVOT diameter is measured in ME Lax view at 130o and measured from endocardium to endocardium at the level of insertion of AV leaflets in midsystole

Inaccuracy in the measurement of diameter can result in gross error since the radius of the LVOT is squared for calculating area (CSA = πr2)

Assessment of LVOT area

ME Lax View Xducer at 130o

The TVI is measured by Doppler interrogation through LVOT using pulse wave Doppler (PWD)

The sample volume is assessed just proximal to the aortic valve within the LVOT where the annular dimension is measured

TVI Measurement in LVOT

Transgastric Lax view

NORMAL MILD MODERATE

SEVERE

Peak velocity (m/s)

1.0-1.2 <3 3-4.5 >4.5

Peak gradient (mmHg)

16-36 36-75 >75

Mean gradient (mmHg)

<20 20-40 >40

AVA (cm2) 3-5 1-1.5 0.8-1 <0.8

Severity of AS

AS and ◦ Mitral regurgitation◦ Low cardiac output ◦ Aortic regurgitation

Fallacies

The MR jet can be mistaken for that of AS. How to avoid the MR jet?

◦ The MR jet should be visualized during colour Doppler imaging and the MR jet path should be consciously avoided.

How to confirm?◦ The MR jet starts early with LV contraction, the AS jet

starts later in systole. ◦ The MR jet starts in the early portion of QRS complex

while AS jet starts in the mid or late portion of QRS complex. Determination is facilitated by recording the jets at a faster sweep speed (100 mm/s)

AS and Mitral regurgitation (MR)

Gorlin formula (AVA = Cardiac output/ 44.3 (SEP) (HR) √mean gradient

The CO is an important determinant of valve area and a decrease in CO result in a decrease in the peak aortic gradient and the severity of AS Accordingly, one should assess LV function before ‘small gradients’ are reported as insignificant.

Dobutamine stress test and dimensionless index are evaluated to assess AS severity in presence of low CO.

AS and Low cardiac output

High CO, similar to low CO, result in over estimation of peak gradient and AS severity.

The discrepancy is corrected by measuring the blood flow velocity in the LVOT and applying a correction if the measured LVOT peak velocity exceeds 1.5 m/s.

Peak gradient in presence of significant aortic regurgitation =

4 [(peak velocity)2 – (LVOT velocity)2]

AS and Aortic regurgitation

Dobutamine (5-10 μg/kg/min) is infused to increase CO

An increase in pressure gradient suggests severe valvular disease.

No or borderline increase in pressure gradient suggest primary myocardial disease as the cause of low gradient and contraindicate valve replacement as the primary therapy;

However, AS is a unique cardiovascular disease where patients with a low EF may normalize after valve replacement.

Dobutamine stress test

LVOT and aortic TVI ratio or peak LVOT and aortic velocity ratio of 0.25 or less indicates critical AS.

Useful in evaluation of patients with prosthetic aortic valves where measurement of aortic annular dimensions is not clear.

Dimensionless index

Aortic Regurgitation

ME Lax view Transducer at 130o

Based on◦ Color flow Doppler (Jet width and jet area

measurement)◦ Continuity equation◦ Regurgitant jet velocity assessment

AR quantification

TEE view for jet width measurement

ME Lax view Transducer at 130o

Jet width to LVOT diameter ratio

Jet width-LVOT diameter ratio > 65% indicate severe AR

Color M mode

75/214=0.35

LVOT Shadowing◦ Aortic prosthesis◦ Mitral prosthesis◦ Site and shape of the orifice (Eccentric jet,

multiple jet)

Jet width limitations

TEE views for jet area measurement

ME Sax view Transducer at 40o

1+ < 4% (trivial)2+ 4-24 (mild) 3+ 25-59 (moderate) 4+ >60 (severe)

Jet area/LVOT area

Vena Contracta

Vena Contracta width of> 6 mm indicate Severe AR

Blood flow through LVOT = CSA LVOT X TVI LVOT

Blood flow through RVOT = CSA RVOT X TVI RVOT

Regurgitant volume = CSA LVOT X TVI LVOT – CSA RVOT X TVI

RVOT

EROA = Regurgitant volume/VTI(VTI measured by PWD)

Continuity equation

Deceleration Slope and Pressure-half time

The velocity of regurgitant jet during diastole is directly related to pressure gradient between aortic root and LV.

A large regurgitant defect will rapidly decrease pressures gradient and the velocity of regurgitant jet, hence slope of AR jet indicate severity of AR CWD analysis of AR jet transgastric

or deep transgastric view

Regurgitant jet Slope Decay

Ao

LV pressure

CWD LVOT

Mild AR Severe AR (>3m/sec2)

Ao

LV

LVEDP – Ischemia, LV dysfunction Low Aortic diastolic pressure Eccentric jets Acute AR vs. C/c AR

CWD-Deceleration slope limitations

Holo-diastolic flow reversal

Severe AR

Severity of Regurgitation

<3 mm 3-6 mm