Presentation is loading. Please wait.

Presentation is loading. Please wait.

Paul Nolan, Galway University Hospitals. Echo evaluation of AS  Define aetiology  Quantitation of the severity  Assessment of LV function  Assessment.

Similar presentations


Presentation on theme: "Paul Nolan, Galway University Hospitals. Echo evaluation of AS  Define aetiology  Quantitation of the severity  Assessment of LV function  Assessment."— Presentation transcript:

1 Paul Nolan, Galway University Hospitals

2 Echo evaluation of AS  Define aetiology  Quantitation of the severity  Assessment of LV function  Assessment of co-existing valvular lesions  Assessment of secondary effects  Pulmonary pressures  Aortic dilatation

3 Quantification of AS by echo  Peak velocity  Mean velocity  Peak gradient  Mean gradient  Aortic valve area  Continuity equation

4 Jet velocity – too simple?  Otto 1997  123 asymptomatic patients  End point  Death  Aortic valve surgery  Jet velocity > 4m/s is an independent predictor of clinical outcome

5 Quantification of AS by Cardiac Cath  Maximum instantaneous gradient  Equivalent to peak gradient by echo  Mean gradient  Equivalent to mean gradient be echo  Peak to peak gradient  Not equivalent to any echo measure  ?not physiological

6 Quantification of the AVA in the Cath Lab  Gorlin formula  AVA = Cardiac output  44.3 (SEP)(HR) √pressure gradient

7 So why sometimes do they not agree?

8 Technical sources of error in Echo  Doppler angle

9

10 Technical sources of error in Echo  Doppler angle  Accuracy of the LVOT measurement  Any error is squared  Average of a number of measurements  Same measurement retained for serial echos  Placement of sample volume within LVOT  Non-simultaneous measurement of Ao and LVOT Doppler profiles  Especially important in irregular rhythms  Average of number of beats  Use max Ao and max LVOT velocities

11 The “Gold Standard”

12 Sources of error in the lab  Assessments of Cardiac Output can be prone to error  Common practice of comparing LV to femoral/radial pressure  Damped pressures  Positioning of LV catheter  Alignment of LV and Ao trace

13 Effect of incorrect alignment Mean grad =47mmHgMean grad =26mmHg

14 So where is the error?  “we are constantly seeing these discrepancies between Cath Lab and echo gradients  Consultant Cardiologist  “on occassion we see these discrepancies, particularly in asymptomatic patients”  Physiologist rebuttal  “Do not trust the echo report unless you have personally seen the quality of the study”  “In many patients, echo will provide discordant data necessitating confirmatory hemodynamics in the cath lab” Susheel Kodali, Columbia Univ Medical Centre

15 Case 1

16

17

18 Case 2 AVA=0.8cm2 Mean grad=54mmHg

19

20 Pressure gradients are dependent on volume flow rate

21 When gradient and AVA don’t match Low gradient, severe AVA High gradient, moderate AVA  Poor LV systolic function  Small LV cavity  Reduced SV  Reduced flow  Concomitant significant MR  Significant AI  Sepsis  Anaemia  High output states  Pressure recovery phenomenon In theory the AVA should reflect the severity of the stenosis better than the gradient

22 AS and poor LV function  Reduced LV function  Reduced cardiac output and stroke volume  Reduced volume flow rates  Reduced gradient across aortic valve  Discordance between AVA and gradient  Severe AS by AVA but low gradient may reflect  Truly severe AS  Psuedo-severe AS

23 Role of dobutamine  Dobutamine  Increase stroke volume  Gradual infusion of dobutamine (20ug/kg)  Truly severe AS  LVOT and Aortic velocities increase proportionally  AVA remains constant  Pseudo-severe AS  LVOT velocity increases disproportionally Ao velocity  AVA increases

24 Role of dobutamine  Main role is to assess for inotropic reserve  Increase in stroke vol of >20% with dobutamine  Clinical question  Is the severe AS leading to poor LV function  Will replacing the valve improve function  Lack of inotropic reserve is an independent predictor of mortality post AVR

25 Small LV cavity  Newer concept  Paradoxical low flow AS  Low flow/low grad severe AS with preserved EF  Small LV cavity  Hypertrophy  Reduced LV filling  Reduced stroke volume  Discordance between gradient and AVA  PLF AS patients have worse outcome

26 We are measuring different things  Cath lab and echo measure different things  Doppler  Max flow velocity at the level of the vena contracta  Cath  Net pressure gradient between the LV and the aorta

27 Pressure recovery  Conservation of energy  Blood flow decelerates as it goes through valve  Kinetic energy - velocity is “lost”  Converted into potential energy – pressure  Therefore we get a recovery of Ao pressure distal to the valve

28 Pressure recovery  Extent of pressure recovery inv proportional to Ao CSA  Thus the max gradient by echo will over estimate the severity compared to the max grad by cardiac cath  Echo reflect the true valve orifice area  Cath reflects the physiological valve area

29 So where are we now  Is there anything extra that echo can add  Can we aid in the clarification of these discrepancies

30 Jet velocity – too simple?  Otto 1997  123 asymptomatic patients  End point  Death  Aortic valve surgery  Jet velocity > 4m/s is an independent predictor of clinical outcome

31 Dimensionless Index  Potential error in echo calculation is determining LVOT diameter  Dimensionless index removes LVOT diameter from the assessment  DI= LVOT VTI/Ao VTI  Value of less than 0.25 represents severe AS

32 Indexed aortic valve area  Body size can lead to an incorrect classification of AS severity based on AVA  Has been demonstrated that an iAVA of <0.6cm/m2 is a marker of mortality  Guidelines classify severe AS as iAVA of <0.6cm/m2

33 Indexed aortic valve area  Case 1  AVA of 1.2 cm 2  moderate  BSA = 2.1 m 2  iAVA=0.57 cm 2 /m 2  Case 2  AVA of 0.9 cm 2  Severe  BSA= 1.3 m 2  iAVA=0.7 cm 2 /m 2

34 Remember Pressure recovery?  Cath reflects the physiological valve area  Can we somehow correct for pressure recovery

35 Energy loss index  [(AVA x Aa)/(Aa-AVA)]  BSA

36 Prognostic Value of Energy Loss Index in Asymptomatic Aortic Stenosis  Aortic valve events  AVR, HFH, CV mortality

37 What about the third dimension?  Continuity eqn  Assumption that LVOT is circular  LVOT more elliptical  3D TOE  Allows direct measurement of LVOT CSA

38 Conclusion  There are sources of error in echo assessment of AS  Take care  Averaged values for LVOT  There are also sources of error in the Cath Lab  So be careful there too  And try and get the Consultants to be careful

39 What I would take away  Use the suite of measurements/assessments  Use new measurements  Indexed AVA  Consider new techniques if available  If your gradient and AVA don’t match think about/explain why?  Poor LV  Small LV cavity/low stroke volume  Concomitant AI or MR


Download ppt "Paul Nolan, Galway University Hospitals. Echo evaluation of AS  Define aetiology  Quantitation of the severity  Assessment of LV function  Assessment."

Similar presentations


Ads by Google