1 / 256

Valvular Regurgitation

Valvular Regurgitation. Susan A. Raaymakers, MPAS, PA-C, RDCS (AE)(PE) Assistant Professor of Physician Assistant Studies Radiologic and Imaging Sciences - Echocardiography Grand Valley State University, Grand Rapids, Michigan raaymasu@gvsu.edu du. Basic Principles. Etiology Congenital

arion
Download Presentation

Valvular Regurgitation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Valvular Regurgitation Susan A. Raaymakers, MPAS, PA-C, RDCS (AE)(PE) Assistant Professor of Physician Assistant Studies Radiologic and Imaging Sciences - Echocardiography Grand Valley State University, Grand Rapids, Michigan raaymasu@gvsu.edu du

  2. Basic Principles Etiology • Congenital • Acquired abnormalities

  3. Fluid Dynamics of Regurgitation Characterized • Regurgitant orifice area • High-velocity regurgitant jet • Proximal flow convergence area • Downstream flow disturbance • Increased antegrade flow volume

  4. Fluid Dynamics of Regurgitation Regurgitant orifice • characterized by high-velocity laminar jet • Related to instantaneous pressure difference (∆P=4v2) • Upstream side of regurgitant acceleration proximal to regurgitant orifice • PISA • Narrowest segment of the regurgitant jet occurs just distal to the regurgitant orifice reflects regurgitant orifice area • Vena Contracta

  5. Fluid Dynamics of Regurgitation Size, Shape and Direction of Regurgitant Jet • Size • Affected by physiologic and technical factors • Regurgitant volume • Driving pressure • Size and shape of regurgitant orifice • Receiving chamber constraint • Influence of coexisting jets or flowstreams • Ultrasound system gain • Depth • Signal strength

  6. Fluid Dynamics of Regurgitation Size, Shape and Direction of Regurgitant Jet • Shape and Directions • Affected by • Anatomy and orientation of regurgitant orifice • Driving force across the valve • Size and compliance of receiving chamber

  7. Volume Overload • Total Stroke Volume • Total volume of blood pumped by the ventricle in a single beat • Forward Stroke Volume • Amount of blood delivered to the peripheral circulation • Regurgitant Volume • Amount of backflow across the abnormal valve

  8. Volume Overload Chronic valvular regurgitation • Results in progressive volume overload of the ventricle • Volume overload in LV results in LV chamber enlargement with normal wall thickness (total LV mass is increased) • Important clinical feature: • An irreversible decrease in systolic function can occur in absence of symptoms

  9. Detection of Valvular Regurgitation • 2D imaging • Indirect evidence • Chamber dilation and function • Color flow imaging • Flow disturbance downstream form regurgitant orifice • Sensitive (90%) when correct settings are utilized • Specific (nearly 100%) compared with angiography • True positives and false positives • False positives due to mistaken origin or timing • False negatives due to low signal strength or inadequate images

  10. Detection of Valvular Regurgitation • Continuous-wave Doppler ultrasound • Identification of high velocity jet through regurgitant orifice • Advantage: • Beam width is broad at the level of the valves when studied from an apical approach

  11. Valvular Regurgitation in Normal Individuals • Physiologic • Small degree of regurgitation in normal individuals • No adverse implications • Typically • Spatially restricted to area immediately adjacent to valve closure • Short in duration • Represents on a small regurgitant volume • May be detected in 70 – 80% mitral • May be detected in 80 – 90% tricuspid • May be detected in 70 – 80% pulmonary • May be detected in 5% aortic (increases with age). • Clinical significance of AI is unknown

  12. Approaches to Evaluation of the Severity of Regurgitation • Semi-quantitative measures • Mild, moderate or severe utilizing • Color jet area • Vena contracta width • Pressure half-time (for aortic insufficiency) • Distal flow reversals

  13. Approaches to Evaluation of the Severity of Regurgitation • Quantitative measures • Regurgitant volume (RV) • Retrograde volume flow across the valve • Expressed either as • Instantaneous flow rate in ml/sec • Averaged over the cardiac cycle in ml/beat • Calculated by • PISA • Volume flow rates across the regurgitant and competent valve (Spectral Doppler Technique) • 2D total left ventricular stroke volume minus Doppler forward stroke volume • Regurgitant fraction • RF = RV/SV total • Regurgitant orifice area

  14. Effective Regurgitant Orifice Area (EROA) • Application of continuity equation • “what flows in must flow out” • Based on theory of conservation of mass • May be calculated utilizing • Spectral Doppler technique • Application of the PISA method

  15. Spectral Doppler Method

  16. Spectral Doppler Technique • Regurgitant volume through an incompetent valve is equal to the flow at the regurgitant orifice • Stroke volume may be calculated from the CSA and the VTI • RVol = EROA x VTIRJ • RVol = Regurgitant volume (cc) • EROA = Effective regurgitant orifice area (EROA) • VTIRJ = Velocity time integral of the regurgitant jet (cm) • Rearrange equation • EROA = RVOL/VTIRJ Non-dynamic

  17. Spectral Doppler Technique“Step by Step” • Calculate stroke volume (SV) through LVOT • Calculate stroke volume (SV) through MV • Calculate the regurgitant volume (cc) • Measurement of VTI of regurgitant signal • Calculate the effective regurgitant area (cm2) Non-dynamic

  18. Spectral Doppler Technique“Step by Step” • Calculate stroke volume (SV) through LVOT • Measure LVOT diameter from PLAX • Inner edge to inner edge • CSA = 0.785 x D2 • Measure the LVOT VTI from apical long axis or apical four chamber anterior tilt • SV (cc) = CSA (cm2) * VTI (cm)

  19. Spectral Doppler Technique“Step by Step” • Calculate the stroke volume through the mitral valve • Measure the mitral valve annulus • Apical four chamber at mid-diastole: inner edge to inner edge • CSA = 0.785 x D2 • Measure mitral annulus VTI • PW Doppler at the level of the annulus • SV (cc) = CSA (cm2) * VTI (cm)

  20. Spectral Doppler Technique“Step by Step” • Calculate the regurgitant volume • R Vol(MR) = SV (MV) – SV (LVOT) • Measurement of VTI of regurgitant signal • Optimize CW Doppler spectrum of regurgitant signal

  21. Spectral Doppler Technique“Step by Step” • Calculate the effective regurgitant orifice area (EROA in cm2) • EROA = RVol(MR) ÷ VTI(MR)

  22. Spectral Doppler TechniqueLimitations • Accuracy of measurements • Inadequate spectral Doppler envelope for mitral regurgitation VTI measurement • Significant learning curve • May be considered time consuming and tedious

  23. Spectral Doppler TechniqueClinical Significance of the EROA and Mitral Regurgitation

  24. Color Doppler Imaging • Jet Area • Screening for significant flow often based on flow disturbance in receiving chamber • Size of flow disturbance evaluated in at least two views • Important to evaluate color flow disturbance based on cardiac cycle timing • Size of jet relative to receiving chamber provides qualitative index of regurgitant severity on scale of 0(mild) - 4+(severe)

  25. Color Doppler Imaging

  26. Color Doppler Imaging • Aortic Regurgitation • Best evaluated from PLAX approach • Shorter distance from transducer to flow region of interest: better signal to noise ratio • Multiple flow directions within jet

  27. Color Doppler Imaging - Mmode • Evaluation of exact timing of flow • In relation to QRS and valve opening and closure • Higher sampling rate

  28. Vena Contracta • Narrowest diameter of the flow stream • Reflects diameter of regurgitant orifice • Relatively unaffected by instrument settings • Recommended • Perpendicular to jet width • Zoom mode • Narrow sector and depth Non-dynamic

  29. Proximal Isovelocity Surface Area Method (PISA)

  30. Proximal Isovelocity Surface AreaBasic Principle • Based on conservation of energy • PISA measurement analogous to calculation of stroke volume proximal to a stenotic valve • Variation of continuity equation • Flow rate proximal to a narrowed orifice is the product of the hemispheric flow convergent area and the velocity of that isovelocity shells • Expressed by Q = 2r2Vr • Q = flow rate • 2r2 = area of hemispheric shell (cm2) • Vr = velocity at the radial distance – r(cm/s) Non-dynamic

  31. Proximal Isovelocity Surface AreaBasic Principle • Continuity principle: blood flow passing through a given hemisphere must ultimately pass through he narrowed orifice • Flow rate through any given hemisphere must equal the flow rate through the narrowed orifice • 2r2Vr = A0*V0 • A0 = area of the narrowed orifice (cm2) • V0 = peak velocity through the narrowed orifice (cm/s) • Rearrange the equation • A0 = (2r2Vr )/V0 Non-dynamic

  32. Proximal Isovelocity Surface AreaBasic Principle • Continuity principle: blood flow passing through a given hemisphere must ultimately pass through he narrowed orifice • Flow rate through any given hemisphere must equal the flow rate through the narrowed orifice • 2r2Vr = A0*V0 • A0 = area of the narrowed orifice (cm2) • V0 = peak velocity through the narrowed orifice (cm/s) • Rearrange the equation • A0 = (2r2Vr )/V0

  33. Proximal Isovelocity Surface Area(PISA) Application in Calculation of Effective Orifice Area (EROA) • Regurgitant valve acts as the narrowed orifice • Peak velocity is equivalent to the peak velocity of the regurgitant jet • Utilizing Doppler colorflow radius and velocity at the radial distance can be identified

  34. Proximal Isovelocity Surface Area(PISA) Application in Calculation of Effective Orifice Area (EROA) • Adjustment of Nyquist limit enlarges size of shell for more accurate measurement • Shift baseline to downward typically 20 to 40 cm/sec • The surface area of a hemisphere is calculated by the formula: • Surface area = 2πr2 • Multiplication of aliasing velocity with surface area yields regurgitant volume Non-dynamic

  35. Proximal Isovelocity Surface Area • Effective Regurgitant Orifice Area (ROA) • EROA = RVmax /VMR • RVmax : Regurgitant Volume (cm3) • VMR : Velocity of mitral regurgitation (cm/sec) Non-dynamic

  36. Steps for Obtaining PISA Regurgitant Orifice Area • Zoom mitral valve • Decrease color scale to identify surface of hemisphere shell • Note alias velocity – color bar (Valiasing) • Measure alias from orifice to color change (r) • Regurgitant volume • RVmax = 2 r2 x Valiasing • Measure peak mitral regurgitant velocity (VMR) • Effective Regurgitant Orifice Area • EROA = RVmax/VMR

  37. Steps for Obtaining PISA Regurgitant Orifice Area Surface area = 2r2 2(0.67 cm)2 = 2.80 cm2 Regurgitant Volume Flow Rate RVmax=Surface Area* Valiasing 2.80 cm2 * 26 cm/sec =72.8 cm3/sec Effective Regurgitant Orifice Area EROA = RVmax/VMR (72.8 cm3/sec) / (66.2 cm/sec) = 1.1 cm2 0.67cm

  38. Simplified Method for Calculation of the Mitral Regurgitant Volume • May be employed when appropriate CW jet is unable to be obtained (i.e. eccentric jet) • Based on premise: • Ratio of maximum MR velocity to VTI MR is equal to a constant of 3.25 • Regurgitant volume = (2r2Valiasing)/3.25 • 2r2 = area of hemispheric shell derived from the radius [r] (cm2) • Valiasing = aliased velocity identified as the Nyquist limit (cm/s) • 3.25 constant

  39. Clinical Significance of the PISA Radius and Valvular Regurgitation

  40. Proximal Isovelocity Surface Area – EROA MV Considerations • Assumption is made that RVmax and VMR occur at the same position in the cardiac cycle • PISA is larger in large volume sets and smaller in smaller volume sets • Also changes size in accordance with color Doppler scale • PISA should be recorded in a view parallel to flow stream typical apical four chamber • If PISA is hemi-elliptical or if valve is nonplanar, alternate approach or alternate corrections

  41. PISA Limitations • Nonoptimal flow convergence • Phasic changes • Eccentric jets • Interobserver variability • Isovelocity surface not always hemisphere • PISA model is a sphere. Mitral regurgitant orifice may be irregular • Multiple regurgitant jets • May not be able to completely envelope the mitral regurgitation trace • Mitral flow rate will vary throughout systole

  42. PISA – EROALimitations • Nonoptimal flow convergence Suboptimal Flow Convergence Flow: not symmetric Suboptimal Flow Convergence Perforated mitral leaflet - TEE

  43. Continuous Wave Doppler Approach • Signal intensity • Proportional to number of blood cells contributing to regurgitant signal • Compare retrograde to antegrade flow intensity • Weak signal = mild regurgitation • Strong signal = severe regurgitation • Intermediate signal = moderate regurgitation

  44. Continuous Wave Doppler Approach • Antegrade flow velocity • Regurgitation results in increase in antegrade flow across the incompetent valve • Greater the severity of regurgitation; the greater the antegrade flow velocity • Consideration of co-existent stenosis

  45. Continuous Wave Doppler Approach • Time course (shape) of mitral regurgitant velocity curve • Dependent on time-varying pressure gradient across regurgitant orifice • Related to pressure gradient • Normal LV systolic pressure = 100 – 140 mmHg • Normal LA systolic pressure = 5 – 15 mmHg • Difference therefore: 85 – 135 mmHg • MR velocity is typically 5 – 6 m/sec

  46. Continuous Wave Doppler Approach • Time course (shape) of mitral regurgitant velocity curve • Normal LV systolic function: • Rapid acceleration to peak velocity • Maintenance of high velocity in systole • Rapid deceleration prior to diastolic opening of the mitral valve • Increase in left atrial pressure results in late systolic decline in the instantaneous pressure gradient

  47. Continuous Wave Doppler Approach • Shape of aortic regurgitant curve • Dependent on time course of diastolic pressure difference • Normal low end-diastolic pressure • Aortic end-diastolic pressure is normal (high pressure difference) • Slow rate of pressure decline • Acute AI results in more rapid velocity decline in diastole

  48. Continuous wave Doppler across AV Decel = 270 cm/sec

More Related