The Physiology of Systole

Transcription

1 The Physiology of Systole James D. Thomas, MD, FACC, FASE Director, Center for Heart Valve Disease Bluhm Cardiovascular Institute Professor of Medicine, Feinberg School of Medicine, Northwestern University Chicago, Illinois Relations with Industry: GE, Abbott, Edwards (honoraria)

2 If you can t measure it, it doesn t exist. AN DeMaria

3 Which is More Remarkable?? That a hollow muscular shell can eject 100 ml at 140 mmhg That this same hollow muscular shell can fill with 100 ml at 10 mmhg That it can fill with 100 ml at 10 mmhg in <200 msec during exercise

4 Systolic and Diastolic Function Myocardium to Ventricle Tissue Elastance Activation Stress/strain Relationship Geometry 20g LV Pressure 20g Systole Diastole Pressure-Volume Curve h LV Volume

5 Pressure (mmhg) Transition from Systole to Diastole P-V Curves as a Function of Time Systole Diastole τ Volume (ml) 2τ 3τ 4τ 5τ

6 Myocardial Architecture is Complex Fitted transmural fiber field Peter Hunter Nielsen PMF, LeGrice IJ, Smaill BH & Hunter PJ. Am. J. Physiol. 260 (4), H1365-H1378, 1991

7 Fiber Orientations Epicardium Mid-wall Endocardium Left-handed helix Circumferential Right-handed helix Nielsen, LeGrice, Smaill & Hunter. Am J Physiol 1991; 260: H1365

8 What About the Torrent Guasp Model? The Heart is a Single Muscle Band I ve not met one pathologist who believes this Many think it s an artifact of boiling the heart before dissecting

9 Collagen Orientation & Density Courtesy of Peter Hunter

10 Courtesy of Peter Hunter Myocyte Organization

11 Mechanics of the Heart Our Imaging Planes Are Not Fiber-Oriented base-apex shortening circumferential shortening axial twist (shear) wall thickening MRI Nash MP and Hunter PJ. J. Elasticity. 61(1-3): , 2001

12 Subendocardial Strains base apex radial circumferential Complex combinations of linear and shear strains

13 So you can see it s pretty complicated And that s BEFORE we get serious with the physics and math! Reaction-diffusion Fluid flow Finite elasticity Electro-magnetic Galerkin finite element method

14 The Heart is an Elegantly Complex Machine Fiber Sheet Oriented LV Strain Model Any echo measure of systolic function is mere approximation J. Hassan P. Hunter

15 Quantitation in Echocardiography Systolic function Dimensions, volumes and ejection fraction Stroke volume and cardiac output 3D methods Advanced methods Strain imaging

16 M-Mode Measurement of LV Dimensions 2D-guided M-mode Lang et al. JASE 2015; 28: 1-39

17 Lang et al. JASE 2015; 28: 1-39

18 M-mode approach Pro: Reproducible, high temporal resolution, wealth of experience Con: Misalignment can over- or underestimate dimension 2D-guided approach Pro: Assures proper orientation of measurement Con: Lower frame rate In general, 2D-guided approach is preferred Lang et al. JASE 2015; 28: 1-39

19 M-Mode Estimation of Volumes and EF 2D-guided M-mode Accordingly, the Teichholz and Quinones methods for calculating LV volumes from LV linear dimensions are no longer recommended for clinical use. V = [7.0/(2.4+D)]D 3 EF = [EDD 2 - ESD 2 ]/EDD 2 + Apex (0, 5, 10%) Lang et al. JASE 2015; 28: 1-39

20 Quantification of LV Volume 2-D Single Plane Assessment LVEDV 105 ml LVESV 78 ml Stroke volume = 27 ml; ejection fraction = 26%

21 Biplane Methods Better in Asymmetric Ventricles Biplane Simpson s Formula dl Biplane Area-Length Formula Lang et al. JASE 2015; 28: 1-39 Biplane Area-Length Formula

22 Simple Methods Still Give Insight Impact of Thrombolysis (T+/-) and Vessel Patency (P+/-) on Ejection Fraction Post MI EF [%] T: p=0.029 P: p=0.081 T+P+ T+P- 45 T-P+ 40 T-P Time from Infarct [Days] Popovic et al. Circulation 1994; 90:

23 Biplane Methods Normal LV Volumes Lang et al. JASE 2015; 28: 1-39

24 Who Are These Normal Subjects? Chamber Quantification Database Overwhelmingly white and American/European Needed: Normative data from around the world

25 World Alliance Societies of Echocardiography WASE Normal Values Study World Map 1700 patients from 17 countries, >18 yo

26 WASE Steering Committee Roberto M. Lang, MD, FASE* Federico M. Asch, MD, FASE* Jose Banchs, MD, FASE Vera Rigolin, MD, FASE James D. Thomas, MD, FASE Neil J. Weissman, MD, FASE Susan Wiegers, MD, FASE Rhonda Price Staff Liaison *Principal Investigators

27 Principal Investigators Scientific Advisory Committee Mei Zhang China Ana Clara Tude Rodrigues Brazil Masao Daimon Japan Wendy Tsang Canada Seung Woo Park Korea Ario Koencoro Indonesia Edwin S. Tucay Philippines V. Amuthan India Greg Scalia - Australia Ricardo Ronderos Argentina Gilbert Habib France Patrizio Lancellotti Belgium Kofo Ogunyankin Nigeria Karima Addetia USA James Kirkpatrick USA Anita Sadeghpour Iran Pedro Gutierrez-Fajardo - Mexico

28 100 Patients Per Country Balanced Age & Gender Distribution Male Female years old > Acquisitions began July 1, scheduled to complete in 8 months

29 Contrast Helps with Quantitation Polar bear in a snowstorm Ah, better!

30 Contrast Improvs Estimation of LV Volume Yields Results Closer to CT/MR No contrast Contrast Thomson et al: JACC 2001; 38:

31 Quantitation in Echocardiography Systolic function Volumes and ejection fraction Stroke volume and cardiac output 3D methods Advanced methods Strain imaging

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33 Measurement of Flow in LVOT

34 Measurement of Flow in RVOT

35 Automated Calculation of Cardiac Output Apical Long-Axis View SV = π r v(r,t) dr dt Profile Velocity Distance Region of Interest Sun et al, Circulation 1997; 95:

36 Accuracy of ACM LVOT SV vs Pulsed Doppler Stroke Volume by ACOM (ml) r=0.95 y=0.98x-0.03 p< ² V=-1.3±5 ml n= Stroke Volume by PWAO ( Sun et al, Circulation 1997; 95: Difference in Stroke Volume (ACOM-PWAO,ml) Mean + 2SD 0 Mean Mean - 2SD Average Stroke Volume by ACOM and PWAO (ml)

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38 Automated 3D Flow More Accurate Than 2D Thavendiranathan et al. JASE 2012; 25: 56-65

39 Quantitation in Echocardiography Systolic function Volumes and ejection fraction Stroke volume and cardiac output 3D methods Advanced methods Strain imaging

40 3D Echo Has Come a Long Way Bob Levine, Mark Handschumacher, MGH ~ Q: Does this reconstruction take minutes, hours, or days? A: Months

41 We Really Have Come a Long Way

42 Nine-Plane Visualization of 3D Echo Quantitation similar to MRI

43 Let s Hear From the 3D Master Himself Normal 3D LV Volumes Lang et al. JASE 2015; 28: 1-39

44 Thanks!