Strain/Untwisting/Diastolic Suction

Transcription

1 What Is Diastole and How to Assess It? Strain/Untwisting/Diastolic Suction James D. Thomas, M.D., F.A.C.C. Cardiovascular Imaging Center Department of Cardiology Cleveland Clinic Foundation Cleveland, Ohio, USA Disclosures: None Dias2010:1

2 LV Diastolic Function 2010 Advanced Echocardiographic Methods Myocardial strain and strain rate Intraventricular pressure gradients Ventricular torsion Dias2010:2

3 Myocardial Strain: What is It?? Strain: dimensionless index of change in length Strain ( ) = L-L 0 / L 0 LV strain may offer a pure index of regional LV function but is difficult to measure L 0 L Dias2010:3

4 Velocity v dt Displacement v s Strain rate dt Strain Dias2010:5

5 Strain: RV, Septum, LV Lat Septum -20% RV -30% Dias2010:6

6 redictors of Systolic and Diastolic Strain Rate Relationship to invasive indices during ischemia Systolic Strain Rates SYS vs: r ES P/V dp/dt max 0.86 EF 0.77 ESV 0.57 Diastolic Strain Rates DIAS vs: r EDP dp/dt max 0.81 Tau 0.72 EDV 0.60 Greenberg et al. Circ 2002; 105: Dias2010:7

7 Strain: More Than a Number 3D Tensor with Linear and Shear Components E xx E xy E xz E yx E yy E yz E ij = E ji E zx E zy E zz Linear strain Shear strain Dias2010:8

8 Limitations of TDI Strain Detects only single component of strain Limited scope of radial (anteroseptum and posterior wall) and circumferential (septum and lateral wall) strain from parasternal window Subject to noise, particularly strain rate Very tedious to perform Dias2010:9

9 Is it possible to derive strain and torsion directly from the B-mode image?? Dias2010:10

10 Longitudinal Strain from B-Mode Echo Normal Subject Dias2010:11

11 Normal Dias2010:12

12 LAD Infarct Dias2010:13

13 60 pts w/ EF>50%, 30 w/ pre-a LVEDP<15 mmhg, 30 over 15 mmhg Normal EDP Elevated EDP Higher LVEDP lower systolic and diastolic strain rate Nguyen et al. JASE 2010; 23: Dias2010:14

14 Systolic Strain vs LVEDP Lower values higher EDP Longitudinal Circumferential Radial Torsion Nguyen et al. JASE 2010; 23: But r 2 only 0.15 to 0.27 Dias2010:17

15 Diastolic Strain vs LVEDP Lower values higher EDP Longitudinal Circumferential Radial Torsion Nguyen et al. JASE 2010; 23: But r 2 only 0.11 to 0.16 Dias2010:18

16 LV Mechanics 2010 Advanced Echocardiographic Methods Myocardial strain and strain rate Intraventricular pressure gradients Ventricular torsion Dias2010:19

17 Color M-Mode Methodology Dias2010:20

18 Color M-Mode Methodology Dias2010:21

19 Measurement of Propagation Velocity 1 sec LV V p = 30 cm/sec 10 cm LA Dias2010:22

20 p w (mmhg) E-Wave/Propagation Velocity Linear Relation to Left Atrial Pressure E-wave Velocity E A 84 cm/s r = 0.80 p < y = 5.27x+4.66 SEE = 3.1 Color M-Mode Propagation Velocity LV LA 28 cm/s E/v p = 84/28 = 3.0 p w = 20 mmhg Garcia et al., J Am Coll Cardiol 1997; 29: Dias2010:23

21 IVPG (Suction)Lets LV Fill at Low Pressure Absence with Ischemia P Normal Ischemic Courtois et al. Circulation 1990;81: Dias2010:24

22 IVPG (mmhg) CMM Calculation of IVPG E A Time (s) P LV apex LV base v v v s t s Greenberg et al. Am J Physiol 2001;280:H Euler equation Dias2010:25

23 Intraventricular Pressure Gradient 8 piv (Doppler) 6 4 y = 0.87x r = 0.96 SEE = 0.35 mmhg p < p IV (catheter) Greenberg et al: Am J Physiol 2001; 280; H2507-H2515 Dias2010:26

24 CMM IVPG (mmhg) Validation of the IVPG in HOCM CCM IVPG = 0.78 * (InvIVPG) r = 0.88, p < 0.01 SEE = 0.34 mmhg Rovner, AJP 2003; 285: H Invasive IVPG (mmhg) Dias2010:27

25 IVPG (mmhg) Change in IVPG After Septal Ablation p < Baseline Baseline Post ablation Rovner, AJP 2003;285:H months post ablation Dias2010:28

26 IVPG are Critical During Exercise Diastole Disproportionately Shortened IVPG IVPG Diastolic Filling Time Full Cardiac Cycle Cheng, Circ Res 1992;70:9-19 Dias2010:29

27 VO2 max (ml/kg/min) Correlation Between Delta IVPG and VO 2 max VO2max = 7.82 * IVPG R = 0.79 P < Delta IVPG (mmhg) Heart Failure Normal Subjects Rovner et al. Am J Physiol 2005; 289: H Dias2010:30

28 Cortina et al. Circulation 2007; 116: Dias2010:31

29 LV Mechanics 2010 Advanced Echocardiographic Methods Myocardial strain and strain rate Intraventricular pressure gradients Ventricular torsion Dias2010:32

30 Left Ventricular Torsion The spiral architecture of the LV produces base-apex torsion This stores energy in systole that is released in diastole (suction) Though important in LV mechanics, torsion has been difficult to measure MRI courtesy of Ed Shapiro, Johns Hopkins University Dias2010:33

31 Normal Strain and Torsion P S A L Contraction Counter-clockwise Apical Rotation as viewed from apex Contraction Basal Time Clockwise Systole Diastole Notomi et al. Circulation March, 2005 Dias2010:34

32 Echo-Torsion Papers, Pubmed search for Echocardiography and Torsion : 43 papers Dias2010:35

33 Measurement of LV Torsion by Doppler tissue imaging Yuichi Notomi, MD, YIA finalist ASE 2005 Notomi et al. Circulation 2005; 111: Dias2010:36

34 Torsion from 2D Echo 8 Apical twist Notomi et al. JACC 2005; 45: Dias2010:39

35 LV LV Torsion, degree Measurement of LV Torsion by Doppler tissue imaging LV Torsional profile in a cardiac cycle HOCM Severe HOCM Dog AS ASevere AS Normal Adult Adult Normal Adult Normal Adult dog Normal Adult child DCM Normal DCMChild Dias2010:40

36 Torsion During Exercise 8 Rest Apical twist 18 Exercise Apical twist Notomi et al. Circ 2006; 113: Dias2010:41

37 Long- and Short-axis, cm/s Torsion/ Untwisting, rad/s Long- and Short-axis, cm/s Torsion/ Untwisting, rad/s Timing and Magnitude of LV Mechanics Impact of Exercise Rest Exercise M C A O EJ A C M O Contraction/ Torsion EF (E) Expansion M C A O EJ A C M O EF (E) Contraction/ Torsion Expansion Untwisting Lengthening Time, % Systolic duration Untwisting Lengthening Time, % Systolic duration Long axis motion Radial motion Torsion Notomi et al. Circ 2006; 113: Dias2010:42

38 Torsion, %max Torsion-Volume Loop TV 100 AC Ejection MO 25 0 Pk-E AO En-E MC LV volume, %SV Notomi et al. Circ 2006; 113: Dias2010:43

39 IVPG, mmhg LV Untwisting Predicts IVPG 7.5 y = -0.44x r = Peak LV untwisting, rad/s Notomi et al. Circ 2006; 113: Dias2010:44

40 Untwisting/IVPG Relationship Holds for Normals and HCM Peak IVPG, mmhg 4 Normal Exercise 2 Normal Rest HCM Exercise HCM Rest 0 0 Peak untwisting velocity, rad/s -5 Dias2010:45

41 Relationship Between Torsion,, and IVPG Y=0.64X r=0.74, p< Y=-0.31X r=0.66, p< Y=0.51X r=0.76, p< Untwisting 200 Tau IVPG Torsion Untwisting Untwisting Notomi et al. AJP 2008; 294: Dias2010:46

42 Wang et al. Circulation 2007; 115: Dias2010:47

43 Putting It All Together During systole, a significant amount of elastic energy is stored in the myocyte and the interstitum as torsion The earliest mechanical manifestation of diastole is an abrupt untwisting that is largely completed before the mitral valve opens This untwisting helps to establish a base-to-apex intraventricular pressure gradient in early diastole that assists in the low pressure filling of the heart Modulation of this mechanism allows the heart to augment its function many-fold during exercise Dias2010:48

44 What Will Be the Role of Torsion Assessment? Clear value as tool to understand pathophysiology Clinical tool? What is needed? Easier use Compelling application New information over existing indices Dias2010:49

45 Apical Rotation Gives Most of the Information 11 dogs Inotropic modulation with dobutamine and esmolol Ligation of LAD or LCx artery Kim W-J et al. Circ Img 2009; 2: Dias2010:50

46 Can Apical Rotation be Part of a Diastolic Stress Test? Tan YT et al. JACC 2009; 54: Dias2010:51

47 Differences in Apical Rotation and Untwisting with Exercise Exercise apical rotation: 13.5±4.7 vs 17.7±3.6 p = Exercise apical untwist: -103±32 /sec vs -129±32 /sec p = Tan YT et al. JACC 2009; 54: Dias2010:52

48 Where do we go from here?? Transmural strain 3D strain Dias2010:53

49 Layer-Specific Strain Analysis LV Function in Rats and Humans Rat Human pex Mid Rat Human Base Bachner-Hinenzon et al. AJP Heart-Lung Physiol e-pub July 2, 2010 Dias2010:54

50 Circumferential Strain Seo et al. Circ Img 2009; 2: Dias2010:55

51 Pros Can measure (in theory) all 3 linear and 3 shear components of strain throughout the volume of interest Speckles do not pass through the interrogation plane and appear/disappear Cons Pros and Cons of 3D Strain Low spatial resolution makes it difficult to localize speckles Low temporal resolution limits ability to track speckles Dias2010:56

52 LV Mechanics: Present State of the Art We now have the echocardiographic tools available to let us assess LV contraction, relaxation, compliance, suction, and filling pressure. 3D Modelling of LV Torsion Dias2010:57

53 Thanks!! Dias2010:58