Diastology Disclosures: None. Dias2011:1

Transcription

1 Diastology 2011 James D. Thomas, M.D., F.A.C.C. Cardiovascular Imaging Center Department of Cardiology Cleveland Clinic Foundation Cleveland, Ohio, USA Disclosures: None Dias2011:1

2 Is EVERYBODY a member!?! Dias2011:3

3 LV Pressure Systolic and Diastolic Function Myocardium to Ventricle Tissue Elastance Activation Stress/strain Relationship Geometry 20g 20g Systole Pressure-Volume Curve h Diastole LV Volume Dias2011:4

4 LV Relaxation Exponential Pressure Decay in IVR = 30 p 0 e -t/ Dias2011:6

5 LV Pressures-Volume Curves Systolic Failure Diastolic Failure Normal Stiffer portion of same LV P-V curve Decreased diastolic chamber distensibility LV Pressure Left Ventricular Volume Left Ventricular Volume Lorell BH. Ann Rev Med 1991;42: Dias2011:7

6 Passive Elasticity Component Contribution Collagen ++++ Titin ++++ Actin ++ Intermediate + Microtubules - Passive Tension in Cardiac Muscle: Contribution of Collagen, Titin, Microtubules, and Intermediate Filaments Granzier HL, Irving TC Biophysical Journal 1995; 68: Dias2011:8

7 Exercise Can Unmask Delayed Relaxation Relaxation Time Constant ( ) Diastolic dysfunction LVEDP Diastolic dysfunction Normal Normal Heart Rate (bpm) Heart Rate (bpm) Dias2011:10

8 What Determines Transmitral Flow? Key parameters of the mitral inflow pattern: E E VTI AT DT A A VTI A Duration E/A Dias2011:11

9 Determinants of Diastolic Function LV Stiffness LA Function LV Relaxation Filling Pressures LV filling indices Dias2011:12

10 Transmitral Flow Physical Determinants In physical terms, we can only speak of factors that accelerate flow and factors that decelerate flow Acceleration is governed by the magnitude of the transmitral gradient relaxation Deceleration is governed by the equilibration of LA and LV pressure compliance LA LV p A A L V p V Dias2011:13

11 Transmitral Flow Physical Determinants of Acceleration By Newton s second law, a = F/m m = mitral inertance, the mass of blood being accelerated across the mitral valve 3 X valve diameter (reduced in mitral stenosis) F = transmitral pressure difference Grows as LV pressure drops exponentially below left atrium p(t) = p 0 e -t/ dp/dt = -p/ = p LA / Dias2011:14

12 MV Acceleration Proportional to p LA / p(t) = p 0 e -t/ mmhg LAP 10 mmhg 0 p Delayed Pseudonormal Normal relaxation Rate of rise is proportional to growth of transmitral pressure gradient, p, and d p/dt = LAP/ Dias2011:15

13 Effect of Relaxation on LV Inflow With delayed relaxation, acceleration is slowed and E peak is lower. Choong, et al, Circ 1987 Dias2011:16

14 Effect of LAP on LV Inflow With rising LA pressure, acceleration is faster and E peak is higher. Choong, et al, Circ 1987 Dias2011:17

15 Physical Determinants of Deceleration Stiffer Ventricle = Shorter Decel Time Compliant S A p Compliant A S V v Stiff S A p Stiff t A S V Dias2011:18

16 DT (msec) LV stiffness? y = e x r = 0.87 p < KLV (mmhg/ml) DT = 140 msec Answer = operating stiffness (dp/dv) increased ( 0.30mmHg/ml) Garcia, Am J Physiol 2001;280:H554 Dias2011:19

17 Left Ventricular Filling Patterns 300 Normal Delayed relaxation Pseudonormal Restrictive Dias2011:20

18 E/A ratio Preload vs Relaxation Confounding Effects best Garcia et al, JACC 1998;32:865 Diastolic function worst Dias2011:21

19 The Problem with Transmitral Doppler Assessment of Diastolic Function Preload Sensitivity E/A ratio Really good Good Bad Really bad Diastolic Function Really, really bad Dias2011:22

20 Tissue Doppler Imaging Blood: High velocity, low amplitude Tissue: Low velocity, high amplitude S E A Dias2011:23

21 Myocardial Wall Velocities Independence from Mitral Inflow Mitral inflow Mitral annulus Normal Delayed relaxation Pseudonormal Restrictive Sohn et al., JACC 1997; 30: Dias2011:26

22 Constriction vs Restriction M-mode Doppler MV Flow Normal Restriction Constriction E 50cm/s 50cm/s E E 20cm/s TDE Ea 5cm/s Ea 5cm/s Ea Garcia et al., JACC 1996; 27: Dias2011:27

23 Transmitral velocity [cm/s] Annular velocity [cm/s] Constriction vs Restriction Doppler Differentiation Mitral Pulsed Doppler Annular DTI p= p= Garcia et al., JACC 1996; 27: C R C R Dias2011:28

24 Assessment of LV Relaxation DTE E-wave Inversely Related to PW-E w E-A E Anterior MI Controls E/A >1 E/A <1 Tau Tau Oki et al, Am J Cardiol 1997;79:928 Dias2011:29

25 Implication E/Ea Can Predict LA Pressure If E LAP/ and Ea 1/, then LAP E/Ea Dias2011:30

26 Estimation of P LA Nagueh et al. JACC 1997;30: Dias2011:31

27 Are DTI Velocities Truly Independent of Preload?? No, not if the heart is normal Dias2011:32

28 E/E'sep Estimation of Left Atrial Pressure Subjects without Heart Disease y = 0.019x r = 0.01 SEE: 3.04 mmhg Pulmonary Capillary Wedge Pressure (mmhg) Firstenberg et al. J Am Coll Cardiol 2000; 36: Dias2011:33

29 And Not if the Heart is REALLY Sick Acute Decompensated Heart Failure Mullens et al. Circ 2009; 119: Dias2011:34

30 Circ 2009; 119: EF = 24% E = 135 cm/sec Lateral e = 2 E/e = 67 PCW = 14 mmhg EF = 31% E = 89 cm/sec Lateral e = 6.9 E/e = 14 PCW = 33 mmhg Dias2011:35

31 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 Dias2011:36

32 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: Dias2011:37

33 Longitudinal Strain from B-Mode Echo Normal Subject Dias2011:38

34 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: Dias2011:39

35 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 Dias2011:40

36 LV Relaxation and Intraventricular Pressure Gradients Active relaxation, occurring earlier and more rapidly at the LV apex generates small (1-2 mmhg) intraventricular pressure gradients in the normal heart. These intraventricular pressure gradients assist in the low pressure filling of the heart Critically impacted by delayed relaxation and dyssynchrony Apex Mid Base Dias2011:41

37 Importance of Diastolic Suction P Normal Ischemic Almost impossible to measure invasively Courtois et al. Circulation 1990;81: Dias2011:45

38 Color M-Mode Methodology Dias2011:46

39 Measurement of Propagation Velocity 1 sec LV V p = 30 cm/sec 10 cm LA Dias2011:47

40 IVPG (mmhg) CMM Calculation of IVPG E A Time (s) P LVapex LVbase v v v s t s Greenberg et al. Am J Physiol 2001;280:H Euler equation Dias2011:48

41 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 Dias2011:49

42 IVPG are Critical During Exercise Diastole Disproportionately Shortened IVPG IVPG Diastolic Filling Time Full Cardiac Cycle Cheng, Circ Res 1992;70:9-19 Dias2011:50

43 VO2 max (ml/kg/min) Augmentation of Diastolic Suction Predicts Exercise Capacity VO2max = 7.82 * IVPG R = 0.79 P < Delta IVPG (mmhg) Heart Failure Normal Subjects Rovner et al. Am J Physiol 2005; 289: H Dias2011:51

44 Torsion from 2D Echo 8 Apical twist Notomi et al. JACC 2005; 45: Dias2011:52

45 Torsion During Exercise 8 Rest Apical twist 18 Exercise Apical twist Notomi et al. Circ 2006; 113: Dias2011:53

46 Timing and Magnitude of LV Mechanics Untwisting is the First Event of Diastole Long- and Short-axis, cm/s Torsion/ Untwisting, rad/s Long- and Short-axis, cm/s Torsion/ Untwisting, rad/s Rest Exercise M C O A EJ Contraction/ Torsion A C M O EF (E) Expansion M C O A EJ Contraction/ Torsion A C M O EF (E) Expansion Untwisting Lengthening Time, % Systolic duration Untwisting Lengthening Time, % Systolic duration Long axis motion Radial motion Torsion Notomi et al. Circ 2006; 113: Dias2011:54

47 Torsion, %max Torsion-Volume Loop TV 100 AC Ejection MO 25 0 Pk-E AO En-E MC LV volume, %SV Half of torsion is released before MV opens Notomi et al. Circ 2006; 113: Dias2011:55

48 IVPG, mmhg LV Untwisting Predicts IVPG 7.5 y = -0.44x r = Peak LV untwisting, rad/s Notomi et al. Circ 2006; 113: Dias2011:56

49 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 Dias2011:57

50 Echo Education This Winter! Register at Hope to see you there! Dias2011:58

51 It s Your Choice!! Dias2011:60