The Physiology of Systole

James D. Thomas, MD, FACC, FASEDirector, Center for Heart Valve DiseaseBluhm Cardiovascular InstituteProfessor of Medicine, Feinberg School of Medicine, Northwestern UniversityChicago, IllinoisConflicts of interest: GE, Abbott, Edwards (honoraria)Spouse employment: Bay Labs

If you can’t measure it, it doesn’t exist.

–AN DeMaria

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

Systolic and Diastolic FunctionMyocardium to Ventricle

Stress/strain Relationship

20g20g

ActivationTissue Elastance

Pressure-Volume Curve

LV Volume

LV P

ress

ure

Diastole

Systole

Geometry

h

0

50

100

150

200

0 50 100 150

Systole

Diastole

1

54

3

2

Pres

sure

(mm

Hg)

Volume (mL)

Transition from Systole to DiastoleP-V Curves as a Function of Time

Myocardial Architecture is ComplexFitted transmural fiber field

Nielsen PMF, LeGrice IJ, Smaill BH & Hunter PJ. Am. J. Physiol. 260 (4), H1365-H1378, 1991

Peter Hunter

Fiber Orientations

Epicardium

Left-handed helix

Endocardium

Right-handed helix

Mid-wall

Circumferential

Nielsen, LeGrice, Smaill & Hunter. Am J Physiol 1991; 260: H1365

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

Collagen Orientation & Density

Courtesy of Peter Hunter

Myocyte Organization

Courtesy of Peter Hunter

base-apexshortening

circumferential shortening

axial twist(shear)

wallthickening

Mechanics of the HeartOur Imaging Planes Are Not Fiber-Oriented

MRI

Nash MP and Hunter PJ. J. Elasticity. 61(1-3):113-141, 2001

Subendocardial Strains

base

apex

radial circumferential

Complex combinations of linear and shear strains

So you can see it’s pretty complicated

Fluid flow

Reaction‐diffusion

Electro‐magnetic

Finite elasticity

Galerkin finite element method

And that’s BEFORE we get serious with the physics and math!

The Heart is an Elegantly Complex MachineFiber Sheet Oriented LV Strain Model

J. Hassan P. Hunter

Any echo measure of systolic function is mere approximation

Quantitation in Echocardiography• Systolic function

– Dimensions, volumes and ejection fraction – Stroke volume and cardiac output– 3D methods

• Advanced methods– Strain imaging

M-Mode Measurement of LV Dimensions

2D-guided M-mode

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

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

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

• 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

V = [7.0/(2.4+D)]D3

EF = [EDD2 - ESD2]/EDD2 + Apex (0, 5, 10%)

M-Mode Estimation of Volumes and EF

2D-guided M-mode

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

“Accordingly, the Teichholz and Quinones methods for calculating LV volumes from

LV linear dimensions are no longer recommended for clinical use.”

Quantification of LV Volume2-D Single Plane Assessment

LVEDV105 ml

LVESV78 ml

Stroke volume = 27 ml; ejection fraction = 26%

Biplane MethodsBetter in Asymmetric Ventricles

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

dL

Biplane Simpson’s Formula

Biplane Area-Length Formula

Biplane Area-Length Formula

Impact of Thrombolysis (T+/-) and Vessel Patency (P+/-) on Ejection Fraction Post MI

40

45

50

55

0 7 14 21 28 35 42

EF [%]

Time from Infarct [Days]

T+P+

T+P-

T-P+

T-P-

T: p=0.029P: p=0.081

Popovic et al. Circulation 1994; 90: 800-807

Simple Methods Still Give Insight

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

Biplane MethodsNormal LV Volumes

Who Are These “Normal” Subjects?Chamber Quantification Database

Overwhelmingly white and American/EuropeanNeeded: Normative data from around the world

World Alliance Societies of EchocardiographyWASE Normal Values Study – World Map

1700 patients from 17 countries, >18 yo

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

Principal InvestigatorsScientific 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

100 Patients Per Country Balanced Age & Gender Distribution

Male Female

18 - 40 years old 20 20

41 - 65 15 15

> 65 15 15

Acquisitions began July 1, scheduled to complete in 8 months

Contrast Helps with Quantitation

“Polar bear in a snowstorm” Ah, better!

Thomson et al: JACC 2001; 38: 867-75

Contrast Improvs Estimation of LV VolumeYields Results Closer to CT/MR

No contrastContrast

Quantitation in Echocardiography• Systolic function

– Volumes and ejection fraction – Stroke volume and cardiac output– 3D methods

• Advanced methods– Strain imaging

Measurement of Flow in LVOT

Measurement of Flow in RVOT

Region of Interest

SV = rv(r,t) dr dtApical Long-Axis View

Distance

Velo

city

Profile

Automated Calculation of Cardiac Output

Sun et al, Circulation 1997; 95: 932-939

00

2020

4040

6060

8080

100100

120120

140140

00 2020 4040 6060 8080 100100120120140140Stroke Volume by PWAO (Stroke Volume by PWAO (

r=0.95y=0.98x-0.03p<0.0001² V=-1.3±5 mln=155

Stroke VolumeStroke Volumeby ACOM (ml)by ACOM (ml)

-15-15-10-10-5-50055

1010151520202525

00 2020 4040 6060 8080 100100 120120 140140

Mean +Mean +2SD2SD

MeanMean

Mean -Mean -2SD2SD

Average Stroke Volume byAverage Stroke Volume byACOM and PWAO (ml)ACOM and PWAO (ml)

Difference in Stroke VolumeDifference in Stroke Volume(ACOM-PWAO,ml)(ACOM-PWAO,ml)

Accuracy of ACMLVOT SV vs Pulsed Doppler

Sun et al, Circulation 1997; 95: 932-939

Thavendiranathan et al. JASE 2012; 25: 56-65

Automated 3D Flow More Accurate Than 2D

Quantitation in Echocardiography• Systolic function

– Volumes and ejection fraction – Stroke volume and cardiac output– 3D methods

• Advanced methods– Strain imaging

Bob Levine, Mark Handschumacher, MGH ~1986-9

3D Echo Has Come a Long Way…

Q: Does this reconstruction take minutes, hours, or days?

A: Months…

We Really Have Come a Long Way…

Nine-Plane Visualization of 3D Echo

Quantitation similar to MRI

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

Normal 3D LV VolumesLet’s Hear From the 3D Master Himself

Thanks!

Channeling my inner Jose Rizal