Echocardiographic Assessment of LV Systolic Function Ryan Tsuda, MD

Causes of LV Systolic Dysfunction CAD HTN Cardiomyopathy (iDCM, HCM, Etoh, Peripartum, Viral, Infiltrative, Toxins, Thyroid Dz., Tachyarrythmias) Valvular Disease

Dimensions and Area Parasternal short-axis at level of papillary muscles Parasternal long-axis Apical 4-chamber Apical 2-chamber

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LV Mass Quantification M-mode Area-length method Truncated ellipsoid method Subjective assessment

LV Mass Quantification 2D M-Mode method using parasternal short axis view or parasternal long axis view Assumes that LV is ellipsoid (2:1 long/short axis ratio) Measurements made at end diastole ASE approved cube formula: LV mass (g) = 1.04 [(LVID + PWT + IVST)3 - (LVID)3] X 0.8 + 0.6 LV mass index (g/m2) = LV mass / BSA Small errors in M-Mode cause large errors in mass values. Can have off axis/tangential cuts due to motion.

LV Mass Quantification Penn convention formula (Another form of the cube equation) LV mass = 1.04[(IVS + LVID + PWT)3 – (LVID)3] – 13.6 g NL LV mass index for males: 93 +/- 22 g/m2 NL LV mass index for females: 76 +/- 18 g/m2

RWT = 2(PWT/LVID)

LV Volume Measurement With M-Mode Assuming nl ventricle morphology: V = (LVID)3 If ventricle is dilated (spherical): Teichholz equation Vdiastole = [7/(2.4 + LVID)] x [LVID]3

LV Systolic Function Variables LVEDD – LVESD FS = -------------------- X 100 LVEDD Percent change in LV dimension with systolic contraction FS approximates EF if there are no significant wall motion abnormalities SV = EDV - ESV CO = SV x HR EDV - ESV EF = ----------------- X 100 EDV

How do we quantify LV function? M-Mode Modified Simpson’s Method Single plane area-length method Velocity of Circumferential Shortening Mitral Annular Excursion E-point to septal separation Rate of rise of MR jet Index of myocardial performance Subjective assessment

M-Mode Quantification Use Parasternal Short-Axis (Mayo) or Long-Axis (ASE) views to measure LVEDD and LVESD May take several measurements at different levels and calculate average Assumes no significant regional wall motion abnormalities present….

M-Mode Quantification Uncorrected (LVEDD)2 - (LVESD)2 LVEF = ------------------------------ X 100 (LVEDD)2 If apical contractility is normal (Quinones group): Corrected LVEF = Unc LVEF + ((100 – Unc LVEF) X 15%) 5% hypokinetic, 0% akinetic, -5% dyskinetic, -10% aneurysm

Modified Simpson’s Method (Disc Summation Method) Use apical 4 chamber and apical 2 chamber views to measure dimension and area Trace borders manually or by acoustic quantification Divides area into 20 cylinders of equal height

Acoustic Quantification Automatic detection of blood-tissue border based on integrated backscatter analysis This is the difference in amplitude of backscatter between the myocardial wall and blood Blood-tissue border is recognized by echo machine, and marked with dots

Acoustic Quantification Area of study is quantified continuously in real time throughout cardiac cycle Therefore, the change in LV cavity area or volume with systolic contraction is calculated instantaneously, thereby providing LVEF. AQ limited by its dependency on echocardiographic gain and image quality Echo gain: Amplification of the returning RF signal which weakens with distance; i.e. an increased echodensity is seen as “tissue,” thereby decreasing accuracy……Lateral wall is especially subject to error…….

Derivation of 3.14(R)2 X D

Modified Simpson’s Method EDV – ESV LVEF = --------------- X 100 EDV

Single plane area-length method

Velocity of Circumferential shortening Vcf is the mean velocity of LV shortening through the minor axis Vcf = FS/ET ET is the time between LV isovolumetric contraction and isovolumetric relaxation Measure by obtaining M-mode of AV opening to AV closure, aortic flow by doppler, or by an external pulse recording of carotid artery NL values are > 1.0 c/s Slow Vcf may suggest diminished systolic function

Mitral Annular Excursion toward LV Apex M-mode tracings in systole The magnitude of systolic motion is proportional to the longitudinal shortening of the LV Normal mitral annular systolic motion is 8mm+ (average 12 +/- 2 on apical4 or apical 2 views) If motion is < 8 mm, the EF is likely < 50%

Normal E point to septal separation is < 6 mm With reduced lvef, EPSS may be increased.

CW doppler to measure rate of rise of MR jet may correlate to LVEF A slow rate of rise may indicate poor systolic function Must have MR present, and good doppler study present (more difficult with eccentric jets)

Index of Myocardial Performance (mayo clinics) Uses systolic and diastolic time intervals to evaluate global ventricular performance Systolic dysfunction causes prolonged isovolumetric contraction time (ICT) and a shortened ejection time (ET). Systolic and Diastolic dysfunction causes a prolonged isovolumetric relaxation time (IRT)… IMP = (ICT + IRT)/ET

Index of Myocardial Performance Normal LV: 0.39 +/- 0.05 LV, DCM: 0.59 +/- 0.10 Normal RV: 0.28 +/- 0.04 Primary Pulm Htn: 0.93 +/- 0.34 Use PW of AV inflow signal, or CW to get AV regurgitant signal…..Also need to measure interval between AV closure and opening (AVco). Then, need to use PW or CW to capture semilunar outflow signal to measure ejection time (ET). After all of this, IMP can be calculated. IMP = (AVco – ET)/ET

Assessment of Regional Function Based on grading wall motion divided into the 16 (17) segment model as proposed by the American Society of Echocardiography Each segment can be viewed in multiple tomographic planes

Assessment of Regional Function 1 = normal 2 = hypokinesis 3 = akinesis 4 = dyskinesis 5 = aneurysmal WMSI = Sum of scores / Number of visualized segments WMSI > 1.7 may suggest perfusion defect > 20%

Assessment of Regional Function Qualitative estimation errors due to: Underestimation of EF due to endocardial echo dropout and seeing mostly epicardial motion Underestimation of EF with enlarged LV cavity; a large LV can eject more blood with less endocardial motion Overestimation of EF with a small LV cavity Significant segmental wall motion abnormalities

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Doppler Tissue Imaging for Wall Motion Analysis Myocardium is color-coded according to velocity On P-Short Axis view, normal LV anterior wall motion during systole is blue (away from transducer), and the posterior wall motion is red (toward transducer); akinesis will have no color

Color Kinesis by 2D-Echo to Evaluate Wall Motion Real time color-coded display of LV endocardial motion on sequential frames Color is added to pixels that are identified as changing from blood to tissue in systole Create a color map of endocardial border This method limited by poor endocardial definition and translational motion of heart.

Summary LV Mass Quantification: M-mode, Area-length method, Truncated ellipsoid method, and Subjective assessment. LV Volume Quantification: M-mode, Subjective assessment LV Function Quantification: Modified Simpson’s and Subjective Assessment by region………….Also by M-mode, Single plane area length method, Velocity of Circumferential Shortening, Mitral Annular Excursion, EPSS, Rate of Rise of MR jet, Index of myocardial performance, etc……..

Summary Modalities limited by quality of echo windows, accurate measurements are based on the ability to identify and capture ideal axis (recognize misleading off axis/tangential slices), and of course, echocardiographer experience……..

Eye Candy

References Oh, Jae K., The Echo Manual 2nd edition, 1999, p. 37-43. Kerut, Edmund, Handbook of Echo- Doppler Interpretation, 1996, p. 54-63. Atlas of Echocardiography Website Braunwald, Eugene, Heart Disease 6th edition, p. 165-169.