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### INDEX OF MYOCARDIAL PERFORMANCE

- “DIASTOLE”-TO SEND APART

Systolic function is affected by preload afterload,contractility and heart rate.

- Asynchronous systolic contraction also may affect systolic function

LV SYSTOLIC FUNCTION

- Quantitative echo
- LV VOLUME
- LV MASS
- EJECTION INDICES

STROKE VOLUME

EJECTION FRACTION

FRACTIONAL SHORTENING

VELOCITY OF CIRCUMFERENCIAL FIBRE SHORTENING

Quantify LV function -MODES

- 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 or Long-Axis views to measure LVEDD and LVESD
- May take several measurements at different levels and calculate average
- Assumes that no significant regional wall motion abnormalities are present

Uncorrected (LVEDD)² - (LVESD)²

LVEF = ----------------- X 100

(LVEDD)²

If apical contractility is normal

Corrected

LVEF = Unc LVEF +(100 – Unc LVEF) X 15%)

5% hypokinetic, 0% akinetic, -5% dyskinetic, -10% aneurysm

- Fractional shortening (FS)
- Assumes symmetric contraction
- Ejection fraction (EF)

INDIRECT M-MODE MARKERS

- EPSS
- GRADUAL CLOSURE OF AORTIC VALVE
- MEAN Vcf-rate of shortening of LV

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%

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

Ejection Fraction

- Quantitative

- accuracy, reproducibility limited

- assumes shape of LV cavity

- best in symmetric ventricles

Simpson’s Rule – the biplane method of disks

LV-ED LV-ES

- Volume left ventricle

- manual tracings in systole and diastole

- area divided into series of disks

- volume of each disc(πr2x h )

summed = ventricular volume

LV-ED LV-ES

A4C

A2C

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

- LV mass = 1.04[(IVS + LVID + PWT)3 –

(LVID)3] – 13.6 g

NL LV mass index for males: 93±22g/m2

NL LV mass index for females: 76±18g/m2

Regional Myocardial Function

- Assessment of motion of regions of the myocardium
- Useful for detection of myocardial ischemia
- Leads to decreased or paradoxical motion of the wall in affected areas
- Regions can be roughly mapped to coronary arteries

Stroke Volume and Cardiac Output

- Flow = Cross sectional area (CSA) x Average velocity
- Average velocity not usually measured directly
- VTI = velocity-time integral
- Area under the velocity curve for a single beat
- Represents ‘stroke distance’
- SV = VTI * CSA

Pitfalls in Echo Calculation of CO

- Accurate measurement of CSA
- Weakest link in the calculation
- VTI very good for assessing change in cardiac output with therapy, by following changes in VTI, since CSA is largely invariant in an individual
- Measures forward flow only
- Regurgitant fraction not considered
- May over-estimate systemic cardiac output
- Echocardiographic window in mechanically ventilated patients may be poor

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

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).

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 PulmHtn: 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)
- PW or CW to capture semilunar outflow signal to measure ejection time (ET)

IMP = (AVco – ET)/ET

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

LV PRELOAD

- Amout of passive tension or strectch on the ventricular walls prior to systole
- This load determines end diastolic sarcomere length and force of contraction
- This inturn decides stroke volume and cardiac output

AFTERLOAD AND CONTRACTILITY

- Afterload is the wall stress during ejection
- Three major components are-peripheral resistance,arterial compliance,& peak intraventricular pressure.
- Contractility is the inherent property of the myocardium to contract independent of the changes in pre & afterload

EVALUATION OF SYSTOLIC PERFO

- CONTRACTILITY INDICES

Isovolumic indices

Maximum dp/dt

Maximum (dp/dt)/p

Vpm or peak([dp/dt]/28p)

(dp/dt)/Pd at Pd=40 mm hg

Ejection phase indices

LVSW

LVSWI

EF

MNSER(mean normalisedsyst eject rate)

Mean Vcf

Isovolumic indices

- Dp/dt-max rate of rise of LV systolic pressure-oldest & widely used
- Nl-1610±290 mmHg/sec

LVSW

- Area within PV diagrams-most accurate
- Other methods

LVSW=(LVSP−LVDP)SV(0.0136)

LVSP&LVDP=MEAN SYST/DIAST PR

SV=STROKE VOL IN ml

0.0136=for converting mm Hg-ml into g-m

LVSW=(AoSP−PCWP)SV(0.0136)

- LVSW –good measure in the absence of vol or pressure overload
- Nl-90±30g-m
- Values ≤25 indicate severe Lvsyst failure & <20 prognosis is grave.
- But reflects syst performance only when ventricle is homogenous in consistency-DCMP
- In ext MI LVSW may be depressed even if contractility is normal

Lvsyst function can be assessed using only volume data from P-V diagram

- EF=[(LVEDV−LVESV)/LVEDV]
- EF/ Ejection time obtained from Ao pressure tracing

=Mean normalisedsyst ejection rate

MNSER=(LVEDV−LVESV)/(LVEDVхET)

NL-EF(angio)=.72±0.08

Nl MNSER(angio)=3.32±0.84EDV/sec

Vcf=velocity of the circumferential fiber shortening

- Rate of shortening of lvmyo fiber in a circmferential plane at the midpoint of the long axis of the ventricle
- MeanVcf=end diastendocardial circum fiber length −end syst length
- Vcf=(Ded−Des)/Ded(ET)
- Nl-1.83±0.56ED circ/sec

Drawbacks-influenced by preload & afterload

- An Lvef≤.40 indicates depressed lv contractility, if there is no loading to account for the reduction.
- Interpretation of ejection phase indices are improved by consideration of the preload & afterload.

ESPVR

- Fundamental principle of end-systolic Pv analysis is that, at end-systole there is a single line relating LV chamber vol to pressure,unique for the level of contractility & independent of loading conditions.
- Most reliable index of contractility
- Insensitive to changes in pre,afterload& heart rate
- Slope of the end syst pr vol curve is called elastance-sensitive parameter

Other indices

- LVdp/dt max and EDV
- Slope of this as an index of contractility

Stress-shortening relationship

- Inverse relation between the two
- ↑afterload→↑systwallstress→↓myocardial shortening

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