The CardioPhiles

Systolic LV systolic function

 

• Diagnostic & prognostic information

•Assessment of therapy –e.g. HF, chemotherapy

•Management and risk assessment of pts with primary ventricular and valvular dysfunction – e.g. decisions regarding AICD placement

 

Determinants of LV systolic function

1. Contractility – Measurement of LV systolic fcn independent of loading conditions is difficult

2. Preload

3. Afterload

 

Endocardium thin bright line when perpendicular to US beam (axial resolution), broad blurred when parallel (lateral resolution)

 

Qualitative Assessment

•Visual estimation

–Severity: ASE Criteria

     •Mild: LVEF 45-54%

     •Moderate: LVEF 31-44%

     •Severe: LVEF <=30%

–Focality (global or regional)

•Best evaluated from multiple tomographic planes

•Attention to endocardial definition

•Typically, the visual assessment of global LV EF is reported in intervals of 5 or 10% and within a range

 

Semi-quantitative Assessment

1. Wall motion score index:

•Score is assigned to each segment permits a semi-quantitative assessment of LV fcn

•Sum of individual segment scores/number of segments visualized à Total score of 0 = normal

•Various scoring systems of wall motion: In general: 1=normal motion or hyperkinesia (or hyperkinesis=0), 2=hypokinesia, 3=akinesis, 4=dyskinesia (or 5=aneurysmal)

•Linear relationships exist between WMI and LVEF –9-segment model: Regression equation LVEF = 30WMI (James H. McGowan. Am Heart J 2003;146:388–97)

2. Mitral annulus motion (MAM) towards apex in systole

–Magnitude proportional to extent of shortening in LV length

–Normal subjects >= 8mm in 2ch or 4ch

–MAM <8mm has 98% sens. & 82% spec. for EF <50% 

 

Quantitative Assessment

Careful with off-axis, tangential imaging and geometric assumptions

 

Shortening Fraction and Ejection Fraction

•SF (%) = (LVIDd – LVIDs)/LVIDd x 100

     –Normal 25-45%

•EF (%) = {[(EDD2 – ESD2)/EDD2]x100} + K

     –K is correction factor for apex (10% normal apex ;

5% HK; 0% AK; Minus 5% DK)

 

•LV volume calculations are based on geometric assumptions about the LV shape

thus Higher accuracy for methods with the fewest assumptions

(data from multiple tomographic views)

•3-D would be most accurate à no assumptions

 

•Modified Simpson's Rule — Better method, especially if WMA.

Summation of discs using a measurement of the LV length (L) from the ap4-ch & LV area at the base (A[psa-b]), mid (A[psa-m]) and apical (A[psa-a]) LV from the PSAX

 –V = [(A[psa-b] + A[psa-m] x L)] + [(A[psa-a] x L) ÷ 2] + (pL3 ÷ 6)

•Alternatively, one can trace the endocardial surface of the LV in 2 orthogonal planes (eg, ap4-ch & 2-ch), although a single plane can be used

•LV EF = [(LVEDV - LVESV) ÷ LVEDV] x 100 (calculated using volume estimates)

•ASE Preferred: Modified Simpson’s rule (Biplane Apical Views) –V = (p/4)Σ20i=1aibi x (L/20)

•Alternative (if 2 views are not available) à Single-plane Ellipsoid Formula –V = 8 x A2 ÷ 3pL @ 0.85 x A2/L

ASE Guidelines. JASE 1989

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

•Use of contrast for improvement of suboptimal echo is strongly validated to improve resolution of endocardial borders

•Suboptimal echo: 2 of 6 segments in standard apical view not visualized or inability to obtain recording of Doppler max vel. profiles

ASE Position Paper. JASE 2000;13:331-42

 

3D vs CMR

•24 subjects - Abnormal (n=14) or normal (n=10) LVs •Compared with volumes and EF obtained by CMRI •3-DE data correlated highly with CMRI (r= 0.98) •LV volumes were underestimated by 3-DE compared with CMRI •The difference for EF was NS between the 2 methods (EF 0.9±4.4%, p=NS). •Observer variability was acceptable, and repeatability of the method was excellent.  Harald P. Kuhl, J Am Coll Cardiol 2004;43:2083–90

 

No systematic under/overestimation of LVEF with Visual vs. Quantitative Analysis

•Systematic review – Simpson’s rule vs. WMI vs. subjective visual assessment, compared with ventriculography –25 studies – data agreement between echo & reference –18 studies – correlation data alone •For Simpson’s rule à limits of agreement (95% CI) ranged from LVEF 7% to 25% (median 18%) •For WMI 13% to 20% (median 16%) •For subjective visual assessment 16% to 24% (median 19%) James H. McGowan. Am Heart J 2003;146:388–97

 

Reasons for Errors in EF Estimation with 2-D images

•Underestimation:

     –Endocardial echo dropout, assessment of EF made by

epicardial motion (specular reflection is angle dependent - better

if perpendicular which makes if different that Doppler which

which is better if parallel)

     –LV cavity significantly enlarged: Larger cavity

can eject larger volume with less endocardial motion

•Overestimation

–Small LV

–Significant regional WMA: Viewer needs to integrate views 

 

Calculation of SV

•Flow rate = CSA x Flow vel.

•Flow velocity varies during ejection period

•Individual vel. Of the Doppler spectrum must be summed (i.e. integrated)

•Sum of vel. is the time velocity integral (TVI)

•TVI = Stroke distance

•SV (mL) = CSA x TVI

     –CSA = (D/2)2 x p = D2 x 0.785

•CO (L/m) = SV x HR

•CI = CO/BSA