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Echocardiography:LV Systolic Function
David M. Whitaker, MD
“I need a stat echo…”
LVEF – most common reason for echo
2nd most common – pericardial effusion
3rd most common - RVSP
The “early days”
Before there was 2D echo M-mode
M-mode was a useful tool but with many limitations
Offered superior temporal resolution
M-mode
LV function was determined using linear measurements
Even as 2D echo advanced, linear measurements still made to assess LV function
Linear Measurements
M-mode
Early limitations related to “quality” of echo image – difficulty separating blood pool from endocardial interface
Improvements in gray scale technology improved this
Other M-mode Limits
Ice Pick evaluation
Leaves out potential regional wall motion abnormalities
May overestimate or underestimate overall LV function
Other M-mode Limits
Because the M-mode line often intersects the LV in a tangential fashion – the minor axis is often overestimated
Could argue that for a given pt the degree of overestimation remains constant and thus could be used for serial evaluation
More Linear M-mode
Other measurements for LV performance Rates of systolic wall thickening of post wall Calculation of velocity of circumferential shortening
(which assumes the LV is a perfect circle) Descent of the base measurement
Descent of the Base
During ventricular contraction – base moves toward apex
Magnitude of this motion directly proportional to systolic function
Same principle that TDI is based on
Indirect Markers of LVEF
Increased E-point septal separation
Gradual end systolic closure of the aortic valve
E-point Septal Separation
Magnitude of MV opening (E wave height) correlates with transmitral flow and with LV stroke volume – if MR is not bad
Internal dimension of LV diastolic volume
So… the ratio of the mitral excursion to LV size reflects the EF
E-point Septal Separation
Normally the MV E-point within 6 mm of the LV septum
In severely depressed EF, this distance is increased…
Aortic Valve Closing Pattern
If the LV stroke volume is decreased, there may be a gradual reduction in forward flow in late systole
Results in “gradual” closing of the AV in late systole
M-mode will show a rounded closure rather than the box cars
2D Measurements
A number of 2D views are used to provide LV function
Some rely exclusively on area measurement
Others rely on calculation of volume from the image
2D Measurements
All the general formulas based on the assumption that ventricle will adhere to a predictable shape
If there are regional wall motion abnormalities, the accuracy of these methods decreases
Simplified Method
Get minor axis measurements in diastole and systole at base, mid and distal LV.
Combine these with assessment of the apex to get EF
Simpsons Method
A.k.a. the “Rule of Disks”
Requires apical 4 or 2 chamber view, outlining the endocardial border in diastole and systole
Ventricle is mathematically divided along its long axis into a series of disks of equal height
Simpsons Method
Individual disk volume is calculated Height x disk area
Height = total length of LV / # of disks
Disk surface area determined for LV diameter at that point
Adding the disk volumes give LV volume
Simpsons Method
Tangential or foreshortened imaging of LV apex will most often overestimate EF
If the LV is assymetric, a bi-plane determination improves accuracy
Simpsons Method
Determine the stroke volume (LV diastolic – LV systolic)
EF = stroke volume / end diastolic volume
LV Mass
Determined using a number of echo formulas and algorithms
Carries significant prognostic importance in all forms of heart disease
LV Mass – Earliest Method
Teichholz Method or Cubed Formula
Based on M-mode measurement of septal and posterior wall thickness as well as LV internal dimension measurement
Again, symmetric geometry is assumed that LV is a sphere
Calculates outer dimensions of sphere, then inner dimension. The difference = presumed LV volume
Cubed Formula
LV Mass =
(IV septum + LV interior + post wall)3 ---
(LV interior)3
This gives volume of stylized sphere of myocardium which, multiplied by SG of muscle (1.05 g/cm3) estimates LV mass
Abnormal LV Mass
Conentric Remodeling
Contentric Hypertrophy
Eccentric Hypertrophy
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