Echo Measurements

Echo Measurements

Fractional Shortening

FS% - ((LVEDD - LVESD)*100)/LVEDD

-in PSSA, at level of paps

-not accurate w flat IVS

-not a measure of global ventric fx

Ejection Fraction

=Diast vol - syst volume

-depends on good endocardial border definition (enhanced w contrast, but we don't in peds...)

-higher incidence of intra-observer and inter-observer variability.

Ejection Fraction

-Diastolic Volume - Systolic Volume

-Simpson's Biplane method- divide LV into 20 disks, check area, calc volume, then calculate diff in sys and diast...

Intracardiac Pressures

RV or PA P

-Normal = 15-30mmHg

RVP= 4(TR pk velocity)² + RA

Systolic BP = 4(VSD pk velocity)²

-if no LVOTO

Systolic BP = 4(PDA pk velocity)²

LV Systolic BP = 4(VSD pk velocity)² = (systolic BP + 4*LVOT²) - (4*VSD²)

-Must obtain TR, VSD, and PDA velocities from various views with CW Doppler. Use the highest velocity; ensure complete envelope.

PA Diastolic P

-Normal = 10-12mmHg

-PA End Diastolic P = 4(PR end diastolic velocity)² +RA P (because RAP =RVEDP)

-PA mean P = 4(PR early diastolic velocity)²

LV Systolic P

-Normal = Newborn: ~70mmHg, Child 90mmHg, Teen 100-110mmHg

-LVP = 4MR² + LAP

-LVP = Systolic BP if there's no LVOTO

-LVP = Systolic BP +4LVOT² (measure LVOT with CW at Aortic Valve)

LV Diastolic P

=Diastolic BP at arm - 4(end diastolic Ao regurg)

LAP

-Normal 4-12mmHg

LAP = Systolic BP -4MR²

Mutliple Levels of Obstruction

Pressure gradient = 4(V₂² -V₁²)

-Must obtain V1 by PW

-where V1 is the velocity at 1 point (e.g. subAo) and V2 is at 2nd pt (e.g. Ao vlv)

Mean Pressure Gradients

-use CW beam

-must check from multiple views to ensure good alignment; CW beam should be parallel to flow

-Excessive gain may overestimate pk and mean gradient

-trace the gradients over several beats and average them

AS Severity:

-Mild <25; Mod 25-50; Sev >50mmHg

MS Severity:

-Mild 3.5-5; Mod 6-12; Sev >12mmHg

Pulm Vn:

-Nl mean gradient is <0.8mmHg

dP/dt

-Measures pressure changes over time to assess ventricular systolic function

-use MR for LV; TR for RV

-use CW jet in AP4C view

-Use sweep speak of 150-200mm/s (higher sweep speed allows better resolution of the slope...)

-Measure time bn 1m/s and 3m/s velocity

- dP/dt (mmHg/s) = 4*1000*(V₂² -V₁²)/ (delta t msec)

-because you use 1 and 3m/s for each V, then:

dP/dt = 32000/(delta t msec)

-LV Normal >1200, Borderline 1000-1200, AbNl <1000 mmHg/s

-RV Normal >400 mmHg/s

-low number indicates that you need a longer amount of time to gain a higher pressure

-advantages- not affected by ventric geometry

-disadvantages- normalized by incr AL (htn, AS)

-relies on MR being present

RVSTI

RV Systolic Time Interval

-the time between the signal to contract and the actual start of contraction, relative to overal contraction time...

-measure with PW through pulmonary valve

-RVSTI = PEP - EP

-PEP = Pre-Ejection Period = time fr Q wave on EKG to start of ejection

-EP = Ejection Period = measured ejection time

-Nl RVSTI <0.34

-Not accurrate if there is atrial/ventricular shunting

Myocardial Performance Index (MPI)

-Measures LV systolic + diastolic function

-On AP4C w PW at MV tip leaflets for LV, and TV tip leaflets for RV for inflow

-& on AP5C with PW at Ao vlv for LV, and PSSA with PQ at Pulm vlv annulus

-Measure A - time bn MV or TV closure to the next MV or TR opening. Or if pt has MR or TR, measure the duration of the MR or TR.

-Measure B - Ejection time (time obtained fr the Ao PW tracing...)

-MPI = (A-B)/B

-Nl in adult LV = 0.39 +/- 0.05 ...

-not based on ventric geom, independent of HR, BP, age, but not good w arrhythmia, or if AV vlv xx, or poor envelope...

Pressure Half-Time (assess AR severity)

-Time it takes for the peak pressure to drop to half its original pressure

-Position CW in line with Ao Regurg jet

-set Doppler scale to at least 5m/s

-measure 3-5 beats if HR regular, 8-10 if HR irregular

-use package on the machine...

-AR Severity by PHT (msec)

-Mild >500, Mod 250-500, Mod-Sev 200-350, Sev <200

-thus with more severe AR the Ao and LV will more quickly reach the same pressure bc of the regurg, so the time to get to half the initial pressure difference will be low.

-Pitfalls- doesn't always reflect AR severity well

-determined by LV diastolic compliance and P, so incr LV diastolic P will decr the PHT

-systemic vasodilation (e.g. vasodilators) will lower the Ao P and thus decr the PHT

-ch LV adaption to severe AR will increase the PHT

Pressure Half-Time (assess MS severity)

-Time it takes for the peak pressure to drop to half its original pressure

-Position CW on AP4C parallel to MV inflow

-Use machine's package to place caliper on a deceleration slope [Luke: take the line all the way to the baseline (through the a wave...)]

-The more severe the MS, the less steep the slope.

-Normal PHT 30-60msec; borderline 60-90msec; mild 90-150msec, moderate 150-219, sev >220.

-Pitfalls: elevated LVEDP because of signif Ao regurg --> incr PHT (bc increased LV P)

-if impaired LV diastolic relaxation--> inaccurate PHT

-if poor CW alignment--> inaccurate PHT