Chapter 7: References 131
References
Left Ventricular Posterior Wall Fractional
Thickening (LVPWFT), percent
Laurenceau,J.L.,M.C.Malergue.The Essentialsof
Echocardiography.LeHague:MartinusNijhoff,
(1981),71.
LVPWFT=((LVPWS–LVPWD)/LVPWD)*100%
where: LVPWS=LeftVentricularPosterior
WallThicknessatSystole
LVPWD=LeftVentricularPosterior
WallThicknessatDiastole
Mean Velocity (Vmean) in cm/s
Vmean=meanvelocity
Mitral Valve Area (MVA) in cm
2
Reynolds,Terry.TheEchocardiographer’sPocket
Reference.2nded.,SchoolofCardiacUltrasound,
ArizonaHeartInstitute,(2000),391,452.
MVA=220/PHT
where: PHT=pressurehalftime
Note: 220isanempiricalderivedconst antandmay
notaccuratelypredictmitralvalveareainmitral
prostheticheartvalves.Themitralvalvearea
continuityequationmay
beutilizedinmitral
prostheticheartvalvestopredicteffectiveorificearea.
MV Flow Rate in cc/sec
Reynolds,Terry.TheEchocardiographer’sPocket
Reference.2nded.,SchoolofCardiacUltrasound,
ArizonaHeartInstitute,(2000),396.
Flow=6.28(r
2
)*Va
where: r=radius
Va=aliasingVelocity
Pressure Gradient (PGr) in mmHG
Oh,J.K.,J.B.Seward,A.J.Tajik.TheEchoManual.
2nded.,Lippincott,Williams,andWilkins,
(1999),64.
PGr=4*(Velocity)
2
PeakEPressu reGradient (E PG)
EPG=4*PE
2
PeakAPressureGradient(A PG)
APG=4*PA
2
PeakPressureGradient(PGmax)
PGmax=4*PV
2
MeanPressureGradient(PGmean)
PGmean=Averageofpressure
gradients/Durationofflow
Pressure Half Time (PHT) in msec
Reynolds,Terry.TheEchocardiographer’sPocket
Reference.2nded.,School ofCardiacUltrasound,
ArizonaHeartInstitute,(2000),391.
PHT=DT*0.29
where: DT=decelerationtime
Proximal Isovelocity Surface Area (PISA) in
cm
2
Oh,J.K.,J.B.Seward,A.J.Tajik.TheEchoManual.
2nded.,Boston:Little,BrownandCompany,
(1999),125.
PISA=2r
2
where: 2 =6.28
r=aliasingradius
Qp/Qs
Reynolds,Terry.TheEchocardiographer’sPocket
Reference.2nded.,School ofCardiacUltrasound,
ArizonaHeartInstitute,(2000),400.
Qp/Qs=SVQpsite/SVQssite
SVsiteswillvarydependinguponthelocationof
theshunt.
Regurgitant Fraction (RF) in percent
Oh,J.K.,J.B.Seward,A.J.Tajik.TheEchoManual.
Boston:Little,BrownandCompany,(1999),125.
RF=RV/MVSV
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