Cardiac Calculations
6-22
ACUSON Cypress™ Operator’s Manual
Aortic Valve
Area by the
Continuity
Equation using
TVI
AVA is Aortic Valve Area (cm
2
).
CSA
LVOT
is cross-sectional Area of LVOT (cm
2
).
TVI
LVOT
is the Time Velocity Interval in the LVOT (m).
TVI
AoV
is the Time Velocity Interval across the aortic valve
(m).
LVOT is Left Ventricular Outflow Tract.
cm
2
Flow Area from
Diameter
d is diameter (cm).
cm
2
Mitral Valve
Area by the
Continuity
Equation using
LVOT
MVA is Mitral Valve Area (cm
2
).
CSA
LVOT
is cross-sectional Area of LVOT (cm
2
).
TVI
LVOT
is the Time Velocity Integral of LVOT (m).
TVI
MV
is the Time Velocity Integral of mitral valve (m).
LVOT is Left Ventricle Outflow Tract.
cm
2
Mitral Valve
Area by the
Continuity
Equation using
Pulmonary
Artery
MVA is mitral valve Area (cm
2
).
CSA
PA
is cross-sectional Area of pulmonary artery (cm
2
).
TVI
PA
is the Time Velocity Integral of pulmonary artery (m).
TVI
MV
is the Time Velocity Integral of mitral valve (m).
cm
2
Right Ventricu-
lar Systolic
Pressure from
Tricuspid
Regurgitation
P
RA
is estimated Right Atrial pressure (mmHg).
V
max
is regurgitant Velocity of tricuspid valve (m/s).
mmHg
Right Ventricu-
lar Systolic
Pressure from
Ventricular
Septal Defect
BP
sys
is systolic Blood Pressure (mmHg).
V
max
is maximum Velocity of ventricular septal defect (m/s).
mmHg
TABLE 31.
Doppler Formulas (Cardiac)
Type
Formula
Units
AVA
CSA
LVOT
TVI
LVOT
TVI
AoV
--------------------
•
=
Flow
Area
π
d
2
4
-----
⎝ ⎠
⎛ ⎞
•
=
MVA
CSA
LVOT
TVI
LVOT
TVI
MV
--------------------
•
=
MVA
CSA
PA
TVI
PA
TVI
MV
---------------
•
=
RVSP
P
RA
4
V
max
2
+
=
RVSP
BP
sys
4
V
max
2
–
=