User guide

Chapter 5: Measurement References 77
References
floating-point versus integer-type math, which is
subject to errors introduced by rounding versus
truncating results for display of a given level of
significant digit in the calculation.
Measurement publications
and terminology
The following sections list the publications and
terminology used for each calculation result.
Terminology and measurements comply with AIUM
published standards.
Cardiac references
Acceleration (ACC) in cm/s
2
Zwiebel, W.J. Introduction to Vascular
Ultrasonography
. 4th ed., W.B. Saunders Company,
(2000), 52.
ACC = abs (delta velocity/delta time)
Acceleration Time (AT) in msec
Oh, J.K., J.B. Seward, A.J. Tajik. The Echo Manual .
2nd ed., Lippincott, Williams, and Wilkins, (1999),
219.
Aortic Valve Area (AVA) by Continuity
Equation in cm
2
Reynolds, Terry. The Echocardiographer’s Pocket
Reference
. 2nd ed., School of Cardiac Ultrasound,
Arizona Heart Institute, (2000), 393, 442.
A
2
= A
1
* V
1
/V
2
where: A
2
= Ao valve area
A
1
= LVOT area; V
1
= LVOT
velocity; V
2
= Ao valve velocity
LVOT = Left Ventricular Outflow
Tract
AVA (PV
LVOT
/PV
AO
) * CSA
LVOT
AVA (VTI
LVOT
/VTI
AO
) * CSA
LVOT
Body Surface Area (BSA) in m
2
Grossman, W. Cardiac Catheterization and
Angiography
. Philadelphia: Lea and Febiger,
(1980), 90.
BSA = 0.007184 * Weight
0.425
* Height
0.725
Weight = kilograms
Height = centimeters
Cardiac Index (CI) in l/min/m
2
Oh, J.K., J.B. Seward, A.J. Tajik. The Echo Manual .
2nd Edition, Boston: Little, Brown and Company,
(1999), 59.
CI = CO/BSA
where: CO = Cardiac Output
BSA = Body Surface Area
Cardiac Output (CO) in l/min
Oh, J.K., J.B. Seward, A.J. Tajik The Echo Manual .
2nd ed., Lippincott, Williams, and Wilkins, (1999),
59.
CO = (SV * HR)/1000
where: CO = Cardiac Output
SV = Stroke Volume
HR = Heart Rate
Cross Sectional Area (CSA) in cm
2
Reynolds, Terry. The Echocardiographer’s Pocket
Reference
. 2nd ed., School of Cardiac Ultrasound,
Arizona Heart Institute, (2000), 383.
CSA = 0.785 * D
2
where: D = diameter of the anatomy of
interest
Deceleration Time in msec
Reynolds, Terry. The Echocardiographer’s Pocket
Reference
. 2nd ed., School of Cardiac Ultrasound,
Arizona Heart Institute, (2000), 453.
|time a - time b|