TEE Hemodynamics
Amanda J. Rhee, MD
Assistant Professor, Dept of Anesthesiology
Mount Sinai Medical Center
May 4 2010
Outline
 Volumetric Flow Calculations
 Velocity and Flow
 Regurgitant Volume
 Intracardiac Shunts
 Stroke Volume and Cardiac Output
 The Continuity Equation: Valve Area
 PISA
 Pressures and Pressure Gradients
 The Bernoulli Equation
 Intracavitary Pressures
 Pressure half-time and deceleration time
Velocity and Flow
 Velocity
– the distance blood travels in a given
direction per unit time
d
V = d/t
cm/s
t
 Flow
– the volume blood passing a given
point per unit time
Q = CSA * V
CSA
d
t
CSA = π * r2
cm3/s
Qinstantaneous and Qmean
Q = CSA * V
 Qinstantaneous – volume of blood passing a given
point per unit time
 Qmax = CSA * Vmax
 Qmean – volume of blood passing a given
distance per unit time
 Qmean = CSA * Vmean
VTI = Vmean * t
Qmean * t = CSA * Vmean * t
SV = CSA * VTI
Savage 2005
Stroke Volume
 Stroke Volume - The volume that is produced by
a systolic ejection
 Step 1: Use Doppler to obtain VTI through area of
interest
 LVOT - Deep transgastric view or Transgastric
long axis view
 Step 2: Use 2-D images to measure diameter and
calculate CSA
 LVOT - Mid-esophageal long axis view
SV = CSA * VTI
CSA = π * r2
CSA
CSA = π * r2
Structure
Cross-sectional
shape
Formula for area
LVOT
Circle
π * r2 or 0.785d2
PISA
Hemisphere
2π * r2
MV annulus
Ellipse (or circle)
π(r1 *r2) or
0.785(d1*d2)
AV
Equilateral triangle
0.433s2
SV = CSA * VTI
Other Applications
 Right Ventricular Stroke Volume - volume produced
by each cardiac cycle by the right side of the heart
 Pulmonary Artery, RVOT
 Mid-esophageal ascending aorta short axis, Upper
esophageal aortic arch short axis view.
 Ratio of pulmonic to systemic SV = Qp/Qs
 Useful to assess the severity of intracardiac shunts
Qp/Qs = SVRight heart (RVOT, PA)/SVLeft heart (AoV, LVOT)
SV = CSA * VTI
Regurgitant Volume
 Volume that travels opposite to normal direction
of flow through a regurgitant lesion in a single
cardiac cycle
 Regurgitant Volume = Flow travelling forward
through regurgitant valve – Flow through
reference valve
RVMV = SV MV – SV AV
RVAV = SV AV – SV MV
Regurgitant Fraction = RV / SV
SV = CSA * VTI
Continuity Equation
 Continuity Equation – mass or volume of blood
passing through one site equals the mass or
volume passing through another site
 Based on the principle of conservation of
mass
CSA 1 * VTI 1 = CSA 2 * VTI 2
CSA AV * VTI AV = CSA LVOT * VTI LVOT
SV = CSA * VTI
PISA
 PISA – Proximal Isovelocity Surface Area
CSA 1 * VTI 1 = CSA 2 * VTI 2
EROA * VMR peak = 2π r2 * Nyquist Limit * α/180
RV MV = EROA * VTIMR
Perrino
2008
SV = CSA * VTI
jet
Cardiac Output
Cardiac Output = SV x HR
Cardiac Index = CO/BSA
CSA 1 * VTI 1 = CSA 2 * VTI 2
SV = CSA * VTI
Bernoulli Equation
 Describes the relationship between pressure
gradients and increases in blood flow velocity
across a narrowed orifice
Perrino
2008
 During peak flow, flow acceleration can be
ignored
 Viscous friction can be ignored because it only
contributes significantly in very small orifices
 In clinically significant lesions, v2 is significantly
more than v1, thus v1 can be ignored
Simplified Bernoulli Equation: ΔP = 4v22
Bernoulli Equation
Perrino 2008
ΔP = P1 - P2 = 4v22
Estimation of RV and PA systolic pressures
RVSP (mmHg) = PASP = 4(VTR)2 + RAP
 In patients without significant RV obstruction or
pulmonic valve stenosis, RV and PA systolic
pressures are similar
RVSP = LV systolic pressure – VSD systolic gradient
RVSP (mmHg) = systolic blood pressure - 4(VVSD)2
 In the setting of AV stenosis or LVOT obstruction
this formula is invalid.
ΔP = P1 - P2 = 4v22
PA mean and diastolic pressure
PAMP = 4(Vearly PI)2 + CVP
PADP = 4(Vlate PI)2 + CVP
ΔP = P1 - P2 = 4v22
Estimation of LAP and LVEDP
LAP = LV systolic pressure = LA and LV systolic pressure gradient
LAP (mmHg) = systolic blood pressure - 4(VMR)2
 Invalid with AV stenosis or LVOT obstruction
LVEDP = aortic diastolic pressure – end-diastolic aortic and LV pressure gradient
LVEDP (mmHg) = diastolic blood pressure - 4(Vend AR)2
 In the setting of AV stenosis or LVOT obstruction
this formula is invalid.
ΔP = P1 - P2 = 4v22
Pressure Half- Time
 Pressure half-time (PHT) – time required for the
peak pressure gradient to decline by 50%.
 PHT = time required for peak Doppler velocity
(Vpeak) to decline to Vpeak√2
MVA = 220/PHT
ΔP = P1 - P2 = 4v22
Deceleration Time
 Deceleration time – time from maximum to zero
pressure gradient (which is the same as time
from maximum to zero velocity)
MVA = 759/DT
ΔP = P1 - P2 = 4v22
Thank You
References
 Perrino AC, Reeves ST. A Practical Approach to
Transesophageal Echocardiography. Philadelphia:
Lippincott W &W, 2008.
 Sidebotham D, Merry A, Legget M. Practical Perioperative
Transesophageal Echocardiography. Philadelphia:
Elsevier, 2008.
 Savage RM, Aronson S. Intraoperative Transesophageal
Echocardiography. Philadelphia Lippincott W&W, 2005.