Hemodynamic assessment in cardiology

INTRODUCTION

Conventionally hemodynamics were
obtained by cardiac catheterization.

It is possible to determine the same by
echocardiography.

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Methods

M-mode & 2D echo alone can provide
only indirect evidence of hemodynamic
abnormalities.
These signs are not highly specific /
sensitive.
Doppler echo is the best tool to assess
intra cardiac hemodynamics.


Doppler echo & the accuracy of doppler
derived hemodynamic measurements
has been validated by comparison with
simultaneously derived catheterization
data.


Stroke volume & CO
Flow across a fixed orifice is equal to
the product of the cross sectional area
of the orifice & flow velocity.
Velocities varies during ejection in a
pulsatile system, individual velocities of
the doppler spectrum need to be
summed(TVI or VTI).
Flow rate = CSA x FLOW VELOCITY

SV = CSA X TVI CO = SV X HR


STROKE VOLUME

IS THE PRODUCT OF CROSS
SECTIONAL AREA AND THE
FLOW VELOCITY INTEGRAL.


CSA
The CSA of orifices in the heart is
usually assumed to be a circle and it is
determined from measurement of the
orifice diameter(D).

CSA = (D/2) ² X π = D ² X 0.785

SV = D ² X 0.785 X TVI


MEASUREMENT OF STROKE
VOLUME & CARDIAC
OUTPUT
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Regurgitant orifice area
(ROA)

ESTIMATED BY PISA USING THE
PRINCIPAL OF CONTINUITY
EQUATION.


PISA CALCULATION

REGURGITANT ORIFICE AREA
CALCULATION

REGURGITANT VOLUME

VOLUME OF BLOOD THAT REGURGITATES
THROUGH AN INCOMPETANT ORIFICE
WITH EACH HEART BEAT

RV = TOTAL FORWARD _ SYSTEMIC
FLOW (Q) FLOW(Qs).


An example of regurgitant volume
calculation in MR.

REGURGITANT VOLUME
CALCULATION BY PISA

REGURGITANT INTEGRATED
RV = X VELOCITY
ORIFICE AREA OF MR JET


REGURGITANT FRACTION
It is simply the percentage of
regurgitant volume compared to flow
across the regurgitant valve.

REG VOL
X 100
Regurgitant fraction =
Q valve flow


Pulmonary to systemic flow
ratio (Qp/Qs)
In the presence of intracardiac shunt the flow
ratio between the pulmonary & systemic
circulation usually indicates the magnitude of
shunt.
Pulmonary flow (Qp) is calculated from the
RVOT & systemic flow (Qs) , from the LVOT.


RVOT TVI X RVOT CSA

Qp/Qs =
LVOT TVI X LVOT CSA.

DOPPLER ESTIMATION
OF INTRA-CARDIAC
PRESSURES


RIGHT ATRIAL PRESURE

•IVC diameter measurement adjacent to
right atrium
•Subcostal view
•During quite respiration & forced
inspiration


RV SYSTOLIC PRESSURE BY
TR VELOCITY JET
•Reflects pressure difference
between RV &RA
•TR present in 75% normal adults
•Normal velocity 2- 2.5m/sec
•Higher velocity –PS or PHT

ESTIMATION OF SYSTOLIC
PAP IN THE ABSENCE OF PS

PAP = 4( V TR)² + RAP systolic


ESTIMATION OF
SYSTOLIC PAP IN THE
PRESENCE OF PS

PAP = RVSP – 4(V PS) ² systolic

PAP = (4 (VTR)² + RAP ) – 4(V PS) ² systolic


RVOT FLOW ACCELERATION
TIME
•Pulse wave doppler
•Sample volume at valve annulus
•Ac T=Time between beginning of
flow & peak velocity
•Normal 120 m Sec or higher
•PHT –Ac T Shortened

Fig. 4-43.
Pulmonary
artery
flow in
three
patients
with dif-
fering
pulmonary
artery pres-
sures. The
acceleration
time
(AT)
becomes
shorter as
the
pulmonary
artery
pressure
rises.

ESTIMATION OF MEAN
PAP FROM RVOT Ac T

MAHAN’S regression equation
MPAP = 79 - ( 0.45 X Ac T)


PULMONARY
REGURGITATION
VELOCITY
•Reflects end diastolic pressure gradient
between PA & RV
•At end diastole RV pressure = RAP
•Used to calculate PAEDP & mean PAP


ESIMATION OF END
DIASTOLIC PAP FROM PR
VELOCITY
PAEDP – RVEDP = 4 X PR EDV ²
PAEDP = 4 X PR EDV ² + RVEDP
= 4 X PR EDV ² + RAP


ESIMATION OF MEAN
PAP FROM PR VELOCITY

According to Masuyama

Mean PAP = 4 X peak PR velocity ²


LVEDP
LVEDP & LV diastolic function are closely
related phenomenon.
Changes in mitral flow velocities in early &
late diastole reflect changes in LVEDP.
In presence of AR the LVEDP is easily
calculated.
AR velocity reflects the diastolic pressure
difference between AO & LV.


LA PRESSURE
MR velocity represents the systolic
pressure difference between the LV &
the LA.
In patients without LV outflow
obstruction systolic BP is practically
same as LV systolic pressure.
LA pressure = SBP – 4 x MRV²


Relation of PVF with LAP

LAP = 35 - 0.39 X ( SYSTOLIC FRACTION )

SYSTOLIC FRACTION = Si X 100
Si+Di


PCWP by MITRAL &
TISSUE DOPPLER

PCWP = 1.24 X E + 1.9
E’


LVEDP by MITRAL &
TISSUE DOPPLER

E
> 15

E’

LVEDP > 12 mmHg


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Hemodynamic assessment in cardiology

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