Hemodynamic assessment in cardiology

HEMODYNAMIC ASSESSMENT

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INTRODUCTION

Conventionally hemodynamics were obtained by cardiac catheterization.

It is possible to determine the same by echocardiography.


MethodsM-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 & COFlow 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.


CSAThe 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 = D ² X 0.785

SV = D ² X 0.785 X TVI


MEASUREMENT OF STROKE VOLUME & CARDIAC OUTPUT


Regurgitant orifice area (ROA)

ESTIMATED BY PISA USING THE PRINCIPAL OF CONTINUITY EQUATION.


PISA CALCULATION


PISA CALCULATION

PISA CALCULATION

PISA CALCULATION

PISA CALCULATION

REGURGITANT ORIFICE AREA

CALCULATION


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

TOTAL FORWARD FLOW (Q)

_ SYSTEMIC FLOW(Qs).

RV =

An example of regurgitant volume

calculation in MR.


REGURGITANT VOLUME CALCULATION BY PISA

REGURGITANTORIFICE AREA

INTEGRATED VELOCITY OF MR JET

XRV =


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

REG VOLRegurgitant fraction =

Q valve flowX 100


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

LVOT TVI X LVOT CSA.

Qp/Qs =


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

PAP = RVSP – 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 arteryflow in three patients with dif-fering pulmonary artery pres-sures. The acceleration time(AT) becomes shorter as thepulmonary artery pressurerises.


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


LVEDPLVEDP & 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 PRESSUREMR 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 E 1.9

E’X +


LVEDP by MITRAL & TISSUE DOPPLER

E

E’

> 15

LVEDP > 12 mmHg


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Health & Medicine

Hemodynamic assessment in cardiology