Complex Equations

cross sectional area equation (simplified)

= 0.785 x D²

CSA definition

area of valvular, artery, or any circular opening

cross sectional area full equation

= pi x r²

cross sectional area units

cm²

SL valves CSA measured in

mid-systole

A-V valves CSA measured in

mid-diastole

VTI (velocity time integral) definition

Sum of all the individual instantaneous velocities occurring at the time of ejection

VTI is a measure of —

distance

VTI units

cm

mean pressure gradient measures

velocities at equally spaced intervals

measure gradient is the average of

instantaneous gradients over the ejection period

Mean pressure gradient uses what equation?

Bernoulli equation

Bernoulli Equation

4V²

VTI is equal to the — —-

stroke distance

stroke distance is the

average distance blood travels during 1 beat

stroke volume is the

amount of blood ejected out the ventricle in one beat

SV equation

= VTI (cm) x CSA (cm²)

SV units

cm³ , mL

cardiac output is the

amount of blood ejected within 1 minute

normal cardiac output range

4-8 L/min

CO equation

SV x HR

cardiac index is the measure of

output per square meter of body surface area

cardiac index equation

CO/ BSA (m²)

normal values for cardiac index

2.6-4.2 L/min/m²

calculation errors

inadequate beam alignment, annulus and Doppler VTI not at same location, not averaging cardiac cycles (need at least 3 for NSR)

regurgitant volume is the total volume of blood that

leaks backward through an incompetent heart valve during a single cardiac cycle

regurgitant volume equation

= SV MV - SV AV

regurgitant volume units

cm²

Regurgitant fraction

Percentage of SV leaking back through the valve for mitral or aortic flows

Regurgitant fraction equation

= (SV MV - SV AV / SV MV) x 100

Regurgitant fraction units

Percentage

Regurgitant fraction to cc

Regurgitant volume, RF, turn into percentage

Effective regurgitant orifice area units

cm²

ERO equation

= regurgitant volume / VTI MR

Severe regurgitation MR RV and AI RV

greater than 60 mL

Severe regurgitation ERO

Greater than 40 mm²

Severe regurgitation ERO MR

Greater than 30 mm²

Qp/Qs

Helps determine the magnitude of a shunt in those with an intracardiac shunt

Qp =

Pulmonary flow

Qs =

Systemic flow

Normal Qp/Qs ratio

1:1

PDA Qp

SV LVOT

PDA Qs

SV RVOT

Which is more critical in evaluation of mitral inflow, peak, or mean?

Mean because you can have A reversal

If having trouble clearly delineating the flow envelope what can you do?

Use contrast

If having trouble clearly delineating the flow envelope in the right heart what can you do?

Use saline

what info does Doppler of VSD provide?

instantaneous pressure difference between the ventricles

RVSP is = to — with no RVOT obstruction

systolic pulmonary artery pressure