M1: Doppler Review

Question 1

what are the 2 main disadvantage of PW… what is its limitation and why

Answer 1

inability to measure high velocities
limited by speed of sound in soft tissue/PRF

cannot measure velocities above 2-2.5 m/s due to aliasing/nyquist limit

Question 2

ideally, when should E prime waves be measured and why

Answer 2

at end expiration because they will be the largest

Question 3

what doe green indicate on the doppler colour map

Answer 3

turbulence

Question 4

what is a typical velocity for MR

Answer 4

5-7 m/s (use CW to measure)

Question 5

list the 3 advantages of colour doppler

Answer 5

sensitivity (can detect small amount of abnormal blood flow)
region of interest
laminar vs turbulent flow

Question 6

list the 2 disadvantages of colour doppler

Answer 6

aliasing
directional ambiguity: when blood flow is perpendicular to the beam, multiple colours will appear and direction of flow cant be determined.

Question 7

Is TDI less or more preload dependant and MV inflow

Answer 7

Less

Question 8

What pathologies cause velocities in the myocardium to be lower than the rest of the LV

Answer 8

Prosthetic valves
MAC
Mitral annular ring

Question 9

Is TDI ANGLE dependant

Answer 9

Yes

Question 10

3 pressure estimation methods

Answer 10

Bernoulli (velocity and pressure)
Mean pressure gradient
Max instantaneous pressure gradient

Question 11

How is the max instantaneous pressure gradient calculated

Answer 11

Use the max velocity in the Bernoulli equation

Question 12

How is the Mean pressure gradient calculated

Answer 12

By averaging the instantaneous gradients over the ejection period

Question 13

Limitations of press gradient estimations

Answer 13

Under estimated by non parallel sampling (20 degree offset from flow direction = 6% under est)

Values not the same as invasively derived values

Measure 3-5 beats w/ arrthythmias and average velocities

Question 14

Other factors that lead to under estimation of press gradients

Answer 14

Significant flow acceleration
Viscous forces
Increased prox velocities

Question 15

How do our measurements compare to the cath lab

Answer 15

They will be slightly over estimated due to using Max pressure gradient….. cath uses peak to peak method (we only measure at one point in time, cath chooses highest peak at any point in time)

Question 16

What is the VTI

Answer 16

Mean velocity

Question 17

How does stoke volume change wit regurg

Answer 17

SV will be higher through the RV than competent valve

Question 18

Formula for Regurg volume

Answer 18

RV = SC of RV - SV of CV

Question 19

Formula for regurg fraction

Answer 19

RF = RV /SV of regurg valve

Question 20

Assumptions of volumetric flow calculations

Answer 20

Flow occurs in a rigid circular tube
Uniform velocities
CSA is circular and constant throughout flow period
PW SV stays in same position

Question 21

Shaped of MV and TV annulus

Answer 21

Elliptical

Question 22

What does measuring peak velocity give you

Answer 22

Peak velocity and max/peak instantaneous PG

Question 23

What happens to spend if valve area reduced by half

Answer 23

It doubles

Question 24

What does VTI measurement give you

Answer 24

Peak velocity
Mean velocity
VTI
MAX PG
MEAN PG

Question 25

What method can be used to measure MVA when valve is stenotic

Answer 25

VTI trace of MV Inflow

Question 26

Which sweep speed is used for accurate time measurements

Answer 26

Fast

Question 27

Dp/Dt can only be done when

Answer 27

When there’s MR