doppler

Question 1

Why isnt Angle correction used in cardac

Answer 1

Because blood flow is 3D and its direction is often difficult to determine.

Instead of using Angle correction , multiple windows or off axis imaging is used.

Question 2

Wall filters / Low velocity reject

Answer 2

Allow the elimination of low doppler shifts that typically occur due to motion of cardiac valves or heart walls.

Question 3

What is sweep speed refer to?

Answer 3

The horizontal rate of display for the spectral doppler trace.

For time 100m/s minimum

For tamponade and pericarditis- Slower sweep speeds better

Question 4

How can the position of the sample volume affect the maximal velocity that can be unambiguously displayed?

Answer 4

Increasing the depth of the sample volume reduces the PRF and, therefore, lowers the maximum detectable velocity that can be displayed.

Question 5

Size of sampling box

Answer 5

5-10mm Larger, to allow annular excursion over systole and diastole

1-5mm (small) To allow more precise positioning

A larger sample size means a greater volume of blood , as a result other velocities will be incorporated into the signal leading to spectral broadening

Question 6

Nyquist limit

Answer 6

when the frequency of the doppler signal exceeds the sampling rate

Question 7

Isovolumetric relaxation time

Answer 7

The time between AV closure and MV opening

Question 8

Diastole can be divided into four phases

Answer 8

1. The isovolumetric relaxation time
2. the early, rapid filling phase: E wave, pressure in Left ventricle lower than left atria
3. diastasis his is the middle phase. fairly equal pressures between chambers. The ventricles continue to fill with blood, but at a much slower rate.
4. Atrial contraction. squeezes last blood into the ventricle to create the A wave

Question 9

Why is the E wave measured as a deceleration time and the A wave as a peak velocity?

Answer 9

E Wave: The deceleration slope of the E wave is measured to assess how quickly the early diastolic filling slows down, which provides insights into ventricular relaxation and compliance.
A Wave: The peak velocity of the A wave is measured to evaluate the strength of atrial contraction and its contribution to ventricular filling, providing information about atrial function.