ASCEXAM Practice

Question 1

What best describes the cyclic changes in pressure waves responsible for the creation of sound waves?

Answer 1

Rarefactions and compressions

Question 2

Propagation speed of sound in tissue?

Answer 2

1540m/s

Question 3

How do you resolve aliasing in PW Doppler?

Answer 3

1. Use CW
2. Increase PRF (scale) to the maximum setting for depth
3. Switch to high pulse repetition frequency
4. Utilize a lower frequency transducer
5. Adjust baseline to allow for imaging the maximum velocity

Question 4

What is an ultrasound period?

Answer 4

Time to complete one cycle

Question 5

What does aliasing look like?

Answer 5

Light red to light blue

Question 6

What crystal produces the narrowest far field beam?

Answer 6

Largest diameter crystal and higher frequency

Larger crystals create less divergence. Higher frequencies create less divergence.

Question 7

Equation relating PRF (pulse repetition frequency) and Doppler shift?

Answer 7

The Nyquist limit or frequency is the highest Doppler velocity before aliasing occurs and is equal to half of the PRF.

PRF = 2NL

Question 8

What has a higher NL, PW or CW?

Answer 8

CW, since it is continuously sending and receiving signals (very high PRF).

Question 9

Variance map?

Answer 9

Green is added to normal red/blue to show turbulent flow.

Question 10

You see something you think is an artifact, what’s the first thing you can do?

Answer 10

Change the depth setting, artifact will change with depth. Real will not.

Question 11

What artifact results in a hyperintense signal behind a low attenuating structure, such as a fluid filled structure?

Answer 11

Enhancement.

Question 12

What artifact results in the placement of echogenic lines, equally spaced apart from each other, in a fluid filled structure?

Answer 12

Reverberation

Question 13

What artifact results in the misplacement of a structure in an image due to a change in direction at non-perpendicular boundaries with a difference in tissue impedance.

Answer 13

refraction

Question 14

What artifact results in ghost images of high contrast structures, off axis to the sound beam?

Answer 14

Grating lobes.

Question 15

Lateral resolution is best where the beam is __.

Answer 15

Narrowest

Question 16

What term most accurately defines the percentage of time that an echo machine is actually transmitting a pulse into the body?

Answer 16

Duty factor

The percentage of time that an echo machine is actually transmitting a pulse into the body is very short and is called the duty factor. Most ultrasound machines while imaging in 2D spend approximately 0.2% of the time transmitting and 99.8% of the time “listening” for returning signals.

Question 17

What is the highest Doppler velocity before aliasing starts and is equal to half of the pulse repetition frequency (PRF).

Answer 17

The Nyquist limit

Question 18

What is propagation speed?

Answer 18

The propagation speed is how far (distance) a sound wave travels through a medium in one second. The speed of sound varies depending on the medium. Propagation speed in soft tissue is 1,540 m/sec or 1.54 mm/μsec

Question 19

How do you calculate duty factor? What is the maximum DF?

Answer 19

DF = (pulse duration / PRF) x 100

Maximum is 100%. For example, in CW there are two crystals (one that sends and one that receives). The sending crystal has a DF of 100%.

Question 20

What influences PV S1 wave?

Answer 20

LA relaxation

Question 21

As LV chamber stiffness increases, what happens to mitral inflow velocity?

Answer 21

E wave velocity increases and deceleration time decreases.

Question 22

What are the components of an endocardial cushion defect?

Most common operative problem?

Answer 22

Inlet VSD
Primum ASD
Abnormal MV (often cleft)
Widened anteroseptal tricuspid commissure

MR

Question 23

Congenitally corrected TGA is associated with what other defect?

Answer 23

VSD

Question 24

Fetal echo is not useful for defining what congenital defect?

Answer 24

ASD, because PFO is normal

Question 25

Parameters for aortic prosthetic stenosis?

Answer 25

Normal: >0.85cm2/m2 Mild to moderate: 0.65 - 0.85 Severe: <0.65cm2/m2

Question 26

PPM is not necessarily validated in what population?

Answer 26

Obese, i.e. PPM may not have same detrimental effects in high BMI patient since obese patients may require less cardiac output than non-obese patients of the same BSA

Question 27

When is the risk of dissection in pregnancy the highest?

Answer 27

Third trimester.

Question 28

Paravalvular leak >__% will typically cause rocking and will need surgery rather than device closure.

Answer 28

25% Areas of 3D echo drop-out suspected to be paravalvular defects should be confirmed with color Doppler mapping

Question 29

Normal EF and decreased SV in setting of prosthesis points to what?

Answer 29

Prosthetic stenosis Normal SV = 60-100 Normal SVI >35

Question 30

Weirdly, PAU is rarely associated with __.

Answer 30

Dissection. IS associated with intramural hematoma, pseudoaneurysm, stroke, aneurysm, or rupture.

Question 31

How does VC correlate with anatomic orifice?

Answer 31

VC is slightly smaller. The vena contracta is characterized by high velocity, laminar flow. VC is relatively independent of flow and driving pressure and eccentricity.

Question 32

For prosthetics: Thrombus causes __. Flail/structural issue causes __.

Answer 32

Thrombus causes stenosis. Flail/structural issue causes regurgitation.

Question 33

How doe you calculate PA pressures?

Answer 33

Systolic PAP = 4(TR)2 + RAP Mean PAP = 4(Early-diastolic PR)2 + RAP End-diastolic PAP = 4(end-diastolic PR)2 + RAP

Question 34

Near zone length equation?

Answer 34

NZL = D2f/4c

Question 35

What is a transducer?

Answer 35

Any device that transforms one kind of energy into a different form is called a transducer. The energy type is not limited to sound but in ultrasound piezoelectric crystals convert electrical current into vibrations (sound) and also on the receive side convert vibrations (sound) back to electrical signals.

Question 36

As LV sphericity index becomes closer to one, what happens to the papillary muscles?

Answer 36

Move laterally and apically. True - The normal left ventricle has an elongated, ellipsoid or bullet-like shape. The long axis is normally 1.5X to 2X that of the short axis. The index is therefore ≥ 1.5 B. True - Short axis diameter of the ventricular short axis is usually measured simultaneously to the long axis in the apical 4-chamber view, but can be measured in the parasternal short axis view if necessary. C. True - The index represents the ratio between long and short axis lengths, and is therefore a unitless number D. True — The long axis diameter is measured from apex to the mitral annular plane in the apical 4-chamber view. E. False - As the ventricle becomes more spherical, the short axis diameter increases more than the long axis length. The Index approaches 1. There is displacement of the papillary muscles laterally, but also APICAL displacement (not basal).

Question 37

What post-stress E/e' is suggestive of elevated filling pressures?

Answer 37

13

Question 38

New inferior WMA while on CPB (intraoperative TEE) is suggestive of what?

Answer 38

Air embolism to the RCA.

Question 39

Pre-pump TEE: what parameter is predictive of SAM of MV after repair?

Answer 39

A mitral valve coaptation point to septal distance of less than 15mm