# ASCEXAM Practice Flashcards

1
Q

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

A

Rarefactions and compressions

2
Q

Propagation speed of sound in tissue?

A

1540m/s

3
Q

How do you resolve aliasing in PW Doppler?

A
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
4
Q

What is an ultrasound period?

A

Time to complete one cycle

5
Q

What does aliasing look like?

A

Light red to light blue

6
Q

What crystal produces the narrowest far field beam?

A

Largest diameter crystal and higher frequency

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

7
Q

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

A

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

PRF = 2NL

8
Q

What has a higher NL, PW or CW?

A

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

9
Q

Variance map?

A

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

10
Q

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

A

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

11
Q

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

A

Enhancement.

12
Q

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

A

Reverberation

13
Q

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.

A

refraction

14
Q

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

A

Grating lobes.

15
Q

Lateral resolution is best where the beam is __.

A

Narrowest

16
Q

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

A

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.

17
Q

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

A

The Nyquist limit

18
Q

What is propagation speed?

A

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

19
Q

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

A

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%.

20
Q

What influences PV S1 wave?

A

LA relaxation

21
Q

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

A

E wave velocity increases and deceleration time decreases.

22
Q

What are the components of an endocardial cushion defect?

Most common operative problem?

A

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

MR

23
Q

Congenitally corrected TGA is associated with what other defect?

A

VSD

24
Q

Fetal echo is not useful for defining what congenital defect?

A

ASD, because PFO is normal

25
Q

Parameters for aortic prosthetic stenosis?

A

Normal: >0.85cm2/m2

Mild to moderate: 0.65 - 0.85

Severe: <0.65cm2/m2

26
Q

PPM is not necessarily validated in what population?

A

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

27
Q

When is the risk of dissection in pregnancy the highest?

A

Third trimester.

28
Q

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

A

25%

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

29
Q

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

A

Prosthetic stenosis

Normal SV = 60-100
Normal SVI >35

30
Q

Weirdly, PAU is rarely associated with __.

PENATRUATING aotic ULCER=

A

Dissection.

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

31
Q

How does VC correlate with anatomic orifice?

A

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.

32
Q

For prosthetics:

Thrombus causes __.

Flail/structural issue causes __.

A

Thrombus causes stenosis.

Flail/structural issue causes regurgitation.

33
Q

How doe you calculate PA pressures?

A

Systolic PAP = 4(TR)2 + RAP

Mean PAP = 4(Early-diastolic PR)2 + RAP

End-diastolic PAP = 4(end-diastolic PR)2 + RAP

34
Q

Near zone length equation?

A

NZL = D2f/4c

35
Q

What is a transducer?

A

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.

36
Q

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

A

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).

37
Q

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

A

13

38
Q

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

A

Air embolism to the RCA.

39
Q

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

A

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