High Yield PTEeXAM Review Part 6-8 Flashcards by Tim Montrief

What is a normal DF range?

2 - 0.5%
i. e. Listening 99.8% of time

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What is duty factor determined by?

Sound source only

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What is duty factor inversely related to?

Depth

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What is the Duty Factor % equation?

Pulse Duration* / *Pulse Repetition Period

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How does the Pulse repetition frequency change with shallow vs. deep images?

Shallow = Higher PRF

Deep = Lower PRF

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How does duty factor change with depth?

Shallow = Higher DF
Deeper = Lower DF

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What is the typical value of a pulse duration?

0.5 - 3.0 microseconds

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What is the typical pulse repetition period?

0.1 - 1.0 ms

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What is the typical pulse repetition frequency?

1 - 10 kHz

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What is the typical spatial pulse length?

0.1 - 1.0 mm

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During PWD echo, the frequency of the emitted beam is determined by what two things?

Thickness of piezoelectric crystals
Speed of propagation of sound in the crystals

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What is the equation for resonant frequency?

Velocity of sound in crystal* / [*2 * thickness of the crystal]

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Which ASD is more common:

Superior* sinus venosus VSD or an *inferior sinus venousus VSD?

superior = More common

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What is a superior sinus venousus ASD associated with?

Anomalous Venous Drainage of the RUPV

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What is a inferior sinus venousus ASD associated with?

Anomalous pulmonary venous drainage of a scimitar vein

Scimitar syndrome

Drains from hypoplastic RLL of the lung

Aortopulmonary collaterals

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What 3 things does Scimitar syndrome have?

Inferior Sinus venous ASD
RLL hypoplastic lung with scimitar vein draining into the IVC
Aortopulmonary collaterals going to RLL of the lung

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What is ostium primum ASD associataed with?

Trisomy 21

Near AV valves (Cleft leaflets)

Septal TV
Anterior MV

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What is a partial AV canal?

Primum ASD with No VSD

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What is a transitional AV canal?

Primum ASD with restrictive inlet VSD

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What is a complete AV canal?

Primum ASD + Non-restrictive inlet VSD

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An ostium secundum ASD is a defect in what structure?

Defect in septum primum (Area of fossa ovalis)

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What is ostium secundum ASD associated with?

Mitral valve prolapse

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Transmitral Flow Propagation Velocity:

load dependent or load independent?

Load dependent

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What does the backing material of the echo probe function to do?

Shortens the pulse duration

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The matching layer is how thick in comparison to the wavelength?

About 1/4 length of the wavelength

The piezoelectric crystals are how thick compared to the wavelength?

About 1/2 the wavelength

What is the benefit of a short pulse duration?

**Improved axial resolution** Why? Axial resolution = 1/2 \* Spatial Pulse Length

How does backing material affect bandwidth?

Increases bandwidth

How does increased bandwidth affect Q factor?

Q = RF / Bandwidth

How does frequency affect penetration?

Increased frequency = **Increased** **penetration** (More attenuation)

How does a decreased frequency affect axial resolution?

**Worsens it** Why? worsen frequency = Longer spataial pulse length)

What does decreased frequency do to the focal length?

**Shorter focal length** NL (Near field length) = r² / Wavelengths

What is the doppler velocity index for the aortic valve?

V _LVOT / V Aortic Valve

What are the values for dimensionless index for: **No Aortic Stenosis**

V _LVOT / V _{Aortic Valve} ## Footnote Normal 1.0 or above

What are the values for dimensionless index for: **Mild Aortic Stenosis**

\>0.5 V _LVOT / V _{Aortic Valve}

What are the values for dimensionless index for: **Moderate Aortic Stenosis**

0.25 - 0.5 V _LVOT / V _{Aortic Valve}

What are the values for dimensionless index for: **Severe Aortic Stenosis**

**\<0.25** V _LVOT / V _{Aortic Valve}

What is acceleration time for prosthetic acceleration? What is normal vs. stenotic?

AT \>100 ms = Stenotic AT \<100ms = Normal

How would acceleration time and ejection time affect your determination of stenosis aortic valve prosthesis?

Acceleration Time / Ejection time **\>0.4** = Stenosis

What **peak velocity** is associated with prosthetic valve aortic stenosis?

\> 4 m/s

What **mean gradient** is associated with prosthetic valve aortic stenosis?

\> 35 mmHg

What **effective orifice area** is associated with prosthetic valve aortic stenosis?

\< 0.8 cm²

List 8 risk factors (measurements) for SAM after MVR?

**1. End diastolic diameter \< 45 mm** **2. C-sept distance \>2.5 cm** (Distance from coaptation point to closest part of the ventricular septum) **3. Narrow LVOT** (\< 20 mm) **4. Mitral-Aortic angle \<120 degrees** (Angle formed by intersection of MV annulus and AV annulus 5. **AL / PL** \< 1.3 (anterior mitral leaftlet to posterior leaflet ratio = anterior annulus to coaptation point / posterior annulus to coaptation point) 6. **Basal septal hypertrophy** \> 15 mm 7. **Anterior mitral leaflet length** \> 20 mm (End-diastole from ME 5 chamber view) 8. **Posterior mitral length** \> 15 mm (End - diastole from ME 5 chamber a long posterior leaflet "pushes" the coaptation point towards LVOT)

How does a decrease in beam width affect lateral resolution?

Decrease in beam width = Improved lateral resolution

**What resolution types is most important to least important?** Hint: Include the mneumonic

ALE = Mneumonic (Like the beer) ## Footnote **Axial \> Lateral \> Elevational**

What is the definition of wavelength?

Distance / Length of a single cycle

What is the spatial pulse length?

Length of the entire pulse

What is period?

TIme it takes to complete a single cycle

What is frequency on a wavelength?

inverse of period | (# of cycles / second)

What is pulse duration?

**Time** it takes to complete a single pulse ## Footnote *_Analogous to the spatlal pulse length (Distance)_*

What is the pulse repetition period?

TIme for one pulse to send and then listen

What is the pulse repetition frequency?

Inverse of the pulse repetition period of pulses per second

What is the nyquist limit equation?

1/2 of the Pulse Repetition Frequency

What resolution is important for the pulse repetition frequency?

Temporal Resolution

What is power?

Rate of energy transfer AKA Rate at which work is performed

What is intensity?

Power / Area

During CWD, the frequency of the U/S beam is determined by:

Frequency of the electrical current applied to the crystal

What are the indications for surgery or alcohol ablation therapy for HOCM?

1. LVOT obstruction with resting peak instantaneous gradient \> 30 mmHg 2. SAD (Syncope, Angina, Dyspneaa) symptoms impairing life 3. Persistent symptoms despite medical therapy

What wall thickness on echo would warrant alcohol ablation or septal myectomy with HOCM?

\> 30 mm

What global strain would warrant intervention with HOCM?

\> -18 (More negative than -18