Principles of echo

Question 1

What is the relationship between velocity, frequency and wavelength

Answer 1

c= λ f

Question 2

what is the velocity in air, tissue and blood

Answer 2

330 m/sec, 1540 m/sec, and 1570 m/sec

Question 3

In what frequency range does diagnostic US operate?

Answer 3

2 - 10 MHz (cw human hearing (16 Hz - 16 KHz)

Question 4

What is the relationship between frequency, image quality and penetration?

Answer 4

Higher frequency results in a better image but less penetration

Question 5

What is the Bernouilli equation?

Answer 5

∆P=4 × V^2

Question 6

What is the maximum velocity of PW?

Answer 6

1.5 - 2.0 m/sec

Question 7

What is the Nyquist limit?

Answer 7

The limit to the maximum velocity that we can record with PW doppler

Question 8

What is the Nyquist limit equal to?

Answer 8

1/2 of pulse repetition frequency (i.e. sampling frequency)

Question 9

How to improve M-mode resolution?

Answer 9

Decrease the scanner width

Question 10

What is the normal E wave velocity of the MV?

Answer 10

Usually < 1.0 m/sec

Question 11

What is the normal doppler velocity across the AV?

Answer 11

0.9 - 1.7 m/sec

Question 12

What is the normal velocity across the TV?

Answer 12

1.7 - 2.3 m/sec

Question 13

What views and modes do you use to measure size of LV?

Answer 13

1) M-Mode in short axis view (can also you PS-LAX)
2) 2D 4 chamber view or short axis view

Question 14

What is the normal systolic and diastolic measurements of LV?

Answer 14

1) LVd: 43 +/- 7 mm
2) LVs: 28 +/- 6 mm

Question 15

What are the normal diameters for the aortic annulus, sinus, STJ and Asc aorta? What view do you use on TTE & TEE?

Answer 15

1) Annulus <25 mm
2) Sinus <40 mm
3) STJ <30 mm
4) Asc aorta <35 mm
TTE: PS LAX
TEE: ME AV LAX (120)

Question 16

What is the normal LV wall thickness?

Answer 16

< 12 mm

Question 17

What is the DDx for LVH?

Answer 17

HTN, Outflow obstruction (AS, HOCM), infiltration (amyloid, sarcoid, fabry’s), metabolic (Cushing’s), renal disase, athlete’s heart, obesity & congenital

Question 18

What is the calculation for SV? How do you obtain measurements?

Answer 18

SV: CSA x VTI

1) Measure LVOT in systole just below aortic valve on LAX
2) PW just below aortic valve in LVOT

Question 19

Write the continuity equation

Answer 19

CSA (AV) x VTI (AV) = CSA (LVOT) x VTI (LVOT)

Question 20

What is the normal RV wall thickness?

Answer 20

< 5 mm

Question 21

What is normal TAPSE?

Answer 21

20 - 25mm. Impaired systolic motion if < 10 mm

Question 22

Differentiate RV pressure and volume overload on 2D echo.

Answer 22

Both result in a D-shaped septum (paradoxical motion) at different parts of the cardiac cycle:

1) Diastolic -> volume overload of RV
2) Systolic -> pressure overload of RV

Question 23

What is the DDx for RV dysfunction & dilatation?

Answer 23

1) Volume overload (TR, acute overload, IAH)
2) Primary cardiac problems
- RV ischemia / infarction
- CM (dilated, septic, myocarditis etc)
3) Increased afterload (PH, ASD, VSD, RVOT obstruction)

Question 24

How do you measure TAPSE?

Answer 24

Use M-mode across TV annulus and measure excursion

Question 25

DDx of LAE?

Answer 25

1) HTN
2) MV disease (MR, MS)
3) AV disease (AoS, AI)
4) AF
5) CAD
6) CM (DCM, HCM)

Question 26

What are the two methods that you can measure LA size? What are the normal sizes?

Answer 26

1) AV SAX, M mode at end systolie (<50mm)
2) apical 4 chamber (Area <= 20 mm2)

Question 27

How do you classify LAE using area measure?

Answer 27

Normal <=20 mm2
Mild 20 - 30
Mod 30 - 40
severe >40

Question 28

What are the septal dimension cutoffs for LVH?

Answer 28

• Normal is <= 10 mm.
• Mild 11 - 13
• Moderate 14 - 16
• Severe >=17

Question 29

What is a sigmoid septum? What are the associations? What problems may it cause?

Answer 29

it is a regional problem near LVOT (usually less than 3 cm in length). May lead to SAM. Associated with HTN and LVH

Question 30

How do you quantify LV mass?

Answer 30

1) Measure length of LV in 4ch view at end diastole and measure from apical endocardium to plane of mitral annulus
2) Measure epicardial diameter and endocardial diameter at end-diastole (cut across papillary muscles)

Question 31

What are the echo features of HTN?

Answer 31

1. LAE
2. RVH
3. Diastolic dysfunction
4. Dilated aorta