Echocardiogram Hemodynamics and Doppler Assessment 1 — Questions and Answers
Question 1: The modified Bernoulli equation used in Doppler echocardiography is expressed as:
- ΔP = 2V²
- ΔP = 4V² (Correct answer)
- ΔP = 8V²
- ΔP = V²/4
Correct answer: ΔP = 4V²
The simplified modified Bernoulli equation is ΔP = 4V², where V is peak velocity in m/s and ΔP is the pressure gradient in mmHg.
Question 2: Which Doppler modality is best suited for measuring high-velocity jets such as aortic stenosis?
- Pulsed-wave (PW) Doppler
- Continuous-wave (CW) Doppler (Correct answer)
- Color flow Doppler
- Tissue Doppler imaging (TDI)
Correct answer: Continuous-wave (CW) Doppler
Continuous-wave Doppler has no aliasing limit and can accurately measure high-velocity jets exceeding 4–5 m/s, making it ideal for aortic stenosis.
Question 3: The continuity equation for calculating aortic valve area uses which three measurements?
- LVOT diameter, LVOT VTI, and AV VTI (Correct answer)
- LV dimensions, peak aortic velocity, and TR velocity
- Heart rate, stroke volume, and cardiac output
- RVOT diameter, pulmonary velocity, and aortic velocity
Correct answer: LVOT diameter, LVOT VTI, and AV VTI
The continuity equation (AVA = LVOT area × LVOT VTI / AV VTI) requires LVOT diameter, LVOT velocity-time integral, and aortic valve VTI.
Question 4: Normal left ventricular filling pressure is best assessed by which Doppler ratio?
- E/A ratio alone
- E/e' ratio using tissue Doppler (Correct answer)
- Deceleration time of E wave alone
- Pulmonary vein S/D ratio alone
Correct answer: E/e' ratio using tissue Doppler
The E/e' ratio (mitral E velocity divided by mitral annular e' by TDI) is the most validated non-invasive estimate of LV filling pressure.
Question 5: Aliasing on color flow Doppler occurs when the measured velocity exceeds which parameter?
- The pulse repetition frequency (PRF)
- The Nyquist limit (half the PRF) (Correct answer)
- The frame rate limit
- The transducer frequency
Correct answer: The Nyquist limit (half the PRF)
Aliasing occurs when velocity exceeds the Nyquist limit, which is half the pulse repetition frequency, causing color wraparound from blue to red or vice versa.
Question 6: In the PISA method for quantifying mitral regurgitation, decreasing the Nyquist limit (aliasing velocity) causes the PISA radius to:
- Decrease, underestimating regurgitation
- Increase, making it easier to measure (Correct answer)
- Remain unchanged
- Cause aliasing artifact only
Correct answer: Increase, making it easier to measure
Lowering the aliasing velocity moves the aliasing boundary closer to the orifice, increasing the visible PISA radius and making it easier to measure accurately.
Echocardiogram Hemodynamics and Doppler Assessment 1
The modified Bernoulli equation used in Doppler echocardiography is expressed as: