Pulsed Wave Doppler, Continuous Wave Doppler, and Tissue Doppler Imaging
Matthew Sigakis
Venkatakrishna Rajajee
1. A 67-year-old woman presents to the intensive care unit (ICU) after a syncopal episode. She is afebrile, heart rate 99 bpm, blood pressure 98/34 mm Hg, and oxygen saturation 96% on room air. Echocardiography is performed, and the results are shown in Figure 18.1.
 Figure 18.1 |
What is the calculated stroke volume?
A. 59.94 cc
B. 58.80 cc
C. 56.52 cc
D. 57.28 cc
View Answer
1. Correct Answer: A. 59.94 cc
Rationale: Cardiac output is the product of heart rate and stroke volume. Stroke volume is calculated as the cross-sectional area (CSA) of the LVOT multiplied by the LVOT VTI.
The CSA is calculated as follows: 3.14 × (D/2)2 = 0.785 × D2. The LVOT diameter (D) is obtained in the PLAX. It is important to zoom in on the LVOT image to minimize measurement error. The LVOT diameter is measured in mid-systole from inner edge to inner edge at the level of LVOT (within 0.5 to 1 cm of the valve orifice).
CSA = 0.785 × (2.06 cm)2 = 3.33 cm2
The LVOT VTI is measured with pulsed wave Doppler (PWD), placing the sample volume in the LVOT, which can be obtained in the A5C or apical three-chamber (A3C) view. The PWD sample volume is placed in the center of the LVOT, at the same location where the LVOT diameter was measured (within 0.5 to 1 cm of the valve orifice). The intercept angle should be less than 20° to minimize error in Doppler measurement. The spectral image obtained (PWD velocity curve) should demonstrate a narrow signal, with a rapid upstroke and end-systolic click that terminates the flow signal. The PWD velocity curve is traced to measure the VTI. In the image presented, the LVOT VTI is measured to be 18.0 cm.
Stroke volume = 3.33 cm2 × 18.0 cm = 59.94 cc
Incorrect answers:
Answer B, 3.26 cm2 × 18.0 cm = 58.80 (AV diameter, valve open, used incorrectly)
Answer C, 3.14 cm2 × 18.0 cm = 56.52 (LVOT diameter, valve closed, used incorrectly)
Answer D, 3.33 cm2 × 17.2 cm = 57.28 (AV VTI, used incorrectly)
Selected Reference
1. Mitchell C, Rahko PS, Blauwet LA, et al. Guidelines for performing a comprehensive transthoracic echocardiographic examination in adults: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019;32(1):1-64.
A. 3.33 cm2
B. 3.42 cm2
C. 3.48 cm2
D. 4.02 cm2
View Answer
2. Correct Answer: C. 3.48 cm2
Rationale: The continuity equation is used to solve for the AVA as shown in Figure 18.8.
 Figure 18.8 |
The continuity equation represents the concept that all the volume ejected through the LVOT also passes through the AV orifice. The calculation of the continuity equation to determine AVA requires three measurements: the AV VTI by CWD, the LVOT diameter for calculation of the LVOT CSA, and the LVOT VTI by PWD. The equation is rearranged to solve for the unknown, the AVA.
A1 = LVOT CSA = 3.33 cm2
V1 = LVOT VTI = 18.0 cm
V2 = AV VTI = 17.2 cm
A2 = (3.33 cm2 × 18.0 cm)/17.2 cm = 3.48 cm2
Selected Reference
1. Mitchell C, Rahko PS, Blauwet LA, et al. Guidelines for performing a comprehensive transthoracic echocardiographic examination in adults: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019;32(1):1-64.
3. A 75-year-old man who is being cared for in the ICU develops delirium and, during a period of agitation, pulls out his Swan-Ganz catheter. Instead of replacing the catheter, echocardiography is performed and demonstrates Figure 18.2.
 Figure 18.2 |
Calculate the systolic pulmonary artery pressure (SPAP).
A. 33.6 mm Hg
B. 25.6 mm Hg
C. 16.9 mm Hg
D. 24.9 mm Hg
View Answer
3. Correct Answer: A. 33.6 mm Hg
Rationale: SPAP is calculated as the sum of the estimated right atrial pressure (RAP) and the peak pressure gradient measured between the right ventricle and right atrium. In the absence of a gradient across the pulmonic valve or RVOT, the SPAP is considered equal to the RVSP. The peak pressure gradient between the RV and RA is estimated by applying the modified Bernoulli equation (4V2) to the peak velocity obtained by tricuspid regurgitation CWD signal. Therefore, the SPAP = RVSP = 4(V)2 + RAP.
Of note, there may be variation in the measured flow velocity in different views. Ideally, this measurement should be obtained from multiple views including the PLAX (at the aortic valve level) (RV inflow view), PSAX, or A4C. The highest velocity obtained from a good quality signal should be reported for the final calculation.
In this question, the RV-RA peak pressure gradient = 4(2.53 m/s)2 = 25.6 mm Hg.
The RA pressure is measured as the CVP or assumed based on characteristics of the IVC diameter as shown in Table 18.2.
Table 18.2 Characteristics of IVC Diameter | ||||||||||||||||||||
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In this question, based on the IVC diameter greater than 2.1 cm and 50% collapse with sniff, RAP is estimated as intermediate range, approximately 8 mm Hg.
Therefore, the calculated SPAP = 25.6 + 8 = 33.6.
Selected Reference
1. Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2010;23:685-713.
4. If the patient in Question 18.3 had pulmonary stenosis with a peak pressure gradient of 10 mm Hg, choose the BEST statement:
A. SPAP will be 10 mm Hg higher than right ventricular systolic pressure (RVSP)
B. SPAP will be 10 mm Hg lower than RVSP
C. SPAP = RVSP
D. SPAP cannot be determined
View Answer
4. Correct Answer: B. SPAP will be 10 mm Hg lower than RVSP
Rationale: If there is no pulmonic stenosis or RVOT obstruction, then RVSP will be assumed to equal SPAP. In the presence of pulmonic stenosis or RVOT obstruction, RVSP exceeds SPAP because of the gradient of higher to lower pressure over the stenotic region: RVSP = SPAP + ΔP(RV – PA). Thus, SPAP = RVSP – ΔP(RV – PA).
Selected Reference
1. Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2010;23:685-713.
5. A continuous wave Doppler (CWD) flow across the pulmonic valve in the parasternal short-axis view (PSAX) is depicted in Figure 18.3.
 Figure 18.3 |
The inferior vena cava (IVC) is large, with a diameter of 2.8 cm on inspiration and 2.8 cm on expiration. Calculate the diastolic pulmonary artery pressure (DPAP):
A. 24.00 mm Hg
B. 22.29 mm Hg
C. 20.29 mm Hg
D. 22.00 mm Hg
View Answer
5. Correct Answer: C. 20.29 mm Hg
Rationale: DPAP is calculated from the velocity of the end-diastolic pulmonary regurgitant jet using the modified Bernoulli equation: DPAP = 4 × (end-diastolic pulmonary regurgitant velocity)2 + RAP. The RAP is high based on the explanation above (IVC diameter >2.1 cm and <50% collapsibility) and, therefore, can be estimated at 15 mm Hg.
DPAP = 4 × (1.15)2 + 15 = 20.29
Selected Reference
1. Rudski LG, Lai WW, Afilalo J, et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2010;23:685-713.
6. A 78-year-old man presented to the ICU after a percutaneous coronary intervention to the right main, left circumflex, and left anterior descending coronary arteries for ST-elevation myocardial infarction. On ICU day 4, he developed progressive hypotension. A new murmur is auscultated on your examination. Echocardiography is performed and reveals a new ventricular septal defect (VSD) in the mid portion of the interventricular septum. Additional information from the examination is noted in Table 18.1.
Table 18.1 Patient Examination | ||||||||||||||||||||||||
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