Aortic Valve Disease
Marie-Annick Clavel
Sorin V. Pislaru
Maurice Enriquez-Sarano
Philippe Pibarot
1. A 72-year-old man is referred for a cardiology evaluation after his primary care physician noted the presence of a loud systolic ejection murmur. Transthoracic echocardiogram shows normal left ventricular size with a left ventricular ejection fraction (LVEF) of 65%. The left ventricular outflow tract (LVOT) diameter is 2 cm, and the LVOT time-velocity integral (TVI) is 15 cm with a peak velocity of 0.8 m/s. The peak aortic velocity is 4.8 m/s and the aortic valve TVI is 100 cm.
Your interpretation of the echocardiogram is:
A. Severe aortic stenosis (AS), because the valve area is less than 1 cm2.
B. Severe AS, because the LVOT/aortic velocity ratio is less than 0.3.
C. Severe AS, because the peak aortic velocity is greater than 3.5 m/s.
D. The severity of the AS cannot be determined from the data presented.
View Answer
1. Answer: A. The Doppler findings are consistent with severe AS. Valve area can be calculated with the continuity equation. The basic formula is:
LVOT flow = Aortic Valve flow
AreaLVOT × TVILVOT = Aortic valve area × TVIAortic
= Aortic valve area × TVIAortic
= Aortic valve area × TVIAortic
In the example, the aortic valve area calculates at 0.47 cm2. Answer B refers to the dimensionless index (LVOT/aortic TVI or velocity ratio), which is shown to accurately predict presence of severe AS when the ratio is less than 0.25 (rather than 0.3). This measurement avoids the use of LVOT diameter, which is the largest source of errors in aortic valve area calculations. This is due to the inherent difficulty associated with the measurement in the presence of a heavily calcified valve; any error is further increased by using the squared value in the valve formula. Answer C is false; typical severe AS has aortic velocities in excess of 4 m/s.
2. In this asymptomatic patient in Question 1, the most appropriate recommendation is:
A. Inform the patient that the chance of developing symptoms in the next 5 years is 20%.
B. Recommend coronary angiography in anticipation of surgical intervention.
C. Recommend transesophageal echocardiography.
D. Recommend oxygen consumption treadmill test.
E. Recommend repeat echocardiogram in 2 years.
View Answer
2. Answer: D. The evolution of completely asymptomatic AS is not benign. Several studies have shown that once the stenosis is severe patients will inevitably develop symptoms. Rosenhek et al. have shown that among 128 patients with asymptomatic severe AS, only 47% were free of death or aortic valve replacement after 2 years. Pellikka et al. have shown that among asymptomatic AS patients with aortic velocities greater than 4 m/s at baseline, only 33% remain free of symptoms after 5 years. Therefore, answer A is obviously false.
Available information in this question suggests presence of severe asymptomatic AS. While the patient is likely to require surgery, a decision cannot be made solely on the basis of the information presented so far, and thus answer B is false. Transesophageal echocardiography (TEE) can be used in the evaluation of AS. Indeed, planimetry of the aortic valve area at TEE correlates well with aortic valve area by catheterization laboratory evaluation. However, this test is typically used as an incremental step only when the transthoracic study fails to establish disease severity (answer C is false).
Exercise studies are useful in clinical decision making for asymptomatic AS. Current AHA/ACC guidelines for management of valvular heart disease suggest their use in asymptomatic AS. Development of symptoms or a decrease in blood pressure at peak exercise would suggest a more advanced disease state, and AVR should be considered. Stress testing, either stress echocardiography or oxygen treadmill consumption test, can be used. In our experience, using oxygen treadmill consumption stress testing allows better quantification of a patient’s physical limitation; serial studies are also easier to compare to assess disease progression. Current ACC/AHA guidelines recommend 6-12 months echocardiographic evaluations in patients with severe asymptomatic AS who are not undergoing AVR (answer E is false).
3. Which of the following statements referring to the echocardiographic evaluation of AS is correct?
A. Echocardiographic maximum aortic gradient is usually higher than the pullback gradient obtained during left-sided heart catheterization. This is due to overestimation of the true gradient by echocardiography.
B. Echocardiographic assessment of mean aortic gradient correlates well with the mean gradient obtained in the cardiac catheterization laboratory.
C. The usual echocardiographic measurement of the mean aortic gradient cannot overestimate the true gradient.
D. The assessment of mean aortic gradient with a nonimaging probe is more accurate because these probes allow for better Doppler software processing.
View Answer
3. Answer: B. The peak-to-peak gradient typically evaluated at pullback in the cardiac catheterization laboratory does not reflect a true event, as the peak aortic pressure occurs after peak left ventricular pressure when AS is present. Echocardiographic estimation of the peak aortic gradient is more accurate as it reflects instantaneous pressure differences between aorta and left ventricle (answer A is false). Statement B is correct in the vast majority of situations and has established echocardiography as the main diagnostic tool in valvular disease. A number of assumptions are made in echocardiographic assessment of valvular stenosis; if these are not accurate, Doppler-based estimations can be erroneously high (answer C is false). The simplified Bernoulli equation estimates the pressure gradient according to the formula &Dgr;p = 4V2; this, in turn, is a simplification of the convective acceleration term 
in the original Bernoulli equation. The number 4 in the simplified formula is the approximation of the ½&rgr;, converted for expressing pressure in mm Hg units; it assumes a blood mass density of 1,060 kg/m3. However, blood mass density is lower when significant anemia is present, which would lead to overestimation of the pressure gradient if the same formula is applied. In addition, conditions with increased cardiac output (anemia, fever, subvalvular AS, significant valvular regurgitation) will increase the inflow velocity V1, which is usually considered negligible. This also leads to overestimation of pressure gradients (answer C is false).
in the original Bernoulli equation. The number 4 in the simplified formula is the approximation of the ½&rgr;, converted for expressing pressure in mm Hg units; it assumes a blood mass density of 1,060 kg/m3. However, blood mass density is lower when significant anemia is present, which would lead to overestimation of the pressure gradient if the same formula is applied. In addition, conditions with increased cardiac output (anemia, fever, subvalvular AS, significant valvular regurgitation) will increase the inflow velocity V1, which is usually considered negligible. This also leads to overestimation of pressure gradients (answer C is false).The use of nonimaging probes is required in the assessment of AS not because of hardware or software properties, but because the smaller footprint allows ultrasound interrogation from a deeper position and better alignment of the Doppler signal with the direction of blood flow.
4. A patient is evaluated for AS. Doppler measurements from all available windows show a highest peak aortic velocity of 5 m/s, and an LVOT velocity of 2 m/s. Which of the following calculations are correct?
A. Peak aortic valve gradient is 116 mm Hg.
B. Peak aortic valve gradient is 100 mm Hg.
C. Peak aortic valve gradient is 84 mm Hg.
D. Peak aortic valve gradient is 36 mm Hg.
View Answer
4. Answer: C. Since the aortic valve inflow velocity (LVOT velocity) is 2 m/s, the term V12 cannot be ignored in the Bernoulli equation. The full formula 
has to be used. Therefore, the calculation using the Bernoulli equation would be 100 – 16 mm Hg or 84 mm Hg.
has to be used. Therefore, the calculation using the Bernoulli equation would be 100 – 16 mm Hg or 84 mm Hg.5. A 30-year-old woman is referred for management of a newly diagnosed subaortic stenosis. She is asymptomatic, but during a routine physical examination a loud systolic murmur was heard. An echocardiogram demonstrated a subaortic membrane with a gradient of 44 mm Hg and concomitant presence of moderate aortic valve regurgitation. The left ventricle is borderline enlarged, with an LVEF of 57%. At TEE, the aortic valve does not appear to be calcified. Which of the following statements are correct?
A. This type of lesion responds well to balloon dilatation.
B. The patient should undergo resection of the subaortic membrane and aortic valve replacement.
C. Careful inspection of the pulmonary valve and pulmonary artery should be carried out during TEE.
D. Doppler interrogation of the abdominal aorta provides no information in this case.
View Answer
5. Answer: C. Subaortic stenosis does not respond well to balloon dilatation. The only treatment is surgical resection (answer A is false). Presence of moderate aortic regurgitation is an indication for surgery, as further valve deterioration is expected due to a jet lesion from the subaortic acceleration. However, a noncalcified aortic valve is generally repaired rather than replaced in a young patient (answer B is false). Associated lesions must be evaluated. The most common are patent ductus arteriosus, pulmonary valve stenosis (both can be diagnosed during TEE examination of the pulmonary artery and bifurcation; answer C is correct), coarctation of the aorta (which can be diagnosed by pulsed Doppler of the abdominal aorta; answer D is false), and ventricular septal defect.
6. Which of the following statements regarding aortic regurgitation (AR) is correct?
A. A PISA radius of 0.8 cm with an aliasing velocity of 40 cm/s and a peak aortic regurgitant velocity of 4 m/s is consistent with severe AR.
B. A pressure half-time greater than 250 ms is consistent with severe AR.
C. Vena contracta is best evaluated from the apical long-axis view.
D. The use of the suprasternal notch window is not useful in the assessment of AR.
View Answer
6. Answer: A. This question refers to the proximal isovelocity surface concept in calculating the effective regurgitant orifice area (EROA). According to the continuity equation, the flow converging to the valve must be equal to the flow through the valve. As blood flow accelerates toward a narrowing orifice (in this case the regurgitant orifice), the spatial distribution of points in which the fluid has the same velocity (isovelocity surface) is approximated by a hemisphere.
Based on this concept, one can transcribe the continuity equation as
Isovelocity flow = regurgitant flow
Isovelocity area × aliasing velocity
= EROA × Regurgitant velocity
2 × &pgr; × R2 × aliasing velocity
= ERO × regurgitant velocity
Replacing the numbers, this becomes:
consistent with severe AR (answer A is correct).
A pressure half-time of less than 250 ms is consistent with severe AR. The vena contracta is best measured on the parasternal long axis (best axial resolution); in the apical long-axis view, the vena contracta will be typically parallel to the ultrasonic beam, reducing the spatial resolution (answer C is false). The suprasternal notch window allows Doppler evaluation of flow reversals in the descending thoracic aorta; holodiastolic flow reversals are suggestive of severe AR (answer D is false).
7. Which is the most compatible with the aortic valve presented in Figure 16-1A, B, C and D?
A. A 75-year-old man with tricuspid moderate AS.
B. A 35-year-old man with a bicuspid AS with fusion of the left and right coronary cusps.
C. A 35-year-old man with a bicuspid AS with fusion of the noncoronary and right coronary cusps.
D. A 35-year-old man with a bicuspid AS with fusion of the noncoronary and left coronary cusps.
 Figure 16-1. (continued) |
 Figure 16-1. (Continued) |
View Answer
7. Answer: B. The parasternal long-axis view is not specific and Doppler measurements showed a moderate AS. The parasternal short-axis reveals that the opening of the valve is asymmetric, thus the valve is not tricuspid. Moreover, a raphe is visible between the right and left coronary cusps. Thus, answer C is correct. This is the most frequent type of bicuspid valve.
8. Which of the following is the most accurate interpretation of the images of the aortic valve/left ventricular outflow tract/aortic root presented in Figure 16-2A, B, C and D.
A. Severe AS.
B. Systolic motion of the anterior mitral valve leaflet.
C. Severe subaortic stenosis.
D. Severe supra-aortic stenosis.
E. The Doppler signal is that of mitral regurgitant flow and not that of transaortic flow.
 Figure 16-2. (continued) |
 Figure 16-2. (Continued) |
 Figure 16-3 |
View Answer
8. Answer: C. Parasternal long- and short-axis views show a normal aortic valve. Thus, answer A is not correct. In the parasternal long-axis views, the distance between the anterior leaflet of the mitral valve and interventricular septum is sufficient and cannot explain the high gradient/velocity measured by continuous Doppler. Thus, answer B is wrong. The continuous wave Doppler jet shown in Figure 16-2 has the contour shape and duration of transaortic flow and answer E is thus not correct. Color Doppler shows aliasing of the velocity below the aortic valve, indicating that flow acceleration is at the subvalvular level. The correct answer is thus C. TEE confirms the presence of a membrane in the LV outflow tract causing the severe subvalvular stenosis (Fig. 16-11).
 Figure 16-11. Three-chamber view centered on the LV outflow tract showing a subvalvular membrane. |
9. What are the severity and main mechanism of the AR presented in Figure 16-3A,B?
A. Moderate AR with aortic annulus dilatation and normal cusp motion.
B. Severe AR with aortic annulus dilatation and normal cusp motion.
C. Moderate AR with aortic cusp prolapse.
D. Severe AR with aortic cusp prolapse.
E. Moderate AR with aortic cusp restriction. F. Severe AR with aortic cusp restriction.
View Answer
9. Answer: D. The regurgitant jet (color Doppler) looks at least moderate and the left ventricle in the parasternal long-axis view is severely dilated (˜7 cm). Hence, AR is likely severe. Answers A, C, and E are wrong. As shown in the parasternal long-axis view, the aortic annulus is not dilated and the leaflets are not restricted; thus, answers B and F are wrong. However, the right coronary cusp is prolapsing in the LV in diastole. Thus, the correct answer is D. The prolapsing leaflet is better documented by TEE (Fig. 16-12).
10. What is the most probable etiology of the mass visualized in this 50-year-old patient (Fig. 16-4A, B and C)?
A. Myxoma.
B. Papillary fibroelastoma.
C. Infectious vegetation.
D. Rhabdomyoma.
E. Paraganglioma.
F. Thrombus.
 Figure 16-4. (continued) |
View Answer
10. Answer: C. Myxomas are generally located in the left atrium; thus, answer A is wrong. Thrombi on native valves are extremely rare; thus, answer E is unlikely. Paraganglioma could be located in the aortic root but generally occurs in young adults and is relatively immobile. Thus, answer E is wrong. Rhabdomyoma could be located in the LV outflow tract and/or at the level of the aortic valve; however, it occurs most often in children younger than 4 years. Thus, answer D is not correct. Papillary fibroelastoma are often located on the cardiac valves but are smaller (<1 cm). Thus the most probable etiology of the present mass is endocarditis. The correct answer is thus C.
 Figure 16-12. Three-chamber view in diastole without and with color showing on the left side the prolapse of the aortic cusp and on the right side the eccentric aortic regurgitant jet. |
CASE 1
11. An 81-year-old man presents for evaluation of AS. He has a history of hypertension, pacemaker implantation, and atrial fibrillation. He presents with dyspnea that worsened progressively during the last 3 months and a few episodes of angina during exercise.
 Figure 16-4. (Continued) |
Figure 16-5 shows the evaluation of the aortic valve hemodynamics. This patient has a normal LV outflow (stroke volume index: 50.7 mL/m2; Fig. 16-5A). In the apical 5-chamber view (Fig. 16-5B), the peak aortic jet velocity is 3.7 m/s, the mean transvalvular gradient is 36 mm Hg, and the aortic valve area (AVA) is 1.01 cm2. Figure 16-5C also shows the measurements of transvalvular gradient from the right parasternal window.
By two-dimensional echocardiography, the LV systolic function is preserved (Videos 16-1 and 16-2) with an LV ejection fraction estimated by the biplane Simpson method of 60%. The LV end diastolic diameter is 51 mm, LV outflow tract diameter 26 mm, and ascending aorta diameter 39 mm.
What would be the appropriate management of this patient?
A. The AS is moderate and a follow-up echocardiogram can be obtained in 1-2 years.
B. The AS is severe but a “watchful waiting” strategy is appropriate and a follow-up echocardiogram can be obtained in 6 months to 1 year.
C. The AS is severe, the patient is symptomatic, and surgical aortic valve replacement (AVR) is recommended.
D. The AS is severe, the patient is symptomatic, but given the patient’s age and comorbidities, transcatheter AVR is recommended.
 Figure 16-5 |
View Answer
11. Answer: C. This patient has severe stenosis as defined in ASE and ACC/AHA guidelines (Table 16-1). In this patient, the highest velocity and gradient were not recorded from the apical 5- or 3-chamber views but from the right parasternal view. Indeed, in about 30%-35% of patients, the highest velocity is obtained in views other than the apical ones. This raises the importance of performing multiple windows (apical 5-chamber, apical 3-chamber, right parasternal, suprasternal) for accurate measurement of transvalvular velocity and gradient in patients with AS.
Furthermore, the patient reports recent onset of symptoms (dyspnea and angina) likely related to AS. This patient thus has a class I indication for AVR according to the guidelines (Table 16-2). However, despite his older age, he has an estimated low surgical risk. The Society of Thoracic Surgeon (STS) score is <4%; he is not frail and has no compromised major organs. Hence, this patient should undergo surgical AVR and there is no indication for transcatheter AVR according to current guidelines.
Table 16-1. Recommendations for the Grading of AS Severity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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12. The patient above underwent coronary angiography to assess presence and severity of coronary artery disease prior to AVR. At that time, should the interventional cardiologist systematically cross the aortic valve and reassess the valvular hemodynamics?
A. Yes
B. No
View Answer
12. Answer: B. Doppler echocardiography may underestimate the transvalvular velocity and gradient (and so the severity of the stenosis) due to misalignment of the Doppler beam with transvalvular flow direction. However, Doppler rarely overestimates velocities and gradients. In this patient, the Doppler images are of good quality and those obtained from the right parasternal view clearly show a high gradient with severe stenosis. There is also no discordance between Doppler and two-dimensional echocardiography evaluation of stenosis severity and patient’s symptomatic status. Therefore, there is no indication to perform an invasive assessment of aortic valve hemodynamics in this patient. Furthermore, crossing a stenotic aortic valve with a catheter is not without risk for the patient. Retrograde catheterization of the aortic valve has been shown to be associated with increased risk of cerebral emboli in patients with severe AS.
Table 16-2. Recommendation for Intervention in AS | |||||||||||||||||||||||||||||||||
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13. Coronary angiography revealed a significant stenosis of the mid left circumflex artery. Although this was not necessary in this patient, the interventionalist measured the transvalvular gradient by the pull-back method and obtained a gradient of 37 mm Hg. Which of the following statements most likely explains the discrepancy between catheterization versus echocardiography-derived transvalvular gradient?
A. The phenomenon of pressure recovery downstream of the aortic valve is responsible for the lower gradient measured at catheterization versus at echocardiography.
B. Hypertension during catheterization has resulted in an increase in LV afterload and a reduction in transvalvular flow and gradient.
C. The pull-back catheterization method underestimates the value of transvalvular gradients obtained by echocardiography.
D. Doppler echocardiography from the right parasternal window overestimates the transvalvular gradient and only the gradient from the apical window should be used.
View Answer
13. Answer: B. The most likely explanation for the discrepancies between Doppler echocardiography and catheterization for the measurement of transvalvular gradient is hypertension during catheterization. The pull-back method generally overestimates the peak and mean gradients and thus the stenosis severity in patients with severe AS because of the space occupied by the catheter within the aortic valve orifice during the measurement of the LV systolic pressure. The simultaneous measurement of LV and aortic pressures is preferable for accurate measurement of peak and mean gradients by catheterization, particularly in patients with heart rhythm disorders, such as atrial fibrillation. It is also important to emphasize that the peak-to-peak gradient that can be measured by catheterization (but not by Doppler echocardiography) has no physiologic relevance and is highly influenced by aortic compliance (i.e., it is markedly reduced when compliance is low). This parameter should thus not be used for the assessment of AS severity.
The continuous Doppler interrogation of all windows, including the right parasternal window, allows more accurate estimation of transvalvular velocities and gradients and avoids underestimation of stenosis severity that may occur if only apical views are assessed. One should, however, pay attention not to mistake the mitral or tricuspid regurgitant flow velocity for the transaortic flow velocity in the right parasternal view. To overcome this pitfall, it is important to measure the duration of the flow in both the apical and right parasternal views. In this patient, the duration of the continuous-wave Doppler signals is very similar in both views (350 and 340 ms), thus confirming that the flow velocity recorded in the right parasternal view is indeed the transaortic velocity and this view shows the actual gradient.
Doppler echocardiography and catheterization do not measure the transvalvular pressure gradient at the same location. Doppler echocardiography measures the velocity at the vena contracta where the pressure gradient is maximum, whereas catheterization measures the gradient at a few centimeters downstream of the vena contracta and so after pressure recovery has occurred. Downstream of the vena contracta, part of the pressure initially lost between the LV outflow tract and the vena contracta is recovered. Because of this pressure recovery phenomenon, the transvalvular pressure gradient is generally smaller at catheterization than at Doppler echocardiography. The magnitude of the pressure recovery is essentially determined by the ratio of the effective orifice area of the aortic valve and the cross-sectional area of the ascending aorta. The pressure recovery is clinically significant in patients with moderate or moderate-to-severe AS (AVA between 0.9 and 1.2 cm2) and a small ascending aorta (diameter <30 mm). This patient has a severe stenosis and a medium-sized aorta. The pressure recovery in this patient is likely minimal and cannot explain the important discrepancy observed between Doppler- and catheterization-derived gradients.
Left-sided heart catheterization may be a stressful procedure for the patient and is thus often associated with hyperadrenergic response and an acute increase in blood pressure. This patient already has a history of hypertension, which is only partially controlled by medication. The blood pressure was 148/70 mm Hg at the time of Doppler echocardiography versus 187/90 mm Hg at the time of catheterization. Previous studies have shown that acute hypertension may increase the LV afterload, which may in turn induce a decrease in LV outflow. Given that transvalvular gradients are highly flow dependent, even a modest reduction in flow may result in a major decrease in gradient.
CASE 2
14. A 72-year-old man with a history of hypertension, previous myocardial infarction, coronary artery bypass graft surgery 12 years ago, and congestive heart failure is admitted to the hospital for worsening heart failure symptoms.Two-dimensional echocardiography shows a reduced LVEF and dilated LV (Videos 16-3 and 16-4). The assessment of aortic valve hemodynamics
reveals a peak aortic jet velocity of 3.6 m/s, a mean transvalvular gradient of 29 mm Hg, and an aortic valve area of 0.53 cm2.
reveals a peak aortic jet velocity of 3.6 m/s, a mean transvalvular gradient of 29 mm Hg, and an aortic valve area of 0.53 cm2.
What is the diagnostic test that you would do next in this patient?
A. Exercise stress echocardiography.
B. Full-dose (up to 40 &mgr;g/kg/min) dobutamine stress echocardiography.
C. Full-dose (up to 40 &mgr;g/kg/min) dobutamine stress echocardiography with contrast.
D. Low-dose (up to 20 &mgr;g/kg/min) dobutamine stress echocardiography.
E. Low-dose (up to 20 &mgr;g/kg/min) dobutamine stress echocardiography with contrast.
F. Right/left-sided heart catheterization and coronary angiography.
View Answer
14. Answer: E. In patients with low LV ejection fraction, low-flow, low-gradient AS, a low-dose (up to 20 &mgr;g/kg/min) dobutamine stress echocardiography is useful (class IIa) to assess AS severity and evaluate LV contractile reserve. Exercise stress testing is contraindicated in symptomatic patients with severe AS (class III). Although rest echocardiography is inconclusive with regard to stenosis severity (i.e., AVA is small suggesting severe stenosis but mean gradient is low suggesting moderate stenosis), right-/left-sided heart catheterization will not provide additional information beyond a resting echocardiogram because the patient will still be in low flow state during catheterization. Hence, the AVA-gradient discordance and uncertainty about stenosis severity will persist with rest catheterization and in fact a dobutamine stress catheterization would be required. The use of contrast agents during dobutamine stress echocardiography is safe and may be helpful for myocardial visualization and assessment of LV ejection fraction. Contrast should be used in this patient given that two consecutive segments or less than 80% of myocardium was not visible. Hence, the optimal next step in this patient is to perform a low-dose dobutamine stress echocardiogram with injection of contrast (answer E).
15. The patient underwent a low-dose dobutamine echocardiography with contrast. The dobutamine infusion was stopped at 10 &mgr;g/kg/min. LV ejection fraction increased from 20% to 35% with dobutamine, stroke volume from 45 to 59 mL, mean gradient from 29 to 44 mm Hg, and aortic valve area from 0.53 to 0.60 cm2 (Fig. 16-6A,B).
How would you grade AS severity?
A. Moderate AS because the resting mean gradient is <40 mm Hg.
B. Severe AS because the resting aortic valve area is <1 cm2.
C. Severe AS because at the end of dobutamine infusion, mean gradient is >40 mm Hg.
D. Severe AS because at the end of dobutamine infusion, mean gradient is >40 mm Hg and aortic valve area is <1 cm2.
View Answer
15. Answer: D. In low flow state conditions, the valve may not be opened fully and so the AVA may be “pseudo-severe” (i.e., overestimates stenosis severity), whereas the gradient, which is highly flow-dependent, may be “pseudo-normalized” (i.e., underestimates stenosis severity). Hence, when there is a discordance between AVA (<1.0 cm2) and mean gradient (<40 mm Hg) at rest Doppler examination, such as is the case in this patient, it is impossible to confirm the stenosis severity and a low-dose dobutamine stress echocardiogram should be performed to differentiate true- versus pseudo-severe stenosis. Rest echocardiographic data cannot be used to confirm stenosis severity in such conditions and so answers A and B are wrong.
Given that both gradient and AVA are flow-dependent but to various extents (gradient more flow dependent than AVA) and that the flow augmentation achieved by dobutamine stress may vary extensively from one patient to the other, it may be misleading to rely on only one parameter (gradient or AVA) to determine the stenosis severity during dobutamine stress echocardiography. The guidelines suggest a class IIa recommendation for AVR if dobutamine stress echocardiography shows a true-severe stenosis defined as a mean gradient ≥40 mm Hg and an AVA <1.0 cm2 at any dobutamine stage (not necessarily the maximum dose stage). In this patient, the gradient increased up to 44 mm Hg and the AVA remained below 1.0 cm2 (i.e., 0.60 cm2) during dobutamine stress (Fig. 16-6). Hence, answer C is wrong and the right answer is D. If the AVA-gradient discordance persists with dobutamine stress (e.g., stress AVA is 0.8 cm2 and stress mean gradient is 35 mm Hg), one can calculate the projected aortic valve area at a normal flow rate.
16. The operative risk for surgical AVR in this patient is:
A. High risk (>8% risk of 30-day mortality) because rest LV ejection fraction is <50%.
B. High risk (>8% risk of 30-day mortality) because of the absence of LV flow reserve during dobutamine stress.
C. Intermediate risk (6%-8% risk of 30-day mortality) because rest LV ejection fraction is <50% but there is significant LV flow reserve during dobutamine stress.
D. Intermediate risk (6%-8% risk of 30-day mortality) because rest LV ejection fraction is <50%, but there is significant improvement in ejection fraction during dobutamine stress.
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