Aortic Stenosis

Question 1

What is the most common cause of Aortic Stenosis?

Answer 1

Calcific Degeneration.

Question 2

Calcific Degeneration is characterised by progressive fibrosis and calcification of the aortic valve and is similar to what process?

Answer 2

Atherosclerosis.

Question 3

The early stage of Aortic Stenosis is termed what?

Answer 3

Aortic sclerosis.

Question 4

What is another common cause of Aortic Stenosis (other than Calcific Degeneration)?

Answer 4

Bicuspid AOV.

Question 5

Patients who require surgery for stenosis of a bicuspid AOV do so on average how much earlier than those with calcific degeneration of a tricuspid AOV valve?

Answer 5

5 Years.

Question 6

Identification of the number of AOV leaflets should occur in systole or diastole?

Answer 6

In Systole.

Question 7

Why should identification of the number of AOV leaflets occur in systole?

Answer 7

Because the leaflets of bicuspid valves are unequal in size, and raphe in larger leaflets can, when closed, give the appearance of a tricuspid valve.

Question 8

True of False; Bicuspid AOVs are often familial.

Answer 8

True.

Question 9

Bicuspid AOVs are commonly associated with what?

Answer 9

Coarctations of the Ao and dilated aortic roots.

Question 10

Bicuspid AOVs are found in what percentage of coarctation cases?

Answer 10

70-80%.

Question 11

Bicuspid AOVs are also associated with what (but rarely)?

Answer 11

Bicuspid pulmonary valves.

Question 12

Bicuspid AOVs show what kind of closure line?

Answer 12

An eccentric closure line.

Question 13

True or False; Rheumatic AS is more common than rheumatic MS.

Answer 13

False.

Question 14

How is rheumatic AS identifiable?

Answer 14

Commissural fusion (appearing functionally bicuspid) with a doming leaflet appearance.

Question 15

True of false; in sub- and supravalvular AS, the valve itself is unaffected and the obstruction lies below or above the valve.

Answer 15

True.

Question 16

Subvalvular AS can result from a fixed obstruction in the LVOT, usually due to what?

Answer 16

A fibromuscular ridge or membrane.

Question 17

Other than a fixed obstruction in the LVOT, subvalvular AS can also result from what other type of obstruction (as seen in HOCM)?

Answer 17

A dynamic obstruction.

Question 18

A dynamic obstruction (as seen in HOCM), causes obstruction in what part of systole or diastole?

Answer 18

Mid-late systole.

Question 19

In supravalvular aortic stenosis, which is uncommon, there is fixed obstruction where?

Answer 19

In the Asc Ao.

Question 20

In supravalvular aortic stenosis, what causes the fixed obstruction in the Asc Ao?

Answer 20

A diffuse narrowing or discrete membrane.

Question 21

What can aid in the differentiation of true valvular stenosis from fixed supra- or subvalvular obstruction?

Answer 21

PW Doppler.

Question 22

What are the most common symptoms of AS?

Answer 22

Angina, exertional dizziness and syncope, and breathlessness.

Question 23

A sign of AS is a slow-rising or collapsing pulse?

Answer 23

Slow-rising.

Question 24

A sign of AS is a low systolic BP and a narrow pulse pressure or a low diastolic BP and a wide pulse pressure?

Answer 24

A low systolic blood pressure and a narrow pulse pressure.

Question 25

A sustained apex beat is a sign of AS, this is a result of what?

Answer 25

LVH.

Question 26

In terms of the second heart sound, what is considered a sign of AS?

Answer 26

A soft aortic component to second heart sound (A2).

Question 27

True of False; ejection click and an ejection systolic murmur are signs of AS.

Answer 27

True.

Question 28

Typically a bicuspid AOV shows an eccentric closure line, can they still show a central closure line?

Answer 28

Yes.

Question 29

How does CW Doppler differ between severe and mild AS?

Answer 29

In severe AS, the trace is rounded in shape with a peak velocity occurring in mid-systole. In mild AS, the trace has a more triangular shape with an early systolic peak.

Question 30

With regards to the LV, what are common echo findings in long-term AS?

Answer 30

LVH, LV dilatation and impaired LV function.

Question 31

How is △P calculated using the Bernoulli equation; long form and simplified?

Answer 31

Simplified; △P= 4 X V*2 | Long Form; △P=4 X (V2*2 - V1*2)

Question 32

When must the full Bernoulli equation be used?

Answer 32

When the peak velocity in the LVOT >1m/s.

Question 33

Patients with Marfan's syndrome should be considered for root repair/replacement when?

Answer 33

When the Ao root diameter is ≥4.5cm.

Question 34

Marfan's syndrome is what type of disorder?

Answer 34

A connective tissue disorder.

Question 35

In the Bernoulli equation, what do V1 and V2 represent?

Answer 35

V2 = peak distal velocity (AOV) and V1 = peak proximal velocity (LVOT).

Question 36

The transaortic gradients measured by cardiac catheterisation are what type of gradients?

Answer 36

peak-to-peak.

Question 37

The transaortic gradients measured by echo are what type of gradients?

Answer 37

Instantaneous.

Question 38

Are instantaneous of peak-to-peak gradients greater?

Answer 38

Instantaneous.

Question 39

Are transaortic gradients measured by cardiac catheterisation or echo greater?

Answer 39

Echo.

Question 40

How can △Pmean be estimated from △Pmax?

Answer 40

△Pmean = (△Pmax/1.45) + 2mmHg

Question 41

△Pmean also approximates what?

Answer 41

2.4V*2

Question 42

Conditions that increase what can lead to an overestimation of transaortic pressure gradients?

Answer 42

Stroke volume.

Question 43

What conditions can increase stroke volume?

Answer 43

Aortic regurgitation and pregnancy.

Question 44

Transaortic pressure gradients are underestimated in the presence of what?

Answer 44

LV impairment and mitral stenosis.

Question 45

When and where should LVOT diameters be measured?

Answer 45

Zoom mode, mid-systole, 0.5-1cm from annulus (where PW Doppler would be measured). Minimum 3 beats (5 if AF). Measure inner edge to inner edge.

Question 46

How is EOA(AV) calculated?

Answer 46

EOA(AV) = CSA(LVOT) X VTI(LVOT) / VTI(AV)

Question 47

Some versions of the continuity equation use what, instead of using VTIs, to calculate EOA?

Answer 47

Peak velocities in the LVOT/AOV

Question 48

Does Doppler or planimetry provide the best assessment of valve area?

Answer 48

Doppler.

Question 49

Why does Doppler provide the best assessment of valve area?

Answer 49

Because planimetry is difficult to reproduce accurately.

Question 50

AR can overestimate pressure gradients/velocities. Is AVA calculated by continuity still accurate in the presence of AR?

Answer 50

Yes.

Question 51

Why is AVA calculated by continuity still accurate in the presence of AR?

Answer 51

Because SV(LVOT) is still equal to SV(AOV).

Question 52

What else can be used to calculate stroke volume, that may be more accurate than stroke volume derived from measurements of the LVOT diameter and PW Doppler.

Answer 52

3D LV volumes.

Question 53

What criteria are used to assess AS severity?

Answer 53

AV(Vmax), mean PG, AVA and DSI.

Question 54

What AV(Vmax) figures suggest mild, moderate and severe AS?

Answer 54

Mild; <2.9m/s, Moderate; 3.0-3.9m/s, Severe >4m/s.

Question 55

What mean PG figures suggest mild, moderate and severe AS?

Answer 55

Mild; <25mmHg, Moderate; 25-40mmHg, Severe >40mmHg.

Question 56

What AVA figures suggest mild, moderate and severe AS?

Answer 56

Mild; 1.5-2.0cm*2, Moderate; 1.0-1.4cm*2, Severe <1cm*2.

Question 57

What DSI figures suggest mild, moderate and severe AS?

Answer 57

Mild; >0.5, Moderate; 0.25-0.5, Severe ≤0.25.

Question 58

True or false; pressure gradients/velocities are affected by flow rate.

Answer 58

True.

Question 59

In true severe AS (with normal LV Function), what could be the cause of reduced velocities/gradients?

Answer 59

Low flow secondary to a small LV cavity and/or increased arterial afterload (hypertension).

Question 60

How can flow be assessed?

Answer 60

By using stroke volume index (SVi).

Question 61

A stroke volume index of less than what indicates low flow?

Answer 61

<35ml/m*2.

Question 62

SVi permits the calculation of what?

Answer 62

Valvular-arterial impedance (Zva).

Question 63

Valvular-arterial impedance (Zva) is a measure of what?

Answer 63

The global LV haemodyanmic load (the double afterload on LV from the stenosed AOV and from the vascular system).

Question 64

How is Zva calculated?

Answer 64

Zva = (PGmean + systolic BP)/SVi

Question 65

A Zva of what indicates increased impedance to flow?

Answer 65

>5.5mmHg/ml/m2

Question 66

In non-severe AS, when can AVA <1cm*2?

Answer 66

Because of a small body habitus or as a result of reduced valve opening (because of poor cardiac output).

Question 67

AVA should be indexed. An AVAi of what indicates severe AS?

Answer 67

<0.6cm*2/m*2.

Question 68

In true severe AS (with impaired function), what could be the cause of reduced velocities/gradients?

Answer 68

Simply as a consequence of poor cardiac output.

Question 69

What can be helpful in distinguishing true severe AS from functional severe AS?

Answer 69

A dobutamine stress echo.

Question 70

How can a dobutamine stress echo be helpful in distinguishing true severe AS from functional severe AS>

Answer 70

It augments/increases cardiac output.

Question 71

Sometimes pressure gradients and velocities can indicate severe AS but the AVA does not. When can this occur?

Answer 71

1. If patients have a high flow state and 2. In individuals with a large body habitus.

Question 72

When can high flow states (across the AOV) be seen?

Answer 72

With co-existent AR, or with clinical conditions associated with a high cardiac output such as, anaemia, thyrotoxicosis and arteriovenous fistula or haemodialysis.

Question 73

Calculation of what can help identify patients with high flow states?

Answer 73

Stroke volume.

Question 74

What is Thyrotoxicosis?

Answer 74

The clinical manifestation of excess thyroid hormone.

Question 75

Asymptomatic patients with an AV Vmax >4m/s should be re-assessed how often?

Answer 75

Every six months.

Question 76

Asymptomatic patients with an AV Vmax >4m/s should be considered for surgery if AV Vmax increases by how much per year?

Answer 76

>0.3m/s.

Question 77

For those with lesser degrees of AS, how often should they be re-assessed?

Answer 77

Yearly.

Question 78

What can of drug therapy may potentially slow the progression of AS?

Answer 78

Station Therapy.

Question 79

What is the definitive treatment for AS?

Answer 79

Surgical replacement of the valve.

Question 80

Biological prosthetic valves are generally preferred for who?

Answer 80

Older patients, or for those who wish to avoid the use of long term anticoagulation.

Question 81

Mechanical prosthetic valves are generally preferred for who?

Answer 81

Younger patients.

Question 82

Surgery is indicated for severe symptomatic AS, when should asymptomatic patients be considered for surgery?

Answer 82

If they have LV dysfunction, or a fall in BP/complex ventricular arrhythmias on exercise.

Question 83

Replacement of moderate or severely stenosed AOVs is usually advisable if patients who are what?

Answer 83

Due to undergo heart surgery for another reason.

Question 84

What can be used as a bridge to replacement in unstable patients, or for patients who need urgent non-cardiac surgery?

Answer 84

Balloon valvuloplasty.

Question 85

What is a relatively new technique for AVR patients who are at high risk or excluded from conventional valve surgery?

Answer 85

TAVI.

Question 86

True or False; when measuring the Ao annulus, you should measure from cusp hinge points, ignoring all calcification.

Answer 86

True.

Question 87

Why is planimetry of AVA not recommended as a routine measure?

Answer 87

Because the "effective" rather than "anatomic" orifice is the primary indicator of outcome.

Question 88

When is planimetry of AVA accepted?

Answer 88

When Doppler estimation is unreliable (e.g in the presence of coexisting LVOT obstruction).

Question 89

The blind probe can be used to "hunt for maximum AV velocity" in which views?

Answer 89

Right parasternal, apical, suprasternal and subcostal.

Question 90

What are the three causes of AS?

Answer 90

Rheumatic, calcific degenerative and congenital/bicuspid.

Question 91

What is known to affect operative risk and prognosis?

Answer 91

RV size and function/pulmonary artery pressure.

Question 92

Discrepancies in AOV parameters may occur in what percentage of cases?

Answer 92

Up to 25%.

Question 93

The DSI is a useful measure as it removes the potential inaccuracies of LVOT measurements. However, what does it ignore?

Answer 93

Inaccuracies due to abnormal LVOT anatomy (e.g in isolated basal hypertrophy).

Question 94

Degenerative aortic stenosis (AS) may be associated with a reduction in systemic arterial compliance due to what?

Answer 94

Rigid arterial vessels.

Question 95

A reduction in systemic arterial compliance due to rigid arterial vessels (seen in degenerative AS) is clinically manifested as what?

Answer 95

Systolic HTN.

Question 96

The additional afterload due to HTN can result in an underestimation or overestimation of AS severity?

Answer 96

Underestimation.

Question 97

If AVA suggests severe AS, but AV max and mean PG do not (in the presence of impaired LV function), what are the differential diagnosis?

Answer 97

Truly severe AS or moderate/less severe AS with poor valve opening due to poor cardiac output.

Question 98

When a low-dose dobutamine stress test is used to determine the severity of AS; AS is considered severe when what?

Answer 98

AVA remains <1.0cm*2 and/or mean PG increases >40mmHg.

Question 99

When a low-dose dobutamine stress test is used to determine the severity of AS; AS is considered pseudosevere (moderate or less) when what?

Answer 99

AVA increases >1.0cm*2 and/or mean PG remains <40mmHG.

Question 100

With regards to dobutamine stress testing, when are you unable to comment on the severity of AS?

Answer 100

If there is no contractile reserve (change in SV) and no change in AVA and mean PG.

Question 101

If AVA suggests severe AS, but AV max and mean PG do not (in the presence of normal LV function), what are the differential diagnosis?

Answer 101

Low-flow severe AS or moderate/less severe AS for that individual (such as one with a smaller body habitus).

Question 102

In over-weight patients, indexing AVA may overestimate or underestimate AS severity?

Answer 102

Overestimate.

Question 103

When should low flow severe AS be considered (with normal LVEF)?

Answer 103

If SVi <35 and/or Zva >5.5.

Question 104

If AVA does not suggest severe AS, but AV max and mean PG do, what are the differential diagnosis?

Answer 104

Either, 1. The AVA is correct and there is moderate/or less severe AS with high flow states OR 2. Truly severe AS in a patient with a larger body habitus.