Aortic valve disease

Question 1

What is aortic stenosis?

Answer 1

AS represents obstruction of blood flow across the aortic valve due to pathological narrowing (BMJ)

“Narrowing of the left ventricular outflow at the level of the aortic valve”

Question 2

What are the causes of aortic stenosis?

Answer 2

MAIN CAUSES
1. Calcification of aortic valve over time [in elderly (~50%)] 
2. Calcification of a congenital bicuspid aortic valve(~30%) - most common in young people  (stress on valve on 2 leaflets instead of 3, increased stress causes damage)
3. Stenosis secondary to rheumatic heart disease (MOST COMMON WORLDWIDE) Repeated inflammation and repair = fibrosis. Leaflets of valve fuse together (commisural fusion)

Others: SLE, Paget’s 

Question 3

What murmur is associated with aortic stenosis?

Answer 3

crescendo-decrescendo (gets louder then quiter), ejection systolic murmur

Question 4

How does aortic stenosis lead to concentric left ventricular hypertrophy?

Answer 4

1. Left ventricular hypertrophy (LVH) often develops in response to pressure overload from aortic stenosis
2. This is due to the build up of blood in the left ventricle (as there is an obstruction and less if pumped out of the aortic valve)
3. The heart muscle cells grow in parallel because increased wall thickness reduces wall stress

Question 5

How does aortic stenosis affect the rest of the body?

Answer 5

1. Due to the narrowing of the aortic valve, less blood leaves through the valve to the rest of the body (heart failure)
2. Therefore, many organs are not properly perfused like the brain (resulting in syncope) and the heart muscles (resulting in angina)
3. This worsened during exercise as the body requires more blood
4. RBCs are also damaged as they pass through the narrow aortic valve; resulting in microangiopathic hemolytic anaemia (results in hemoglobinuria)

Question 6

What symptoms of aortic stenosis can be found from the history?

Answer 6

• May be ASYMPTOMATIC initially 
• SAD (syncope, angina & dyspnoea) 
• Angina (due to increased oxygen demand of the hypertrophied left ventricle) 
• Syncope, dizziness or dyspnoea on exercise (due to outflow obstruction) 
• Symptoms of heart failure (e.g. dyspnoea, orthopnoea)
• Others: systemic emboli if infective endocarditis, sudden death 
• H/O rheumatic fever, high lipoprotein, high LDL, CKD
• age > 65

Question 7

What signs of aortic stenosis can be found on physical examination?

Answer 7

• Narrow pulse pressure 
• Slow-rising pulse 
• Thrill in the aortic area (only if severe) 
• Forceful sustained thrusting undisplaced apex beat 
• Ejection systolic murmur at the aortic area, radiating to the carotid artery 
• Second heart sound may be softened or absent(due to calcification) 
• A bicuspid valve may produce an ejection click 
• Crescendo-decrescendo murmur

Question 8

Aortic Stenosis is preceded by aortic sclerosis (defined as aortic valve thickening without flow limitation), true of false?

Answer 8

TRUE

Question 9

What is aortic sclerosis? how is it different from stenosis?

Answer 9

Calcification and thickening of a trileaflet aortic valve in the absence of obstruction of ventricular outflow
- thickening (not narrowing)
- No radiation to the carotids
- usually asymptomatic (no syncope or dizziness)

Question 10

What investigations are used to monitor aortic stenosis?

Answer 10

1. ECG:
   - Signs of left ventricular hypertrophy  
   - Left atrial enlargement
   - Deep S in V1/2 
   - Tall R in V5/6 
   - S+R add up to more than 7 
   - Inverted T waves in I, aVL and V5/6 
   - Left axis deviation 
   - Left Bundle Branch Block LBBB
2. Chest X-Ray:
   - Post-stenotic enlargement of ascending aorta 
   - Calcification of aortic valve 
   - LVH
3. Transthoracic echocardiography: (diagnostic)
   - Visualises structural changes of the valves and level of stenosis (valvar, supravalvar or subvalvar) 
   - Estimation of aortic valve area and pressure gradient across the valve in systole 
   - Assess left ventricular function 
4. Cardiac angiography:
   o Allows differentiation from other causes of angina (e.g. MI)
   o Helps assess valve gradient, LV function and coronary artery disease
   o Allows assessment of concomitant coronary artery disease

 

Question 11

How is aortic stenosis managed?

Answer 11

Surgical management unless contraindicated.

1. Surgical: Valve replacement is recommended if valve pressure difference is >50 mmHg in a symptomatic patient. If unfit for surgery, balloon dilation (valvoplasty).
   (e.g. MI, myocardial perforation, severe AR). 
2. Medical: Manage left ventricular failure: ACE inhibitors/ beta blockers and vasodilators  should be used very cautiously in aortic stenosis. Antibiotic prophylaxis against infective endocarditis.  

Question 12

What complications can be associated with aortic stenosis?

Answer 12

Arrhythmias, Stokes–Adams attacks, MI, left ventricular failure and sudden death.  

Question 13

What is aortic regurgitation?

Answer 13

Aortic regurgitation (AR) is the diastolic leakage of blood from the aorta into the left ventricle a.k.a aortic insufficiency

Question 14

How can aortic stenosis lead to systolic heart failure?

Answer 14

1. The calcified valve makes it hard for blood to be pushed out of the heart from the left ventricle
2. This long-standing pressure overload leads to left ventricular hypertrophy
3. Ventricle attempts to maintain a normal wall stress (afterload) despite the pressure overload produced by stenosis
4. BUT as the stenosis worsens, the adaptive mechanism fails and left ventricular wall stress increases.
5. Systolic function declines as wall stress increases, with resultant systolic heart failure

Question 15

What are the causes of aortic regurgitaion?

Answer 15

1. 50%: Aortic root dilation (valve leaflet pulled apart- can’t seal):
   - 80% idiopathic
   - 20% caused by aortic dissection, aneurysms and syphilis
2. Valvular damage:
   - infective endocarditis
   - Chronic rheumatic fever

Question 16

What kind of murmur is associated with aortic regurgitation?

Answer 16

1. Early decrescendo diastolic murmur over the aortic valve region 
   - Heard better at the left sternal edge when the patient is sitting forward with the breath held at the top of expiration 
   - NOTE: an ejection systolic murmur may also be heard because of increased flow across the valve (due to increased stroke volume) 
2. Austin Flint mid-diastolic murmur 
   - Heard over the apex 
   - Caused by turbulent reflux hitting the anterior cusp of the mitral valve causing a physiological mitral stenosis 

Question 17

How does aortic regurgitation lead to eccentric left ventricular hypertrophy?

Answer 17

Volume overload- induced eccentric hypertrophy due to diastolic reflux of blood from the aorta into the left ventricle
- sacromeres added in series in the left ventricle (attempt to increase wall thickness to decrease wall stress)

Question 18

What are the risk factors for aortic regurgitation?

Answer 18

• Aortic valve leaflet abnormalities or damage 
• Bicuspid aortic valve 
• Infective endocarditis 
• Rheumatic fever 
• Trauma 
• Aortic root/ascending aorta dilatation 
• Systemic hypertension 
• Aortic dissection 
• Aortitis 
• Arthritides (e.g. rheumatoid arthritis, seronegative arthritides) 
• Connective tissue disease (e.g. Marfan’s, Ehlers-Danlos) 
• Pseudoxanthoma elasticum 
• Osteogenesis imperfecta 

Question 19

What symptoms of aortic regurgitation can be found in the history?

Answer 19

Chronic AR: 
- Initially ASYMPTOMATIC 
- Later on, the patient may develop symptoms of heart failure(e.g. exertional dyspnoea, orthopnoea, fatigue) 

Severe Acute AR: 
- Sudden cardiovascular collapse (left ventricle cannot adapt to the rapid increase in end-diastolic volume)
- Dyspnoea
- Fatigue
- Weakness
- Orthopnea (shortness of breath some people experience when lying down, which goes away once they return to an upright position)
- Paroxysmal nocturnal dyspnoea (sensation of shortness of breath that awakens the patient- usually relieved in the upright position)

Question 20

What signs of aortic regurgitation can be found on physical examination?

Answer 20

• Collapsing (water-hammer) pulse (hyperdynamic circulation)
• Wide pulse pressure 
• Thrusting and heaving displaced apex beat
• Pallor
• Mottled extremities (bluish-red/ purple lace-like pattern under the skin)
• Jugular venous distension
• Cyanosis
• Tachypnoea  
• Cardiogenic shock
• Pulmonary edema
• Austin flint murmur
• Early decresendo diastolic murmur
• Special signs

Question 21

What special signs can be found on examination of aortic regurgitation?

Answer 21

Quincke’s Sign- visible pulsation on nail bed 

de Musset’s Sign- head nodding in time with the pulse 

Becker’s Sign- visible pulsation of the pupils and retinal arteries 

Muller’s Sign- visible pulsation of the uvula 

Corrigan’s Sign- visible pulsation in the neck 

Traube’s Sign- pistol shot (loud systolic and diastolic sounds) heard on auscultation of the femoral arteries 

Duroziez’s Sign- systolic and diastolic bruit heard on partial compression of the femoral artery with the stethoscope 

Rosenbach’s Sign- systolic pulsations of the liver 

Gerhard’s Sign- systolic pulsations of the spleen 

Hill’s Sign- popliteal cuff systolic pressure exceeding brachial pressure by > 60 mm Hg 

Question 22

What investigations are used to monitor aortic regurgiation?

Answer 22

1. CXR :
   - Cardiomegaly 
   - Dilatation of ascending aorta 
   - Signs of pulmonary oedema (if accompanied by left heart failure) 
2. ECG:
   - May show left ventricular hypertrophy 
   - Deep S in V1/2 
   - Tall R in V5/6 
   - Inverted T waves in lead I, aVL, V5/6 
   - Left axis deviation 
3. Echocardiogram:
   - May show underlying cause (e.g. aortic root dilatation, bicuspid aortic valve) 
   - May show the effects of aortic regurgitation (e.g. left ventricular dilatation, fluttering of the anterior mitral valve leaflet) 
   - Doppler echocardiogram can show AR and indicate severity 
   - Repeat echos allow monitoring of progression (LV size and function) 
4. Cardiac catheterisation with angiography :
   - If there is any uncertainty about the functional state of the ventricle or the presence of coronary artery disease 

Question 23

How is aortic regurgiation managed?

Answer 23

1. Aortic valve replacement: In patients with symptoms of ventricular decompensation, or LV dysfunction: ejection fraction <50%, LV enlargement (end-systolic dimension >55 mm; end-diastolic dimension >75 mm). 
2. Vasodilators (ACE inhibitor or nifedipine): In patients with LV systolic dysfunction (left ventricular ejection fraction (LVEF) <50%), or progressive LV dilatation.