Aortic regurgitation

Question 1

Define aortic regurgitation?

Answer 1

Reflux of blood from aorta into left ventricle (LV) during diastole.

Also called aortic insufficiency.

Question 2

What is the pathophysiology of aortic regurgitation?

Answer 2

General:
Regurgitation of blood from aorta to LV → Increased systolic pressure and decreased diastolic pressure → widened pulse pressure

Increased systolic pressure - blood regurgitates back into LV → increased preload → increased SV and CO

Increased diastolic pressure - blood regurgitates back into LV during diastole as valve fails to shut completely → less blood in aorta → decreased arterial pressure

Acute AR:
Because LV cannot sufficiently dilate in response to regurgitant blood, LV end-diastolic pressure increases rapidly → pressure transmits backwards into pulmonary circulation → pulmonary oedema and dyspnoea

If severe, you get a lot of blood going back into the pulmonary circulation → less blood ejected from left ventricle → decreased CO → cardiogenic shock and myocardial ischemia

Cardiogenic shock - tissue perfusion inadequate to meet metabolic demand due to heart not being able to pump blood properly

Chronic AR:
Initially you have a compensatory increase in stroke volume due to increased preload → maintains adequate cardiac output despite regurgitation (compensated heart failure)

Over time, increased left ventricular end-diastolic volume → LV enlargement and eccentric hypertrophy
of myocardium → left ventricular systolic dysfunction → decompensated heart failure

Question 3

What is the aetiology of aortic regurgitation?

Answer 3

Aortic root/ascending aorta dilation:

• Aortic dissection
• Systemic hypertension
• Aortitis (e.g. tertiary syphilis)
• Connective tissue disorders (e.g. Marfan syndrome, Ehlers-Danlos syndrome)

Root dilates → pulls apart the valve leaflets → harder for the valves to fit snugly together properly close to prevent backflow of blood

Aortic valve leaflet abnormalities or damage:

• Bicuspid aortic valve
• Infective endocarditis
• Rheumatic fever
• Trauma

Question 4

What is the epidemiology of aortic regurgitation?

Answer 4

Chronic AR often begins in the late 50s

Documented most frequently in patients >80 years

Question 5

What are the symptoms of aortic regurgitation?

Answer 5

Severe acute AR:

• Sudden, severe dyspnoea (due to pulmonary oedema)
• Sudden cardiovascular collapse (circulatory failure due to cardiogenic shock)
• Symptoms related to the aetiology (e.g. chest or back pain in patients with aortic dissection)

Chronic AR: 
Initially asymptomatic
Later, symptoms of heart failure: 
- exertional dyspnoea
- orthopnoea
- fatigue
- occasionally angina (regurgitation in diastole → less blood in aorta → coronary arteries first to branch off aorta → so reduced coronary diastolic perfusion)

Question 6

What are the signs of aortic regurgitation?

Answer 6

BP: wide pulse pressure

Pulse: collapsing ‘water-hammer’ pulse
(when you lift arm → increased venous return to heart due to gravity PLUS regurgitation of blood from aorta to LV → majorly increased preload → increases SV and CO → feel a very strong pulse)

Palpation:
Thrusting and heaving (volume-loaded) displaced apex beat

Auscultation:
Early diastolic murmur at lower left sternal edge
→ decrescendo murmur
- better heard with the patient sitting forward
- with the breath held in expiration.

An ejection systolic murmur is often heard because of increased flow across the valve (due to increased preload → increased SV)

Austin Flint mid-diastolic murmur:
- Over the apex
(from turbulent regurgitated blood hitting anterior cusp of the mitral valve → premature closure of the mitral leaflets → a physiological mitral stenosis)

Inspection:
(due to wide pulse pressure → hyperdynamic pulse)
- Quincke’s sign: visible pulsations on nail-bed
- de Musset’s sign: head nodding in time with pulse

Question 7

What investigations would you do for aortic regurgitation and what would you expect to see?

Answer 7

1st line - ECG, CXR and echocardiogram

ECG: 
Signs of left ventricular hypertrophy 
- deep S wave in V1–2 
- tall R wave in V5–6 
- inverted T waves in I, aVL 
- V5–6 and left-axis deviation 

CXR:

• Cardiomegaly (due to eccentric LVH)
• Dilation of the ascending aorta
• Signs of pulmonary oedema may be seen with left heart failure

Echocardiogram - 2 types:

2D echo and M-mode:

• May indicate the underlying cause (e.g. aortic root dilation, bicuspid aortic valve)
• OR the effects of AR (e.g. LV dilation/dysfunction and fluttering of the anterior mitral valve leaflet)

Doppler:
- For detecting AR and assessing severity

Generally:
- An echo can be done annually to assess LV size and function

Cardiac catheterisation with angiography:

• If there is uncertainty about the functional state of the ventricle
• OR the presence of coronary artery disease