Aortic Stenosis

Symptoms

• Angina: death within 5 years
• Syncope: three years
• Dyspnoea: two years

Physical signs

• Hands: stigmata of infective endocarditis
• Pulse: low volume, slow-rising
• Rhythm: sinus or atrial fibrillation
• Conjunctival pallor (anaemia, co-existent Heyde’s syndrome)
• JVP: not usually elevated but if elevated, look for other signs of pulmonary hypertension
• Apex beat: heaving (left ventricular hypertrophy), displaced (left ventricular failure)
  • May have pre-systolic impulse (atrial contraction against hypertrophied, non-compliant ventricle)
• Palpable thrill over aortic area
• Right ventricular heave (pulmonary hypertension)
• Auscultation:
  • Harsh ejection systolic (crescendo-decrescendo) murmur which is loudest over the aortic area and in expiration
  • Radiates to carotids
  • May also be loudest over the apex (Gallavardin phenomenon)
  • Length of murmur correlates with severity of AS
  • Late peaking of systolic murmur correlates with severity of AS
  • Soft S2 with reversed splitting of the second heart sound also correlates with severity of AS
  • P2 may be loud if there is co-existent pulmonary hypertension
  • Fourth heart sound (hear immediately prior to systole) is a sign of severe aortic stenosis; results from forceful atrial contraction against a non-compliant ventricle
• Lung bases for crepitations (left heart failure)

Clinical markers of severity

• Low volume pulse
• Slow rising pulse
• Narrow pulse pressure
• Heaving apex beat
• Pre-systolic impulse
• Parasternal heave
• Thrill over aortic area (implies transvalvular gradient > 40mmHg)
• Late peaking ejection systolic murmur
• Soft S2 (poorly-mobile and stenotic valve)
• Reversed splitting of second heart sound
• Fourth heart sound
• Crackles at lung bases

Differential diagnosis

• Aortic sclerosis (will not have other signs of AS, does not radiate to carotids)
• Hypertrophic obstructive cardiomyopathy (accentuates with Valsalva manoeuver)
• Pulmonary stenosis
• Supravalvular aortic stenosis

 Causes of aortic stenosis

• Common:
  • Degenerative calcification of aortic valve
  • Bicuspid aortic valve
• Uncommon:
  • Rheumatic heart disease
  • Congenital heart disease
• Rare:
  • Infective endocarditis
  • Hyperuricaemia
  • Alkaptonuria
  • Paget’s disease of bone

Investigations

• ECG:
  • Rhythm (sinus / atrial fibrillation)
  • LVH
  • Evidence of co-existing ischaemic heart disease
  • Enlarged left atrium
• CXR:
  • Cardiomegaly
  • Pulmonary oedema
  • Calcification of aortic valve
• Transthoracic echocardiogram
  • Aortic valve area
    • Normal 3 – 4 cm²
    • Mild: >1.5cm²
    • Moderate: 1 – 1.5cm²
    • Severe: <1cm²
  • Mean pressure gradient across valve
    • Gorlin formula: calculated using cardiac output, valve area, heart rate
    • Severe aortic stenosis: mean gradient > 40mmHg
    • Mild aortic stenosis not usually associated with haemodynamic disturbance
  • Left ventricular size and function
• Coronary angiogram: in case bypass surgery is required at the time of valve replacement

Indications for aortic valve replacement

• Severe, symptomatic aortic stenosis
• Moderate or severe aortic stenosis in patients undergoing other cardiac surgery
• Severe aortic stenosis in the presence of:
  • Left ventricular systolic dysfunction
  • Abnormal blood pressure response to exercise testing
  • Valve area < 0.6cm²
  • Ventricular tachycardia

Management

• Multidisciplinary team approach
• Patient education on symptoms of severe aortic stenosis
• Treat acute episodes of heart failure
• Beta blockers are the preferred anti-hypertensive as aortic stenosis is a low-output state
• Surgery for the indications listed above

Summary

Sir, this patient has severe aortic stenosis. On examination, there is an ejection systolic murmur radiating to the carotids, which is grade 4/6 with a palpable thrill over the aortic area. The murmur is long, and has a delayed peak. The second heart sound is soft, with no clinically detectable reversed splitting. The apex beat is displaced inferolaterally to the sixth intercostal space. There are no associated signs of cardiac failure.

There are no peripheral stigmata of infective endocarditis. The pulse is regular, low-volume and slow-rising. There is no radio-radial delay. I would like to take a blood pressure to ascertain if the pulse pressure is narrow, as well as looking at his temperature chart. The patient is neither clinically anaemic nor jaundiced.

In summary, this patient has clinically severe aortic stenosis complicated by left ventricular dilation. There is no evidence of infective endocarditis or haemolytic anaemia. The most common cause would be degenerative calcification of the aortic valve. In a younger patient, I would consider congenital bicuspid aortic valve as a common cause. Other causes include infective endocarditis and rheumatic heart disease.