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Aortic Stenosis

Title

Ñ    Aortic Stenosis

Definition

Ñ    Narrowing of the aortic valve

Pathogenesis

Causes

Valvular

Ñ    Congenital

Ñ    Bicuspid aortic valve

Ñ    Rheumatic heart disease

Ñ    Degenerative calcification

Subvalvular

Ñ    Hypertrophic obstructive cardiomyopathy

Supravalvular

Ñ    Supravalvular aortic stenosis:

·          William’s syndrome:

Hypercalcaemia, mental retardation, elfin facies, supravalvular aortic stenosis

Pathophysiology

Ñ    Obstruction to left ventricular emptying

Ñ    Increased left ventricular pressure

Ñ    Compensatory left ventricular hypertrophy

Ñ    Relative ischaemia of the myocardium of the left ventricle

This results in:

Ñ    Dizziness

Ñ    Syncope

Ñ    Angina pectoris

Ñ    Arrhythmias

Ñ    Left ventricular failure

Clinical Features

History

Ñ    No symptoms till aortic orifice is reduced to one third of its normal size

CVS

Ñ    Angina

Ñ    Dyspnoea

CNS

Ñ    Syncope

Examination

CVS

Ñ    Small volume, slow rising pulse

Ñ    Brachio-radial delay

Ñ    Blood pressure:

Reduced pulse pressure

Ñ    Apex:

Not displaced

Heaving in nature

Ñ    Systolic thrill in aortic area

Ñ    Soft second heart sound

Ñ    Reversed split of the second heart sound

Ñ    Systolic ejection click

Ñ    Fourth heart sound

Ñ    Ejection systolic murmur at the aortic area radiating into the neck

Severity of Stenosis

Features of severe stenosis:

Ñ    Narrow pulse pressure

Ñ    Brachio-radial delay

Ñ    Systolic thrill

Ñ    Soft S₂

Ñ    Single S₂

Ñ    Reversed splitting of S₂

Ñ    Fourth heart sound

Ñ    Cardiac failure

Investigations

Imaging

Chest X-ray 

Ñ    Small heart

Ñ    Post-stenotic dilatation of the ascending aorta

ECHO

Ñ    Thickened, calcified valves

Ñ    Bicuspid valve

Ñ    LVH (left ventricular hypertrophy)

Ñ    Gradient across the valve may be measured

Ñ    Aortic valve area measured

Ñ    LV function determined

Cardiac catheterisation

Ñ    Not essential if the diagnosis is well established

Ñ    Indicated if the site is in doubt

Ñ    Indicated if severity is in doubt

Ñ    Analyse ventricular function

Ñ    Coronary angiography in the elderly

Ñ    Define coronary anatomy:

·          Age > 40 years males

·          Post-menopausal females with 1 or more cardiovascular risk factor

Electrophysiology

ECG

Ñ    Left atrial hypertrophy:

P mitrale

Ñ    LVH and strain

Ñ    Left axis deviation

Ñ    Left bundle branch block

Ñ    Atrio-ventricular block

Management

Control

Drugs

Ñ    Modify risk factors for atherosclerosis

Diet

Ñ    Modify risk factors for atherosclerosis

Exercise

Ñ    Modify risk factors for atherosclerosis

Surgery

Indications

Ñ    Symptomatic patients

Ñ    Severe aortic stenosis:

·          Aortic valve area < 1 cm²

·          Gradient > 40 mm Hg

Ñ    Asymptomatic patients with aortic stenosis and systolic LV dysfunction:

LVSF < 50%

Ñ    Asymptomatic patients with abnormal exercise testing:

·          Symptoms on exercise

·          Fall of blood pressure below baseline on exercise

Ñ    Patients with moderate aortic stenosis (valve area 1.0 to 1.5 cms²):

·          Undergoing coronary artery bypass grafting (CABG)

·          Surgery on ascending aorta

·          Surgery on another valve

Techniques

Ñ    Valvotomy in childhood and adolescence:

As a bridge

Ñ    Valve replacement:

Definitive treatment

Ñ    Balloon valvuloplasty:

·          Moribund patients, poor life expectancy

·          Patients with symptomatic severe aortic stenosis who require urgent major non –cardiac surgery

Prevention

Ñ    Endocarditis prophylaxis

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