Auscultation remains the main screening test for valvular heart disease. Systolic murmurs in the young and slim are very common and are generally benign and of non-consequence. The cause of a murmur should however be ascertained, particularly when dealing with an applicant planning to do a career in aviation or in older pilots first presenting with a heart murmur. An innocent murmur is systolic, usually soft and musical, and heard at the upper left sternal border. There is no historical clinical suggestion of any heart disease.
Bicuspid aortic valve affects around 1% of the population. It increases the risk of endocarditis, and may lead to aortic stenosis, regurgitation and aortic dilatation. Haemodynamic changes occur slowly and problems generally only occur in the fifth decade or later. Bicuspid aortic valve requires surveillance but is seldom a cause to decline medical certification. A flow velocity across the valve of 2 m/sec or less and an ascending aortic dimension of less than 3.8 cm should generally not affect eligibility.
Aortic regurgitation, if acute, may be caused by endocarditis, dissecting aneurysm and trauma. Chronic aortic regurgitation may be caused by bicuspid aortic valve, rheumatic heart disease, myxomatous degeneration, aneurysm of the ascending aorta, annulo-aortic ectasia, Marfan syndrome and similar. Other possible causes are Syphilis and ankylosing spondylitis.
Aortic regurgitation is generally well tolerated for prolonged period until left ventricular failure, pulmonary oedema, palpitations or angina develop. Clinical signs are wide systodiastolic blood pressure gradients, bounding pulses (water hammer pulse) and bifid pulse.
The ECG may show signs of LA enlargement or LVH. The chest X-ray may show a dilated aortic root or a large heart. Echocardiography is the most useful and often the only test needed. It allows to evaluate chambers size and function, identify any anatomical abnormalities, estimate the severity of any regurgitation and establish a base line for follow-up.
Even moderate aortic regurgitation may be acceptable as long as there is good exercise tolerance and no evidence of diastolic dilatation.
Aortic stenosis may result in the inability to maintain cardiac output and blood pressure if faced with increased output demand or vasodilation. This may result in the inability to provide adequate cardiac perfusion to a hypertrophied myocardium.
The stenosis may be congenital, secondary to a bicuspid aortic valve, degenerative, or secondary to rheumatic heart disease. It is generally marked by a long asymptomatic phase during which the pressure gradient across the valve increases at a quoted rate of around 7 mmHg / year and the valve area decreases by around 0.15 cm2 / year. These figures are however highly variable.
When a patient becomes symptomatic the clinical progression may be rapid with a high mortality incidence, the five year survival being less than 50%. There is a high risk of syncope or sudden death. Symptoms are poor exercise tolerance, light headedness, syncope and angina.
Aortic stenosis ECG changes consist of signs of left ventricular hypertrophy and left atrial enlargement seen in around 80 % of patients.
Aortic Stenosis Severity Criteria [European Society of Cardiology guidelines]:
|Aortic Jet Velocity||Aortic valve area
|Mild||< 20||2.6 – 2.9 m/s||> 1.5|
|Moderate||20 – 40||3.0 – 4.0 m/s||1.0 – 1.5|
|Severe||> 40||>4.0 m/s||< 1.0|
An applicant with aortic stenosis or bicuspid aortic valve should be considered as having a condition that is of aeromedical significance unless:
In doubt the MEs should contact CAA for advice.