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echocardiography is required.
Mitral valve disease
Rheumatic mitral stenosis/regurgitation, unless minimal with the subject in sinus rhythm, disbars from
all forms of certification to fly. This is due to the excess risk of incapacitation, secondary to the
unpredictable onset of atrial fibrillation, and a significant risk of cerebral embolism. In mitral stenosis the
onset of atrial fibrillation, if the rate is rapid, may be associated with hypotension or pulmonary oedema.
Non-rheumatic non-ischaemic mitral regurgitation in subjects of pilot age is usually due to prolapse of
either or both leaflets of the valve. When caused by rupture of the chordae or ischaemic injury to the
papillary musculature, it disbars from certification to fly. Mitral leaflet prolapse is a common condition
affecting up to five per cent of males and eight per cent of females, but definitions vary. It has been
associated with a tendency to atrial and/or ventricular rhythm disturbances and atypical chest pain. There
is a very small risk of cerebral embolus, sudden death and endocarditis (all <0.02 per cent per annum) and
also of chordal rupture. Thickening or significant redundancy of the valve leaflets is associated with a
higher embolic risk and needs special consideration.
Precautions need to be taken against the risk of endocarditis in the context of dental or urinary tract
manipulation although this has recently been challenged for a subject with no history of previous
infection. Isolated mid-systolic click needs no special precaution other than occasional cardiological
review. Minor degenerative mitral regurgitation in the presence of a pan or late systolic murmur, normal
left ventricular dimensions on echocardiography and no other potentially disqualifying abnormality may
be consistent with unrestricted certification but requires close cardiological review with early restriction if
there is any change, especially in the end-systolic/diastolic diameters of the heart. Ischaemic mitral
regurgitation is disqualifying.
In non-rheumatic non-ischaemic mitral regurgitation, annual cardiological review will be required, to
include echocardiography and 24-hour ambulatory monitoring. Exercise ECG may also be indicated. A
left ventricular systolic diameter > 4.1 cm and /or an end-diastolic diameter > 6.0 cm should disbar
from all classes of certification to fly. The presence of atrial fibrillation in this context is also disbarring.
Valvar surgery
In a review of the long-term outcome of prosthetic heart valve insertion over a 15-year period, survival
was better (P < 0.02) with a mechanical prosthesis than with a tissue prosthesis; bleeding rates were
higher with mechanical valves in the aortic (but not mitral) position and replacement rates were higher
with bio-prosthetic valves. Rates of haemorrhage were approximately 2.5 per cent per annum for
mechanical valves and 0.9 to two per cent for porcine valves in the aortic position. In the mitral position,
the haemorrhage rate was similar.
Survival at 15 years is of the order of 66 to 79 per cent following aortic valve replacement and 79 to 81
per cent following mitral valve replacement. Risk factors for a poorer outcome include greater age, left
ventricular dysfunction, higher New York Heart Association (NYHA) functional class1, concomitant
1 New York Heart Association (NYHA) Functional Classification: a simple way of classifying the extent of
heart failure. It places patients in one of four categories based on how much they are limited during physical
activity:
I No symptoms and no limitation in ordinary physical activity.
ICAO Preliminary Unedited Version — October 2008 III-1-33
coronary disease/surgery, hypertension, renal failure and lung disease. Bioprosthetic valves, including
homograft prostheses in the aortic position in patients < age 40 years, have a structural deterioration rate
of 60 per cent at ten years and 90 per cent at 15 years.
With modern mechanical valves, the thromboembolic risk in patients receiving anticoagulants is similar
to that of the bioprosthetic valves without anticoagulants but the additional haemorrhagic risk in the
former has to be considered. Bioprosthetic valves start to deteriorate at five years in the mitral position
and at eight years in the aortic position, deterioration being more rapid in younger subjects. There
appeared to be no important performance differences between the stented and stentless porcine valves in
one review. The Carpentier-Edwards porcine xenograft has an embolic risk approximating to one per cent
per annum which, in the absence of a history of cerebral embolism, is normally managed with aspirin
alone.
Aortic valve replacement with the unmounted aortic homograft valve performs most favourably in terms
　
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本文鏈接地址：Manual of Civil Aviation Medicine 1(93)