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Amiodarone is usually barred, on account of its side effects and likely coexisting pathology, although in
some Contracting States flight engineers have been certificated while using it.
Warfarin and anticoagulation in atrial fibrillation
Warfarin is associated with a risk of bleeding in the order of one per cent per annum, for a 70 per cent
reduction of stroke risk. It is not permitted in European aviators at present although it has been allowed in
individual cases as “special issuances” by the FAA1 in the United States. A number of primary strokeprevention
trials have identified the following risk factors for thrombo-embolic stroke in paroxysmal or
persistent atrial fibrillation :
• males / females > 65 years of age
• diabetes mellitus
• previous transient ischaemic attack (TIA)
• reduced ventricular fractional shortening
• coronary heart disease
• hypertension (systolic blood pressure >160mm Hg)
• left atrial internal diameter >4.5cm (2.5 cm/m2 of body surface)
In about a third of subjects < age 65 years, atrial fibrillation will be "lone" (being excluded from the
above). They will be at a low (< one per cent per annum) risk of a cerebral thromboembolic event per
annum and warfarin, conventionally, will not be indicated. Pilots satisfying this requirement and the
criteria expressed in the previous section may be certificated with a restriction (Class 1 OML). Aspirin
reduces the embolic risk by about 20 per cent and should be given if it is tolerable. Studies are under way
to determine whether higher-risk subjects are protected with aspirin and clopidogrel, and by new direct
thrombin inhibitors; the latter do not need the INR to be checked regularly.
Atrial flutter
1 FAA: Federal Aviation Administration (before 1967 the Federal Aviation Agency), the Licensing Authority of the
United States.
ICAO Preliminary Unedited Version — October 2008 III-1-25
Atrial flutter presents special problems. It usually originates in the right atrium as a continuous reentry
circuit, often around a ridge between the superior and inferior caval orifices called the crista terminalis. It
reciprocates at a rate approximating 300bpm. Rates of 150bpm are commonly encountered with 2:1
AV conduction deficit whilst the risk remains for 1:1 conduction at 300bpm to occur. Symptoms may
be troublesome due to abrupt rate change. For these reasons it is incompatible with flying status.
The introduction of radiofrequency ablation of the flutter circuit has revolutionized treatment. If the
flutter circuit has undergone successful ablation with demonstrated bidirectional block, the arrhythmia
has not recurred for three months, and the following protocol can be fulfilled, a Class 1 Medical
Assessment with restriction to multi-crew operations may be issued subject to cardiological follow-up:
• exercise ECG (completion of at least three stages of the Bruce protocol) is normal
• echocardiography shows a structurally normal heart
• absence of atrial flutter on Holter monitoring (evidence of atrial fibrillation will need further
review)
• electrophysiological study shows bidirectional isthmus block.
Unrestricted certification may be considered after 12 months.
Atrioventricular nodal reciprocating tachycardia
Atrioventricular nodal reentry is the most common single cause of regular narrow complex tachycardia,
accounting for some 50 per cent of all tachycardias. It is caused by a micro reentry circuit with two
pathways, one fast and one with decremental conduction. It often has a rate of about 200 bpm, sufficient
to cause breathlessness, chest discomfort and sometimes polyuria due to the release of atrial natriuretic
peptide. As the disturbances tend to recur throughout life and cannot reliably be suppressed completely,
the condition is normally incompatible with certification to fly. An exception may be the subject who has
undergone slow pathway modification and in whom the rhythm cannot be induced on
electrophysiological study (cf. atrial flutter, above).
Atrioventricular reciprocating tachycardia
Atrioventricular reentrant tachycardias are caused by an extranodal fast-conducting pathway which
“pre-excites” the ventricle. This pathway is known as the Kent bundle1, although other variations (e.g.
Mahaim2 fibers with a nodofascicular pathway) are also seen. The eponymous term,
Wolff-Parkinson-White3 (WPW) pattern, implying the appearance only of the characteristic configuration
of the ECG, is often applied. If there is a tachycardia (from a number of causes), the term “syndrome” is
applied. In a study of WPW pattern in 238 military aviators of mean age 34.3 years, 17.6 per cent were
　
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本文鏈接地址：Manual of Civil Aviation Medicine 1(87)