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certification is the only possibility following recovery.
CARDIOMYOPATHY
Cardiomyopathy is a primary heart-muscle disorder not associated with coronary heart disease, valvar
heart disease, hypertension (which are all secondary diseases of heart-muscle) or congenital abnormality.
1 WHO – World Health Organization
ICAO Preliminary Unedited Version — October 2008 III-1-36
If the ventricle is dilated with predominantly systolic dysfunction (it may also demonstrate secondary
diastolic dysfunction), the term ’dilated cardiomyopathy’ is appended. If it is inappropriately
hypertrophied, sometimes grossly and asymmetrically, in the absence of provocative circumstance, the
term ’hypertrophic cardiomyopathy’ is used. In this case systolic function is normally preserved, but
diastolic function is likely to be impaired. If the ventricle is stiffened due to infiltration by, for example,
amyloidosis, sarcoidosis or a glycosphingolipid (Fabry’s disease1), the term ’restrictive cardiomyopathy’
is more appropriate, although hypertrophy may also be present as will both systolic and diastolic
dysfunction.
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy (HCM) has a prevalence of about one in 500 adults. Most adults with the
condition have inherited it as an autosomal dominant characteristic, and about 60 per cent have one of
over 100 mutations involving 11 genes that encode the contractile proteins. It is marked by the diversity
of its phenotypes and has a fairly specific histological appearance, which includes disarray of the
myocytes with bizarre forms. An otherwise inexplicable wall diameter >1.5 cm, often with characteristic
asymmetry of the interventricular septum, may lead to the diagnosis but there is much variation. About 25
per cent will have sub(aortic) valve obstruction caused by the hypertrophied septum. One to two per cent
die each year, half of these suddenly and usually due to ventricular arrhythmia. Stroke is also a cause of
death in such individuals.
Although often asymptomatic, the patient with established HCM may suffer breathlessness (50 per cent);
a smaller percentage will also suffer syncope at some point. The condition is likely to present in aviators
with an abnormal resting ECG, There are no truly typical features and changes range from diffuse ST-T
abnormalities through QS waves in the inferior or high septal leads (the so-called pseudo-infarct pattern
with a discordant QRST angle) to significant and widespread voltage increase with deep symmetrical T
wave inversion. See Appendix 1b: 22. It may also present as a sustained ejection systolic murmur
reflecting at least “physiological” obstruction in the left ventricular outflow tract together with a third or
fourth heart sound. Mitral regurgitation may be present due to distorted architecture. The association of
systolic anterior motion of the mitral valve (SAM) with (asymmetric) septal hypertrophy (ASH) and
premature closure of the aortic valve on M mode echocardiography2 is more or less pathognomonic of the
condition.
The natural history of the condition complicates certification. Outcome may be genetically determined but
progress can be very slow and the condition benign. Risk factors for sudden cardiac death include
previous cardiac event, family history of sudden death, ventricular tachycardia on ambulatory monitoring,
abnormal blood pressure response (a fall) on exercise ECG, inter-ventricular septum > 3 cm and subaortic
gradient > 30mmHg. Half of the sudden deaths occurring in young male athletes > 35 years of age
are due to the condition. Atrial fibrillation, especially if paroxysmal and uncontrolled, may prove
incapacitating and also worsens the prognosis.
Certification requires that:
• the subject can complete at least three stages of the Bruce treadmill protocol without symptoms,
electrical instability or a fall in the blood pressure (which may be predictive of sudden cardiac
death (SCD))
1 Fabry’s disease: diffuse angiokeratoma. An X-linked lysosomal storage disease of glycosphingolipid catabolism,
leading to accumulation of ceramide trihexoside in the cardiovascular and renal systems., After Johannes Fabry,
German dermatologist (1860-1930).
2 M mode echocardiography: recording of the amplitude and rate of motion (M) of a moving structure in real time
by repeatedly measuring the distance of the structure from the single transducer at a given moment. It yields a
monodimensional image, sometimes called an “icepick” view of the heart.
ICAO Preliminary Unedited Version — October 2008 III-1-37
• there is no ventricular tachycardia (defined as three or more consecutive ventricular complexes)
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Manual of Civil Aviation Medicine 1(96)
