these modalities impractical as screening devices, at this
point in time.- Despite the fact that many conditions that cause
sudden death in young athletes are familial (hyper-
trophic cardiomyopathy-autosomal dominant defect
in sarcomere formation; Long QT syndrome-autoso-
mal dominant sodium channel defect; Marfan’s
Syndrome-autosomal dominant mutation of FBN1
fibrilin gene; Brugada Syndrome-autosomal dominant
SCN5A channelopathy; ARVC-autosomal dominant
defect), genetic testing is not routinely recommended.
SYNCOPE-AND EXERCISE-ASSOCIATED
COLLAPSE
- Syncope is most often defined as a sudden loss of
consciousness for a brief duration, not secondary to
head trauma but usually secondary to a sudden drop in
cerebral blood flow or metabolic change (e.g., hypo-
glycemia and hypoxia). Exercise-associated collapse
(EAC) refers to athletes who are unable to stand or
walk unaided because of lightheadedness, faintness,
dizziness, or outright syncope. The potential differen-
tial diagnosis is extensive and includes multiple car-
diovascular and neurologic etiologies (Kapoor, 1992;
Manolis et al, 1990). Athletes who present with a his-
tory of “passing out with exercise” require a careful
history and physical to differentiate benign from life
threatening etiologies (Kugler, O’Connor, and
Oriscello, 2001) (see Table 25-5).- The first step involves determining if the event was a
brief, true syncopal episode versus the more common
and generally benign EAC event which involves a
longer time period of “being out of it” even in the
supine position with normal vital signs. The second
step is to differentiate between syncope that occurs
during the event (suggesting a more ominous
arrhythmic etiology) and syncope that occurs fol-
lowing the event, usually associated with orthostatic
hypotension on exercise cessation (suggesting a less
ominous etiology). It is also critical to identify pro-
dromal symptoms that may have occurred during
exercise such as palpitations (arrhythmia), chest pain
(ischemia or aortic dissection), nausea (ischemia or
vagal activity), wheezing, or pruritus (anaphylaxis). - The physical examination should include a careful
assessment of orthostatic vital signs, precordial aus-
cultation especially focusing on ruling out the mur-
murs of aortic stenosis and HCM, and a careful search
for the morphologic features of Marfan’s syndrome.
An EKG should be ordered in most cases and should
be evaluated closely for rate, rhythm, QT interval,
repolarization abnormalities, left or right hypertrophy,
preexcitation evidence, and complications of ischemic
heart disease. Further testing, including blood work,
echocardiogram, and stress testing may be done
depending on whether a diagnosis has been made,
suggested, or remains unexplained. - See Fig. 25-1 for a suggested algorithm for the primary
care evaluation of exertional syncope in the young
athlete (Kugler, O’Connor, and Oriscello, 2001).
- The first step involves determining if the event was a
144 SECTION 3 • MEDICAL PROBLEMS IN THE ATHLETE
TABLE 25-5 Clinical Clues to Common Etiologies Presenting with Exertional Syncope
SUGGESTED DIAGNOSTIC
DIAGNOSIS CLINICAL CLUES ELECTROCARDIOGRAM TESTING
Neurocardiogenic syncope Noxious stimulus, prolonged Normal Exercise testing
upright position
Supraventricular Palpitations, response to carotid Preexcitation Electrophysiologic study and
tachyarrhythmias sinus pressure definitive therapy
Hypertrophic cardiomyopathy Grade III/VI systolic murmur, Normal, pseudoinfarction Echocardiography with doppler
louder with valsalva, when pattern, left ventricular
present hypertrophy with strain
Myocarditis Prior upper respiratory tract Simulating a myocardial Viral studies, echocardiogram,
infection, pneumonia, shortness infarction with ectopy drug screening
of breath, recreational drug use
Aortic stenosis Exertional syncope, grade III/VI Left ventricular hypertrophy Echocardiography with doppler
harsh systolic
crescendo-decrescendo murmur
Mitral valve prolapse Thumping heart, midsystolic click QT interval may be prolonged Echocardiography with doppler
with or without a murmur
Prolonged QT syndrome Recurrent syncope with family Prolonged corrected QT Family history; exercise stress
history of sudden death interval (>0.44) test with ECG after exercise
Coronary anomalies Usually asymptomatic, sudden Normal rest electrocardiogram Coronary angiography,
death event cardiac MRI
Acquired coronary artery Chest pain syndrome, Ischemia, may be normal Exercise testing with or without
diseases family history perfusion or contractile imaging
Right ventricular dysplasia Asymptomatic until syncope, T-wave inversion v1-v3 PVCs Echo/doppler study
tachyarrhythmias with LBBB configuration electrocardiography