A 23-year-old woman has had 2 episodesof syncope during the past month.Her mother witnessed 1 episode inwhich the patient collapsed and lostconsciousness for a few minutes. Sheexperienced tonic-clonic seizure activitybut no subsequent confusion.
A 23-year-old woman has had 2 episodesof syncope during the past month.Her mother witnessed 1 episode inwhich the patient collapsed and lostconsciousness for a few minutes. Sheexperienced tonic-clonic seizure activitybut no subsequent confusion.Her mother is also concernedabout her daughter's amenorrhea andobsessive preoccupation with weightand appearance. The mother reportspurging behavior, which the patient denies.On further questioning, the patientstates with pride that she has lost20 lb during the previous 6 months. Areview of systems reveals cold intoleranceand fatigue.The patient is 70 in tall andweighs 102 lb (body mass index[BMI], 15). Her blood pressure is90/53 mm Hg; heart rate is 43 beatsper minute. The patient is thin but inno apparent distress. She has fine lanugo-type hair over her face and arms.Results of neurologic, pulmonary, andabdominal examinations are normal.However, cardiovascular examinationreveals a soft systolic murmur and midsystolic click consistent with mitralvalve prolapse.A baseline chemistry panel demonstratesmild hypokalemia (potassiumlevel, 3.1 mEq/L); all other componentsare normal. A complete bloodcell count and thyroid and liver functiontests are also normal. A 12-leadECG demonstrates sinus bradycardiawith prolongation of the QT interval(Figure 1). Immediate 24-hour Holtermonitoring is ordered.The patient returns to her physician'soffice 2 days later and reports 1episode of profound dizziness but nosyncope. A review of Holter monitordata shows that this event correlatedwith a short, self-terminating episode ofpolymorphic ventricular tachycardia,consistent with torsade de pointes(Figure 2). The patient is admitted tothe hospital for cardiac monitoring andfurther management.MAKING THE DIAGNOSISPatients with anorexia nervosaare frequently in denial. Often, a familymember urges the patient to seekmedical attention because of concernabout substantial weight loss. In contrastto medically ill patients, thosewith anorexia are unconcerned abouttheir weight loss. A high index ofsuspicion for this disorder is warranted,because patients often presentwith nonspecific symptoms oramenorrhea.Many severely anorectic patientshave fine lanugo-type hair onthe sides of their face and arms,brittle nails, and thinning hair. Theymay also report cold sensitivity,abdominal pain, light-headedness,and fatigue.The Diagnostic and StatisticalManual of Mental Disorders lists the followingcriteria for anorexia nervosa1:
Our patient met all of thesecriteria.In addition to eating disorders,the differential diagnosis in this casecould include primary cardiac arrhythmia(eg, congenital long QTsyndrome), use of QT-prolongingdrugs, malabsorption syndrome, andhypermetabolic syndrome.Only rarely do serious symptoms,such as syncope, occur. Syncopethat results from an anorexiarelatedcardiac arrhythmia may beconfused with a seizure disorder.
CARDIAC COMPLICATIONSOF ANOREXIA
Some of the deaths among patientswith anorexia may result fromcardiac complications
. Oneof the most common cardiovascularfeatures of this disease is
This may in part be an adaptiveresponse to weight loss andnegative energy balance. However, abnormallyelevated cardiac vagal activityhas been demonstrated in patientswith anorexia.
This suggests thatbradycardia in this setting may not beentirely physiologic, nor should it bedismissed as a normal adaptation toathletic conditioning, despite the factthat many affected patients exercisecompulsively.Another common cardiac abnormalityis
mitral valve prolapse,
whichoften remits with weight gain.
Clinically important mitral valve regurgitationis, however, exceedingly infrequent.A rare but potentially lethal complicationis
congestive heart failure
that results from the rapid refeedingof cachectic patients.
The exactmechanism underlying this phenomenonis unclear, although evidence suggestsa potentially important role forhypophosphatemia.
Anorexia is alsoassociated with
which should be suspected when achest film reveals an enlarged cardiacsilhouette.Anorexia can result in
.However, autopsy studies donot demonstrate significant coronaryartery disease.
This suggests that despitea high incidence of sudden deathin patients with anorexia, prematurecoronary artery disease is probablynot the cause.The most likely explanation forpremature sudden death in patientswith anorexia is ventricular arrhythmia,in particular torsade de pointes.This form of polymorphic ventriculartachycardia occurs exclusively in thesetting of QT-interval prolongationand is often triggered during periodsof bradycardia.A study of 58 patients withanorexia nervosa demonstrated QTprolongation in nearly half.8 The authorsalso found a 2-fold increase inQT dispersion (a strong marker ofarrhythmia risk) in these patientscompared with controls. Clinicalfactors that correlated with QT prolongationwere low BMI, rapid rateof weight loss, and a low serumsodium level.
Although there are no evidencebasedcriteria for hospitalization,indications center on cardiac instability
. If the heart rate of apatient with moderate or severe anorexiais below 40 beats per minute,inpatient cardiac monitoring maybe indicated. Hospitalization may bewarranted if atrioventricular blockis detected, although advanced conductionabnormalities are exceedinglyrare in anorexia.
Hospitalizationmay also be indicated for patientswith symptomatic hypotension, syncope,rhythms other than sinus, ora markedly prolonged QT interval(more than 500 milliseconds). Whenthe QT interval is only modestlyprolonged (470 to 500 milliseconds),hospitalization may be indicated ifconcomitant profound electrolyteimbalance is detected.
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