A High School Wrestler with Severe Bradycardia
A
17-year-old boy was referred for management of anorexia nervosa. He reported a 23 kg weight loss over 6 months in an attempt to qualify for a lower wrestling weight class. Additionally, he described exertional lightheadedness and dyspnea. Examination revealed a teenager with a body mass index of 16 kg/m2. Pulse was 34 beats per minute; blood pressure was 90/53 mmHg. Electrocardiogram (ECG) showed narrow QRS complexes without P waves, consistent with a junctional rhythm (Figure 1). He was admitted for cardiac monitoring because of concern for symptomatic bradycardia. A double standard ECG (20 mm/mV) was subsequently performed, and P waves were seen before the QRS complexes, consistent with sinus bradycardia (Figure 2; available at www.jpeds.com). Sinus bradycardia is common in athletes and patients with anorexia nervosa because of increased vagal tone. Physiologic adaption to inadequate calories and decreased metabolism also contributes to bradycardia in patients with anorexia nervosa.1 Junctional escape rhythms are uncommon in patients with anorexia nervosa. On the other hand, 8% of highly trained athletes have a junctional rhythm at rest.2 This occurs because the automaticity of the sinoatrial node is suppressed with increased vagal tone; therefore, the secondary pacemaker (atrioventricular node) exceeds the resting sinus rate, and a junctional rhythm is seen.
In patients with bradycardia and exertional symptoms such as dizziness, syncope, or fatigue, exercise stress testing should be pursued to determine whether an appropriate chronotropic response occurs and if the rhythm originates from the sinoatrial node.3 A double standard ECG should be performed in patients with low voltages on ECG in order to help visualize P waves that may not be readily identifiable on standard ECG. Pacemaker placement is not usually necessary in patients with anorexia nervosa because reversal of cardiac conduction disturbances occur with normalization of weight and proper nutrition.4 n Cynthia H. Ho, MD B. Jason Brotherton, MD Department of Pediatrics Department of Internal Medicine
Keith E. Lewis, MD Department of Pediatrics Division of Critical Care Medicine
Merujan Y. Uzunyan, MD Department of Pediatrics Division of Cardiology Los Angeles County + University of Southern California Medical Center Keck School of Medicine Los Angeles, California
References 1. Kollai M, Bonyhay I, Jokkel G, Szonyi L. Cardiac vagal hyperactivity in adolescent anorexia nervosa. Eur Heart J 1994;15:1113-8. 2. Papadakis M, Basavarajaiah S, Rawlins J, Edwards C, Makan J, Firoozi S, et al. Prevalence and significance of T-wave inversions in predominantly Caucasian adolescent athletes. Eur Heart J 2009;30: 1728-35. 3. Krantz MJ, Gaudiani JL, Johnson VW, Mehler PS. Exercise electrocardiography extinguishes persistent junctional rhythm in a patient with severe anorexia nervosa. Cardiology 2011;120:217-20. 4. Mont L, Castro J, Herreros B, Pare C, Azqueta M, Magri~ na J, et al. Reversibility of cardiac abnormalities in adolescents with anorexia nervosa after weight recovery. J Am Acad Child Adolesc Psychiatry 2003;42:808-13.
Figure 1. Standard calibration ECG (10 mm/mV) showing a narrow QRS complex bradycardia (40 bpm) with absence of P waves, consistent with a junctional escape rhythm, and concerning for sinus node dysfunction. QTc interval was normal at 368 milliseconds. QTc, corrected QT interval.
J Pediatr 2014;-:---. 0022-3476/$ - see front matter. Copyright ª 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jpeds.2014.03.016
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THE JOURNAL OF PEDIATRICS
www.jpeds.com
Vol. -, No. -
Figure 2. A, Double standard ECG (20 mm/mV) showing monomorphic P waves (arrows) prior to the QRS complexes, consistent with normal sinus rhythm with a ventricular rate of 41 bpm. B, Double standard ECG performed after asking the patient to bicycle pedal in bed for 5 minutes. Note the P waves (arrows) prior to the QRS complexes, consistent with a normal sinus response to exercise with an increase in heart rate to 75 bpm. Of note, the patient’s maximum heart rate reached 108 bpm after 10 minutes of exercise.
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Ho et al
A
17-year-old boy was referred for management of anorexia nervosa. He reported a 23 kg weight loss over 6 months in an attempt to qualify for a lower wrestling weight class. Additionally, he described exertional lightheadedness and dyspnea. Examination revealed a teenager with a body mass index of 16 kg/m2. Pulse was 34 beats per minute; blood pressure was 90/53 mmHg. Electrocardiogram (ECG) showed narrow QRS complexes without P waves, consistent with a junctional rhythm (Figure 1). He was admitted for cardiac monitoring because of concern for symptomatic bradycardia. A double standard ECG (20 mm/mV) was subsequently performed, and P waves were seen before the QRS complexes, consistent with sinus bradycardia (Figure 2; available at www.jpeds.com). Sinus bradycardia is common in athletes and patients with anorexia nervosa because of increased vagal tone. Physiologic adaption to inadequate calories and decreased metabolism also contributes to bradycardia in patients with anorexia nervosa.1 Junctional escape rhythms are uncommon in patients with anorexia nervosa. On the other hand, 8% of highly trained athletes have a junctional rhythm at rest.2 This occurs because the automaticity of the sinoatrial node is suppressed with increased vagal tone; therefore, the secondary pacemaker (atrioventricular node) exceeds the resting sinus rate, and a junctional rhythm is seen.
In patients with bradycardia and exertional symptoms such as dizziness, syncope, or fatigue, exercise stress testing should be pursued to determine whether an appropriate chronotropic response occurs and if the rhythm originates from the sinoatrial node.3 A double standard ECG should be performed in patients with low voltages on ECG in order to help visualize P waves that may not be readily identifiable on standard ECG. Pacemaker placement is not usually necessary in patients with anorexia nervosa because reversal of cardiac conduction disturbances occur with normalization of weight and proper nutrition.4 n Cynthia H. Ho, MD B. Jason Brotherton, MD Department of Pediatrics Department of Internal Medicine
Keith E. Lewis, MD Department of Pediatrics Division of Critical Care Medicine
Merujan Y. Uzunyan, MD Department of Pediatrics Division of Cardiology Los Angeles County + University of Southern California Medical Center Keck School of Medicine Los Angeles, California
References 1. Kollai M, Bonyhay I, Jokkel G, Szonyi L. Cardiac vagal hyperactivity in adolescent anorexia nervosa. Eur Heart J 1994;15:1113-8. 2. Papadakis M, Basavarajaiah S, Rawlins J, Edwards C, Makan J, Firoozi S, et al. Prevalence and significance of T-wave inversions in predominantly Caucasian adolescent athletes. Eur Heart J 2009;30: 1728-35. 3. Krantz MJ, Gaudiani JL, Johnson VW, Mehler PS. Exercise electrocardiography extinguishes persistent junctional rhythm in a patient with severe anorexia nervosa. Cardiology 2011;120:217-20. 4. Mont L, Castro J, Herreros B, Pare C, Azqueta M, Magri~ na J, et al. Reversibility of cardiac abnormalities in adolescents with anorexia nervosa after weight recovery. J Am Acad Child Adolesc Psychiatry 2003;42:808-13.
Figure 1. Standard calibration ECG (10 mm/mV) showing a narrow QRS complex bradycardia (40 bpm) with absence of P waves, consistent with a junctional escape rhythm, and concerning for sinus node dysfunction. QTc interval was normal at 368 milliseconds. QTc, corrected QT interval.
J Pediatr 2014;-:---. 0022-3476/$ - see front matter. Copyright ª 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jpeds.2014.03.016
1
THE JOURNAL OF PEDIATRICS
www.jpeds.com
Vol. -, No. -
Figure 2. A, Double standard ECG (20 mm/mV) showing monomorphic P waves (arrows) prior to the QRS complexes, consistent with normal sinus rhythm with a ventricular rate of 41 bpm. B, Double standard ECG performed after asking the patient to bicycle pedal in bed for 5 minutes. Note the P waves (arrows) prior to the QRS complexes, consistent with a normal sinus response to exercise with an increase in heart rate to 75 bpm. Of note, the patient’s maximum heart rate reached 108 bpm after 10 minutes of exercise.
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Ho et al
