01 Long QT Syndrome

17 year-old M who 

collapsed in 

overtime

PMH 

• Passed out once 

• Migraines 

PSH 

Noncontributory 

Allergies 

NKDA 

Medications 

Ibuprofen prn 

Sumitriptan prn 

Fam Hx 

• Paternal uncle died at age 30 - 

unexplained MVA 

• Cousin died from SIDS at 3 mo 

Soc Hx 

• LAHW both parents. 

• Plays basketball year-round. 

• Does well in school. 

• Tried marijuana. No other 

drugs. No alcohol. 

• 2 sexual partners, uses 

condoms.

Gen: 

HEENT: 

CV: 

Resp: 

Abd: 

MSk: 

Neuro: 

Skin: 

VS: 

37.5 112/64 88 14 99% RA 

Wt: 188 lbs Ht: 6’4” BMI: 22.9

• 15% before adulthood 

• Mostly benign causes 

• 75% have vasovagal syncope 

Why do we care? 

“The only difference between syncope and sudden death is 

that in syncope you wake up.” 

-- G L Engels

Cardiac syncope 

• Electrical disturbances 

• Long or short QT Syndrome 

• WPW 

• Structural heart disease 

• Hypertrophic CM 

• AS 

• DCM 

• pHTN 

• Myocarditis 

• Myocardial dysfxn 

Neurocardiac syncope 

• Vasovagal 

• Tilt table test 

Noncardiac syncope 

• Seizures 

• Migraines 

• Orthostatic hypotension 

• GER 

• Metabolic disease 

• Situational 

• Breath holding spells 

• Toxic exposure 

• Conversion disorder 

• Hyperventilation 

• Choking game 

• Pregnancy 

• Anemia 

• CNS lesions

137 102 9 

3.9 27 0.6 

14.2 

6.1 236 

42.6 

63N 14L 

Initial Labs 

103 Ca 8.8 Mg 1.9 Phos 3

The 

Dreaded 

…

• Rate 

• Rhythm 

• Axis 

• Hypertrophy 

• Infarction 

• Intervals

• Rate 

• 300-150-100-75-60-50 

• 6-second strip

• Rhythm 

• Sinus?

• Axis 

• Normal? 

• LAD? 

• RAD?


• RAE 

• LAE 

• RVH 

• LVH

RAE – too tall LAE – too wide 

LVH RVH 

II 

VI


• RAE 

• LAE 

• RVH 

• LVH

• Infarction 

• ST segments 

• T waves 

• Q waves

• Intervals 

• PR 

• QRS 

• QT 

• RR

QTc = QT 

RR

Prolonged QTc interval

Types 

1) Acquired 

2) Congenital 

• >50 genetic mutations in 4 cardiac ion channels 

• >10 LQT gene loci, KVLQT1 

Epidemiology 

• 18 Italian hospitals 

(2001-2006) 

• 7 LQTS genes found 

• Prevalence 1:2534 

(95% CI 1:1583 to 1:4350) 

Prevalence of the Congenital Long-QT Syndrome. 

Schwartz, P., Stramba-Badiale, M, et al. Circulation 

2009; 120: 1761-1767.

Life-threatening arrhythmias 

• Torsades de pointes

http://www.nature.com.proxy.uchicago.edu/nrd/journal/v3/n3/fig_tab/nrd1361_F3.html 

HERG 

• encodes K ch 

• important in repolarization 

• protects vs early after- 

depolarizations 

HERG blockade (LQT2) 

• Meds block IKr current 

mediated by K channel

• Antiarrythmics 

• Antihistamine 

• Benadryl 

• Antimicrobials 

• Macrolides 

• Quinolones 

• Bactrim 

• Pentamidine 

• Azoles 

• GI agents 

• Cisapride 

• Zofran 

• Psychiatric drugs** 

• Haldol 

• TCAs 

• Anti-migraine 

• Triptans 

• Electrolyte disturbances 

• Other medical conditions 

• Arrhythmias 

• Endocrine 

• Neurologic 

• Nutritional

Romano-Ward Syndrome 

• AD 

• KCNQ1, KCNE1, KCNH2, 

KCNE2, and SCN5A 

• Normal hearing 

186 J-LN pts 

• Severe variant of LQTS 

• Major QTc prolongation (557) 

• KCNE1 mutation 

• Early presentation 

• SCD rates >25% 

• Persistence of sx/SCD on BB 

Jervell and Lange-Nielsen Syndrome 

• AR 

• KCNQ1 or KCNE1 

• Congenital AVB 

• Syndactyly 

• Sensorineural hearing loss 

Schwartz PJ, et al. The Jervell and Lange-Nielsen syndrome: natural history, 

molecular basis, and clinical outcome. Circulation. 2006; 113 (6): 783.

Ackerman, M. Consultation with the Specialist: The Long QT Syndrome. Pediatr. Rev. 1998; 19; 232-238.

Medications 

• Beta blocker 

• IV Magnesium or Isoproterenol 

• Pacer/Defibrillator 

• Growth 

• Longevity of device 

• Increased physical activity in children 

• Sympathetic ganglionectomy 

• QTc > 600 msec = poor prognostic factor 

• NO competitive sports 

• Buddies 

Schwartz study 

• 233 pts over 15 years 

• w/o BB: 1-year mortality rate >20% 

• w/o BB: 15-year mortality rate >53%

• Discuss the causes of 

syncope 

• Review of EKG 

interpretation 

• Review presentation 

of LQTS 

• Review types of LQTS 

• Review tx of LQTS

10-day-old infant with difficulty feeding and cyanosis. 

What is her diagnosis?

References 

• Willis, J. Syncope. Pediatr. Rev. 2000; 21; 201-204. 

• Ackerman, M. Consultation with the Specialist: The Long QT Syndrome. Pediatr. Rev. 1998; 19; 

232-238. 

• Coleman B, Salerno J. Causes of syncope in children and adolescents. UpToDate. June 2008. 

• McLeod, K. Dizziness and syncope in adolescence. Congenital Heart Disease. 2001; 86: 350-354. 

• Berul C, Seslar S, et al. Acquired long QT syndrome. UpToDate. June 2011. 

• Ackerman M, Clapham D. Ion Channels – Basic Science and Clinical Disease. N Engl J Med 1997; 

336: 1575-1586. 

• Zimetbaum, P, Josephson M. Pathophysiology of long QT syndrome. UpToDate. May 2008. 

• Schwartz PJ, et al. The Jervell and Lange-Nielsen syndrome: natural history, molecular basis, and 

clinical outcome. Circulation. 2006; 113 (6): 783. 

• Zimetbaum P, Seslar S, et al. Prognosis and management of congenital LQTS. UpToDate. May 2011. 

• Schwartz, P., Stramba-Badiale, M, et al. Prevalence of the Congenital Long-QT 

Syndrome. Circulation 2009; 120: 1761-1767. 

• 

•

01 Long QT Syndrome

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