SEVERE BRADYCARDIA IN A PEDIATRIC LITHIUM TOXICITY

Background: Although CNS, renal, and GI effects are commonly encountered in lithium toxicity, cardiovascular effects are less well understood and infrequently described. Case Report: An 11-year-old, nonverbal, autistic female with no history of cardiac abnormalities presented with 1 week of fever, anorexia, and vomiting and subsequently developed ataxia, lethargy, and respiratory distress. In the PICU, she had several general tonic-clonic seizures that were managed with benzodiazepines and phenobarbital. She had no independent access to her medications which were continuously dispensed by her parents even throughout her GI illness despite her anorexia. They included sustained release lithium, methylphenidate, haloperidol, benztropine, and guanfacine. The initial vital signs were: BP, 80/40 mmHg; P, 30-40 bpm; RR, 24-44 min; T, 102 [degrees] F rectal; [O.sub.2]Sat, 80% on room air. The physical examination was significant for bradycardia without murmurs, clonus, and hyperreflexia. Her ECG showed a junctional bradycardia with a QRS 64 ms and [QT.sub.c] 507 ms. Transesophageal esophogram showed an ejection fraction of 21% and global hypokinesis of the left ventricle. The laboratory results were normal except for her BUN/Cr (24/0.9) and a lithium level of 6.54 mEq/L for which she received emergent hemodialysis. During dialysis, the patient's cardiac rhythm spontaneously reverted to normal sinus rhythm. A repeat echocardiogram following her second dialysis showed an ejection fraction of 31% and a normal LV shortening fraction. Conclusion: Although lithium poisoning is infrequently associated with reversible cardiac conduction abnormalities, this has not been previously reported in children. This case also demonstrates lithium-induced myocardial depression and its reversal by hemodialysis.
Hahn I, Kwok M, Hoffman RS, Nelson LS. New York City Poison Control Center and Long Island Jewish Medical Center, New York, New York, [...]