NEW YORK (Reuters) -- The tragedy of an unexplained drowning may be the first clue to an inherited form of disturbed heartbeat called long QT syndrome (LQTS), according to a report in the February issue of the journal Pediatrics.
Researchers at the Mayo Foundation in Rochester, Minnesota, say cardiac arrhythmias "may be an important and possibly overlooked consideration" in the medical evaluation of unexplained drownings.
In their report, Drs. Michael J. Ackerman and Co-burn J. Porter of the Mayo Eugenio Litta Children's Hospital describe the case of a 10-year-old boy who survived a drowning incident in a public pool. On an electrocardiogram, doctors noted that the boy had LQTS, where the QT segment of the heart trace is abnormally prolonged, signifying a problem with electrical conduction through the heart muscle. Long QT syndrome is estimated to occur in about 1 in 10,000 people.
Subsequent evaluation revealed that the boy had blacked out "once while walking home from school and once while playing baseball in the year preceding this event," the authors state. Several other family members had experienced similar symptoms and are believed to also carry a gene for the disorder.
The boy was started on drug therapy for the disorder, and has had no further ventricular arrhythmias, report the researchers.
"As evidenced by this child, an unexplained drowning (survived or fatal) may be the initial clue to revealing a family with the inherited LQTS," the authors state.
"In the absence of a clear identification as to the cause of drowning, we suggest that families be asked for a history of sudden death, spells, 'black outs,' fainting, ...seizures not responsive to usual antiepileptic therapy, or any unexplained accidents occurring previously in the drowning victim or any related family members," the authors state.
They also recommend electrocardiogram testing for victims of any unexplained near-drownings.
"Interestingly, swimming is a commonly cited precipitating activity for syncope (fainting)," write the research team. "...Realizing swimming can be an arrhythmogenic trigger again underscores the importance of considering cardiac causes in unexplained drownings."
SOURCE: Pediatrics (1998;101:306-308)
