Patients With Rare Arrhythmias: Could They Have Brugada Syndrome?
Date: March 1, 2013
Knowing what to look for can make a big difference in the diagnosis and treatment of rare genetic diseases like Brugada syndrome.
“We thought it was a very rare condition, but once you know what to look for, you find more cases,” says Jane Crosson, one of a handful of pediatric cardiologists worldwide who cares for children with this potentially lethal condition.
Patients are often asymptomatic and are typically identified in several ways: first following cardiac arrest associated with an abnormal EKG pattern, the hallmark of the disease—particularly characteristic ST elevation inV1 and V2. Other manifestations include intraventricular conduction delay. Or, the characteristic abnormal pattern may come to light when patients have an EKG for some other reason. Lastly—because the syndrome is autosomal dominant—patients can be identified through genetic screening after a family member has been diagnosed.
The major gene alteration identified in Brugada syndrome, SCN5A, causes loss of function of the sodium channel. “That can result in abnormal repolarization,” Crosson says. And the repolarization can extend to different areas of the heart, setting the patient up for potentially fatal ventricular fibrillation or ventricular tachycardia.
Among the patients under Crosson’s care are several family members of a teenager who had a cardiac arrest and the abnormal EKG pattern. Nine siblings were genetically screened and four children (ages 6 to 18 years) were found to have the gene defect, all of whom are asymptomatic.
Although more patients are diagnosed with the disease during their 20s and 30s, Crosson is currently caring for a patient diagnosed at 1 year.
A defibrillator is the primary treatment for Brugada syndrome, “which is difficult because you don’t want to go putting defibrillators in every child,” Crosson says.
So far, no proven drug therapies exist, though some are being tried off-label. Crosson’s 1-year-old patient already has a defibrillator but is also on quinidine. Using such sodium channel blockers may counteract the faulty gene’s effect. Beta-blockers also have helped, Crosson notes.
But pediatric expertise with this disease is scarce. Though she made the diagnosis in the 1-year-old fairly easily, Crosson says she consulted with one of the Brugada brothers, who described the syndrome in 1992, to develop a treatment strategy. “There are just very few of us who deal much with this condition.”