14774
Of particular interest in this patient is the fluctuation of the QT interval at a stable dose of methadone , suggesting that a single normal electrocardiogram ( ECG ) does not guarantee that the patient is not at risk of ventricular arrhythmias .
 fluctuation of the QT interval, methadone
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 fluctuation of the QT interval, methadone