October 2025 POCUS Case of the Month: Lung Ultrasound

Patients receiving treatment for chronic pain with methadone require a baseline 12-lead ECG, a repeat ECG after one month of treatment, and an ECG at least yearly. Methadone may lead to QT interval prolongation and even torsades de pointes. This occurs due to inhibition of the human cardiac ether-a-go-go related gene (hERG). The gene encodes for potassium ion channels and abnormalities cause delayed termination of the cardiac action potential and QT prolongation. The effect is most likely dose-related with increased risk in patients receiving large doses several times daily for chronic pain. Risk factors for QT prolongation and torsades de points include patients with pre-existing long QT syndrome, a family history of sudden death, female gender, older age, other rhythm abnormalities or structural heart disease, cytochrome (CYP) enzyme inhibitors, concurrent administration of other drugs that increase the QT interval, and electrolyte abnormalities including hypokalemia, hypomagnesemia, and hypocalcemia. In addition, QT interval prolongation has occurred in susceptible patients receiving low dose methadone for maintenance treatment of opioid addiction.