heroin and Long-QT-Syndrome

(1) Methadone is an opiate used for replacement therapy of opiate addiction that causes dose-dependent QT prolongation. (2) Severe ventricular arrhythmias such as torsades de pointes have been reported, usually in patients on high doses (100 mg to 400 mg/day). (3) Methadone has a long plasma elimination half-life, and this poses a risk of accumulation. Accumulation is especially problematic when the dose is increased too rapidly. Combining methadone with a CYP 3A4 inhibitor increases the risk of torsades de pointes, as methadone is metabolised by this enzyme system. (4) Factors potentially predisposing patients to torsades de pointes must be analysed in each case; these include preexisting bradycardia, congenital QT prolongation, hypokalemia, and concomitant use of other drugs inducing QT prolongation. (5) This adverse effect has also been reported with levacetylmethadol (another opiate) and with heroin. It does not seem to occur with buprenorphine.

Topics: Analgesics, Opioid; Aryl Hydrocarbon Hydroxylases; Drug Interactions; Heroin; Humans; Hypokalemia; Long QT Syndrome; Methadone; Narcotics; Opioid-Related Disorders; Pain; Retrospective Studies; Risk Factors; Switzerland; Torsades de Pointes

We describe the anaesthetic management of a spontaneous vaginal delivery at 39 weeks' gestation in a 22-year-old patient with congenital long QT syndrome. With a strong family history of sudden deaths, the patient had an initial QT interval corrected for rate (QTc) of >600 ms. Following a once-daily 50-mg dose of atenolol over the previous 11 months, her QTc remained prolonged at 560 ms. To minimise any increase in catecholamine levels and consequent risk of malignant ventricular arrhythmias, a combined spinal-epidural technique was selected using intrathecal diamorphine and levobupivacaine, with intravenous and oral magnesium and potassium supplementation. Levobupivacaine was substituted for routine racemic bupivacaine to decrease the risk of drug-induced cardiotoxicity. Delivery outcome was successful and uneventful. We outline the pathophysiology, risks and treatments of long QT syndrome, and discuss the analgesic management of this patient in labour with congenital long QT syndrome.

Topics: Adult; Analgesia, Epidural; Analgesia, Obstetrical; Analgesics, Opioid; Anesthetics, Local; Anti-Arrhythmia Agents; Atenolol; Bupivacaine; Delivery, Obstetric; Female; Heroin; Humans; Levobupivacaine; Long QT Syndrome; Monitoring, Physiologic; Pregnancy; Pregnancy Complications, Cardiovascular