oxytocin and Long-QT-Syndrome

There are no guidelines for the anaesthetic management of caesarean section in women with long QT syndrome; the description of myocardial ventricular repolarisation in healthy women during caesarean delivery could be a first step. The aim of this study was to describe modification of the QT interval, corrected for heart rate, and the interval between the peak and the end of the T-wave (Tpeak-Tend interval) during caesarean section under spinal anaesthesia. We studied 40 patients scheduled for caesarean section under spinal anaesthesia. Patients were randomly assigned to receive either ephedrine or phenylephrine to prevent hypotension. We injected 5 IU oxytocin after delivery. Corrected QT and Tpeak-Tend intervals were unchanged from pre-operative values after induction of spinal anaesthesia, but increased significantly after oxytocin injection. The choice of vasopressor did not affect the Tpeak-Tend interval. The risk-benefit balance of oxytocin bolus during caesarean delivery should be discussed with women with a history of long QT syndrome.

Topics: Adult; Anesthesia, Obstetrical; Anesthesia, Spinal; Cesarean Section; Electrocardiography; Ephedrine; Female; Humans; Hypotension; Intraoperative Complications; Long QT Syndrome; Oxytocics; Oxytocin; Phenylephrine; Pregnancy; Vasoconstrictor Agents; Young Adult

Although oxytocin, a uterotonic agent, may cause short-term vasodilation that results in severe hypotension, it is still routinely given as an intravenous bolus injection during surgical suction curettage. Two reported cases of ventricular tachycardia after oxytocin bolus in patients with long QT interval syndrome led us to assess the effect of oxytocin on QT interval.. Thirty-eight healthy women scheduled for a surgical suction curettage with general anesthesia were enrolled. General anesthesia was induced by propofol and maintained by either propofol (n = 18) or sevoflurane (n = 20). Electrocardiographic recordings were obtained before and at 1, 2, 3, and 5 minutes after a 10-U intravenous bolus of oxytocin.. Intravenous oxytocin induced a pronounced QTc interval prolongation of 41 +/- 21 ms ( P < .0001), which was maximal 1 minute after administration. The QTc interval returned to control values 3 minutes after oxytocin bolus. Oxytocin bolus also induced an increase in heart rate of 19 +/- 10 beats/min and a significant decrease in systolic arterial pressure of 11 +/- 9 mm Hg (both P < .0001). The drug used to maintain anesthesia was not an independent factor of QT interval prolongation in ANOVA analysis.. Oxytocin intravenous bolus induced a large and transient QTc interval prolongation, suggesting that it may lead to proarrhythmia in circumstances favoring QTc interval increase.

Topics: Abortion, Induced; Adult; Electrocardiography; Female; Humans; Infusions, Intravenous; Long QT Syndrome; Oxytocics; Oxytocin; Pregnancy; Vacuum Curettage

Topics: Female; Humans; Long QT Syndrome; Oxytocin; Postpartum Period; Prolactin

Topics: Female; Humans; Long QT Syndrome; Oxytocin; Postpartum Period; Prolactin

Women with long QT syndrome 2 (LQT2) have a particularly high postpartal risk for lethal arrhythmias. We aimed at investigating whether oxytocin and prolactin contribute to this risk by affecting repolarization.. In female transgenic LQT2 rabbits (HERG-G628S, loss of IKr), hormone effects on QT/action potential duration (APD) were assessed (0.2-200 ng/L). Hormone effects (200 ng/L) on ion currents and cellular APD were determined in transfected cells and LQT2 cardiomyocytes. Hormone effects on ion channels were assessed with qPCR and western blot. Experimental data were incorporated into in silico models to determine the pro-arrhythmic potential. Oxytocin prolonged QTc and steepened QT/RR-slope in vivo and prolonged ex vivo APD75 in LQT2 hearts. Prolactin prolonged APD75 at high concentrations. As underlying mechanisms, we identified an oxytocin- and prolactin-induced acute reduction of IKs-tail and IKs-steady (-25.5%, oxytocin; -13.3%, prolactin, P < 0.05) in CHO-cells and LQT2-cardiomyocytes. IKr currents were not altered. This oxytocin-/prolactin-induced IKs reduction caused APD90 prolongation (+11.9%/+13%, P < 0.05) in the context of reduced/absent IKr in LQT2 cardiomyocytes. Hormones had no effect on IK1 and ICa,L in cardiomyocytes. Protein and mRNA levels of CACNA1C/Cav1.2 and RyR2 were enhanced by oxytocin and prolactin. Incorporating these hormone effects into computational models resulted in reduced repolarization reserve and increased propensity to pro-arrhythmic permanent depolarization, lack of capture and early afterdepolarizations formation.. Postpartum hormones oxytocin and prolactin prolong QT/APD in LQT2 by reducing IKs and by increasing Cav1.2 and RyR2 expression/transcription, thereby contributing to the increased postpartal arrhythmic risk in LQT2.

Topics: Action Potentials; Animals; Disease Models, Animal; Female; Heart Conduction System; Long QT Syndrome; Myocytes, Cardiac; Oxytocin; Postpartum Period; Prolactin; Rabbits

Topics: Adult; Analysis of Variance; Cesarean Section; Electrocardiography; Female; Humans; Long QT Syndrome; Oxytocics; Oxytocin; Postpartum Hemorrhage; Pregnancy

Patients with congenital long QT syndrome (LQTS) are at increased risk of ventricular arrhythmia, particularly during labour and the puerperium.. A 28-year-old primigravida with known LQTS underwent induction of labour at 41 weeks' gestation using a Foley catheter balloon and IV oxytocin. Vaginal delivery with passive second stage and outlet forceps was undertaken with early epidural analgesia to prevent tachycardia and psychological stress. The patient gave birth to a healthy female, and had an uncomplicated postpartum period under continuous electrocardiogram monitoring.. Vaginal delivery with use of oxytocin for the induction of labour can be safely undertaken in patients with LQTS.

Topics: Analgesia, Epidural; Analgesia, Obstetrical; Contraindications; Delivery, Obstetric; Female; Humans; Infant, Newborn; Labor, Induced; Long QT Syndrome; Oxytocin; Pregnancy; Pregnancy Complications, Cardiovascular; Pregnancy Outcome

Topics: Adverse Drug Reaction Reporting Systems; Humans; Long QT Syndrome; Oxytocin; United States

Oxytocin is widely used in obstetric settings to stimulate uterine contraction and prevent postpartum hemorrhage. Its adverse effects which include transient hypotension and increase heart rate could be life-threatening in patients with fixed cardiac output or hypotension resulting from hemorrhage. We reported two cases suspected to have preexisting prolonged Q-T interval syndrome (PQTS) who developed ventricular tachycardia immediately after intravenous injection of oxytocin. Anesthetic management of and use of oxytocic agents in patients with PQTS were discussed.

Topics: Adult; Female; Humans; Long QT Syndrome; Oxytocin; Tachycardia, Ventricular