Intramyometrial injection of vasopressin resulting in severe bradycardia during myomectomy.

Abstract

To the Editor: Myomectomy is an important treatment option for removing a hysteromyoma, along with intramyometrial vasopressin to reduce intraoperative bleeding.[1,2] Sometimes, however, it results in life-threatening complications.[3] We report two rare cases of sudden severe bradycardia after intramyometrial injection of vasopressin during myomectomy. The two patients were diagnosed with uterine leiomyomas. The preoperative laboratory studies, chest radiography, electrocardiography, and blood pressure were normal in both patients. The first case was a 36-year-old woman who underwent laparoscopically assisted myomectomy under general anesthesia. After anesthesia induction, endotracheal intubation, and ensuring that mechanical ventilation was established, laparoscopic myomectomy was performed at 12 mmHg abdominal pressure in the Trendelenburg position. After trocar insertion, the abdominal cavity appeared smooth, and multiple uterine myomas were found covering the entire uterine wall. After negative aspiration, 10 mL of diluted vasopressin (0.6 U/mL) was injected into the myometrium using a 16-gauge needle. Approximately 2 min after the injection of the diluted vasopressin, sudden severe bradycardia was developed. The heart rate (HR) suddenly decreased from 68, to 47, to 25 beats/min. Both the operation and anesthesia were immediately discontinued, and the operative bed was adjusted to a supine position. The patient's HR returned to 55 beats/min and then, within 30 s, dropped to 30 beats/min, and then 25 beats/min. Intravenous atropine (0.5 mg) was administered immediately. Approximately 2 min later, the patient's HR gradually returned to baseline levels. After 10 min of observation, the operation continued and went smoothly. The patient recovered uneventfully and was discharged 4 days later. The second case was a 38-year-old woman who underwent abdominal myomectomy under combined spinal-epidural anesthesia. The operation commenced after anesthesia induction. Bleeding occurred during excision of the myoma, and 10 mL of diluted vasopressin (0.6 U/mL) was injected into the myometrium to relieve bleeding. Approximately 3 min after the injection, the patient's HR dropped suddenly from 70, to 50, to 25 beats/min. One minute later, her blood pressure was 70/40 mmHg. Intravenous atropine sulfate (0.5 mg) was administered. Severe bradycardia (30 beats/min) lasted for nearly 2 min. The patient was ventilated with 100% oxygen. Intravenous ephedrine (6 mg) was also administered immediately, resulting in the HR returning to 108 beats/min and the blood pressure to 125/80 mmHg 3 min later. The operation went smoothly. No more vasoactive drugs were administered. The patient recovered uneventfully and was discharged 6 days later. Vasopressin, an extremely potent vasoconstrictor, is widely used to control acute hemorrhage during myomectomy. The vasopressor effect of vasopressin is primarily mediated by the VIa receptors in vascular smooth muscle, resulting in increased vascular resistance and slowing of the HR. Our two patients showed that intramyometrial injection of vasopressin may result in severe bradycardia, regardless of whether general anesthesia or combined spinal–epidural anesthesia had been used or whether laparoscopically assisted myomectomy or abdominal myomectomy was performed. Anesthesiologists should be vigilant while injecting vasopressin during surgery. Severe bradycardia may be the first symptom. If left untreated, it may lead to life-threatening complications, including cardiac arrest.[4] Stopping the surgical procedure and ejecting carbon dioxide gas from the abdominal cavity to reduce abdominal pressure does not completely relieve this severe bradycardia. Early use of atropine alone may be an appropriate choice for alleviating the severe bradycardia associated with vasopressin and preventing it from progressing to cardiac arrest. We strongly recommend early cardiopulmonary resuscitation if atropine is not effective and the severe bradycardia deteriorates to <25 beats/min. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the article. The patients understands that their names and initials will not be published and due efforts will be made to conceal the identity of the patients, although anonymity cannot be guaranteed. Conflicts of interest None.