Conversion of supraventricular tachycardia to normal sinus rhythm by dexmedetomidine treatment

Abstract

Cardiac dysrhythmias are an important cause of morbidity and mortality in the perioperative period, and they are more common after thoracic surgery and are most often supraventricular in origin [1]. Dexmedetomidine, a highly selective α-2 adrenoceptor agonist, is increasingly being used in anesthesia and critical care because it not only produces sedation and analgesia but also decreases sympathetic tone and attenuates stress responses to surgery leading to potential antiarrhythmic effects [2]. Here, we present a case of dexmedetomidine treatment of paroxysmal supraventricular tachycardia (PSVT) that occurred during thoracic surgery. A 72-year-old man, 168 cm tall and weighing 63 kg, was scheduled for right lower lobectomy suspicious of non-smallcell lung cancer. He has medical history of diabetes mellitus and hypertension for 10 years, which were both well controlled with medications. Preoperative electrocardiography (ECG) and chest radiography was unremarkable. Moreover, laboratory data were within normal limits. The patient was monitored with pulse oximetry, ECG, invasive radial arterial blood pressure, capnography, bispectral index (BIS), esophageal temperature probe. Induction of anesthesia was commenced with a slow (60 second) intravenous bolus dose of remifentanil (1 μg/kg), followed by propofol (1 mg/kg) tracheal intubation was facilitated with rocuronium (0.9 mg/kg). Anesthesia was maintained With O2 1.5 L/min, N2O 1.5 L/min and desflurane. Single-lung ventilation using a double-lumen endotracheal tube was the mode of anesthesia. After one-lung ventilation, arterial blood gas analysis showed normal findings. During retraction of the right lung apex, blood pressure abruptly decreased to 70/45 mmHg and heart rate increased to 185 beats/min. ECG findings showed PSVT. After notifying the surgeon, the surgery was stopped, and sinus rhythm and blood pressure returned to normal within 2030 seconds after carotid sinus massage. Right lower lobectomy was performed, and during lung retraction for hemostasis, PSVT accompanying a low blood pressure of 70/40 mmHg and high heart rate of 180-190 beats/min occurred again. The dopamine dose (5-10 μg/kg/min) was titrated to stabilize vital signs, and carotid sinus massage was performed to terminate the PSVT. However, the PSVT did not revert to normal sinus rhythm even after adenosine was administered using the standard two-stage protocol, i.e., 0.1 mg/kg (6 mg) followed by 0.2 mg/kg (12 mg). The PSVT disappeared temporarily and reappeared later. At that time, arterial blood gas analysis showed the following results: pH, 7.25; PaCO2, 53 mmHg; PaO2, 139 mmHg; Na + , 140 mEq/L;