[Asystole during electroconvulsive therapy in a patient with depression and myasthenia gravis]

A 44-yr-old woman presented with major depression. She was scheduled to receive electroconvulsive therapy under anesthetic care because of drug-induced leukopenia. Her significant past medical history was myasthenia gravis. She had been treated with thymectomy and pyridostigmine. She showed no evidence of muscle weakness while receiving the medication. After preanesthetic assessment, pyridostigmine was continued and routine anesthetics were chosen. Under 100% oxygen inhalation, thiamylal and suxamethonium were administered intravenously. Alternate current was delivered for 5 seconds, which induced seizure satisfactorily. However, asystole lasted for 10 seconds during the procedure. Spontaneous beating appeared followed by tachycardia and bigemina. Normal sinus rhythm returned four minutes later. She recovered smoothly, and showed no evidence of confusion nor muscle weakness. We speculated that pyridostigmine potentiated the ECT-induced vagal reflex and provoked asystole. In the following session, we pretreated her with intravenous atropine prior to thiamylal and suxamethonium. Although the current delivery increased RR-interval up to 1.2 seconds, neither asystole nor serious tachyarrhythmia occurred. Seven sessions of ECT relieved her psychiatric symptoms uneventfully. We presented a case of depression for which ECT was applied. Asystole with ECT seems associated with administration of pyridostigmine for the treatment of myasthenia gravis. Pretreatment with atropine can prevent asystole without inducing hazardous tachyarrhythmia.