THE AUTHORS TREATED a 14-year-old girl with posthemorrhagic hydrocephalus and an infected ventriculopleural shunt. She was taken for endoscopic third ventriculostomy with the hope of removing the hardware entirely, but she developed an arrhythmia and hypertension, followed rapidly by complete cardiac arrest. She was resuscitated successfully, made a complete recovery, and subsequently underwent a conventional shunt replacement. This is a newly reported life-threatening complication of neuroendoscopy that must be anticipated by any surgeon undertaking such a procedure.