On the case of a patient who had medical care on account of a febrile disease diagnosed as pleuritis the authors draw attention to a relatively new pathological unit described as the „Bruga- da syndrome“. It is a genetically conditioned anomaly of sodium channels, which, when fully expressed, is manifested by a picture resembling right bundle branch block, elevation of ST segment in leads V1 - V3 and the occurrence of malignant ventricular arrhythmias or sudden death without structural heart disease. Neither the reported patient nor his family suffered from arrhythmias. The authors present however a typical electrocardiographic picture ad positive test with ajmaline, a substance which by blocking sodium channels can frequently induce latent and variable changes.

        Key words: Brugada syndrome - Sudden death - Right bundle branch block - Segment elevation