People with epilepsy die unexpectedly for unknown pathological reasons at a rate 24 times greater than the general population. Such deaths are classified as sudden unexplained death in epilepsy (SUDEP). The etiology of the SUDEP is frequently unclear which prevents the development of a rational treatment of this problem. Mice lacking Kv1.1 Shaker-like potassium channels encoded by the Kcna1 gene exhibit severe seizures and die prematurely. In this article the authors postulated that Kv1.1-potassium deficiency may underlie primary neurogenic cardiac dysfunction and cause SUDEP. EEG–ECG recordings showed that Kcna1-null mice display atrioventricular (AV) conduction blocks, as well as bradycardia and premature ventricular contractions. During seizures the occurrence of AV conduction blocks increased, which might cause SUDEP. Then the authors used atropine and propranolol to block the autonomic nervous system and found that atropine ameliorated AV conduction block indicating excessive parasympathetic tone may cause a neurocardiac defect. There were no changes in Kv1.1-deficient cardiac structure, but extensive Kv1.1 expression in juxtaparanodes of the wild-type vagus nerve, the primary source of parasympathetic input to the heart. The authors concluded that Kv1.1 deficiency leads to impaired neural control of cardiac rhythmicity due in part to aberrant parasympathetic neurotransmission, making Kcna1 a strong candidate gene for causing human SUDEP.