Sudden death across brain and heart: cardio-cerebral ion channel dysfunction as a potential risk-modifying mechanism linking epilepsy and long QT syndrome

Figures

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  Figure 1. Conceptual framework of the cardio-cerebral channelopathy linking long QT syndrome (LQTS) and epilepsy/SUDEP. This schematic illustrates the profound phenotypic and genetic intersection between LQTS and epilepsy/sudden unexpected death in epilepsy (SUDEP), supporting the concept that shared ion channel dysfunction may contribute to neurocardiac vulnerability in a subset of patients. The left panel depicts typical cardiac manifestations of LQTS, including QT prolongation and Torsades de Pointes. The right panel shows neurological features of epilepsy/SUDEP, such as seizures, EEG slowing, and autonomic dysfunction. The overlapping region represents the core convergence characterized by clinical comorbidity and a shared molecular basis driven by pleiotropic genes (e.g., KCNH2, KCNQ1, SCN5A). Variants in these genes simultaneously disrupt electrophysiological homeostasis in both cardiomyocytes and neurons, highlighting the critical pathophysiological link between disorders traditionally categorized into distinct cardiac and neurological domains.

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  Figure 2. The two-hit pathophysiological model of sudden unexpected death in epilepsy (SUDEP). Latent genetic susceptibility in the form of shared cardio-cerebral ion-channel variants that cause subclinical LQTS or cardiac electrical instability constitutes the first hit. Postictal respiratory dysfunction, hypoxemia, hypercapnia, acidosis, sympathetic surge, and abnormal vagal activation are seizure-induced physiological stressors that act as the second hit by amplifying autonomic dysregulation and repolarization vulnerability. These interacting mechanisms may lead to QT prolongation, bradyarrhythmia or asystole, and terminal cardiorespiratory collapse. In susceptible individuals they may also trigger malignant ventricular arrhythmias such as torsades de pointes, albeit less frequently. MDR, mammalian diving reflex; SUDEP, sudden unexpected death in epilepsy; LQTS, long QT syndrome; TdP, torsades de pointes.