Electrophysiological Changes in Simulated Atrial Sheets Due to Sympathetic Hyperactivity

The electrophysiological changes in the atria due to sympathetic hyperactivity during episodes of psychological distress are unclear. We simulated sympathetic hyperactivity by rapidly pacing atrial sheets with increasing adrenergic stimulation (AS) spatial densities. We measured changes to the electrophysiological parameters of atrial sheets, such as captured waves (CW), conduction speed (CS), slope of depolarization (SoD), isolated conduction channels (ICC), and wavefront ratio (WFR), using videos and action potential signals. The number of CWs could be limited by as much as 90% in atrial sheets with 50% AS elements, indicating a physiological block. While CS is maintained, SoD for atrial sheets with 15% AS elements is 20% faster than plain atrial sheets. ICCs appear in atrial sheets with ≥15% AS spatial densities. ICCs temporally vary by as much as 60% in atrial sheets with 20% AS elements. WFR decreases by as much as 40% due to minimal ICCs. We found significant differences for each parameter across AS spatial densities via Kruskal-Wallis test (p ≤ 0.001). Our findings may provide a potential electrophysiological basis for atrial arrhythmias due to psychological distress.