Circadian rhythm of cardiac electrophysiology, arrhythmogenesis, and the underlying mechanisms

Area of Science:

• Cardiology
• Chronobiology
• Molecular Biology

Background:

• Cardiac arrhythmias are a primary cause of cardiovascular mortality.
• Life-threatening arrhythmias like ventricular tachycardia and fibrillation are often observed in the morning.
• A circadian rhythm influences cardiac pacemaking and electrophysiological properties.

Purpose of the Study:

• To review the current understanding of circadian rhythms in cardiac electrophysiology.
• To explore the mechanisms underlying circadian variations in arrhythmogenesis.
• To summarize the molecular basis of these daily rhythms in the heart.

Main Methods:

• Literature review of studies on circadian rhythms and cardiac arrhythmias.
• Analysis of proposed mechanisms involving central and local cardiac clocks.
• Examination of neurohumoral and molecular factors influencing cardiac electrophysiology.

Main Results:

• Circadian rhythms affect various arrhythmias, including bradyarrhythmias and supraventricular arrhythmias.
• Two primary mechanisms are proposed: central circadian clock influence via neurohumoral factors and local cardiac clocks regulating ion channel expression.
• These rhythms contribute to variations in the cardiac arrhythmic substrate.

Conclusions:

• Daily rhythms significantly impact cardiac electrophysiology and arrhythmia susceptibility.
• Both central neural pathways and intrinsic cardiac clocks play roles in circadian regulation of heart function.
• Understanding these mechanisms is crucial for managing cardiac arrhythmias.