Heart Rhythm Harmony Becomes Discordant as We Age

Area of Science:

• Cardiology
• Physiology
• Biophysics

Background:

• Heartbeats originate from sinoatrial node (SAN) pacemaker cells, driven by an intrinsic coupled-clock system (CCS).
• This CCS maintains a dynamic equilibrium, influenced by autonomic input, generating rhythmic electrical activity known as "heartbeat music" or the "Heart-Brain Grand Symphony" (HBGS).
• Heartbeat rhythms are observable via electrocardiogram (EKG) RR-interval variability.

Purpose of the Study:

• To explore the relationship between aging, SAN function, and the emergence of cardiac disease.
• To elucidate how age-associated physiological changes contribute to cardiac pathologies.

Main Methods:

• Conceptual analysis of the coupled-clock system (CCS) in sinoatrial node (SAN) pacemaker cells.
• Examination of age-related alterations in neuroautonomic regulation and cardiac networks.
• Correlation of subclinical SAN changes with clinical cardiac diseases.

Main Results:

• Aging leads to the deterioration of physiological coupling within the SAN and atrial networks.
• This deterioration results in "cacophony" within the HBGS, characterized by reduced firing rates and rhythms of SAN cells.
• Subclinical age-associated changes in SAN structure and function act as co-morbidities for clinical cardiac diseases like Sick Sinus Syndrome and atrial fibrillation.

Conclusions:

• Age-associated decline in SAN structure and function is a primary driver of cardiac disease.
• These intrinsic aging processes are significant contributors to the development and progression of cardiovascular conditions.
• Understanding these age-related changes is crucial for managing and preventing heart diseases.