Correlation between sonographic morphology and function of the cervical vagus nerves

Area of Science:

• Cardiovascular physiology
• Autonomic nervous system research
• Medical imaging and diagnostics

Background:

• The heart's autonomic innervation involves both parasympathetic (vagal) and sympathetic inputs.
• The vagus nerve (VN) is the primary component of the parasympathetic nervous system influencing cardiac function.
• Morphological changes in the VN may reflect alterations in cardiac autonomic innervation.

Purpose of the Study:

• To investigate the correlation between morphological changes in cervical vagus nerves (VN) and autonomic cardiac innervation.
• To assess the relationship between vagus nerve cross-sectional area (CSA) and heart rate variability (HRV) parameters.
• To explore age-related changes in VN morphology and cardiac autonomic function.

Main Methods:

• High-resolution ultrasound (HRUS) was used to measure the cross-sectional area (CSA) of the cervical vagus nerves (VN).
• Heart rate variability (HRV) was measured to assess autonomic cardiac innervation.
• Data were collected from 88 healthy subjects, with analysis considering age and sex.

Main Results:

• Both HRV parameters and VN CSA showed an inverse correlation with age.
• An inverse correlation was observed between the left VN CSA and HRV, including parasympathetic parameters.
• These findings suggest potential differences in vagal innervation between the left and right sides of the heart.

Conclusions:

• Morphological characteristics of the vagus nerve, assessed via HRUS, correlate with autonomic cardiac innervation.
• Age-related decline in both VN size and cardiac autonomic function is indicated.
• The study implies an asymmetric parasympathetic (vagal) innervation of the heart, with the left VN potentially playing a more significant role.