Cardiovascular autonomic reflex tests: normal responses and age-related reference values.

Area of Science:

• Cardiology
• Autonomic Nervous System Physiology

Background:

• Cardiovascular autonomic function is crucial for maintaining homeostasis.
• Age-related changes can impact autonomic nervous system (ANS) responses.
• Establishing normal reference values is essential for clinical assessment.

Purpose of the Study:

• To investigate normal cardiovascular autonomic function responses.
• To determine age-related reference values for autonomic function tests.
• To assess the influence of age and sex on cardiovascular autonomic indices.

Main Methods:

• Recruited 143 healthy, unmedicated subjects aged 20-80 years.
• Performed cardiovascular autonomic function tests: Valsalva maneuver, deep/quiet breathing, and active orthostatic test.
• Analyzed heart rate and blood pressure responses.

Main Results:

• Most cardiovascular indices reflecting heart rate responses decline with age.
• Indices are generally sex-independent but influenced by resting heart rate.
• Wide inter-individual variations observed, with lower reference values less suitable for older adults.
• Reproducibility is satisfactory for heart rate indices but poor for blood pressure indices.

Conclusions:

• Age-specific reference values are necessary for accurate interpretation of cardiovascular autonomic function tests.
• These values facilitate diagnosis in younger/middle-aged adults and exclusion of autonomic disorders in older adults.
• Heart rate indices show better reproducibility than blood pressure indices.