Heart Failure-Specific Relationship Between Muscle Sympathetic Nerve Activity and Aortic Wave Reflection

Area of Science:

• Cardiovascular Physiology
• Neurovascular Coupling
• Heart Failure Pathophysiology

Background:

• Arterial wave reflections augment left ventricular (LV) afterload.
• Patients with heart failure and reduced ejection fraction (HFrEF) are sensitive to afterload and exhibit sympathetic activation.
• The relationship between sympathetic vasoconstrictor discharge and aortic wave reflection in HFrEF is not well understood.

Purpose of the Study:

• To test the hypothesis that HFrEF patients exhibit a positive relationship between sympathetic vasoconstrictor discharge and aortic wave reflection.
• To investigate the role of neurovascular coupling in HFrEF pathophysiology.

Main Methods:

• Noninvasive measurements of radial pulse waveforms to assess central blood pressures and aortic wave reflection characteristics (augmentation pressure, augmentation index).
• Microneurography to record muscle sympathetic nerve activity (MSNA) burst frequency.
• Comparison between 16 HFrEF patients and 16 age-matched healthy controls.

Main Results:

• HFrEF patients demonstrated higher augmentation index and MSNA burst frequency compared to controls.
• Muscle sympathetic nerve activity (MSNA) showed a positive correlation with augmentation pressure and augmentation index in HFrEF patients.
• No significant correlation was found between MSNA and wave reflection indices in healthy control subjects.

Conclusions:

• A positive correlation exists between aortic wave reflection indices and MSNA in HFrEF patients, but not in healthy controls.
• This neurovascular coupling may increase LV afterload, potentially impairing LV performance and exacerbating heart failure.
• Therapies targeting neurogenic vasoconstriction may offer benefits for HFrEF patients by reducing arterial wave reflection.