Cardiac Sympathetic Nerve Activity Is Not Elevated in Ovine Hypertensive HFpEF

Area of Science:

• Cardiology
• Exercise Physiology
• Autonomic Nervous System

Background:

• Heart failure with preserved ejection fraction (HFpEF) is characterized by exercise intolerance.
• The role of sympathetic nervous system activity in HFpEF pathophysiology remains unclear.
• Evidence for heightened cardiac sympathetic nerve activity (CSNA) in HFpEF is lacking, potentially explaining the limited benefit of beta-blockers.

Purpose of the Study:

• To test the hypothesis that resting CSNA is not elevated in HFpEF.
• To investigate the impact of beta-blockers on exercise hemodynamics in HFpEF.

Main Methods:

• Utilized a conscious large animal (ovine) model of hypertensive HFpEF.
• Performed direct recordings of CSNA at rest.
• Assessed hemodynamic responses to graded treadmill exercise before and after beta-blocker administration.

Main Results:

• Resting CSNA levels were not elevated in the HFpEF ovine model.
• Beta-blocker administration impaired exercise hemodynamics, including cardiac output, heart rate, and pulmonary capillary wedge pressure, in HFpEF sheep.
• Differential exercise hemodynamic responses to beta-blockers were observed between HFpEF and non-HFpEF sheep.

Conclusions:

• CSNA is not elevated in this ovine model of hypertensive HFpEF.
• Favorable exercise hemodynamics in HFpEF appear to depend on beta-adrenergic activation.
• Findings suggest beta-blockers may be detrimental and should be avoided in HFpEF patients.