Computationally managed bradycardia improved cardiac energetics while restoring normal hemodynamics in heart failure

Area of Science:

• Cardiovascular Physiology
• Heart Failure Pathophysiology
• Medical Device Engineering

Background:

• Acute heart failure necessitates control of arterial pressure (AP), cardiac output (CO), and left atrial pressure (P(LA)).
• Improving cardiac energetic efficiency is crucial for managing heart failure.
• Theoretical models suggest reduced heart rate (HR) can enhance efficiency if left ventricular (LV) function is optimized.

Purpose of the Study:

• To investigate if computationally managed bradycardia can improve cardiac energetic efficiency in acute heart failure.
• To assess the feasibility of using an automated hemodynamic regulator to achieve this state.

Main Methods:

• An automated hemodynamic regulator was used in seven anesthetized dogs with induced acute heart failure.
• The regulator controlled LV Starling's curve slope (S(L)) with dobutamine, systemic vascular resistance with nitroprusside, and stressed blood volume with dextran/furosemide.
• Zatebradine was administered to induce bradycardia, and hemodynamic parameters were monitored.

Main Results:

• Normal hemodynamic conditions (AP, CO, P(LA)) were restored and maintained despite a significant HR reduction (-27%).
• Left ventricular end-systolic elastance (E(es)) increased (+34%), indicating improved contractility.
• LV mechanical efficiency increased (+22%), and myocardial oxygen consumption (MVO2) decreased significantly (-17%).

Conclusions:

• Computationally managed bradycardia is a viable strategy to improve cardiac energetic efficiency in acute heart failure.
• This approach successfully restored hemodynamic stability while reducing myocardial oxygen demand.
• The developed automated hemodynamic regulator effectively managed complex cardiovascular interactions.