Changes in Myocardial Microstructure and Mechanics With Progressive Left Ventricular Pressure Overload

Area of Science:

• Cardiovascular physiology
• Cardiac mechanics
• Heart failure research

Background:

• Progressive left ventricular pressure overload (LVPO) leads to significant changes in heart structure and function.
• Understanding the mechanisms of myocardial stiffness is crucial for diagnosing and treating heart failure with preserved ejection fraction (HFpEF).

Purpose of the Study:

• To investigate regional changes in myocardial geometry, microstructure, and mechanical properties during progressive LVPO.
• To determine if early biomechanical function can predict later chamber stiffness and atrial changes.
• To explore the role of myocardial collagen in the development of HFpEF.

Main Methods:

• Utilized a large animal model to induce and study progressive LVPO.
• Employed an index of local biomechanical function to assess early-stage LVPO.
• Quantified myocardial collagen content and assessed left ventricular chamber stiffness (Kc) and left atrial area.

Main Results:

• Early assessment of local biomechanical function successfully predicted left ventricular chamber stiffness and left atrial area at later LVPO stages.
• Increased LV myocardial collagen content alone was insufficient to explain the mechanisms of myocardial stiffness progression in HFpEF.
• Regional biomechanical function demonstrated dynamic changes throughout the progression of LVPO.

Conclusions:

• Serial assessment of regional biomechanical function offers a potential method for monitoring HFpEF progression.
• This approach may aid in evaluating the efficacy of new therapeutic strategies for HFpEF.
• Myocardial stiffness in HFpEF is a complex process not solely attributable to collagen content.