Afterload mismatch and preload reserve: a conceptual framework for the analysis of ventricular function

Area of Science:

• Cardiology
• Physiology

Background:

• Left ventricular ejection characteristics depend on the interplay between afterload, inotropic state, and preload reserve.
• Afterload mismatch can impair cardiac function, especially when preload reserve is limited.
• Ejection phase indices are generally stable in normal hearts under basal and adapted conditions.

Purpose of the Study:

• To evaluate the utility of a two-dimensional framework for analyzing left ventricular ejection.
• To investigate the relationship between afterload, inotropic state, and preload reserve in cardiac function.
• To justify the use of ejection phase indices for detecting depressed inotropic states.

Main Methods:

• Utilizing a two-dimensional framework to analyze left ventricular ejection characteristics.
• Inducing acute afterload mismatch under controlled conditions.
• Assessing ejection phase indices like ejection fraction and mean velocity of circumferential fiber shortening (VCF).

Main Results:

• Ejection phase indices remain within a narrow range under basal conditions in normal hearts.
• These indices show limited change even after adaptation to chronic overload.
• Reduced inotropic state leads to evident afterload mismatch and reduced mean VCF, detectable even at baseline.

Conclusions:

• Ejection phase indices are reliable for assessing the basal inotropic state due to their sensitivity to afterload.
• The framework of afterload mismatch with limited preload reserve explains the value of ejection phase indices.
• This framework aids in understanding the implications of therapeutic afterload reduction.