Ventricular Function

Ventricular function describes how well the ventricles fill and empty - their performance as pressure-generating, blood-ejecting chambers. It is conventionally split into systolic function (the strength and completeness of ejection) and diastolic function (the ability to relax and fill at low pressure), and is summarised graphically by the ventricular function curve and the pressure-volume loop.

Definition

Ventricular function is the capacity of a cardiac ventricle to fill during diastole and eject blood during systole, characterised by systolic indices such as ejection fraction and by diastolic filling properties.

Scope

The topic covers the chamber-level mechanics of the ventricle: the cardiac cycle, the pressure-volume loop, the determinants of systolic and diastolic performance, and the common indices used to quantify them such as ejection fraction and strain. It builds on cellular contraction and feeds into measures of cardiac output, which are treated in their own topics.

Core questions

• What distinguishes systolic from diastolic ventricular function?
• How does the pressure-volume loop summarise a single cardiac cycle?
• What is ejection fraction and what does it indicate?
• How do preload, afterload, and contractility shape ventricular performance?
• How are newer indices such as myocardial strain used to assess function?

Key concepts

• Systolic versus diastolic function
• Pressure-volume loop
• Ejection fraction
• End-systolic pressure-volume relationship (contractility)
• Preload and afterload
• Myocardial strain and speckle-tracking imaging

Key theories

Frank-Starling mechanism and ventricular function curves

Ventricular performance depends on filling: plotting stroke work or output against end-diastolic volume yields a function curve that shifts upward with increased contractility and downward with depressed contractility, the relationship Sarnoff used to describe contractility.

Mechanisms

Over a single cardiac cycle the ventricle traces a pressure-volume loop: isovolumic contraction, ejection, isovolumic relaxation, and filling. Systolic function reflects how completely and forcefully the chamber empties and is influenced by contractility, preload, and afterload, with the Frank-Starling relationship - mapped by Sarnoff's ventricular function curves - linking filling to stroke work. Diastolic function reflects the chamber's ability to relax and fill at low pressure. Ejection fraction, the fraction of end-diastolic volume ejected, is the most widely used summary index, while strain imaging standardised by the EACVI/ASE task force (Voigt) quantifies regional myocardial deformation that may change before ejection fraction does.

Clinical relevance

Ejection fraction is used to classify heart failure and is associated with cardiovascular outcomes across a broad spectrum of patients, as shown by Solomon and colleagues, and strain imaging extends functional assessment to subtle dysfunction. This entry describes the physiology and the meaning of these indices for reference and is not a basis for individual diagnosis or treatment decisions.

Evidence & guidelines

Systolic-diastolic concepts and the function curve come from classic physiology (Sarnoff) and textbooks; the prognostic meaning of ejection fraction is supported by large cohort analyses (Solomon, 2005); and strain assessment follows the EACVI/ASE consensus on deformation imaging (Voigt, 2014).

History

Ventricular function curves grew out of the Frank-Starling tradition and were formalised by Sarnoff in the 1950s. The pressure-volume framework and the end-systolic pressure-volume relationship as a load-independent index of contractility were developed by Suga and Sagawa in the 1970s. More recently, imaging-based indices such as ejection fraction and myocardial strain have become the practical language of ventricular assessment.

Debates

Is ejection fraction an adequate measure of ventricular function?

Ejection fraction is load-dependent and can appear normal despite impaired contractility or significant diastolic dysfunction, motivating complementary measures such as strain; how much weight to place on ejection fraction versus newer indices remains an active methodological discussion.

Key figures

• Ernest Starling
• Stanley Sarnoff
• Hiroyuki Suga
• Kiichi Sagawa

Seminal works

• sarnoff-1955
• solomon-2005
• voigt-2014

Frequently asked questions

What is ejection fraction?

Ejection fraction is the proportion of the blood in the ventricle at the end of filling that is pumped out with each beat, calculated as stroke volume divided by end-diastolic volume. It is the most common summary index of systolic ventricular function.

What is the difference between systolic and diastolic dysfunction?

Systolic dysfunction is impaired emptying - the ventricle contracts and ejects less forcefully. Diastolic dysfunction is impaired filling - the ventricle is stiff or relaxes poorly, so it fills only at higher pressures even when its emptying is preserved.