From the Guidelines
The Frank-Starling curve is a fundamental concept in physiology that describes the relationship between the stroke volume of the heart and the end-diastolic volume, where an increase in end-diastolic volume leads to an increase in stroke volume [ 1 ].
Key Points
- The Frank-Starling mechanism is a key factor in increasing cardiac output during exercise, particularly at moderate to high intensities [ 1 ].
- It operates by increasing the end-diastolic volume, allowing the heart to pump more blood with each beat [ 1 ].
- The Frank-Starling curve is also relevant in pathological conditions, such as acute pulmonary embolism, where it plays a role in the right ventricular failure due to acute pressure overload [ 1 ].
- The mechanism is mediated by an increase in wall tension and myocyte stretch, leading to an increase in contractile force and stroke volume [ 1 ].
Clinical Relevance
The Frank-Starling curve has important implications for clinical practice, particularly in the management of patients with heart failure or other conditions that affect cardiac function. Understanding the relationship between end-diastolic volume and stroke volume can help guide treatment decisions and optimize patient outcomes.
Pathophysiological Mechanisms
The Frank-Starling mechanism is a complex process that involves multiple physiological and pathological mechanisms, including changes in preload, afterload, and contractility [ 1 ]. In summary, the Frank-Starling curve is a critical concept in physiology that describes the relationship between end-diastolic volume and stroke volume, and has important implications for clinical practice and our understanding of pathological conditions.
From the Research
Definition of the Frank-Starling Curve
- The Frank-Starling curve is a fundamental concept in cardiovascular physiology that relates change in cardiac filling to its output 2.
- It describes the relationship between the distension of a ventricular chamber and its force of ejection, where an increase in preload (ventricular filling) leads to an increased cellular force and an increased volume of ejected blood 3.
Mechanism and Significance
- The Frank-Starling mechanism is a regulatory property that underlies the cardiac output adaptation to venous filling, and length-dependent activation is generally assumed to be its cellular origin 3.
- The mechanism plays a crucial role in adapting left to right ventricular output, and its functional importance lies mainly in enhancing stroke volume during upright physical exercise 4.
- The Frank-Starling mechanism is maintained in end-stage failing human hearts, although significant alterations of diastolic myocardial distensibility are evident in chronic heart failure 5.
Roles and Functions
- The Frank-Starling mechanism has three different and complementary roles: (1) it decreases the demands of a central controlling system over the circulatory system; (2) it smooths out perturbations in volumes; and (3) it guarantees faster transitions between operation points, allowing for rapid changes in cardiac output 6.
- The mechanism is not necessary to give stability to an operation point, but it plays a stabilizing role for short-term variations in the working of the cardiovascular system 6.
Measurement and Assessment
- The Frank-Starling relationship can be measured by relating right atrial pressure (P ra) to stroke volume (SV), and a wearable Doppler ultrasound can infer the P ra-SV relationship by simultaneously capturing jugular venous and carotid arterial Doppler in real time 2.
- Provocative maneuvers such as the passive leg raise (PLR) can be used to identify "fluid non-responders", and simultaneous assessment of venous filling and arterial output can help interpret and compare these maneuvers 2.