Final answer:
Stroke volume is mainly determined by ventricular compliance, ventricular contractility, aortic or pulmonary artery pressure, and venous blood return. These factors are connected to the preload, afterload, and contractility, all of which influence the volume of blood the heart pumps with each beat.
Step-by-step explanation:
Stroke volume (SV) is determined by several factors that influence cardiac performance: ventricular contractility, ventricular compliance, the pressure in the aorta or pulmonary artery (afterload), and the volume of venous blood return. These determinants are closely related to the concepts of preload (the stretch on the ventricles prior to contraction influenced by venous return), afterload (the resistance ventricles need to overcome to eject blood), and myocardial contractility (the forcefulness of ventricular contraction).
Ventricular compliance, which may also be referred to as ventricular dispensability, affects the end-diastolic volume (EDV), contributing to the preload mechanism. Venous return plays a major role in setting this initial volume of blood in the ventricles, thus affecting SV indirectly by influencing EDV and thus preload. Contractility refers to the strength of the cardiac muscle's contraction and is determined largely by autonomic innervation and hormones. Aortic or pulmonary artery pressure reflects the afterload, as blood needs to be ejected against this pressure. When the afterload is increased, the heart must work harder to pump blood, which can affect the SV if ventricular contractility does not compensate adequately.