In cardiovascular physiology

Cardiovascular physiology

Cardiovascular physiology is the study of the circulatory system. More specifically, it addresses the physiology of the heart and blood vessels ....

, end-diastolic volume (EDV) is the volume of blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 in the right and/or left ventricle at end Load

Load

Load may refer to:*Structural load, forces which are applied to a structure*Cargo*The load of a mutual fund *The genetic load of a population*The parasite load of an organism...

 or filling in (diastole

Diastole

Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...

). Because greater EDVs cause greater distention of the ventricle, EDV is often used synonymously with preload, which refers to the length of the sarcomere

Sarcomere

A sarcomere is the basic unit of a muscle. Muscles are composed of tubular muscle cells . Muscle cells are composed of tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as dark and light bands...

s in cardiac muscle

Cardiac muscle

Cardiac muscle is a type of involuntary striated muscle found in the walls and histologic foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle...

 prior to contraction (systole

Systole (medicine)

Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...

). An increase in EDV increases the preload on the heart and, through the Frank-Starling mechanism of the heart, increases the amount of blood ejected from the ventricle during systole (stroke volume

Stroke volume

In cardiovascular physiology, stroke volume is the volume of blood pumped from one ventricle of the heart with each beat. SV is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood in the ventricle at the end of a beat from the volume...

).

Parameters affecting EDV

Because nearly two-thirds of the blood in the systemic circulation

Systemic circulation

Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey...

 is stored in the venous system, end-diastolic volume is closely related to venous compliance.

• Increasing venous compliance elevates the capacitance
  Capacitance
  In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
  
   of the veins, reducing venous return and therefore end-diastolic volume.

• Decreasing venous compliance has the opposite effect. For example, activation of the baroreceptor reflex (occurring, for instance, in acute hemorrhage) causes vasoconstriction
  Vasoconstriction
  Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
  
  , which decreases venous compliance, improves venous return, and therefore increases end-diastolic volume.

Sample values

The values below are for the left ventricle:
The right ventricular end-diastolic volume (RVEDV) ranges between 100 and 160 mL. The right ventricular end-diastolic volume index (RVEDVI) is calculated by RVEDV/BSA

Body surface area

In physiology and medicine, the body surface area is the measured or calculated surface of a human body. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass...

and ranges between 60 and 100 mL/m².