Preload

As a preload (engl .: preload ) in which is Cardiology the force indicated, which to stretch the fibers of the heart chambers (ventricles) at the end of diastole leads and the rest by the maximum length of the muscle fibers is limited.

When the venous filling pressure increases (increase in preload), the ventricles of the heart are filled more diastolically and the muscles are stretched more, which leads to an intensification of the contraction with an increase in the stroke volume ( Frank-Starling mechanism ).

In practice, the preload is referred to as the end-diastolic volume or (less precisely) the end-diastolic pressure in the heart . To simplify matters, the volume can be replaced by the pressure to determine the preload, but this does not lead to exact measurements in all situations (e.g. non-elastic or stiff ventricle walls).

In diseases such as systolic heart failure , the preload is increased due to the increased end-diastolic volume and filling pressure. As a result, edema develops , which - in the case of pulmonary edema - leads to shortness of breath . The same applies to reduced elasticity of the ventricles (diastolic heart failure): If the ventricle becomes stiffer, the diastolic filling deteriorates , which leads to venous blood back pressure. The preload can e.g. B. can be lowered by ACE inhibitors , diuretics or nitrates such as nitroglycerin .

See also

• Afterload
• Frank Starling Mechanism

literature

• Huppelsberg Walter: Short textbook physiology. Thieme, Stuttgart; 2nd edition 2005. ISBN 978-3-13-136432-6