The term preload not part of dictionary of the Royal Spanish Academy (RAE) . The concept, however, is often used in the field of medicine with reference to the work that the heart .
It is known as preload to volume from blood which is responsible for distend the left ventricle of the organ before the contraction . This volume is the one that is recorded when the filling of the ventricle is completed.
The preload, therefore, is the Pressure which causes distention of the ventricle when filling is completed and the corresponding contraction is performed. In theory, the preload consists of first stretching of the cardiac muscle fiber : Since it is impossible to measure this at the time it occurs, certain estimates are appealed.
The pressure exerted by the blood when circulating through the organism , its greater or lesser speed to return and the blood volume affect the preload, which is also linked to the final diastolic volume of the ventricle (a larger volume will imply a greater preload). When physical activity is performed or blood volume is increased, the preload also increases.
On many occasions, medical professionals are in need of attending patients who arrive at the hospital having altered what is the preload, which is measured by what is known as Swan Ganz catheter.
In that sense, it is important that they be clear that there are a number of factors that allow the preload to be increased, compared to what would be the normal parameters. Specifically, three can be the main causes of these circumstances:
-That the person suffers from congestive heart failure.
-That there is a vasoconstriction. This can be caused by hypersermia, exogenous sympathetic stimulation or endogenous sympathetic stimulation.
-For what is called hypervolemia. This in turn is caused by two fundamentally circumstances: an oligoanuric renal failure or a volume overload.
On the other hand, we have to be clear that the preload can also be decreased. Why causes? For several, as we show below:
-The person in question has a tachycardia, which exceeds what are the 120 beats per minute.
-The individual is suffering what is called hypovolemia. This can be caused, in turn, by different factors such as diarrhea, hemorrhage, dehydration, abusive diuretic intake or even vomiting.
-A vasodilation. This may be related to several factors, the most common being a case of sepsis and even what is called anaphylaxis.
It can be said, in short, that the preload is responsible for distend the heart before its contraction occurs, from the pressure supported by the wall of the ventricle at the end of diastole. The preload is directly proportional to the radio and at the pressure; instead, it is inversely proportional to the thickness of the ventricular wall.
